can i overcharge my leisure battery

pongo69

can i overcharge my leisure battery from my split charger if i am driving for 5/6 hours where does the overcharge current go when the battery is fully charged all that is a draw when driving is the fridge

crabbypaddy

pongo69 wrote: »

can i overcharge my leisure battery from my split charger if i am driving for 5/6 hours where does the overcharge current go when the battery is fully charged all that is a draw when driving is the fridge

Depends on the battery, temperature, alternator, wiring etc.

Most van alternators put out 14.4v max thats not much of an issue if you have a flooded battery as long as you keep your battery watered.

It can be an issue with sealed batteries over long periods but if you have a diode isolator in your slit system then the voltage drop across that makes overcharging with alternator very unlikely.

fergal.b

Another problem with over charging is that the battery can produces hydrogen so have them vented to the outside also most CO alarms will pick up hydrogen so worth having one if you don't already.





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pongo69

pongo69 wrote: »

can i overcharge my leisure battery from my split charger if i am driving for 5/6 hours

...not likely. It takes days to charge a battery a few hours won't do it any harm.
It's nigh impossible charge a deep cycle battery with an alternator let alone overcharge it.

pongo69 wrote: »

where does the overcharge current go when the battery is fully charged all that is a draw when driving is the fridge

The alternator throttles and just runs the loads. There's no overcharge current only spared horse power.

14.4V is ambitious for a 50m of light cable running a fridge. High thirteens usually.

crabbypaddy wrote: »

...if you have a diode isolator in your slit system then the voltage drop across that makes overcharging with alternator very unlikely.

It would also make charging very unlikely.
Have I thought you nothing?

crabbypaddy

crabbypaddy wrote: »

Most van alternators put out 14.4v max

Should say that if you've converted a mk6+ transit afaik those have a smart alternator so you could have very high voltages when the pcm detects cold starting and a low battery and when the flimsy wiring to the 3 pin connector on the alternator goes it defaults to 14.7v. I think the latest sprinter has smart alternator too.

Sir Liamalot wrote: »

It would also make charging very unlikely.
Have I thought you nothing?

I wasn't suggesting he buy one afaik its a diy conversion so may have one fitted. Most diode isolators are schottky diodes now so the voltage drops are more like 0.3v-0.35v at a couple of amps to 0.45V-0.6V at full rating. Might even be desireable if you had crappy gel batteries :P

It's not the forward drop it's the combination forward drop and no alternator feedback and an asymmetric battery....asking too much of a simple alternator regulator.

I managed to run at discharge with enough loads on while driving before I abandoned series diodes in charge circuits.
I saw 60A today across a relay...Mwahaha!

...yes smart alternators are a bother...best put a dumb one beside them :pac: