Club 80-90 Forums

Hi all.

I've just ordered 4 110ah leisure batteries which I will be connecting to my existing 110ah in paralell to give me a total of 550ah of luverly power.

So quick question for you electrickery guru's. What size cable do I need to connect them together safely and where's the best place to get it?

Thanks.

Martin

Edmundson Electrical
Rexel Senate
City Electrical Factors (C.E.F.)

These companies usually have trade counters and deal with large cable, wire and give good advice.

I would use 10mm copper.
unless B&Q do it

Whats the max ampage that will be drawn from the battery? Thats the only way you can safely tell what guage wire to use. I'd go for the the thickest you can afford....

I'd be very reluctant to do this Martin. The reason i say this is because i've had two batteries in parrallel for the last 5 years until this year when i stopped it - so i have experience.

The reason i stopped, is because when one battery fails, it brings the other batteries down with it. So twice, i had to replace two batteries. Also, the time i really wanted the capacity of two batteries - it didnt seem to last much longer than one battery...

What i have done is dedicate a battery to a task. So for example, i've got one battery for lights, pumps etc and one battery for the eberspacher.

Alternatively, use a very big switch (like a battery isolator switch) to switch a battery in and out of the circuit. Bit of pain but it means that you get the most from your batteries.

Alternatively again, spend the money on a very big solar panel charger that will keep the battery charged.

HTH's

Ringo

Cheers Ringo.

Already have a 4 foot solar panel so the system is constantly charging anyway. However I need quite a bit of power to run everything else for any length of time.

I also have the backup of the genny but at 6.5kw I've been told they use nearly a gallon of fuel an hour. Bit rich for my blood just to watch tv etc.

Dedicating a battery to task is a great idea for a camper but just too complicated in the RV.

Cheers

Martin

kevtherev wrote:Edmundson Electrical
Rexel Senate
City Electrical Factors (C.E.F.)

These companies usually have trade counters and deal with large cable, wire and give good advice.

I would use 10mm copper.
unless B&Q do it

Cheers Kev.

I'll give them a try.

shame you have the leisures now I would have looked at Traction batteries for the sort of usage you need.
eye wateringly expensive but double the life (10 years) and oooooodles of power without the need for recharging so often

Yeah I did think about traction batteries but just can't justfy the cost for the amount of time I'll be spending without a hookup.

The leisures should be ample. Like I said I've always got the genny as a backup. I can aways run that for a couple of hours to recharge the battrries if I manage to flatten them. Plus the solar panel so I reckon 5 leisure batteries should be more than ample.

As others have said....a large bank of batteries can be difficult and often troublesome to keep. The issue is around keeping all the cells equally charged and the damage one failed battery can do to the other good ones.
There are ways to minimize the problems, special charges, diodes but all very expensive.
If you are set on connecting them all in parallel then charge them individually from time to time, check the specific gravity of each cell routinely (the most accurate way of checking charge state and an early indicator of a failing...dead cell) 1.280 SG = full charge ---- 1.150 SG flat.
The actual leasure amp draw is probably alot lower than you might think but the worry for me would be connecting these to the existing split charge system and the FRIGHT! that circuit is going to get after 3-4 days without mains.

It might also be a good idea to have a Maxi fuse between each battery in case of one having an internal short.

Martin....whats going to be charging these on mains....and same question, when running?

Martin

Red Westie wrote:As others have said....a large bank of batteries can be difficult and often troublesome to keep. The issue is around keeping all the cells equally charged and the damage one failed battery can do to the other good ones.
There are ways to minimize the problems, special charges, diodes but all very expensive.
If you are set on connecting them all in parallel then charge them individually from time to time, check the specific gravity of each cell routinely (the most accurate way of checking charge state and an early indicator of a failing...dead cell) 1.280 SG = full charge ---- 1.150 SG flat.
The actual leasure amp draw is probably alot lower than you might think but the worry for me would be connecting these to the existing split charge system and the FRIGHT! that circuit is going to get after 3-4 days without mains.

It might also be a good idea to have a Maxi fuse between each battery in case of one having an internal short.

Martin....whats going to be charging these on mains....and same question, when running?

Martin

Cheers Mart but most of that was Greek to me.

When on hookup the RV has a built on charge system which charges the leisure battery (or batteries as it was originally had 2 but now only one.)

It also charges from the solar panel whether on hookup or not.

When driving there is a switch on the dash which links the driving battery to the leisure. Sort of a maually operated split charger.

I'm sure there's some sort of jiggery pokery which manages it all and other RV's have several batteries connected without trouble so I'm sure it's designed to take it.

