Test for battery problem

Tintin

Tintin

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Can anyone tell me a quick battery test. Not sure if i have a problem. After charging what should the standing volts be? Bog standard leisure batteries 3 x 90. Thx. Cr.
 
Charge and let stand for 12 hours.

A good battery should then read at least 12.7 ish

If lower cahrge some more and try again.

If you cannot get above say 12.6 then suspect.

Allow to stand and monitor for several days. Weeks if possible.
Volts will fall quickly at first then more slowly but a battery holding its charge well should take several weeks to fall to 12.5

Not a comprehensive battery test but a quick and easy first thing to do
 
Comrade Red said:
Can anyone tell me a quick battery test. Not sure if i have a problem. After charging what should the standing volts be? Bog standard leisure batteries 3 x 90. Thx. Cr.
Click to expand...

If you want a very quick test, turn on the cabin lights,

Start the engine, do the lights get brighter, if yes the charging system is probably working, if they stay the same you are not charging the batteries.

Stop engine, the lights will go dimmer, then hold a level brightness, if they are the same brightness after an hour or so batteries not to bad, if the slowly get dimmer and dimmer you have a battery problem.

Very crude but gives a quick pointer.

Brian
 
Brian, vic, nigel - thanks all. Just what was needed. No problem with charging. I suspect one of the batteries is on its last legs.

I have a fridge that draws 5a and from 12.7v it dropped rapidly over 2 hours to 11.7 last night
 
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Hi brian. As an aside, i am just down the road from you off kiln quay. Will be back on board later pm with kids after i have collected daughter from a party at newquay.

halcyon said:
If you want a very quick test, turn on the cabin lights,

Start the engine, do the lights get brighter, if yes the charging system is probably working, if they stay the same you are not charging the batteries.

Stop engine, the lights will go dimmer, then hold a level brightness, if they are the same brightness after an hour or so batteries not to bad, if the slowly get dimmer and dimmer you have a battery problem.

Very crude but gives a quick pointer.

Brian
Click to expand...
 
Comrade Red said:
Brian, vic, nigel - thanks all. Just what was needed. No problem with charging. I suspect one of the batteries is on its last legs.

I have a fridge that draws 5a and from 12.7v it dropped rapidly over 2 hours to 11.7 last night
Click to expand...
So having drawn 10 amp/hours out of the battery the battery is heading towards flat...

I think you know the answer!
 
Just to reiterate you need to separate the batteries from the bank of 3 after charging. Do the fridge test on each battery. Quite likely one is worse than the other 2. Possible also they are all poor. You need to decide if you can afford new batteries or manage with what you have. The drop you have seen indicates a pretty poor battery somewhere. But a battery exhibiting 50% of claimed AH capacity is perhaps OK. good luck olewill
 
nigelmercier said:
Just to clarify, he has drawn 10Ah (not 10 amp/hours) out of the bank. A single faulty battery will screw the result if they are not split.
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What's the difference? 10 amp/hours = 10 Ah

I wasn't confident (from his comments about electricity) that he would recognise the abbreviation for amp/hours i.e. 'Ah' and I was trying to spell it out to make it clearer.
 
john_morris_uk said:
What's the difference? 10 amp/hours = 10 Ah

I wasn't confident (from his comments about electricity) that he would recognise the abbreviation for amp/hours i.e. 'Ah' and I was trying to spell it out to make it clearer.
Click to expand...

An ampere-hour (Ah) is a unit of charge equal to a current of 1 ampere flowing for a time of 1 hour.

Total Ah is calculated by multiplying the current in amperes ( or amps) by the time in hours. That is implied by the name and the symbol Ah

Writing amp/hours implies amps divided by hours ......a useless and meaningless quantity
 
nigelmercier said:
The "/" symbol is an abbreviation for "per", so amp/hours is easily mistaken for the meaningless term "amps/hour" (amps per hour). If you want to spell out Ah, I suggest amp-hours.
Click to expand...
Point taken. My apologies; I agree I should have written amp-hours.

'twas a case of I knew what I wanted to say, but didn't say it very well and compounded the problem by using a symbol that altered the meaning!
 
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