# Battery query.



## Obanboy666 (Dec 16, 2016)

Not being at all knowledgeable with electrics can anyone advise on the following.
Friend has a 6 month old Lucas leisure battery surplus to his requirements that I can have foc -

12V 86 AH Lucas Leisure Battery LX24MF - Alpha Batteries

I got to thinking and wondered if I could use it in my PVC which only has a basic Sargent EC155 control unit and charger which is only rated at 155 watt / 12 amp, it also state a maximum battery size of 120 amp. I have a 110 amp battery at present so cannot add another 110 amp battery. It would give me an additional 40 amps of usable power and as I tend to wild 2/3 nights then on ehu for a night I could recharge it with my Ctek before wilding again.
Would it be safe to locate it in a wardrobe, secured in a suitable battery box and use it to power my tv and charge iPads, phones etc ? Obviously it wouldn't be charged from the onboard charger or vehicle when driving.
Would it be a simple job to wire the battery up to a 12 volt socket ? Would I need a fuse on the positive cable to the socket ?
Any advise would be much appreciated.


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## 1 Cup (Dec 16, 2016)

*foc thats good*

Should have matching ah.  86-110 not a good balance. Free battery exspencive electrical upgrade to your system. 

You can use it,  as a trip hazard! 

.multi test and see the voltage?
 Like you said it's extra stored power.

86 amp hour is a starter unit or a stop gap, not a upgrade.


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## Obanboy666 (Dec 16, 2016)

band driver said:


> Should have matching ah.  86-110 not a good balance. Free battery exspencive electrical upgrade to your system.
> 
> You can use it,  as a trip hazard!
> 
> ...



Shouldn't need to be 110 amp as completely separate to present battery.
No trip hazard as would be in wardrobe with no cables outside of wardrobe even when i charge it with my Ctek as i have a 240v socket in the wardrobe.
i was mainly concerned about whether i needed to vent it as that would be a problem if its in the wardrobe. its a sealed battery, does that mean venting not required ?
Wouldn't have thought there would be much cost involved, battery box, cable, fuse and a 12 volt socket.
No upgrade to present electrical system as would be seperate.


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## maingate (Dec 16, 2016)

I was accused the other day of talking utter bollocks and knowing nowt about batteries ..... but I see no problem with what you suggest ...... apart from one thing.

If the battery is a sealed type then it should be OK in a wardrobe. If it is not, then you may need to find a better place for it. Sealed batteries often have vent holes where a plastic tube is fitted and the tube is vented to the outside of the vehicle. Check each end of the battery top to see if there are any small holes (about 6 mm diameter)


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## Deleted member 9849 (Dec 16, 2016)

I can't see a problem in putting the battery in a proper box in the wardrobe and wiring up a 12v socket providing it is vented to the outside as Jim said.It is desirable to have 2 matching batteries of the same capacity and age but this doesn't apply in this case as they will not be wired together.

My question is- do you really need an extra battery eating into the payload and storage space if you have managed with the existing 12v system.If you have wild camped for a few days and then gone on to a site to recharge the leisure battery it sounds like you have managed perfectly well with one leisure battery.


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## harrow (Dec 16, 2016)

Recharge the new spare battery with you ctek charger when at home or on electric hook up, and make sure it is strapped or fixed down when the van is moving, if possible keep it in a plastic storage box.

There are lots of other permutations of what you could do but that is it in its simplest form. :ninja:

Oh always a good idea to have a fuse in the output


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## Byronic (Dec 16, 2016)

If the battery is not going to be charged in the van then gassing is unlikely to occur in the van. I wouldn't confine it by boxing it in, unless properly vented to the exterior of course. I'd just leave the wardrobe door slightly ajar to circulate a bit of air to be on the safe side, and protect the battery terminals, you don't want a steel coat hanger shortcircuit!


