Split charging system good one?? HOW?

[dark legend]

The only 'proper' way to do it is with a DC-DC Battery to battery charger like this one: http://www.sterling-power.com/products-battbatt.htm

But a split charge relay and similar capacity batteries will give you a close enough system for a lot less pennies.

I'm knackered because I use 2 110Ah leisure batteries in the camper and 2x85Ah starting batteries in the van, so really I need something like the above to do it properly, at the moment I just charge leisure batts off the mains as 2x110Ah last pretty well even running the LCD TV off an inverter for a few days, lights, pump etc. It would be nice to charge up as you drive, but for £300 i can buy a lot of petrol for the genny! Going away racing you tend to spend the whole weekend parked up anyway so running the engine just to charge the batts is a false economy vs. generator and charger.

Hopefully the charger will survive on the dirty mains from the genny...

Still looking to fit a relay for the fridge 12v though, just to keep it cool while travelling.

[matjammeg]

hi i used the same drawing as shown to do mine twin battery set up
i also have 2 solar chargers connected to my batteries to trickle charge them,
Solar-Powered 12V 1.5W Battery Trickle Charger only £12.99 which came from maplins
http://www.maplin.co.uk/Module.aspx?ModuleNo=98358
you could also use this from maplins

http://www.maplin.co.uk/module.aspx?moduleno=37767

Lead Acid Battery Split Charge Module
only £8.99

Order Code: N73AU
In Stock*

Charges 2 sealed lead batteries from the same power source
Ideal for use in motor homes, boats and caravans
20A maximum
Using this module it is possible to charge two 6-24V lead acid batteries (e.g. car batteries) from the same power source. The charging current is distributed in such a manner that a discharged battery is charged more intensively than a battery which is almost charged. Ideal for use in motor homes, boats or caravans where the TV, radio, etc. is operated from one battery and the second battery must remain charged for starting the motor.
but i cant swear by it as ampage looks low
so many options available so choose carefully

[haggis21]

That's ok for knowledgeable boys like you Luke, but what is it for ? &/or why do I need it ?

[matjammeg]

the link wire is what switches the relay on to charge the second battery.
ie when the light goes out on the dash it switches the coil on the relay to on,
(clever electric circuitry)
trust us it works
my second battery has never gone flat yet and it powers all the 12v electrics in back of my van ie 12v lights,amp,240-12v invertor for ps2 and flat screen monitor for kids
but the other battery for main starting went flat over xmas due to cold and standing idle for 2 months,jump lead across positve to positive and it started no problem
i have now put another solar charger to trickle battery during daylight hours and now problem cured

[Luke]

That's ok for knowledgeable boys like you Luke, but what is it for ? &/or why do I need it ?

think of it as an automatic switch that when the engines running (and charging) it connects both batterys together

when the engine is off it splits them so the one you are using (back) can go flat without flatening the front one

[Terry]

Hi
I have a split charge system that charges the trailer battery (as it would a caravan) and am having the 2 battery relay thingy from Maplin fitted (into that circuit) next week, (more than 2 wires & I get confused ), so I can charge the underfloor battery (for the electric winch & hot water for the sink), I have had 2 solar chargers (12 watt ?) connected to the underfloor battery & they just don't work. Its just permanently flat.Thats in the tranny.
I had a small 1.5 watt (as shown) solar charger connected to the car battery when we went on holiday (3 weeks) and it was flatter than a witches t*ts when I came back ! Much as I would like to be wrong but using solar power for generating electricity just don't seem to be any good/work. A friend has 3 large (water fed) panels on his farmhouse roof (in Italy) and he reckons they do ALL his hot water no problem.

[Jackals]

I'm sorting my split charging system out this weekend!!
i have one 180amp battery...i have one very inteligent relay...

basically... i'm going to run a good sized cable from starter battery... With a 30amp fuse near the starter battery just incase of a short.
Its going to run into a Split Charge Intelligent box thingy that i bought from my auto electricans the 12v charge wire goes through this box and the box is also earthed..
The box will only start charging the aux batterys when the starter battery has got to a certain voltage... If no charge is going into the starter battery the system will cut off from the aux batterys...

Hopefully it should work... Easyer system to wire i think... and £34 for the box...

Jack

[Savagator]

the link wire is what switches the relay on to charge the second battery.
ie when the light goes out on the dash it switches the coil on the relay to on,
(clever electric circuitry)
trust us it works
my second battery has never gone flat yet and it powers all the 12v electrics in back of my van ie 12v lights,amp,240-12v invertor for ps2 and flat screen monitor for kids
but the other battery for main starting went flat over xmas due to cold and standing idle for 2 months,jump lead across positve to positive and it started no problem
i have now put another solar charger to trickle battery during daylight hours and now problem cured

Hi guys, newbie on here do go easy! Lol.
I know this is an old thread, i'm obviously being a bit thick, but how does the light know when to go out and how? If that makes sense? Thanks

[robbie.cee]

It doesnt. The lamp on dash is connected between the + on battery and the + output of alternator.
So when engine not running the battery + feeds into lamp in dash and goes out to the (currently) dead alternator which gives enough of a continuity to earth to illuminate the lamp.
When engine runs the lamp gets + from battery one side and + from (now running) alternator so it goes out as its getting 12v in both sides.
Simples!!!

[robbie.cee]

Most reliable way but needs at least 60amp fuses 30 would pop if leisure battery depletes then tries sucking all the power from main battery when relay energises...
Also needs thick wire to and from relay ideally 100amp amd get a 100 amp 12v relay for 6quid on eBay

[mistericeman]

Just fit one of these between your starter battery and your AUX battery....

http://www.ebay.co.uk/itm/191899198454

Automatically senses when the starter battery is fully charged before allowing the AUX battery to charge.

I use one to keep the 3 X 100ah leisure batteries topped up (as, well as having 2 100w solar panels) the split charge relay will also kick in IF the solar is charging and the starter battery is low.

only 3 wires to connect and foolproof