How to test and assess a second-hand leisure battery?

[MtB]

What method would the board recommend I use to test and assess the condition/usefulness of a second hand leisure battery of unknown provenance, recently given to me? (Other than by lugging it down to the boat, installing it and using it for a few weeks!)

 

It's here, in my house, and I have a battery charger, multimeter etc.

 

Many thanks,

 

MtB

 

 

 

[the grinch]

fully charge it, test it immediately you turn off charger should be 13 -14 volts, leave about an hour test again if its lost more than ½ a volt its kacked

[Starcoaster]

Isn't this what we're doing with the one we put in Springy last weekend (that may or may not smell funny?)

[Keeping Up]

Charge it fully, then connect a car headlamp (or spotlight) to it. That will be about a 5 amp drain. Leave it for 10 hours, that will take 50 Ah from it. A good battery will have been only 50% discharged (if it's a 110 Ah battery) so will still have over 12v and the light will be good and bright. If the light is really dim the battery was no good. For even greater accuracy, after disconnecting the lamp, wait for an hour and measure the voltage with no load on it. You can tell the exact state of charge from the voltage (plenty of tables available) so you can estimate its exact capacity.

 

For a smaller battery, or if you suspect it is already knackered to a lot less than its 110 Ah capacity, try a shorter time such as 5 hours instead

[bizzard]

I've given this tip before, but for those who never saw it, here is a repeat;-------Or the severe drop test can be carried out to check for dead cells. Charge battery. Dress up in a rubber suit, donning a pair of goggles.

Convey your battery and a thick steel bar to a quiet location away from buildings, combustibles and prying eyes such as a soggy wet field. Place battery of unknown condition at your feet, and remove cell stoppers. Grasp hold of the steel bar with both hands,''like holding bicycle handlebars''. Approach battery with caution eyeing up the two electrical posts. Don't be intimidated by it but take a big deep breath and without dithering lunge forward and down plonking the bar across onto the two posts whilst peering through the goggles into the cells. If any cell or cells boils within about 3 seconds they are on the way out and the battery is not much good. If it goes off pop your rubber outfit should protect you.

Hope this helps. bizzard.

Edited April 13, 2013 by bizzard

[Phil Ambrose]

Get a hydrometer and check the Specific Gravity of each cell to ascertain that there are no dead cells, then proceed as above, no! no! not Bizzards method unless you like hospital food, the posts above Bizzards.

 

Phil

[onionbargee]

stage 1. take to scrappy

 

stage 2. collect 30p per kilo

 

stage 3. go to pub

[RickH]

Stick your tongue across positive and negative , take a picture , show it to the next woman you wish to impress !

[bizzard]

Stick your tongue across positive and negative , take a picture , show it to the next woman you wish to impress !

A Bipolar woman.

[ChimneyChain]

Can someone please explain to me again in laymans terms why you can't drop test leisure batteries. Thanks

 

Darren

Edited April 13, 2013 by ChimneyChain

[bizzard]

Can someone please explain to me again in laymans terms why you can't drop test leisure batteries. Thanks

 

Darren

You can, folks are wimps these days.

[Darren72]

Can someone please explain to me again in laymans terms why you can't drop test leisure batteries. Thanks

Darren

Cos they crack and all the acid spills out!

[Ex- Member]

If no individual cells are dead you can successfully revive Lead Acid batteries using Epsom salts. I've done this a couple of times now on what appeared to be knackered batteries, one I revived 2 years ago is still working ok on our fork lift truck after being told it was knackered and wouldn't hold a charge.

 

There's some tutorials on how to do this on YouTube.

[Rebotco]

If no individual cells are dead you can successfully revive Lead Acid batteries using Epsom salts. I've done this a couple of times now on what appeared to be knackered batteries, one I revived 2 years ago is still working ok on our fork lift truck after being told it was knackered and wouldn't hold a charge.

 

There's some tutorials on how to do this on YouTube.

 

I've tried that ..... but all it did was give me wind

[magnetman]

Get a hydrometer....

 

Phil

another tool for the job is a refractometer - i'm getting one next week looks like a handy bit of kit

 

I definitely agree with the 5a discharge for 10hours as this is the sort of thing a normal boat leisure battery gets used for anyway.

 

I also think the scrap man is a good option but don't forget fuel costs and fill the battery with canal water they buy 'wet' batteries and a full one weighs a little bit more

[ChimneyChain]

You can, folks are wimps these days.

I can see your old school like me. A woodbine hanging from your lips, oil encrusted cap, bib and brace overalls and skin that's like a well worn leather driving glove. :-) :-)

 

Darren

[Timleech]

I've given this tip before, but for those who never saw it, here is a repeat;-------Or the severe drop test can be carried out to check for dead cells. Charge battery. Dress up in a rubber suit, donning a pair of goggles.

Convey your battery and a thick steel bar to a quiet location away from buildings, combustibles and prying eyes such as a soggy wet field. Place battery of unknown condition at your feet, and remove cell stoppers. Grasp hold of the steel bar with both hands,''like holding bicycle handlebars''. Approach battery with caution eyeing up the two electrical posts. Don't be intimidated by it but take a big deep breath and without dithering lunge forward and down plonking the bar across onto the two posts whilst peering through the goggles into the cells. If any cell or cells boils within about 3 seconds they are on the way out and the battery is not much good. If it goes off pop your rubber outfit should protect you.