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## st3v3 (Dec 16, 2016)

maingate said:


> I was accused the other day of talking utter bollocks and knowing nowt about batteries ..... but I see no problem with what you suggest ...... apart from one thing.
> 
> If the battery is a sealed type then it should be OK in a wardrobe. If it is not, then you may need to find a better place for it. Sealed batteries often have vent holes where a plastic tube is fitted and the tube is vented to the outside of the vehicle. Check each end of the battery top to see if there are any small holes (about 6 mm diameter)



This time you're quite right though.

Oban, yes you need a fuse as close to the battery as possible.


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## Obanboy666 (Dec 17, 2016)

Spoke to Sargent technical support late afternoon about fitting an additional 110 amp battery and the manual stating no more than a 120 amp battery with the EC155 control / charger unit.

He said it would be ok but obviously the charge time to restore depleted charge  to 220 amps of battery versus 120 amps would be longer. He assured me the charger would be ok and it would not be detrimental to the charger unit.
I have decided to not bother with my friends foc battery and fit an additional 110 amp battery to match my existing battery.
A couple of questions  - 
The additional battery will be located approximately 4 feet from the first battery, what size cable should I use ?

Would this type of fuse on the positive be ok on the positive cable MIDI fuse holder ALT FH560 and what size fuse should I use ?

I will run the cables in plastic conduit to give the cable some protection from possible damage from the bodywork etc and house the battery in an appropriate battery box. 
The original battery has no vent outlets as it's a sealed maintenance free type so the new battery being the same will not be vented.


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## Deleted member 775 (Dec 17, 2016)

if the offer is still there for you and assuming it a good one ,you say six months old should be ok if it hasent gone flat that is ,grab it as a spare battery is always handy ,even kept topped up at home in the garage or even shed for emergencies .i always keep a spare fully charged battery in the garage just in case .


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## Obanboy666 (Dec 17, 2016)

mandrake said:


> if the offer is still there for you and assuming it a good one ,you say six months old should be ok if it hasent gone flat that is ,grab it as a spare battery is always handy ,even kept topped up at home in the garage or even shed for emergencies .i always keep a spare fully charged battery in the garage just in case .



Yes, still going to have it. As you say it will be handy.


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## Auld Pharrrt (Dec 17, 2016)

As mentioned above two POSSIBLE difficulties ... venting (if required) charging.

Venting  ... and this is just my idea ... get a smallish plastic bottle (milk carton?) and neatly drill a hole in the lid for vent tube to fit tightly.  Squeeze bottle and tighten lid ... emergency vent!

Charging. Assuming your charger that keeps your 110ah battery charged doesn't need to be in constant use, and as you have mentioned you aren't that knowledgeable on electrics, get a friend or electrician to wire a switch (double pole single throw - DPST) to swap the charger from one battery to the other.


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## Obanboy666 (Dec 17, 2016)

Obanboy666 said:


> Spoke to Sargent technical support late afternoon about fitting an additional 110 amp battery and the manual stating no more than a 120 amp battery with the EC155 control / charger unit.
> 
> He said it would be ok but obviously the charge time to restore depleted charge  to 220 amps of battery versus 120 amps would be longer. He assured me the charger would be ok and it would not be detrimental to the charger unit.
> I have decided to not bother with my friends foc battery and fit an additional 110 amp battery to match my existing battery.
> ...



Bump


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## wildebus (Dec 17, 2016)

Obanboy666 said:


> Spoke to Sargent technical support late afternoon about fitting an additional 110 amp battery and the manual stating no more than a 120 amp battery with the EC155 control / charger unit.
> 
> He said it would be ok but obviously the charge time to restore depleted charge  to 220 amps of battery versus 120 amps would be longer. He assured me the charger would be ok and it would not be detrimental to the charger unit.
> I have decided to not bother with my friends foc battery and fit an additional 110 amp battery to match my existing battery.
> ...



