The state of my Leisure battery?

[Madge Gentle]

Could anyone tell me whether I should worry about the state of my leisure battery - or not.

 

I wanted to check how good or bad the one year old carbon fibre monobloc 100Ah battery was and disconnected it from any power supply, mains and solar, and after 24 hours it is reading 12.94v on my multimeter.

 

Is this good, bad or normal?

[lennyhb]

Sounds good but you really need to test it under load.

 

Best way to check the battery is make sure it is fully charged, leave it on charge at least 24 hours, disconnect your mains & solar chargers switch the control panel off leave for about an hour then check the battery voltage, should be approx 12.8v.

Now switch on some lights until the battery shows a current drain of 5 amps leave for 5 hours (25% discharge) switch off lights and panel leave for half an hour and check voltage should read 12.5 - 12.6v.

Now repeat above test so you now have discharged the battery by 50% reading should be 12.2 - 12.3 v

Repeat again 75% discharge should now Read 12v.

I do not recommend you discharge the battery's any further, if you attain the above readings not much wrong with your battery.

[Madge Gentle]

lennyhb - thanks for the advice - I'll try that.

[Dr Dave]

For those who are interested in the charge / voltage curves this is very informative.

 

http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

[Tracker]

Voltage alone can disguise a duff battery and 12.94 does seem a bit high, so as Lenny says, a discharge test is the best way to tell.

 

You can help the discharge along by using a fan or a tv which will consume more than a light especially if you have led lighting which burns next to to nothing.

 

Well done for taking the trouble as most folk just wait until the lights go out and then grumble they didn't know!