Split charging with early dynamo and split diode

[john matthews]

Hi Folks, I've been shying away so far from asking my '68 dynamo to charge a leisure battery as well as my starter battery.
But it would be nice.

I have a 110ah leisure that I charge from the mains before a trip and from hookup should I get it.
It runs the radio, fridge ignition (not the cooling, just the lighter), LED lights and a sinewave inverter.

I bought a split diode from a Landrover place on ebay for a tenner (looks brand new in packing to me) but in two minds whether to fit it or not.
Don't want to compromise the main battery for the sake of some convenience.

If I split the charge to both batteries, could it affect the charging of my main starter battery ? Not sure what voltage loss the diode will take , or how charging two batteries affects the charge voltage to the main ? Especially if the leisure is quite low if we've been going nowhere for days.

If I drive home with a low leisure, say 70% charge, will my main not get any charge 'til the leisure comes back up ?

Thanks you clever people

 

[sharky71]

as far as i am aware the liesure battery will only come into charge after the vehicle battery is fully charged,only then will the relay trip and let the liesure battery take any charge.
that's how mine is wired in after i talked to the local vehicle sparky's by me.

 

[BJ1]

Yep - that's how it works! I have a couple of split charge set-ups using dynamos and they work very well. One of the LBs is at least 6 years old and still going strong so the split charge unit isn't punishing it. The starter batteries are always full after a run so no issue there. Get on and fit it

Brian

 

[bac2ba6]

I just use a bog standard 4 pin switch over relay about £3 from any motor factors which is charged via a dynamo , when ignition is on the relay flips to split the charge and when the engine is off the relay flips back thus not allowing the main battery to be come discharged while useing the leisure battery , been useing this system for years and never had a problem and the dynamo charges both quite nicely when on a good run

 

[john matthews]

Thanks guys

I have a diode from sterling products, rather than a relay

but sounds like I should be ok to charge both batteries from a dynamo

The diode means the two batteries are never connected so no problem drawing off from main

sounds like the cheap option will be fine

other option was to fit a battery to battery charger like this

http://www.ebay.co.uk/itm/221126791347?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2648#ht_608wt_1139" onclick="window.open(this.href);return false;

I'm sure they're great, but if unnecessary then they are also expensive !

thanks folks

 

[mattd]

Thanks guys

I have a diode from sterling products, rather than a relay

Same here, I ran mine off the dynamo for about 6 months then went alternator (for no particular reason) without issue. The only problem I have had is I cooked the leisure battery when I left the charger attached on 'supply' mode this summer.

 

[john matthews]

Spoke to Peter at Sterling products yesterday who advised me not to use the split diode I'd already bought with such a low powered generator, that the voltage drop across the diode would compromise headlight brightness (!), lucky I only paid a tenner for it.

So hanging on for a Sterling battery to battery charger s/h off a well known online auction site instead.

cheers folks !