Battery Charging

[willriding]

Charging our battery right now, it was working although the van had not been used for a while. It's a leisure 85 been on charge two days, not sure how long to leave it, no green light and charger still not on maintenance mode. Any advice would be welcome.
Thanks

 

[willriding]

Think I'm in wrong forum area. Sorry

 

[Damian]

If you are using a CTec or similar then if the battery was really low to start with, like 2v or so, then it will not recognise the battery and you need to use a charger that does not sense voltage to bring it up to around 12v. Then put the intelligent charger on it.

 

[willriding]

Thanks, it looks like an option....

 

[DrZhivago]

If you are using a CTec or similar then if the battery was really low to start with, like 2v or so, then it will not recognise the battery.

Marvellous! Battery chargers have become self-aware and find it beneath their dignity to deal with a flat battery :S It reminds me of the lift in The Hitch-Hiker's Guide to the Galaxy that was afraid of heights and lurked at basement level all the time.

At least they don't require an internet connection and your credit card details - not yet anyway.

 

[willriding]

Nice one! Not so smart smart chargers for you.

 

[Grey13]

The battery fully charged should be about 12.7 volts. The next point is assuming it was absolutely flat, 85 amp hour battery being charged by a charger delivering say 10 amps will take about 8.5 hours to become fully charged. Simple, remove connections and measure the voltage, if 12.7 or so it is fully charged, if not after a few days perhaps have the battery checked for a dead cell ??? Remember look at what charging current the charger is or can deliver!

 

[willriding]

Sealed battery, it delivers 3.7a(RMS)
Original charger stopped working so went back. Battery at 10.06v after nearly 48 hrs. D'you think it's knackered?

Cheers

 

[Damian]

A 3.7a charger is very small and if trying to recondition a well discharged battery it will struggle and take a minimum of 23 hours, if it can manage that.
You really need a smart charger which delivers an initial boost of 14v + to disulphate the plates and then go into charge mode and drop to maintainence mode at the appropriate time.

I would give yours another 48 hours then se how it is doing.

 

[Woodentop]

Then there's the old fashioned way.

If you have or can find a power supply capable of supplying a few amps at 13.5V or thereabouts connect it to the battery with a flasher or headlight bulb (note BULB) in series. If the battery is really low the bulb will shine brightly but as the battery comes up the bulb will dim and eventually go out. Leave it for another couple of hours then disconnect and check the battery volts - should be over 12. Now connect your smart charger and leave it a couple of days.

 

[willriding]

Left it a few hours, came home and remeasured... 8.6v. Think it's done for...

 

[willriding]

Update, new Charger says fully charged, showing 10.06 two mins after plugging in....
sounds abit low to me, it'll probably drop too overnight.

 

[thosoneill]

Ninety five squid currently gets you a halfrauds 110 ampere battery - good quality too

 

[Beehpee]

I've only done none electric site the once and I got hold of a couple of supposedly unchargable batteries, using my ctek smart charger on them seemed to not be possible as soon after switching it on it had a flashing red light saying faulty not possible to charge, all I did was restart the charge sequence by simply switching off and back on, did that 3 maybe 4 times and it then fully charged, reconditioned etc and I'm still using it 3 years later, I think each time I restarted the charger a small amount of charge would get taken by the battery until there was enough for the smart charger to not object to fully charging it, I expect someone will now tell me I was at risk of a nuclear explosion by overcoming the initial failure of the charger but it worked and I've done it again since for someone who had let their van battery sit at zero volts for several months.

BP

 

[Grey13]

Well worth a read for all van owners - basics explained http://www.caravantalk.co.uk/library/files/Beginners-Guide-To-Electrics.pdf
http://www.aussiebatteries.com.au/blog/charging-deep-cycle-agm-batteries/

 

[willriding]

Thanks everyone for your replies, I've lots of valuable advice in the last three weeks

 

[willriding]

Battery now at 3.9v. I think it's dead.....
It's just been idle since it's last charge....

 

[Damian]

Yep, its had its day , time to go.

 

[willriding]

Thought as much. . Thanks.

 

[welshti]

Interesting read

whats different to charging a caravan battery compared to a car battery ? Only owned my caravan a month so been on the drive using house mains so not even checked the battery. cheers

 

[Damian]

Car batteries are designed to deliver a heavy load for a short time.
Caravan, or Leisure Batteries, are designed to deliver a long, relatively light discharge, for supplying power to things like pumps, etc.

Depending on the model and year of your van the charger will, on older vans, only charge the battery to a maximum of 13.8v to avoid gassing.
Smart chargers deliver a short higher charge to 14 + volts then drops through a series of stages to a mainainence charge.

 

[VicMallows]

I think it should also be explained that 13.8v (as typical on older caravans) WILL eventually fully recharge the battery, though it may well take quite a few days. Modern, so called 'smart', chargers will charge at a higher voltage (typically 14.4v - 14.8v) until the battery reaches a terminal voltage in that range. They then maintain that voltage for typically 1 to 2 hours, before reducing to a maintenance 'float' charge of around 13.8v. This considerably reduces the time it takes to recharge a depleted battery.

The precise ideal charging characteristics for a given situation will vary depending on a multitude of factors, and some sophisticated chargers (and also PV controllers) will allow you to create a charging profile customised to your particular circumstances.

 

[xtrailman]

I think it should also be explained that 13.8v (as typical on older caravans) WILL eventually fully recharge the battery, though it may well take quite a few days. Modern, so called 'smart', chargers will charge at a higher voltage (typically 14.4v - 14.8v) until the battery reaches a terminal voltage in that range. They then maintain that voltage for typically 1 to 2 hours, before reducing to a maintenance 'float' charge of around 13.8v. This considerably reduces the time it takes to recharge a depleted battery.

The precise ideal charging characteristics for a given situation will vary depending on a multitude of factors, and some sophisticated chargers (and also PV controllers) will allow you to create a charging profile customised to your particular circumstances.

Yes a lot of people think 13.8 volts isn't going to charge a battery, it does just takes longer, as you say.

 

[willriding]

Thanks all, we've hedged our bets and bought a new battery.