2 leisure batteries

Post by **timthetrader** » 04 May 2007, 08:57

As my leisure battery is under the passenger seat and its not really a leisure as there is limitted space I,ve wired a second one via the zig unit so when I'm driving Im charging 3 battieries. Ive put a in line fuse on all the batteries. Has anyone else tried this and does anyone know of any probs I,m likely to have?

Post by **Mocki** » 04 May 2007, 09:12

your alternator has no chance of effectively charging three batterys, you will have three nearly charged batterys!

let us know what happens, just for the recordÃ‚Â¬!

Post by **timthetrader** » 04 May 2007, 10:16

What I thought I could is plug the van in to the mains the night before and charge all 3 with the mains zig. Then when I setoff for a week I would be full charged, But I was wondering if I should put an issolator switch between the 2 leisures1 I will let you know what happens!

Post by **normalbloke** » 06 May 2007, 18:31

I beg to differ.I have 2 leisures, and one starter battery.
The alternator charges all sufficiently.Just do the maths.For arguments sake, if all batteries are of the same capacity, it'll just take twice as long to charge if you have 2 leisure batteries, as opposed to one.

Post by **andysimpson** » 06 May 2007, 18:41

I also have 2 leisure 110ah each and starter battery with no problems at all.

Post by **tonytech** » 06 May 2007, 19:14

OK. Maths.
In an ideal world.

According to my information 45 Ahr and 65 Ahr alternators were origionaly fitted. Some folk have fitted uprated 95 Ahr units.

Batteries are complex beasties and dont charge in a linear fashion.So the following is a very rough approximation.

A 65 Ahr battery should take an hour to charge with a 65 Ahr alternator (running at 2500 + revs)
To charge 2 110Ahr batteries + a 45 Ahr starter battery ( 265 Ahr)
will take over 4 hours.

Now as said batteries dont play simple math so you are looking at about 6 hrs of driving.
So when you start up the alternator will start supplying current to the batteries, the flatest will take the most, leaving your starter battery weakend.

If your batteries are old or the alternator worn then the charging times will increase dramatically.

T

Post by **timthetrader** » 06 May 2007, 19:24

Well all seems fine! The main probs with autohomes the leisure battery is under the passenger seat and as your limited for space the is normally a car battery not a leisure and as such only lasts a night/day in the winter if your running a heater (propex) so by George I think we,ve cracked it!

Post by **kevtherev** » 06 May 2007, 19:45

tonytech wrote:OK. Maths.
In an ideal world.

According to my information 45 Ahr and 65 Ahr alternators were origionaly fitted. Some folk have fitted uprated 95 Ahr units.

Batteries are complex beasties and dont charge in a linear fashion.So the following is a very rough approximation.

A 65 Ahr battery should take an hour to charge with a 65 Ahr alternator (running at 2500 + revs)
To charge 2 110Ahr batteries + a 45 Ahr starter battery ( 265 Ahr)
will take over 4 hours.

Now as said batteries dont play simple math so you are looking at about 6 hrs of driving.
So when you start up the alternator will start supplying current to the batteries, the flatest will take the most, leaving your starter battery weakend.

If your batteries are old or the alternator worn then the charging times will increase dramatically.

T

very useful stuff there mate thank you...
uprating the alternator to 90A/h and good batteries would help the charging speeds?

Post by **"WEAZLECHIN"** » 06 May 2007, 21:50

if one is knackered or in a worse condition that the other two, the whole system will only be as good as the worst battery.

Post by **normalbloke** » 07 May 2007, 18:56

I have 2 identical leisures,wired in parallel,as such the alternator only sees one large AH battery.

It works.

Simple.

Post by **"WEAZLECHIN"** » 07 May 2007, 20:19

if only it was as simple as that???? the alternator actually sees a load, good or bad! by the way its 3 batteries, what do you start the van with?
in simple terms theyre all working as a team, and a team is only as good as its weakest member

and that is in SIMPLE terms.

Post by **ringo** » 07 May 2007, 20:27

I've got three leisure batteries and one engine battery. Had them for about two years.

I must say i've never had a problem with the batteries charging at all.

However, mines a diesel and the engine battery is in the engine bay - this makes a difference...

Due to the length of the wires to the liesure batteries from the split charge relay, there is a considerable voltage drop to the liesure batteries - the leisure batteries charge at 12.8 volts, as oppossed to 13.6 on the engine battery. This difference means that the engine battery gets topped up faster.

Some of the more up to date electrically guys on here (Irish Dave for one) have recommended a diode in the split charge circuit. This takes care of such volt drop (0.7volts for a silicon diode).

Theres loads on this subject...

I must re-read this thread when i have a moment..

http://forum.club8090.co.uk/viewtopic.p ... sc&start=0

HTH

Ringo

Post by **"WEAZLECHIN"** » 07 May 2007, 21:21

they must all be good batteries then. its not rocket science

Post by **irish.david** » 08 May 2007, 07:16

Batteries work as a sum of their parts. If you've got a bad battery in a three battery system then you'll only effectively have 2 1/2 batteries but the duff battery won't drag the others down.

That is unless it's shorted across all its cells and then you'd have bigger problems than just one bad battery....

Dave

Post by **"WEAZLECHIN"** » 08 May 2007, 08:03

but its not going to be good while charging, if the duff battery is replaced with a new one the other 2 batteries will recieve an equal charge, at the moment the problem is that his leisure batteries wont charge. same problem that i recently encountered. my leisure battery was always half flat but was new and my engine battery was old and failing so i replaced the engine battery(because it was taking all the alternator charge) anyway both batteries are now always fully charged.

unless ive been using 240v gadgetry through the inverter.