Roryboy Posted September 13, 2019 Share Posted September 13, 2019 I have an old lead acid leisure battery, about 7 years old, and after charging when out of a vehicle it reads 13.1v after being left overnight – would there be any useful 'life' in this battery ? Second, I'm getting two new Yuasa L36-EFB batteries – what should they read on the multimeter when fully charged and ready to go in the Motorhome ? I am not an expert electrician. *-) Link to comment Share on other sites More sharing options...
Ocsid Posted September 13, 2019 Share Posted September 13, 2019 That a battery reads 13.1 volts only implies it has been on charge and is about as fully charged as it can get. However, don't confuse this with being any real good as when batteries age the amount of energy they can hold when full deminishes, so whilst full it can be full but full with little useful quantity of energy. I was told think of them as buckets, when fresh from the shop they can hold say 3 gallons of water. But age is like tossing bricks in them, you can still fill them with water but the amount of water they hold is less. The fully charged voltage of a battery depends on when read and on the batteries construction and the trace elements added to the lead alloy used; the maker should publish a guide figure for their different models. This should only be read after the battery has stood since charging for quite a lot of hours and when not on any load; it could mean 48 hours is needed for a "surface charge" to dissipate back to the standing fully charged voltage. Link to comment Share on other sites More sharing options...
747 Posted September 13, 2019 Share Posted September 13, 2019 The battery has reached the end of its useful life as a Leisure battery. That does not mean you have to throw it away. I have my 2 old Numax leisure batteries. They are a handy source of 12 volt power for small applications and testing purposes. I have one rigged up in my garden shed, kept topped up by a 9 watt solar panel. It powers up an old Dashcam rigged through a PIR and it acts as a security camera to cover a blind spot in the garden. Link to comment Share on other sites More sharing options...
mikefitz Posted September 13, 2019 Share Posted September 13, 2019 Your Yuasa batteries will have an off load voltage when charged around 12.8 to 13 volts. An accurate method is to measure current when under charge with the recommended charge voltage, perhaps 14.4 volts. When the current falls to less than 1 amp per 100 Ah of capacity ( idealy 0.5 amp) you can consider the battery fully charged. The same efb battery is available from Halfords under their brand label, https://www.halfords.com/motoring/bulbs-blades-batteries/leisure-batteries/halfords-leisure-battery-hlb700 Mike Link to comment Share on other sites More sharing options...
Keithl Posted September 13, 2019 Share Posted September 13, 2019 mikefitz - 2019-09-13 6:18 PM Your Yuasa batteries will have an off load voltage when charged around 12.8 to 13 volts. An accurate method is to measure current when under charge with the recommended charge voltage, perhaps 14.4 volts. When the current falls to less than 1 amp per 100 Ah of capacity ( idealy 0.5 amp) you can consider the battery fully charged. The same efb battery is available from Halfords under their brand label, https://www.halfords.com/motoring/bulbs-blades-batteries/leisure-batteries/halfords-leisure-battery-hlb700 Mike And if you can find someone with a Halfords trade card you will save even more!!! Keith. Edit: Actually 20% more!!! Link to comment Share on other sites More sharing options...
Roryboy Posted September 13, 2019 Author Share Posted September 13, 2019 Thanks for all the helpful replies. A couple of Yuasa L36-EFB for £175 - fitted and seem okay. 8-) Link to comment Share on other sites More sharing options...
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