Hi,
I actually have an installation very similar to the one you are proposing and this is what I have (and did)

Sargent EC155 
2 x 100AH AGM Batteries (Xplorer, from Alpha, not that that matters)
First Battery is directly behind the EC155
Second Battery is approximately 6 feet away from first
First Battery is fused using the kind of fuse holder you linked to on the postive side (I say first battery as it is fused on the connection from this Battery to the electrical systems)
Second Battery is fused with one of those holder, but this is the key thing ... the fuse is on the NEGATIVE side, and NOT positive, and I have NO Fuses on the cables between the two batteries.  The Negative of the second battery is connected to chassis ground (via the fuseholder) and the Negative of the first battery ONLY goes to the second battery, and NOT to ground (this is important and it means you will need to rework your current setup a little.  It is usually a lot more easy to rework  battery ground then a battery +12V connection which is why I suggest doing it this way)
I used 10mm cable (rated for 71A) for the +ve and -ve connections between the two banks and of the tp of my head memory used either 50A or 60A strip fuses in the fuseholders. to me 70A rated cable is fine as the maximum ever possible draw I could even have would be under 60A (Inverter at full whack plus fridge kicking in, and TV on and Eber Heater on - and the chance of that is so remote it doesn't really matter thinking about it.

Doing the wiring as above will make the battery bank fully balanced in draw and charge, and also offer the best all-round protection against shorting.


FWIW, after I did some battery use testing, I didn't rely on the Sargent charger to refill the batteries for the reason the you got from Sargent Tech Support and plugged in my CTEK smart charger to each battery in turn before reconnecting them.  Never had a reason to do that since and the charger, on the occasion I do use it (rarely as the Solar takes care of things generally) it has done the job fine.


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## trevskoda (Dec 17, 2016)

Just use battery starter cable which you can buy at motor shop to join up,if you ex les battery is grounded then you only require a red to red + connection and a earth strap on neg,if you wish a block fuse can be added,as for venting its always a good idea but the is no vents on my bus from new and service battery lives in front passenger foot well.


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## wildebus (Dec 17, 2016)

trevskoda said:


> Just use battery starter cable which you can buy at motor shop to join up,if you ex les battery is grounded then you only require a red to red + connection and a earth strap on neg,if you wish a block fuse can be added,as for venting its always a good idea but the is no vents on my bus from new and service battery lives in front passenger foot well.


Expensive way to do it ... £15+ worth of cable just for positive and you will end up with an unbalanced battery bank and not get the most out of it.

Yes, this would work, but is not the best way and may as well do it right if going to the expense of buying a new battery as closely matched as possible to the existing one.


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## Obanboy666 (Dec 17, 2016)

wildebus said:


> Hi,
> I actually have an installation very similar to the one you are proposing and this is what I have (and did)
> 
> Sargent EC155
> ...



Going to have a good look after lunch regarding access for cable runs etc. I have a Ctek smart charger and if / when I get round to doing the installation I will charge both batteries before connecting everything up. I have a 100 watt solar panel and mppt victron controller so hopefully if I leave home fully charged then it may keep the batteries charged, perhaps not this time of the year but spring / summer should be ok. Infact I have roof space to fit another 100 watt panel if I find I need to. Regarding the wiring.i was going to do as per this link with fuses in the appropriate places -
https://caravanchronicles.files.wor...w-to-connect-two-batteries-in-parallel-01.pdf


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## wildebus (Dec 17, 2016)

yup, that is spot on   (but remember to fuse  )

The only thing I would change is mentaly regard battery 2 as the existing one and battery 1 as the new one you are adding as, as mentioned, it is usually a lot easier to adjust the ground then the positive, but you will know which is best way to go yourself when you start doing the addition


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## Byronic (Dec 17, 2016)

trevskoda said:


> Just use battery starter cable which you can buy at motor shop to join up,if you ex les battery is grounded then you only require a red to red + connection and a earth strap on neg,if you wish a block fuse can be added,as for venting its always a good idea but the is no vents on my bus from new and service battery lives in front passenger foot well.



