Battery issues

[Fab5Freddy]

Hi all - had a van for almost a year and previous owner had mentioned that because van wasn't in constant use, the battery had gone flat and AA replaced with a new one not long before I bought it. Never thought much about it really. So,quality Bosch battery 1 year old in there.(70aH)

Just been out for a run of 200 miles the other weekend and returned to the van this week to a flat battery (I think, it's on charge now)

So, none of that makes any sense to me. However, this is where it gets more complex and I am out of my depth on it. The van has a leisure battery at back for12v stuff. The other weekend I went to use it and realised I had no read-out on the panel for leisure/12v.(normally when switching on it gives readout of output) Didn't have time to do anything about it and thought I would look this weekend when I had more time, and presumed I'd loosened the connection when the plastic panel moved a bit or something.

Now, I do not know the relationship between these 2 batteries and if the two issues are related?

I wonder if anyone has any ideas that I can try before I call out breakdown for a home start and see if they can see where it's going wrong.

 

[nitro23456]

Normally a leisure battery is charged via a split charge system using a volt sensing relay that opens the circuit to charge the leisure battery when the engine is running. That way both get charged via the alternator and when the engine is off the leisure battery is isolated.

I would check the relay is switching correctly and if so then check what loads are being pulled from both batteries with the engine off using a multimeter. You might have something specific discharging the batteries to ground.

 

[Wayners]

Buy a Bluetooth monitor for battery and put app on phone. Fitting is easy 5 min diy job. Will monitor charging and crank voltage and general battery health.
With my van crack voltage was killing battery as starter was pulling too much. Had 3 batteries in 3 years but swapped starter and this current battery is 3 years old and still going.
Bluetooth monitor picked this problem up and sent notification to phone. Best £25 I spent

 

[Fab5Freddy]

Normally a leisure battery is charged via a split charge system using a volt sensing relay that opens the circuit to charge the leisure battery when the engine is running. That way both get charged via the alternator and when the engine is off the leisure battery is isolated.

I would check the relay is switching correctly and if so then check what loads are being pulled from both batteries with the engine off using a multimeter. You might have something specific discharging the batteries to ground.

Cheers - yes, just got my paperwork out and it is a split charge system. I'll check the relay for it (if I can find it)

 

[Fab5Freddy]

Buy a Bluetooth monitor for battery and put app on phone. Fitting is easy 5 min diy job. Will monitor charging and crank voltage and general battery health.
With my van crack voltage was killing battery as starter was pulling too much. Had 3 batteries in 3 years but swapped starter and this current battery is 3 years old and still going.
Bluetooth monitor picked this problem up and sent notification to phone. Best £25 I spent

Sounds like a handy thing. I'll get on to Amazon now and have a look

 

[ericmark]

Years ago we used a pair of diodes so dynamo could charge two batteries, however the 0.6 volt drop with an alternator could not be compensated for, so we moved to the split charging relay.

However a lead acid battery with float charge at 50% discharged takes around 2 days to charge, so OK if battery not often discharged, but in the main we need to speed up the charge rate of the leisure battery, two methods, stage charging and pulse charging.

Stage charging charges at around 14.8 volt until around 80% charged then reduces voltage, but 14.8 volt too high for a lot of 12 volt equipment and also can't be sure will drop voltage if used at same time as being charged.

Pulse charging monitors how the volts drop between each pulse so better when battery being used while being charged.

So we use a battery to battery charger, so leisure battery charged at higher rate to engine starting battery, so it turns DC to AC transforms it up then back to DC at a higher voltage. This is essential with stop/start cars as the alternator does not charge all the time, only on over run so split charging the old way does not work.