# Charging systems



## windyjools (Oct 29, 2011)

I'm trying to find a more efficient method of charging the leisure batteries when the engine is running!
I currently have the standard split charge relay which works but have read abou the Sterling Battery to Battery charger which claims to charge the betteries quicker and to a higher level. The price however is a bit of a shocker, so has anyone found a better way of charging the leisure batteries using another relay system?
I wild camp all the time so 240v hook-up is not much good for us. Any thoughts would be good!


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## Bernard Jones (Oct 29, 2011)

Just a matter of minimising the resistance in the connections between the main and leisure batteries.  Cable ratings tend to be based on the maximum current the cable can carry without risk of catching fire, but will produce a lot of resistance at the maximum rating.  The cables supplied in the split charging kits sold by the likes of halfords are just too thin for fast charging.  Fuses priovide further resistance.  I use a 100amp relay, connected with 25 sq mm copper cable, and no fuses, so the leisure batttery charges just as fast as the main battery.  Of course, if you omit the fuses, you have to be sure it is very well insulated so there is no chance of a short circuit.  Anywhere the cable touches metal I feed it through hose for an extra layer of insulation.  
If you need to buy thick copper cable from a retail outlet, it will probably be cheaper to buy a set of jump leads, and use the cable from them.


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## David & Ann (Oct 29, 2011)

Normally your Alternator charges your battery while on the run. Solar panel will charge when engine is off. Someone with electrical and wiring knowledge will come along and advise you. If you can afford a Solar panel and a second battery, your problem for not wanting to stay at campsites will be solved.


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## Bernard Jones (Oct 29, 2011)

I've never needed a solar panel, but it does depend on the capacity of the alternator fitted to your van.  The X2/50 has 160 amp alternator as standard, which is plenty to fast charge a leisure batery, even on tickover, providing there is low resistance (thick cable) connecting it to the main battery.
Of course, the 'experts'/salesmen will advise you to buy something more expensive, because most of the free advice on the internet derives from those in the business of selling expensive equipment.  They will consequently ridicule my suggestion of omitting fuses through using extra insulation, (no profit for them in that)  and others will repeat their advice


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## Admin (Oct 29, 2011)

I use a CTEK d205s which charges up to 300ah of batteries using the alternator. Before this my inverter batteries were on split charge. I have a  NASA Marine battery monitor installed so the results I give are based on its readings not just my personal opinion. Before the d205s the batteries charged to about 78% of capacity and now they charge to 105%. That is 105% of rated capacity (250ah).

The charger outputs 20A @ 14.4v and also does multi stage charging.

Another plus is the second input for solar panels, so it regulates your solar charging too (up to 22v input)



			
				CTEK said:
			
		

> [h=3]CTEK D250S DUAL General Information[/h]
> 
> Input voltage: max 22VDC
> Output voltage: 14.4V at 25°C
> ...


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## AuldTam (Oct 29, 2011)

I bought a 70amp relay from ebay for £8 (for use on a mobility scooter), then I bought a set of 100amp jump leads from poundstrecher (just for the cable), then 2 x 40amp inline fuses, spade connectors, etc...job done for under £20


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## caspar (Oct 29, 2011)

Doesn't a car spotlight relay do the same job?

Phil - never come across that - brilliant piece f kit, just don't like the £214 pricetag! lol


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## Bernard Jones (Oct 29, 2011)

Phil said:


> I use a CTEK d205s which charges up to 300ah of batteries using the alternator. Before this my inverter batteries were on split charge. I have a  NASA Marine battery monitor installed so the results I give are based on its readings not just my personal opinion. Before the d205s the batteries charged to about 78% of capacity and now they charge to 105%. That is 105% of rated capacity (250ah).
> 
> The charger outputs 20A @ 14.4v and also does multi stage charging.
> 
> Another plus is the second input for solar panels, so it regulates your solar charging too (up to 22v input)



Must take a long time to charge 300ah batteries with 20A?
Must be quicker to wire it straight through to use all available alternator output (works for me)

I don't know how it measures 105% of charge capacity?
I was taught (admittedly many years ago) that the only way to measure the charge of a lead acid battery accurately is with a hydrometer and thermometer.  Just measuring the voltage is notoriously inaccurate, particularly if its within about 12 hours of the battery being charged or used.
In any case, if its 105% of capacity isn't that oovercharging it, and reducing the life?

