Battery low voltage... is it knackered?

[markw996]

Hi,

I've just popped down to my Lotus Esprits hibernating place to start it up and run it to temperature, and the battery was flat. It's only been tucked away for 3 months, so I removed the battery and brought it home to charge it up.

Anyway, voltage reading is 5.78v on a Bosch Super S5 that is only about 3 months old.

I know it has a 5 year warranty, but should this happen, and will it recover if I charge it up?

Thanks,
Mark.

[littleredrooster]

Static voltage tells you very little, but yes - <6v certainly says it's flat!

Trickle charge it for 24hrs and see what the voltage is, and, if you can, do a load test to measure the voltage under load; it may be OK.

If fully charged, lead-acid batteries can be stored for quite a long time, but when flat a process known as sulphation occurs which coats the reactive plates and increases the internal resistance and signals the early demise of the battery. The longer they are left flat, the quicker this occurs.

[theshrew]

Yes its normal for the battery to drain if a car has been stood for a while. Remember the clock uses power etc.

If its a new ish one you should be ok with it. Just charge it up. Next time when you leave teh car for a while remove or just disconnect the battery it will last longer + added bonus of no sticky fingerd people will be able to start the car and pinch it.

[ouch]

Try to use a smart-charger - rather than the older style chargers which are nothing more than a transformer & rectifier.

A smart charger will stand a better chance of reviving the battery, and some can be left attached for 'maintenance' long term - assuming you have power.

[one eyed mick]

theshrew said:

Yes its normal for the battery to drain if a car has been stood for a while. Remember the clock uses power etc.

If its a new ish one you should be ok with it. Just charge it up. Next time when you leave teh car for a while remove or just disconnect the battery it will last longer + added bonus of no sticky fingerd people will be able to start the car and pinch it.

Especialy if it has alarm /immobiliser ,investing in a battery cut of could be wise

[Doctor Volt]

When your vehicle is stood still for months, you will find it worth your while to connect a small wattage bulb (3W or less)to it and leave it to drain to a low state of charge, once the battery is low you then need to trickle charge it at 2 to 3 Amps until fully charged. Repeat this process once a month and your battery will last longer than it would being left stood fully charged or fully flat

I hope this helps

[Locknut]

Doctor Volt said:

... and your battery will last longer than it would being left stood fully charged or fully flat

I see where you're coming from but I'm not sure if that applies anymore. There are so many types of batteries such as silver calcium, glass mat etc. The OP needs to say what type of battery is in his car before giving specific advice.