I believe you have an Iveco. Strange that they didn't have a floor vent, unless they only intended for sealed no maintenance batts be used, or a vent tube to be fed out somewhere or merely the risks to be insignificant.. 
On my mb van the twin starter batteries live in the driver seat pedestal box and have a floor vent to the exterior. However since hydrogen is less dense than air you'd think they'd vented at the top, probably too difficult. Or maybe they thought worst case scenario that some burke may overcharge in situ damaged batteries and produce hydrogen sulfide which is heavier than air? Who knows


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## harrow (Dec 17, 2016)

Quote... https://caravanchronicles.files.wor...w-to-connect-two-batteries-in-parallel-01.pdf

Honestly unless you connect the 2 batteries together using extremely thin cable (such as walkman headphone cable) then this document is complete and utter rubbish.

As long as you use 6 or 10mm or thicker cable that document is complete and utter ridiculous tosh. 

The biggest problem is how much space do you have for the cables, how big are the connectors for the battery clamps and the fuse holders, all these things have to be considered when compiling your shopping list, there is no easy answer.

You have to adapt according to what items you can obtain.


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## maingate (Dec 17, 2016)

I had a second Leisure battery added to my van when I bought it. The Dealer fitted wiring that was only about 1.0 mm or 1.5 mm diameter. When I said that I wanted it removing and better wiring installed, I was informed that what they had used was an Autotrail kit supplied by them for an additional battery. I stood my ground and refused to accept it, so they changed it to a thicker cable size.


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## Obanboy666 (Dec 17, 2016)

harrow said:


> Quote... https://caravanchronicles.files.wor...w-to-connect-two-batteries-in-parallel-01.pdf
> 
> Honestly unless you connect the 2 batteries together using extremely thin cable (such as walkman headphone cable) then this document is complete and utter rubbish.
> 
> ...



Going to use 10mm cables and fit new battery post clamps. I like the look of these or something similar -CAMPER VAN 12V PAIR OF LEISURE BATTERY TERMINAL CLAMPS WITH 3 BOLT ON CONNECTION | eBay
 A friend has a heavy duty crimp tool for the heavy duty copper type eyelets so will be fitting them. Had a quick look this afternoon and the cable run is easy, holes already there and loads of space under settee for battery box. If I go for the + to + and - to - method the job will literally take 30 minutes. If I decide to go for let's call it the 'proper' method there would be a considerable amount of work to do looking at the cables at present.


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## trevskoda (Dec 17, 2016)

wildebus said:


> Expensive way to do it ... £15+ worth of cable just for positive and you will end up with an unbalanced battery bank and not get the most out of it.
> 
> Yes, this would work, but is not the best way and may as well do it right if going to the expense of buying a new battery as closely matched as possible to the existing one.



Nonsense my van came with a 90ah starter and a 110 service battery & balance out just fine as all you are doing is adding amperage ,the voltage is the same and it will be just like charging a bigger battery.


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## trevskoda (Dec 17, 2016)

Byronic said:


> I believe you have an Iveco. Strange that they didn't have a floor vent, unless they only intended for sealed no maintenance batts be used, or a vent tube to be fed out somewhere or merely the risks to be insignificant..
> On my mb van the twin starter batteries live in the driver seat pedestal box and have a floor vent to the exterior. However since hydrogen is less dense than air you'd think they'd vented at the top, probably too difficult. Or maybe they thought worst case scenario that some burke may overcharge in situ damaged batteries and produce hydrogen sulfide which is heavier than air? Who knows



Yes i agree with you but mine is a coach built unit and only the lower half bulkhead is used all the rest is wood grp & alloy,i think some older vh had floor drop outs in case batterys boiled over and spat acid out,it could then escape to the road.
I put a new battery in after getting her and rewiring most parts,both batts now eq ah.
I also think some coach builders dont know to much about batterys & charging either to be honest.


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## trevskoda (Dec 17, 2016)

Obanboy666 said:


> Going to use 10mm cables and fit new battery post clamps. I like the look of these or something similar -CAMPER VAN 12V PAIR OF LEISURE BATTERY TERMINAL CLAMPS WITH 3 BOLT ON CONNECTION | eBay
> A friend has a heavy duty crimp tool for the heavy duty copper type eyelets so will be fitting them. Had a quick look this afternoon and the cable run is easy, holes already there and loads of space under settee for battery box. If I go for the + to + and - to - method the job will literally take 30 minutes. If I decide to go for let's call it the 'proper' method there would be a considerable amount of work to do looking at the cables at present.