Pardon my cynicism, but I have read so much stuff designed to sell expensive tackle, and my own simple system works a treat.  I have recently had a discussion with a guy who maintains I should buy a generator because it severely damages your engine to leave it ticking over charging the battery.  Despite fleets of ice cream vans doing it all day, and having original engines over 20 years old


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## Bernard Jones (Oct 29, 2011)

AuldTam said:


> I bought a 70amp relay from ebay for £8 (for use on a mobility scooter), then I bought a set of 100amp jump leads from poundstrecher (just for the cable), then 2 x 40amp inline fuses, spade connectors, etc...job done for under £20



Whatever is claimed on the pascket you are not going to get proper 100 amp cable in a pound sghop because the copper would cost more than that.  100 amp is most likely the maximum current it could stand for a few seconds without catching fire.


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## Bernard Jones (Oct 29, 2011)

caspar said:


> Doesn't a car spotlight relay do the same job?
> 
> Phil - never come across that - brilliant piece f kit, just don't like the £214 pricetag! lol



Yes, but they are generally only 30 amp.  Again, this light duty stuff will work, but it will create a resistance that will slow down the charging of your leisure battery. 
Its like trying to force water through a narrow pipe to fill your bath.  It will work, but it will take longer.


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## AuldTam (Oct 29, 2011)

Bernard Jones said:


> Whatever is claimed on the pascket you are not going to get proper 100 amp cable in a pound sghop because the copper would cost more than that.  100 amp is most likely the maximum current it could stand for a few seconds without catching fire.




Wasnt the poundshop?, I think they were about £5 a set, been fitted a while now and aux battery is always charged. I did a 300 mile round trip a few weeks ago, no problems so far.


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## maingate (Oct 29, 2011)

It is well and good to be able to bang a large charge into a battery in a short time but it will cut down the useful life of a battery. less than a 20 amp charging rate should do no harm to a large battery and it will be capable of more charging cycles before failing. If you have a good quality deep cycle battery, it may last a bit longer but the outlay for one will be a lot more.

The most important thing is to have enough battery capacity and not to discharge the batteries by more than 50%. I can manage fine with 2 x 110 Ah batteries and a 90 watt solar panel. 

If you are wildcamping, you should be moving around on a regular basis (not overstaying your welcome) and putting some charge back in that way.


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## Canalsman (Oct 30, 2011)

I am considering this battery-to-battery charger eBay - The UK's Online Marketplace

Take a look ...


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## Teutone (Oct 30, 2011)

Hi, newbie here and it's my first post.
Bought a motorhome recently and working my way through all the bits and bobs.

I am also looking to improve efficiency for the leasure battery.

From younger days I have some experience with in car stereo and wanted to use some of the car stereo stuff.
all the fuses and cables are of high quality (if you pick the right ones) because resistance is the the big enemy of a high power in car stereo and you will get stuff reated high enough, i.e. 100amp blade fuse gold plated.

Sure this isn't cheap stuff and everybody has to decide of how much one is prepared to spend for the last digit behind the comma.
But even the "cheaper" car stereo stuff is better than the usual low price of the mill stuff.


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## Bernard Jones (Oct 30, 2011)

I appreciate that charging more slowly tends to increases the life of the battery, but restricting a 300 amp hour battery bank to a 20 amps charge rate is ridiculous.  My X2/50 van has a 160 amp alternator and a 95amp hour battery as standard equipment.  Whatever size battery you add on you are increasing the battery capacity above what the manufacturer deemed necessary.  The alternator has its own regulator, you don't need anything else to slow down the charge rate.  Just get some good thick copper cables, preferably at least 10mm sq (I use 25mm sq) to couple the batteries together through a 100amp or above relay.  Works fine for me.