OK....so the jiggery pokery (mains) is going to effectively 'trickle charge (slow charge) this mass of cells. I say slow charge because even a heafty 16 amp unit split over 5 batteries (30 cells) 550ah is only tickling the cells but as a 'constant' this isn't a bad thing. Ideal charge is generally regarded as being 1 tenth the amp hour value (55amp) but I can't see your RV having anything like that, I'm guessing 20amps at best.
How sophisticated this charger is (whether it is staged and turns on to float charge when it senses full charge state) either way there will be a lot of constant activity and the cells will use a fair amount of water (depending on what type you have bought). Good old fashioned lead/acid cells which have removable caps may use more water but at least the cells can be topped up and maintained.
The weak pont will be the amount of 'initial' current demand put on the alternator after those five batteries have been run down. At least by your description there is a mechanical switch 'engaging' the split charge circuit, this is a positive as the wiring is likely more robust.
I think we also have to bare in mind that this is a humungous RV that must have been prepared (designed) for such use, so all the associated circuits and switches must be man enough for the job.

Martin

California Dreamin wrote:OK....so the jiggery pokery (mains) is going to effectively 'trickle charge (slow charge) this mass of cells. I say slow charge because even a heafty 16 amp unit split over 5 batteries (30 cells) 550ah is only tickling the cells but as a 'constant' this isn't a bad thing. Ideal charge is generally regarded as being 1 tenth the amp hour value (55amp) but I can't see your RV having anything like that, I'm guessing 20amps at best.
How sophisticated this charger is (whether it is staged and turns on to float charge when it senses full charge state) either way there will be a lot of constant activity and the cells will use a fair amount of water (depending on what type you have bought). Good old fashioned lead/acid cells which have removable caps may use more water but at least the cells can be topped up and maintained.
The weak pont will be the amount of 'initial' current demand put on the alternator after those five batteries have been run down. At least by your description there is a mechanical switch 'engaging' the split charge circuit, this is a positive as the wiring is likely more robust.
I think we also have to bare in mind that this is a humungous RV that must have been prepared (designed) for such use, so all the associated circuits and switches must be man enough for the job.

Martin

Thanks Martin.

I think you're right. The charge system must be at the very least sophisticated enough to sense full charge and cut off becaused it's designed to trickle charge the leisure battery's when on hookup or with the generator running. It also has an lcd readout which tells me the current voltage and the voltage that the solar panel is putting in. As you say there will be constant activity on the batteries. Even when on hookup all the lighting etc runs on 12v from the leisure and the batteries constantly monitored and charged. So at leat the batteries are constantly active and will not stagnate. I think being stood probably kills more batteries than anything else.

Cheers

Martin

Right then...this is how the the insane do it....Assuming battery terminals are the threaded type.
Put your batteries in a row and measure the distance between the outside terminals. (say 750mm for example) .
Go to plumbers merchants and buy twice this length of 15mm copper pipe.
Beat it flat with big hammer.
Drill holes in copper to line up with battery terminals.
Tape up the rest of the copper with pound shop electrical tape...one red, one black.
Bolt positives together with the red one and the negatives together with the black one .
You have now made one big battery.
Keep it charged with cheapo charger from halfords (£50) that has voltage display and can be left permanantly connected.
Use and abuse for 2 to 3 years then replace batteries as they will be about shot and cheapo new ones are only about £80 a go.
Been working perfectly on the boat for the last god knows how many years...
Give me a ring mate if you want more bad advice from someone who actually uses this kit day to day.....
Loads of info on the boating forums about this too.

yep sounds good to me
then when they are shagged get the traction batteries, you wont need as many either.... tight wad

Andy, Julie, & Bobdog wrote:Right then...this is how the the insane do it....Assuming battery terminals are the threaded type.
Put your batteries in a row and measure the distance between the outside terminals. (say 750mm for example) .
Go to plumbers merchants and buy twice this length of 15mm copper pipe.
Beat it flat with big hammer.
Drill holes in copper to line up with battery terminals.
Tape up the rest of the copper with pound shop electrical tape...one red, one black.
Bolt positives together with the red one and the negatives together with the black one .
You have now made one big battery.
Keep it charged with cheapo charger from halfords (£50) that has voltage display and can be left permanantly connected.
Use and abuse for 2 to 3 years then replace batteries as they will be about shot and cheapo new ones are only about £80 a go.
Been working perfectly on the boat for the last god knows how many years...
Give me a ring mate if you want more bad advice from someone who actually uses this kit day to day.....
Loads of info on the boating forums about this too.

I like it.

Unfortunately the connectors are the round type which take clamps and the charger is a built in system. Also I need to fit the extra batteries in a side locker a couple of feet from the main leisure battery so flexi cable is the only way to go.

Apart from that, a good plan.

kevtherev wrote:yep sounds good to me
then when they are shagged get the traction batteries, you wont need as many either.... tight wad

You know mw so well.

I may indeed invest in some traction batteries the next time around, but the ones I've got have a 4 year guarentee so it won't be for a while yet.

Cheers

Martin