Leisure battery charging

Post by **airhead** » 13 Dec 2007, 09:32

Someone very kindly gave me a leisure battery last weekend that he wasn't using. Its a proper leisure battery now, not a standard car battery. Its rated at 85ah so its pretty beefy. I stuck it on charge on monday night and its stayed on charge up until now and its still not full. It was completely dead when I got it. What I would like to know is, my charger is rated for use with batteries of between 25 and 50ah. Does this mean that it will never be fully charged with this charger or whats the story?

Post by **Westy.Club.Joker** » 13 Dec 2007, 16:18

Charger really isn`t up to the job, AND it needs to be a type that will charger leisure batts (usually have a selector switch for the different types)

If it was totally pancaked, then it may not come back, or you may need a specialist charger that will bring it back from the dead, like an Optimate or C-Tek charger.

Post by **airhead** » 13 Dec 2007, 17:27

Its got a bit of juice in it now. I measured it last night and there was a half decent 11.8v. Maybe I'll leave it on for another while and then bang it into the van and it should finish it off.

Now, next question.... I already have a standard car battery in my leisure circuit. Can I parallel the 2 batteries to get the extra 50ah out of the car battery as well, or will this be bad for the leisure battery?

Post by **Westy.Club.Joker** » 13 Dec 2007, 18:44

Not a good idea to mix battery sizes and types from the same charging system, the smaller or worse condition one will pull the good one down.

Have you got an on-board charger (camper conversion) or just the split charge from the alty?? As long as the 2 batteries can remain independant of each other via a relay then it may work, but it`s always advised against when you read up on it, so there may be something in it.

The standard van alty will never fully charge it, they don`t put enough into the battery to get it up to a proper state of full charge, unless you spend a mint on a fancy (read expensive) independant electronic regulator, that will do a similar thing to what the modern 3 or 4 stage battery chargers do.

Post by **airhead** » 13 Dec 2007, 22:47

I saw those battery charge conditioners before. Theyre great but fiercly expensive as you said. My split charge system is a little cleverer than a relay. Its a 2 way diode pack. The main feed comes from the alternator and into both batteries via the diode pack so neither batteries are ever connected to each other. It also has a thermal and overload trip out function. The great thing about this system is there are effectively 2 entirely independant electrical systems which never meet, regardless of whether or not the engine is running. I also have a 90A alternator. You sure this system won't give the battery a good charge?

Post by **Westy.Club.Joker** » 14 Dec 2007, 20:02

From what I`ve read about it, it`s to do with the alty regulator not allowing a proper full voltage through to top off the batteries to a fully charged state, it`s the last 5 or 10% bit that makes all the difference.

I`ve got a modern 3 stage charger fitted in my `van, works from the hook-up, and charges both batteries. If I leave it hooked up for a few days it fully charges the batts, then goes into "float" or maintenance charge just to keep `em topped. I have a C-Tek charger, so connected that to the leisure batts, to see what it would find after using the on-board charger, and it switched to charge straight away and continued to charge for another day, until it showed fully charged

Seems the C-Tek chargers can get that last bit in the battery, which can make all the difference when things like the Eber will fail to work when voltage drops just a bit to much.