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## Bernard Jones (Oct 30, 2011)

AuldTam said:


> Wasnt the poundshop?, I think they were about £5 a set, been fitted a while now and aux battery is always charged. I did a 300 mile round trip a few weeks ago, no problems so far.


sorry, I thought poundstretcher was a pound shop.  Even so, you won't get much copper for £5.  The professionals measure cable by its cross section, in square mm, then there is much debate about how much amps it should cary because it depends on a lot of factors, like how well the cable is ventilated to reduce the heat.  Cables rated at 100 amp for jump leads (intermittent use and well ventilated) would probably be rated at 30 amps continuous maximum, much less if you need to minimise the resistance as in coupling to a second battery.
I'll stick my head above the parapet and say that as a very rough guide 1 square mm equates to about 10 amps max.  Thats why I said 10 sq mm for 100 amps max, but 25 sq mm to minimise the resistance.
Of course many people will say they use much thinner cable and it works. I don't doubt that.  But like filling the bath through a straw, it takes longer.


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## AuldTam (Oct 30, 2011)

Bernard Jones said:


> sorry, I thought poundstretcher was a pound shop.  Even so, you won't get much copper for £5.  The professionals measure cable by its cross section, in square mm, then there is much debate about how much amps it should cary because it depends on a lot of factors, like how well the cable is ventilated to reduce the heat.  Cables rated at 100 amp for jump leads (intermittent use and well ventilated) would probably be rated at 30 amps continuous maximum, much less if you need to minimise the resistance as in coupling to a second battery.
> I'll stick my head above the parapet and say that as a very rough guide 1 square mm equates to about 10 amps max.  Thats why I said 10 sq mm for 100 amps max, but 25 sq mm to minimise the resistance.
> Of course many people will say they use much thinner cable and it works. I don't doubt that.  But like filling the bath through a straw, it takes longer.



Thanks for this advice, you appear to know what your talking about. Better to be safe than sorry!

I had a quick look on the internet for proper 100amp rated cable and found marine cable rated at 110amp at £3.29 per metre, does this sound like the RIGHT stuff? How do I crimp on the ends? Should I cut cable to lengths required and take to an auto electrician to crimp?  I dont think soldering the connectors on would be strong enough with all the movement of a vehicle.

I only have a basic hand crimper for auto/household cables.


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## caspar (Oct 30, 2011)

A fascinating post. Keep it coming folks - I'm learning!


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## maingate (Oct 30, 2011)

Bernard Jones said:


> I appreciate that charging more slowly tends to increases the life of the battery, but restricting a 300 amp hour battery bank to a 20 amps charge rate is ridiculous.  My X2/50 van has a 160 amp alternator and a 95amp hour battery as standard equipment.  Whatever size battery you add on you are increasing the battery capacity above what the manufacturer deemed necessary.  The alternator has its own regulator, you don't need anything else to slow down the charge rate.  Just get some good thick copper cables, preferably at least 10mm sq (I use 25mm sq) to couple the batteries together through a 100amp or above relay.  Works fine for me.



You should be able to charge batteries at up to 20% of their total Ah capacity without incurring any damage, in your case 60 amps. Alternatively, you could tow a Power Station on a trailer.  :idea-007:

What I want to know is what equipment are you using to need 300 Ah of storage and make a big dent in it on a daily basis? A 20 amp charger is usually sufficient for most people. In fact with a 90 watt solar panel, we are self sufficient all summer (it charges at 5.5 amps on a good day). In winter we can last a long time with 220 Ah of battery power and the panel (as long as it is not chucking it down every day).


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## Bigpeetee (Oct 30, 2011)

I've used meter tails from Screwfix to connect to leisure batt.

I soldered to the lugs, I used flux and a kitchen cooks blow torch to heat.

I've got 2x 110 AH batts, but try to never let the batts get too low. If they go low, you still get a voltage drop, not much but makes a difference to charging.

I use a 2000w inverter, but if I'm in doubt, I run the engine.

Preferably reduce the amount of power you use.


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## Bernard Jones (Oct 31, 2011)

Easiest way to fit terminals is to get the right size for the cable and then they crimp on firmly quite easily in a vice or pliers.  - I used these for 25 mm sq cable which I already had from somewhere else 25/6mm Lugs * 10 - Tube/Lugs - Terminals - Raw Components Ltd - Auto electrical Supplies - Specialists in Split Charge Kits 

If you can find the d+ wire from the alternator you can use an ordinary relay like this 100 Amp 12v Relay - 12V - Relays & Holders - Raw Components Ltd - Auto electrical Supplies - Specialists in Split Charge Kits 

Otherwise you will need a voltage sensing relay will be easiest to fit and least likely to interfere with a modern vans electronic control unit Intelligent "TIMED" Voltage Sensing 100 Amp 12v Relay - Intelligent Relays - Raw Components Ltd - Auto electrical Supplies - Specialists in Split Charge Kits 

Sorry about the commercial links – but I can’t see another way to illustrate what I am talking about.  I am nothing to do with RAW components, but have bought a few items from them in the past with no problems.


