Battery to battery charger

[stephen t25]

Hi all, spotted this and wondered what people thought to charge my leisure battery up, a lot cheaper than a sterling charger, I run a engel compressor fridge and the split charge system I've got does not work very well, any thoughts or ideas.?

Thanks..
http://www.ebay.co.uk/itm/230617138411? ... 1423.l2649" onclick="window.open(this.href);return false;

[HarryMann]

Think if you search Syncro or Syncro archives you'll find a fair bit of discussion of bat2bat and specialist chargers...
Using Advanced Search I'd try authors syncrosimon or lloydy or v-lux...

[v-lux]

I think in reality the Sterling stuff is probably cheaper if you compared it spec for spec.
That unit provides 12A output which is considerably lower than the output from your alternator. Unlike the Sterling battery to battery units it does not appear to have anything that amplifies/controls the output going to the leisure circuit.

I would guess that the unit on ebay is probably a split charge diode and voltage sensing relay in a fancy box. The problem with unit's like this is that they will create a voltage drop across the diode giving you an insufficient voltage for charging. I tried a set up much like this and found that any voltage drop in the system will cause your batteries to never get an adequate charge, eventually resulting in your batteries failing.
Personally, if i was going to spend about £100 on a simple set up to look after a split charge i'd probably get one of these: http://campervanculture.com/shop/sterli ... 2x-output/

[stephen t25]

looks like good piece of kit, I have my leisure battery under my drivers seat and and my main under the passenger, if I use this to wild and camp for 24hrs with the Engel fridge on will it be able to charge the leisure properly once it's flat as I run the engine to the next destination, as my current system won't charge a flat battery ?
Sorry if this is a silly question

[Oldiebut goodie]

You are most probably running your battery below it's limit - that's why your current system will not recharge it. You need to rethink your use of power and adding solar panels would help. But all said and done you are using a tiny leisure battery of roughly 85Ah which will give you around 40Ah to use. If you are using say 2A to run this fridge (you don't say what model) you don't have a lot to play with for music/tv/lighting etc. For wild camping I use a 110Ah battery in my VW (just for the odd night) and 220Ah in my Merc for a month or two. Both backed up with solar panels.

[AdrianC]

That unit provides 12A output which is considerably lower than the output from your alternator.

You sure about that? 12A @ 14v is 168w. IIRC, 90w alternators are the biggest standard fitting for our vans.

[Oldiebut goodie]

Strange - they originally came with 45A alternators. Not 90w!!! Try 90A!!! 90w alternators wouldn't light a fart let alone run a van!!

[AdrianC]

Strange - they originally came with 45A alternators. Not 90w!!! Try 90A!!! 90w alternators wouldn't light a fart let alone run a van!!

You're right. Brainfart this end.