There good,but i just used quick clamps but others here say no good but there used a lot in marine sector,i wired in 3 strands of heavy wire to fuse box out of same clamp as heavy charge cable coming in,i like these because i can remove battery fast with out spanners.


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## Auld Pharrrt (Dec 17, 2016)

For my heavy cables I bought a set of 5m long jump leads from Halfords (£10 on sale at the moment,) cut the clamps off cut them to the length I wanted (also had enough to feed my inverter) and soldered on the heavy duty ring connectors (I prefer soldering to crimping.)


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## trevskoda (Dec 17, 2016)

maingate said:


> I had a second Leisure battery added to my van when I bought it. The Dealer fitted wiring that was only about 1.0 mm or 1.5 mm diameter. When I said that I wanted it removing and better wiring installed, I was informed that what they had used was an Autotrail kit supplied by them for an additional battery. I stood my ground and refused to accept it, so they changed it to a thicker cable size.



I had a elddis in 2 weeks back with thin wire and a 10ah relay,all burnt out & service battery flat which had been fitted 5 weeks before being sold to chap i know,last owner only had her 7 weeks so i was suspicious.
Common sense tells me if you run a battery down 50% and start engine no way can thin cable shunt 50amps battery to bat through a 10ah relay.
So i fitted 200ah relay and battery cable to do job and also 10ah smart charger door step lights on a remote and fixed rear camera, plus new led lights cigy sockets with usb ports and a volt meter,all worked well and he is now a happy bunny.
New vans have fancy charge units or b2b chargers but this old girl was from the stone age and now back in service,parts cost £200 labour £250 only cos he lives a few doors away so half price and i think fair,i do have to eat.


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## malagaoth (Dec 17, 2016)

> For my heavy cables I bought a set of 5m long jump leads from Halfords



Good move - just make sure that they are copper and not aluminium.
another "cheap" source of extra heavy duty wire is welding cable (35mm  good for about 250amp) which isnt colour coded but a reel of red gaffer tape solves that or starter motor cable (16mm good for 110amp) which is colour coded  the former is widely available at about £6.5 per metre the latter costs about half that.

Although welding cable is ultra heavy duty it is also very flexible - more flexible that starter cable


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## Obanboy666 (Dec 17, 2016)

trevskoda said:


> There good,but i just used quick clamps but others here say no good but there used a lot in marine sector,i wired in 3 strands of heavy wire to fuse box out of same clamp as heavy charge cable coming in,i like these because i can remove battery fast with out spanners.



Had quick clamps on my c class and had no bother whatsoever.
Would 2 x 10 amp and 1 x 6 amp cables fit in them ? The reason I ask is at present my battery positive post clamp has 1 x 6 amp cable from the Sargent unit and 1 x 10 cable from the solar panel. Fitting the additional battery will mean another 10 amp cable in the clamp.


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## trevskoda (Dec 18, 2016)

Obanboy666 said:


> Had quick clamps on my c class and had no bother whatsoever.
> Would 2 x 10 amp and 1 x 6 amp cables fit in them ? The reason I ask is at present my battery positive post clamp has 1 x 6 amp cable from the Sargent unit and 1 x 10 cable from the solar panel. Fitting the additional battery will mean another 10 amp cable in the clamp.



Six amp cable seems to thin for it to me,but yes just hammer the clamps flatter and they will do fine,dont pay more than a £5 on ebay.


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## Auld Pharrrt (Dec 18, 2016)

malagaoth said:


> Good move - just make sure that they are copper and not aluminium.
> another "cheap" source of extra heavy duty wire is welding cable (35mm  good for about 250amp) which isnt colour coded but a reel of red gaffer tape solves that or starter motor cable (16mm good for 110amp) which is colour coded  the former is widely available at about £6.5 per metre the latter costs about half that.
> 
> Although welding cable is ultra heavy duty it is also very flexible - more flexible that starter cable



Yes, I did.  Copper is more flexible, handles higher currents and is easily soldered ... ally doesn't take solder well. 