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## windyjools (Oct 31, 2011)

*Thanks to all!!*

Thanks for all the replies.......as I suspected, there are as many ways to solve the problem as you care to look at. I currently run a 175watt solar panel through a 20 amp regulator to help the batteries but have a 12 volt compressor fridge which hammers the batteries!! Anyone who wants more details, I can promise I will put you off compressor fridges for life (I won't fit one in the next conversion that's for sure)
So, I'll be looking for a decent relay and some hefty cable to see if that does the job. I posted a similar question on on of the motorhome forums and got surprisingly similar response (i.e. keep it simple and use hefty cables and relay).
Keep the info coming though, anyone  who wants info on compressor fridges, please fire away......I still have a new one that has a faulty thermostat that Waeco won't believe has a problem,,,,,,,,,but that's another story!


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## windyjools (Oct 31, 2011)

*Charger*



Canalsman said:


> I am considering this battery-to-battery charger eBay - The UK's Online Marketplace
> 
> Take a look ...



Might be me, but can't find the link...........


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## Canalsman (Oct 31, 2011)

It works OK for me ...


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## scampa (Nov 1, 2011)

*A Winters Tale.*

Like Bernard, I also use a heavy duty 100 Amp (continuous) split-charge relay and 25mm (170 Amp) flexible cable to link to my leisure battery.  Leaving out the fuse from the circuit WILL reduce the resistance and make the circuit more efficient, in the same way that using a 6 inch (copper) nail in your home lighting circuit in place of the 5 Amp fuse or mcb would make it more electrically efficient!  As long as nothing goes wrong within the circuit, everything will be fine.

Feeding the cable through hose will help to add to the insulation and the abrasion resistance, but will not protect against all eventualities, whether caused by electrical faults within the circuit, or by external damage.  A great example of this happened to me on a freezing cold night last winter, but luckily the vehicle involved was parked at home at the time instead of at some remote wilding spot.

The short version of the story is that one or more rodents, probably rats, decided to enjoy the warmth of my engine compartment after I'd parked up for the night ( most likely members of the infamous "wildcamping for rodents club").  After chewing through a large rubber grommet in the bulkhead, they had a feast on the cable insulation behind the facia.  Luckily, at some stage this caused a fuse to melt, so saving the rats and the vehicle from going up in flames. 

My point is this: I would much rather waste some electrical efficiency, and incur very slightly longer charging times by having a fuse in every circuit. A melted fuse is inconvenient, but much better than a melted cable, battery, alternator etc. and the possible total loss of your vehicle!

As for fitting heavy duty lugs to your cable without a h/d crimper, try using a vice or a lump-hammer and punch.

(Incidentally, the rats had made such a good job of hiding their handiwork from view that I couldn't find the reason for the blown fuse or inoperative fuel injection system the next morning. Neither could the AA man that I called out later, although I did earn some brownie points by towing his van out of a snowdrift with my 4x4!)

PS.. Rats and mice will often be attracted to your warm engine bay on a cold night, and are well known for starting fires by chewing on cable insulation.


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## Harmergeddon (Nov 1, 2011)

The infamous charging system debate raises its head again.
There are many ways to skin this cat, some cheap, some expensive, some simple and some complicated. All work to a degree but this depends entirely on your own power requirements and you must also factor in your own space requirements, i.e how many batteries are you prepared to carry against how much power you need. Also you need to remember that what works for one van does not necessarily work for another.
Right the one thing that doesn't change and this is important as it should effect how you go about desining your charging system.
A vehicle alternator will only charge what ever batteries you have installed to about 80% of their actual capacity. Why, because it uses a cheap easy to manufacture voltage regulator that charges at a flat rate of 14.4v. It doesn't take into account things like, temperature voltage drops down cabling and the flat rate of charge just isn't capable of charging your battery much. A bigger alternator will charge your batteries quicker, but still only to about 80% and all split charge relay systems are the same about 80%.
If you decide you need to get the most out of your batteries then you need to replace the standard voltage regulation with something a bit more clever and this costs money. Not everyone needs this kind of system and for them the simplier solutions work just fine.
Personally i run an adverc advanced voltage regulation system with blocking diode and a good friend of mine runs a sterling battery to battery charger. Both have proven to be very relaible and efficient. Mine was a little more complicated to fit and was slightly more expensive but has the capability to charge the main as well as leisure batteries to a much higher level. Makes starting the van in -25 degrees much easier and this is important for me and was one of the reason why i went down this route. There are other reasons too.


