Split charge

[Ollie]

I currently have a diode style split charge system. It's working well, but after buying and fitting a battery moniter, I can see that I'm not getting enought juice back into each battery. There must be a voltage drop through the diodes.
Is it possible to get an up-rated alternator? If so, where from?

Cheers
Ollie

[turtle]

Ollie - Give these guys a call M.K.S on 01908 225494, they supply people like Joe Edwards and Coyleys with Alternators and starters. Prices are good, They uprated my alternator and fitted it. Give them a call :)

[Bob696]

I stand to be corrected on this but wouldnt an uprated alternator just give you more current rather than volts? You would still get a 0.6V drop across the diode.
It would be cheaper to ditch the diode and get a relay instead.

[muddyweb]

Spot on Bob... an uprated alternator won't help unless you get one with proper battery sensing and external control.  (and that's a lot more money)

That 0.7 volts sounds like a small amount, but as a percentage of the charging voltage, it is significant.   The same thing applies to keeping the batery connections clean and secure... a volt here or there makes a massive difference.

[Ollie]

I stand to be corrected on this but wouldnt an uprated alternator just give you more current rather than volts? You would still get a 0.6V drop across the diode.
It would be cheaper to ditch the diode and get a relay instead.

Ahhh, yes, your right Bob.
So, ditch the diode setup then, and replace it with what?
The diode setup was simple, (and cheap)???

Ollie

[Bob696]

http://www.vehicle-wiring-products.co.uk/VWPweb2000/relays/relays.html

There is a 180 amp relay in there for £12, 70 and 30 amp for £5

connect the 2 posatives together via a relay and the switch voltage to something that only comes on whilst the ignition is on. ( I THINK thats right)

[pondy653]

Hi all,
the time I have spent researching this is shocking.
If you use the ignition switched method you have the potetial to dischage your starter battery if the second battery is flat prior to starting. I have used the triger method using the ind wire to energise a small diode protected relay (back EMF can wipe out your voltage reg in the Alt) which in turn pulls in a 150amp solonoid (gives me extra capacity when winching) which connects the batteries together. I have had this system running for 6 months now with no problems at all. It cost about £20 and about 1 hour to install.
I have now fitted a second alternator from a Mk6 escort (changed the pulley) in the space where the air con pump fits on a 200Tdi Defender this is triggered by and feeds the second battery (the theory being if I loose one I will always have the other and second hand ones are a bloody sight cheaper than 1 x 130 amp)  http://www.kampenwagen.co.uk/Split%20Charge.htm may help
Hope this has helped??

[130alan]

The solution depends on why you need split charge.  If it is for winching, then it's cheaper to buy two new batteries of exactly the same spec. to replace the existing battery.

Then join + to + and then - to - of these batteries to each other using very thick wire - the same size as used for a winch or starter motor.

Then refit the vehicle live to one battery +ve and the vehicle earth to the -ve of the OTHER battery.

If like me you have an extra 270Ah and extra 75Ah battery then look at http://www.sterling-power.com for their solution.

Alan

[Ollie]

Cheers chaps.
As it seams, the diode split charge system isn't the best, and after a while, my batteries will fail. Currenty, to counter this, I have been charging the batteries periodically. Not ideal at all to be honest, but will have to do until I can sort out a way of over-coming the voltage drop!
The links to the two articals were execellent, thanks.

Ollie