Welding cable is what I used for the Anderson connectors from MB toplugto plug which gives easy access to MB for jump leads (also have Andersin connector on one end) but it's more expensive, not usually available in red (I used heat shrink to identify + from - and the last bit I had left was used to make a super duper earth strap between chassis and engine when I noticed original was broken.


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## Obanboy666 (Dec 18, 2016)

trevskoda said:


> Six amp cable seems to thin for it to me,but yes just hammer the clamps flatter and they will do fine,dont pay more than a £5 on ebay.



My eyes deceive me !
Checked cable versus some known 10mm I have and it's the same.


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## trevskoda (Dec 18, 2016)

Obanboy666 said:


> My eyes deceive me !
> Checked cable versus some known 10mm I have and it's the same.



All depends if its the on board charger doing the biz or if charging from alt which can pump out 70ah or more ,but a lot of vans have a b2b or fancy charge units if its a factory built van,me i have a split diode box which came fitted from coach builder but it does drop the volts at full charge to 13.7,i could bypass with a relay if i wished.


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## Obanboy666 (Dec 18, 2016)

trevskoda said:


> All depends if its the on board charger doing the biz or if charging from alt which can pump out 70ah or more ,but a lot of vans have a b2b or fancy charge units if its a factory built van,me i have a split diode box which came fitted from coach builder but it does drop the volts at full charge to 13.7,i could bypass with a relay if i wished.



God knows what mine is, it's a professional conversion done by Devon Conversions so I'm assuming they know what they are doing. They have been in business for 60 years so I reckon it should be ok. Looking at the Sargent wiring it appears Devon use a wiring harness kit that Sargent supply.


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## trevskoda (Dec 18, 2016)

Obanboy666 said:


> God knows what mine is, it's a professional conversion done by Devon Conversions so I'm assuming they know what they are doing. They have been in business for 60 years so I reckon it should be ok. Looking at the Sargent wiring it appears Devon use a wiring harness kit that Sargent supply.



Then it should be ok with sargent as the charging will be set low so thin wires will be ok.


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## maingate (Dec 18, 2016)

The wiring between my original leisure battery and the added one (both 110 Ah) is still relatively thin but is good enough for the way I use the van. I have no huge Inverter or anything else that will be a big drain on the batteries. In fact this thread has reminded me that I need to remove the 30 amp fuse between them and install a 20 amp fuse.


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## Obanboy666 (Dec 18, 2016)

maingate said:


> The wiring between my original leisure battery and the added one (both 110 Ah) is still relatively thin but is good enough for the way I use the van. I have no huge Inverter or anything else that will be a big drain on the batteries. In fact this thread has reminded me that I need to remove the 30 amp fuse between them and install a 20 amp fuse.



Same here, no inverter as don't bother with microwave or the sky box as in previous c class.
So do you reckon a 20 amp fuse between the batteries is adequate as was going to fit a 30 amp.
Out of curiosity how are your batteries wired up,  Pos  to pos & neg to neg or positive from one battery and negative from tother?


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## Auld Pharrrt (Dec 18, 2016)

Obanboy666 said:


> Same here, no inverter as don't bother with microwave or the sky box as in previous c class.
> So do you reckon a 20 amp fuse between the batteries is adequate as was going to fit a 30 amp.
> Out of curiosity how are your batteries wired up,  Pos  to pos & neg to neg or positive from one battery and negative from tother?



OB ... DO NOT PUT POS TO NEG ETC if you do this will double the VOLTAGE of your battery bank to 24v and will burn out any 12v gear attached to it ... this is what is called connected in SERIES.

What you need is batteries connected in PARALLEL that is pos to pos and neg to neg ... this will doubke your storage capacity but will remain 12v.


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## Auld Pharrrt (Dec 18, 2016)

Think of it as two bits of rope ... end to end is SERIES and makes rope longer but side by side is PARALLEL which makes them stronger


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## maingate (Dec 18, 2016)

Obanboy666 said:


> Same here, no inverter as don't bother with microwave or the sky box as in previous c class.
> So do you reckon a 20 amp fuse between the batteries is adequate as was going to fit a 30 amp.
> Out of curiosity how are your batteries wired up,  Pos  to pos & neg to neg or positive from one battery and negative from tother?