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## Viktor (Nov 1, 2011)

> Rats and mice will often be attracted to your warm engine bay on a cold night, and are well known for starting fires by chewing on cable insulation



Amazing what as a newbie to Campervanning you find out on this forum....that's one I wouldn't have known about until perhaps faced
with the problem.  Any tips for discouraging them....would one of the small home ultrasonic plugs do the job if put in the glove compartment
etc?


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## Bernard Jones (Nov 1, 2011)

I take your point about rats scampa, but I have fed the cable through car heater hose wherever it touches metal, and I have not heard of rodents chewing through that?
I think it also depends where the cables are.  Rodents prefer to be in places where they are hidden from predators, hence they were living inside your dashboard.  I learned that the hard way when I covered a stored sofa with a blanket to keep it clean and found them living underneath the blanket!
The thing about voltage drop through fuses (and/or minimum size cables) is that in most cases it doesn't matter.  As a very approximate example, if there is a voltage drop of one volt in the wiring to your spotlights you won't even notice.  But if there is a voltage drop of one volt in the wiring between your main and leisure battery you would have to run your engine for about twice as long to charge it.


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## Bernard Jones (Nov 1, 2011)

Harmergeddon said:


> A vehicle alternator will only charge what ever batteries you have installed to about 80% of their actual capacity.



I've checked mine with a hydrometer, which I was taught is the most accurate way to check them, and they are showing fuly charged :idea-007:
Sorry, but I think you have been reading too much sales literature.


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## maingate (Nov 1, 2011)

Heavy cable without fuses!

Crimping with a vice!

Quite a few people need to read some literature, including the terms and conditions of their vehicle insurance certificate (unless you have had the installation passed as safe by a competent person and informed your Insurance company).

Far better to solder joints and fit appropriate rubber sleeves to fittings.

Better still, do not risk an expensive motorhome by saving a few pound.


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## Harmergeddon (Nov 1, 2011)

Bernard Jones said:


> I've checked mine with a hydrometer, which I was taught is the most accurate way to check them, and they are showing fuly charged :idea-007:
> Sorry, but I think you have been reading too much sales literature.



I didn't believe them either so i checked too. I removed my batteries from my system left them overnight to equalise and found before the system was fitted 77%, after 95%. Did you remove your batteries and leave to equlaise before checking?


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## Bernard Jones (Nov 1, 2011)

Harmergeddon said:


> I didn't believe them either so i checked too. I removed my batteries from my system left them overnight to equalise and found before the system was fitted 77%, after 95%. Did you remove your batteries and leave to equlaise before checking?



I have no need to remove any batteries because I am only measuring the leisure battery which has nothing connected to it when I am not using the van.  I just check the leisure battery with a hydrometer when the van has been parked up at home for a few days, effectively disconected, and find it showing about 1280 (the middle of the green sector) on the hydrometer scale.  (Having had the journey home to charge it a few days previous)

How are you measuring the charge as a percentage?


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## Harmergeddon (Nov 1, 2011)

I compared both the specific gravity and the open circuit voltage against the manufactuers figures.


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## Teutone (Mar 7, 2012)

well, after reading whatever I could find about batteries I have decided to fit a battery to battery charger.

came across this Power Integrator 
and quite like the idea of having just one box to deal with the charging and I can add a solar panel (or two) at a later date once I have an idea of how much power we really consume.

the other choices are Ctek and Sterling. but that will be another long read to find out what I may need or not.

Battery I want to use will be a good quality flooded type. From what I read they seem to tolerate the higher currents better when using a B2B charger. So the money I save on buying the "cheaper" type can be invested in a larger battery which then (hopefully) get's discharged less than a smaller "better" battery and live a long and happy live.


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