Leisure battery won’t charge now it’s low.

[Craig T6]

Hi all, I’ve just been told by the conversion company that did my T6 that I can’t run down the leisure battery below 10 volts as if you do it won’t recharge itself is this normal? We ran a fridge from the battery overnight and it went down to about 5 volts and now the lights won’t work either and it’s stuck on 5 volts and won’t increase during driving. I took it back and they said you need to buy a charger and bring it back up using 240v. The battery is only 18 months old so shouldn’t be knackered as we’ve hardly used it.
I’m no electrician but clearly badly designed system if this is normal
Appreciate any feedback or help
Thanks
Craig

 

[Loz]

Yes AGM batteries have a floor of 10.6 volts, if it gets that low charge immediately.

I forgot about one I had in a portable pack and it was toast.

 

[Mud Digger]

hi Craig someone will be along shortly to reply and properly explain. Have you got the battery details and what the relay you have fitted to the alternator a smart charger will only charge to 80% relying on the breaking of the engine to top up the other 20% . you needed to take your van for a drive or run your engine at 11v from 13.7v full charge if your going to drain the battery that low you will only get about 500 charges out of a deep cycle battery. you only get 50% usage of the battery charge to actually use. you will need either a bigger battery if your fridge drained it over night or back it up with solar power and yes a 240v battery charger to bring it back up to full charge. don't leave it discharged for long t will damage it. finally was the battery fully charged before you used it there is limitations to the kit regards Nick

 

[Deleted Member]

The long and short of it is AGM batteries don’t like to be run completely flat, they won’t generally come back to full charge unlike the old lead/acid batteries.

Stick it on charge overnight in the garage, you might get lucky or at least get some charge back into it.

 

[Dellmassive]

Good advice above.

Your battery setup may not give you the run time you need when powering your fridge etc...?. Any 12v battery below 10.5v is dead flat... 0%.

So what LB battery do you have ?

How is it charged?... Do you have a DC-DC charger?

Any solar?

What fridge and lights are you running?

What battery monitor are you using to measure those 5v readings etc.
...


Post some pics of your setup.

 

[Ads_Essex]

Hi all, I’ve just been told by the conversion company that did my T6 that I can’t run down the leisure battery below 10 volts as if you do it won’t recharge itself is this normal? We ran a fridge from the battery overnight and it went down to about 5 volts and now the lights won’t work either and it’s stuck on 5 volts and won’t increase during driving. I took it back and they said you need to buy a charger and bring it back up using 240v. The battery is only 18 months old so shouldn’t be knackered as we’ve hardly used it.
I’m no electrician but clearly badly designed system if this is normal
Appreciate any feedback or help
Thanks
Craig

I think the converter’s get out clause here will be that the DC-DC charger won’t function if the leisure battery is flat, hence their suggestion of a battery charger. It seems like a badly designed system but it’s just that the charger needs to know the battery state of charge, and a flat battery can’t give that.
You’ll want a battery charger anyway, for times when the van is sat up. The post above will give you guidance on that element.

And as stated above, just so the best advice can be given out, do yourself a favour and post up some photos of your setup (l/battery, charger, 12v fuse board or power management system, and connections to the starter battery.

 

[MartinMc]

The best course of action is to charge the battery properly with a decent modern charger that has a recovery or repair mode as soon as possible and repeat a few times. Deep cycle batteries can recover to some extent, they also charge more effectively in mild temperatures so around 18C - 20C will give you strong fighting chance of rescue while you determine route cause. Hope this helps.

 

[Eclipse Custom Vans]

Hi all, I’ve just been told by the conversion company that did my T6 that I can’t run down the leisure battery below 10 volts as if you do it won’t recharge itself is this normal? We ran a fridge from the battery overnight and it went down to about 5 volts and now the lights won’t work either and it’s stuck on 5 volts and won’t increase during driving. I took it back and they said you need to buy a charger and bring it back up using 240v. The battery is only 18 months old so shouldn’t be knackered as we’ve hardly used it.
I’m no electrician but clearly badly designed system if this is normal
Appreciate any feedback or help
Thanks
Craig

It could simply be that the fuse has blown, if the battery is low, when charging a large current is drawn and the fuse can blow. Check that first and then bring battery up to a decent level and charge accordingly fron then on. Typically the fridges will cut out around 10v to protect the battery, so I assume you have an older fridge without this function.

Good luck

 

[Craig T6]

Thanks for the reply…here’s what I did.
I’ve charged the Leisure battery (LB) using a 240 charger but the so called “advanced charger” (bought new today from Halfords) kept cutting off, I think due the LB being too low (5.5v) Decided to start the engine and low and behold the C-tex thingy under the seat started to light up and flash it’s lights. Managed to get the LB up to 12v in a few minutes..so I’m assuming now all I need to do is drive for a few miles to get the LB to hold its charge of appx. 14v.
It’s a big learning curve..
Craig.

 

[Craig T6]

Thanks everyone for replying…I’ve read them all and will heed all advice. I’ll get some photos of the set up too
Craig.

 

[Deaky]

I’d be very surprised if you can get that battery to hold charge if it’s been that low, even if you can, a few miles isn’t going to touch it. Let’s assume it’s a 100ah battery, your CTEK can charge at 20ah max, even if your battery could continuously absorb 20 amps per hour till it was full (which it can’t) it would take 5 hours to fully charge.

 

[Deaky]

If it is now accepting charge, put it back on your smart charger and leave it 24 hours

 

[Spaghetti]

It could simply be that the fuse has blown, if the battery is low, when charging a large current is drawn and the fuse can blow. Check that first and then bring battery up to a decent level and charge accordingly fron then on. Typically the fridges will cut out around 10v to protect the battery, so I assume you have an older fridge without this function.

Good luck

That happened when my converter used a relay. Battery was very low, and it took out a 40a fuse! Threw the relay in the bin and fitted a CTEK and a new battery.

 

[Craig T6]

Hi there,
The indicator reads 7.34v 2 minutes ago, lunchtime today it was reading 12v after I charged it for about 40 minutes So do you think the LB is damaged and not holding charge?
I haven’t driven the van either and all lights are off etc..

 

[Craig T6]

Thing is the charger only wanted to work when the van was running .. otherwise the charger cut out and the red light around the battery symbol lit up..

 

[Deaky]

Hi there,
The indicator reads 7.34v 2 minutes ago, lunchtime today it was reading 12v after I charged it for about 40 minutes So do you think the LB is damaged and not holding charge?
I haven’t driven the van either and all lights are off etc..

It’s fubared

 

[Craig T6]

If it is now accepting charge, put it back on your smart charger and leave it 24 hours

The charger stopped charging after about 2 minutes, it cuts off. But stayed on when engine was running so charging for 24 hours not possible

 

[Deaky]

The charger stopped charging after about 2 minutes, it cuts off. But stayed on when engine was running so charging for 24 hours not possible

I guess the charger will carry out a number of tests before charging, measuring the voltage and internal resistance of the battery. If your engine is running then the results will be skewed, hence the charger appearing to charge.

 

[Craig T6]

I guess the charger will carry out a number of tests before charging, measuring the voltage and internal resistance of the battery. If your engine is running then the results will be skewed, hence the charger appearing to charge.

I’ve managed to plug in the charger and charged it until 11v turned off the engine and leave it charging and miraculously the charger stayed on ..it is now on 11.3v and I’ll try leaving it charging for a few hours and check it later, give i5 a chance to recover….thanks for your input Deaky