As the auld farter says, pos to pos to put them in parallel. 

My onboard charger is rated at 16 amps output, which is 8 amps to each battery (in theory but one might take a bit more than the other). Therefore 20 amps is enough in my estimation.

Let's consider that your second battery suffers a catastrophic failure and because it is hidden from sight, you don't know this. The faulty battery can absorb as much power as the Alternator or the onboard charger can throw at it. With a 30 amp fuse fitted, you could have nearly half a Kilowatt of electricity running through your cabling (30 amps multiplied by 14.5 volts) before the fuse thinks about blowing. This can generate heat, especially if you have poorly made connections and thin wiring. 

Another good tip I got when I visited Allan at A & N Caravans 2 years ago was to change all the fuses in my Reich E box control system. He said it was common to fit fuses equal to the maximum rated amps for each circuit (ie fitting a 30 amp fuse in a circuit capable of a 30 amp current). I had never heard this said before and took him at his word, there was a Motor Accessory Shop next door to his Unit, so I bought them there and then. When I did the calculations for the likely power draw of things like the water pump, electric step, 12 volt power circuits, lights etc), I found that the fuses were indeed a bit on the big side.


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## Auld Pharrrt (Dec 18, 2016)

Generally I will use my multimeter to see what current is being drawn by any device ... then fit the smallest value fuse above that reading ... if in doubt simply start with a low rated fuse and work your way up until you find one that copes with the demands.


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## Obanboy666 (Dec 18, 2016)

Auld Pharrrt said:


> OB ... DO NOT PUT POS TO NEG ETC if you do this will double the VOLTAGE of your battery bank to 24v and will burn out any 12v gear attached to it ... this is what is called connected in SERIES.
> 
> What you need is batteries connected in PARALLEL that is pos to pos and neg to neg ... this will doubke your storage capacity but will remain 12v.



Didn't explain it very well, I'm aware of how to connect the batteries. I meant which way reference as per this link https://caravanchronicles.files.wor...w-to-connect-two-batteries-in-parallel-01.pdf
Top or bottom example ? Both parallel.


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## Auld Pharrrt (Dec 18, 2016)

Obanboy666 said:


> Didn't explain it very well, I'm aware of how to connect the batteries. I meant which way reference as per this link https://caravanchronicles.files.wor...w-to-connect-two-batteries-in-parallel-01.pdf
> Top or bottom example ? Both parallel.



I only have my MB  and 1 LB which are connected in parallel via my basic split charge relay, they are connected as per figure 1, but I can see the logic involved if two LB's were connected as per figure 2, but I'm not convinced it would make any difference.


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## Obanboy666 (Dec 18, 2016)

Auld Pharrrt said:


> I only have my MB  and 1 LB which are connected in parallel via my basic split charge relay, they are connected as per figure 1, but I can see the logic involved if two LB's were connected as per figure 2, but I'm not convinced it would make any difference.



As I mentioned in a previous thread to wire mine as per fig 1 would be a 30 min job. To go as per fig 2 would involve joining / extending the existing cable so reckon I'll go with fig 1.
Going to order up what I need tomoss and get the job sorted.

Many thanks to all who have offered advise, much appreciated. I will repost when job done.


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## harrow (Dec 18, 2016)

maingate said:


> As the auld farter says, pos to pos to put them in parallel.
> 
> My onboard charger is rated at 16 amps output, which is 8 amps to each battery (in theory but one might take a bit more than the other). Therefore 20 amps is enough in my estimation.
> 
> ...



The thing with this sort of fuse is it listed with it's continuous rating so a 30 amp fuse will disconnect at twice its rating ie 60 amps 

So never fit a bigger fuse than the circuit can cope with, if anything fit a lower rated fuse to give you a bigger safety margin.

