I have read that a flat battery can destroy a battery! At what point does it become damaged? If you have just a battery no EH at what point do you re-charge or use EH?
A good rule of thumb is not to discharge below 50% of full capacity unless the battery can be recharged straight away.
You can use the no load voltage as a guide. A fully charged battery will show 12.7V after being left to settle for an hour or two. At 50% it is about 12V to 12.1V. 11.9V is about 40%.
Even if recharging immediately, it would be unwise to go below 20% at all (about 11.6V) if you want to avoid permanent damage, i.e. a reduction in total capacity.
Of course many people do repeatedly deeply discharge their batteries, but it does result in reduced capacity and shorter useful life.
Incidentally, you can't gauge the actual capacity from the voltage. A battery with a much reduced capacity will still show 12.7V when fully charged.
A battery will overheat or on rare occassions explode if the water inside of it is left to evaporate.Running down a battery and failing to charge it over a time will make the cells not being able to charge back up.If what your powering with it goes slow or dull its time to charge it.Think of it as a torch..if the light goes dull recharge it..You can recharge at any time.
If you have a meter you can check the amount of charge the battery has left in. A fully charged leisue battery should read around 12.7 volts or above, 12.6 volts is around half charged and 12.5 volts or below is a discharged battery. When the battery has been re-charged to full capacity, take it off charge then re-check with the meter about 6 hours after as this will give you a true reading. If you re-check again a couple of days later you can determine if the battery is holding the charge or not. If the reading is down to 12.6 volts or below then it's not holding the charge and a replacement battery will be required.
EDIT: The above details were taken from a caravanning handbook.
I have a vehicle, it has 2 starting batteries, when I got the vehicle both batteries were flat, before I got the vehicle it had been left since 2006 un-used (due to a cracked head, while I was replacing the head in 2010 I charged the batteries - first one then the other then both together.
They accepted the charge and started the vehicle and have been doing so to date - although they are getting a bit tired now.
The fact that a battery is flat does not automatically mean that it is shot...
Although it may do...
Best advice is suck it and see...
------------- Caravanning is a way of getting a cheap holiday out of an expensive hobby
Thanks for all the replies. I wanted to understand at what point you potentially damaged a battery through running it down too much. So 12.6 is low enough then get on EH or a charger.
Hi Skidmarks i would go with Alans post as it's pretty much on the money . I don't think you'll find a battery is half charged when reading 12.6 volts . If your on a site and you've paid for EH just connect straight away , no need to wait until the battery needs charging .
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Topic: Batteries - How?
