Leisure battery.

[The Grand Wanderer]

Hi all,

Thanks for your on going help

I have followed the advice and checked all the terminals and everything seems fine...
I checked the usage tonight by leaving two of the campers lights on for an hour (was more like 50 mins), the second battery didn't go down at all, whilst the 1st battery went from fully charges 12.9 to 12.4 in that short time... Is this normal?

Bit worried as we will be in the camper full time in 2 weeks and don't want to ruin the batteries or be without power.

John

Please can you tell us how long the wires are between your two batteries? The greater the distance the more resistance and so the wire must be thicker to cope. I did say 3mm was a mininum. You may be better off using a 10mm wire. If all connections are between the batteries only and not to earth then it might be worth while looking at the original battery conections partically the original earth connection from the original battery to the van body.
Wanderer

 

[millso]

The positive lead is no more than 200mm and the negative about 800mm so distance isn't an issue.

I'll have a look at the earth, if its ok i'll have a look at some thicker lead over the weekend.

 

[Bigpeetee]

Send me your phone No to peter@starsound.org.uk

 

[solarman]

Hi all,

Thanks for your on going help

I have followed the advice and checked all the terminals and everything seems fine...
I checked the usage tonight by leaving two of the campers lights on for an hour (was more like 50 mins), the second battery didn't go down at all, whilst the 1st battery went from fully charges 12.9 to 12.4 in that short time... Is this normal?

Bit worried as we will be in the camper full time in 2 weeks and don't want to ruin the batteries or be without power.

John

do you have it wired to a split charger,if so you can run the engine for a while to keep batteries up,but on my recent experience i used an old battery and new battery wired in parallel and had tv running all night till voltage showed 11.97,but best to keep voltage level no less than 12.2 volts and then recharge it as soon as possible,
Solarman.

 

[solarman]

i wouldn't worry too much about the voltage reading appearing to drop fast,in my experience that's normal,it should slow down a bit from 12.4 volts,but everything depends on battery condition,age,loads pulling power,temperature etc;Just as long as you have the means to recharge your batteries when they are critical so you can get them topped back up,
Solarman.

 

[Bigpeetee]

Problem solved for John, took out positive cable with fuse in line, replaced with solid cable, all's well. acting as 1 big batt.

It's amazing how the fuse, holder etc can add resistance and cause poor charging etc.

As John's positive cable went under the seat frame, I suggested additional insulation like pipe insulation, the split foam stuff is ideal

 

[millso]

Hi Pete,

You beat me to it

Thanks to everyone for their help, but especially Pete for being very patient over the phone!

As a rule I don't pay to become a member of forums, however after Pete's help this community seems to be something worth paying for!

 

[Leltel]

Can you help me too please

Ok we are fitting 2 110ah batteries and have 16mm copper wire, we have exhausted ourselvex trying to find spade lugs big enough to fit the wire for the fuses. Hubby wants to use 25amp fuse wire instead, is this ok?? One battery will be under the passenger seat and one in the door well space. Thanks

 

[oldish hippy]

Ok we are fitting 2 110ah batteries and have 16mm copper wire, we have exhausted ourselvex trying to find spade lugs big enough to fit the wire for the fuses. Hubby wants to use 25amp fuse wire instead, is this ok?? One battery will be under the passenger seat and one in the door well space. Thanks

lugg for the size of cable go to a electrical wholesaler ie like city elelctrical they uk based they should be able to help you or if you have a local on then they should if not get in touch with a freindly local electrician who got account and ask him to get you some lugs might have to be circle but quick trim with hacksaw they become spade

16mm² Copper Tube Lug 8mm Stud Hole Pack of 10 | Screwfix.com

PRO POWER|STTK25-10|UNINSULATED CRIMP TERMINALS 25MM | CPC

 

[Leltel]

Thank you, we have spent all our time trailing motor factors, didn't even think of electrical wholesales!
Guess where we will be going tomorrow. Thanks again

 

[Bigpeetee]

Why the fuse between the batteries??

Millso had charging problems when a fuse was installed.

Your cable runs are short, if you're worried about shorting the cable, add additional insulation on the positive lead only, cover the positive terminals and you're fine.