Miniature circuit breakers trip at about 1 and a third rating according to their manufactured specification.:rulez:


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## Obanboy666 (Dec 19, 2016)

Regarding the proposed location of my additional leisure battery under the settee, it will be within a couple of feet of my Truma Combi. This is the only available place I can mount the battery.
Is this safe ? Any reasons why it cannot be within 2 feet of the combi ? I got to thinking about the battery gassing and a spark from the combi when it fires up.
I'm probably being over cautious but better safe than sorry.


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## wildebus (Dec 19, 2016)

Obanboy666 said:


> As I mentioned in a previous thread to wire mine as per fig 1 would be a 30 min job. To go as per fig 2 would involve joining / extending the existing cable so reckon I'll go with fig 1.
> Going to order up what I need tomoss and get the job sorted.
> 
> Many thanks to all who have offered advise, much appreciated. I will repost when job done.



So is there no place in the location on the second battery where you can run a short cable to a vehicle earth? That is all that is needed and removing the existing earth on the first battery (only need to remove the  battery post connection).
If you are stuck for an earth there, it is still easy enough to do. Instead of two cables to 2nd battery, just run three  .... +ve and -ve to link the two batteries and a  -ve return. You then connect the -ve return to one side of the fuse holder, and the old earth to battery one to the other side. Adds no time to the install.

With respect to trevskoda, sorry but he is wrong about the way it is connected making no difference, and you saw yourself the diagram about how you SHOULD do it!
Doing it the "simple" way will of course work, but it is not the way to get optimum use from battery OR best life span. I tested both setups on my T5 to see how much difference and doing it the correct way gave me an extra 12 hours of usable (until down to 12.1V) battery time.


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## Obanboy666 (Dec 19, 2016)

Obanboy666 said:


> Regarding the proposed location of my additional leisure battery under the settee, it will be within a couple of feet of my Truma Combi. This is the only available place I can mount the battery.
> Is this safe ? Any reasons why it cannot be within 2 feet of the combi ? I got to thinking about the battery gassing and a spark from the combi when it fires up.
> I'm probably being over cautious but better safe than sorry.



Bump


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## The laird (Dec 19, 2016)

Obanboy666 said:


> Bump



If the battery is in a proper box,vented and a sealed battery I think it would be OK.


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## ricc (Dec 22, 2016)

wildebus said:


> So is there no place in the location on the second battery where you can run a short cable to a vehicle earth? That is all that is needed and removing the existing earth on the first battery (only need to remove the  battery post connection).
> If you are stuck for an earth there, it is still easy enough to do. Instead of two cables to 2nd battery, just run three  .... +ve and -ve to link the two batteries and a  -ve return. You then connect the -ve return to one side of the fuse holder, and the old earth to battery one to the other side. Adds no time to the install.
> 
> With respect to trevskoda, sorry but he is wrong about the way it is connected making no difference, and you saw yourself the diagram about how you SHOULD do it!
> Doing it the "simple" way will of course work, but it is not the way to get optimum use from battery OR best life span. I tested both setups on my T5 to see how much difference and doing it the correct way gave me an extra 12 hours of usable (until down to 12.1V) battery time.



sorry but i have to dissagree,  theres absolutly no reason why both ways wont work equally well provided thick enough cable is used and the joints are good.  theres also no reason to link the 2 battery negs together , they can be seperatly connected to earth.
the experience with the t5 can be explained by either thin wire or a faulty connection, probably where a lug is crimped to a cable.


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## wildebus (Dec 22, 2016)

ricc said:


> sorry but i have to dissagree,  theres absolutly no reason why both ways wont work equally well provided thick enough cable is used and the joints are good.  theres also no reason to link the 2 battery negs together , they can be seperatly connected to earth.
> the experience with the t5 can be explained by either thin wire or a faulty connection, probably where a lug is crimped to a cable.


Explain why my experience is confirmed by various articles in various publications?
Thin wire? Would 10mm cable be insufficient for an average 1.9Amp draw?
All cables correctly and  very securely tightned down

I have no problem with people who want to take short cuts, just don't pass on suggestions with no foundation.


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