In the engine compartment, there isn't a fuse in the cable to the starter motor, that's a big cable and is just clipped to the body work.

As long as you cannot short the positive cable to earth (Almost any metal) then you're OK.

As stated previously, a fuse is a resistance (Quite small), when you charge the battery, you will never get the full voltage on the second battery, so it never becomes fully charged, when stopped, the two batteries settle to the lower voltage.

Don't forget, you also have a fuse in the line from the split charge relay, that resistance plus that of the cable results in a voltage drop anyway.

If you have a voltmeter, first put it across the engine battery with the engine running, then across the leisure battery, you will probably see a difference in voltage caused by the resistance of the fuse and cable.

The flatter the leisure battery, the greater the voltage differential, the slower the charge.

PS, I use foam pipe insulation to protect the positive cable, you can get plastic clip on protectors for the terminals. Battery depots are the best starting places for the bits and bobs.

 

[Leltel]

Thank you so much

Why the fuse between the batteries??

Millso had charging problems when a fuse was installed.

Your cable runs are short, if you're worried about shorting the cable, add additional insulation on the positive lead only, cover the positive terminals and you're fine.

In the engine compartment, there isn't a fuse in the cable to the starter motor, that's a big cable and is just clipped to the body work.

As long as you cannot short the positive cable to earth (Almost any metal) then you're OK.

As stated previously, a fuse is a resistance (Quite small), when you charge the battery, you will never get the full voltage on the second battery, so it never becomes fully charged, when stopped, the two batteries settle to the lower voltage.

Don't forget, you also have a fuse in the line from the split charge relay, that resistance plus that of the cable results in a voltage drop anyway.

If you have a voltmeter, first put it across the engine battery with the engine running, then across the leisure battery, you will probably see a difference in voltage caused by the resistance of the fuse and cable.

The flatter the leisure battery, the greater the voltage differential, the slower the charge.

PS, I use foam pipe insulation to protect the positive cable, you can get plastic clip on protectors for the terminals. Battery depots are the best starting places for the bits and bobs.

Thank you so much for this reply. Hubby has been able to go out and about today with work so has been halfway round the south, or he says it feels like it, trying to get the connections or a different fuse thingy without any joy!
We are new to Motorhome DIY and needs must, this is the first time he is attempting something like this. Where we have researched over the last week, looking for information, I think we have had information overload and had read somewhere that fuses were used!
You are right in that there is a short distance in wires so we are not going down the fuses route, he is now going back to the office to pretend that he has been out on work purposes, whilst I eagerly await the delivery of our batteries.....ready for the off tomorrow!
We are so grateful for the person who started this post and to all who have contributed, especially yourself. I know it is a subject that comes up alot, but people still have the patience to reply.

 

[Deleted member 3011]

At the risk of upsetting people, and regardless of whether engine batteries have a fuse between it and the starter motor, they DO normally have a fusible link somewhere in the wiring supplying the rest of the circuitry.
To be so adamant about not needing fuses in habitation systems is against normal good safe practice and unfortunately the reason given for not having fuses is the very poor quality of components and workmanship that goes into a typical habitation battery installation - PARTICULARLY a second battery that is usually installed by the dealer or a handyman.

The correct fuse to use is one rated to blow only in the case of a serious fault, and is one that is bolted, not one of these crappy spade fuses in a plastic holder so beloved by the trade. The correctly-sized cable (3mm??? what does that mean? 3mm cable diameter, 3 mm conductor diameter, or is it 3 square mm conductor area??) is fitted with the correct lugs either crimped with the correct crimper (the $2 kits containing 79 assorted crimp lugs AND a crimper, is not the one I mean) or soldered by someone with the right equipment and the knowhow to use it - and then the whole lot is installed according to best practices.

 

[Leltel]

Hi Tony, it is the crappy plastic ones that we have got hold of. Hubby wanted the bolt downs, no where local sells them, I have had a pm which assists. As for crimpers, he does at least have a set of proper ones that he borrows from his work van! I am waiting for him to get in from work tonight to show him the comments and messages.
Thank you as all comments are appreciated.
Lel