Hope this helps. bizzard.

 

I know this wasn't entirely serious, but there is a significant risk of lead poisoning if you do try it direct onto the lead posts. Lots of lead vapour in the air from the arcs you will inevitably get..

 

Tim

[alan_fincher]

Allan Jones' advice, (i.e. "Keeping Up"), is spot on in my view.

 

I intend to do similar with all three batteries currently in Sickle's "domestic" bank, to assess which still have a useful life, and which need swapping out. (They are of different ages, so some are expected to be worse than others).

 

Bear in mind that if the bulb has gone noticeably dimmer by the end of the test, you were no longer drawing amps at the same rate, so you need to adjust any estimate you make about "surviving capacity" to allow for the current slowly falling as you did the test.

 

I don't think drop testing is really a useful test of leisure batteries. A starter battery needs to be able to deliver hundreds of amps, but only for seconds, usually. Leisure batteries are usually only required to deliver "tens" of amps, (often less), but for many hours. A battery may be perfectly fine for this, but quite unable to perform as a starter, if you attempted to use it in that way.

[Keeping Up]

Can someone please explain to me again in laymans terms why you can't drop test leisure batteries. Thanks

 

Darren

 

A drop test checks whether a battery can deliver a high current for a short time, ideal for an engine starter battery but no good for a leisure battery which needs to deliver a low current for a long time. A perfectly good leisure battery may be unable to deliver the current for a drop test so it may register as faulty (and may even suffer damage from the test)

[alan_fincher]

A drop test checks whether a battery can deliver a high current for a short time, ideal for an engine starter battery but no good for a leisure battery which needs to deliver a low current for a long time. A perfectly good leisure battery may be unable to deliver the current for a drop test so it may register as faulty (and may even suffer damage from the test)

I agree again - what I have tried to say in a slightly different way above.

 

I can see no useful way of testing leisure batteries other than actually charging them as well as possible, then seeing how many amp hours they are good for under a test load.

 

I have had examples previously that fully pass tests about a fully charged voltage, and also a fully charged specific gravity, but which have proved incapable of delivering 5 amp hours, let along the 50 amp hours you would hope to get from a new one.

 

As Allan suggests, the test needs to be a controlled attempt to make it do what it would be doing if you put it in a bank. I have actually got slightly better than a headlamp bulb I can press into service, as I have a large rheostat, (variable resistor), that I can actually adjust to say pass 5 amps, (meter in circuit to), and can then see how well that current is maintained. But a headlamp bulb is a good test, and you can easily see how dim it is getting, if things are not going well.

[Geoff Taylor]

Hi Mike, I used a battery tester that we have at work on my leisure batteries and it successfully seeded out the faulty one,it is a Snap on Tools code no YA2612, expensive piece of kit but you may find that a local tyre/battery sales outlet will have a similar tester and do your battery free of charge if they think you may be a potential customer. This tester does not harm or dead short the battery and will read out volts and condition ampwise. Hope this helps.

[Guest]

Charge it fully, then connect a car headlamp (or spotlight) to it. That will be about a 5 amp drain. Leave it for 10 hours, that will take 50 Ah from it. A good battery will have been only 50% discharged (if it's a 110 Ah battery) so will still have over 12v and the light will be good and bright. If the light is really dim the battery was no good. For even greater accuracy, after disconnecting the lamp, wait for an hour and measure the voltage with no load on it. You can tell the exact state of charge from the voltage (plenty of tables available) so you can estimate its exact capacity.

 

For a smaller battery, or if you suspect it is already knackered to a lot less than its 110 Ah capacity, try a shorter time such as 5 hours instead

Pretty much what I did a few years ago with four big Yuasa ex backup batteries that I acquired. I used a VW Beetle headlamp that was in the shed. They all passed the test, and all served me well for four years or more.

[dmr]

Testing batteries is obviously a slow and complicated process!

Despite what Alan says I reckon if a battery has good specific gravity on all its cells it is almost certain to be a good one.

If its a typical second hand leisure battery then sulphation, or possibly a bad cell, are the most likely faults and specific gravity will show these.

Of course if its a sealed battery the specific gravity is "difficult".

The controlled discharge is still the ultimate test but do take care not to totally flatten the batteryl Whilst waching a battery discharge for ten hours or so its very easy to let your mind wander a bit!!!!!

If you do this test on a brand new battery you may be rather surprised and dissapointed.

I reckon take maybe 30% of the rated amp-hours out, let the battery stand for an hour or two then measure the voltage to assess the state of charge! If its well above 50% then the battery has probably got a bit of life left in it.

Bizzards sheme does however sound like fun, but if you search the www you will find that you don't need a second hand battery to justify wearing rubber clothes.

...............Dave

[alan_fincher]

If its a typical second hand leisure battery then sulphation, or possibly a bad cell, are the most likely faults and specific gravity will show these.

This has not been my experience, and I have scrapped not particularly old batteries that will charge to the maximum volts you might expect, and where every cell has an SG that indicates it is fully charged.

 

I reckon I have at least one in my current bank of three that is in this state now. I separated them all some days ago, and none were down on volts, and the SGs of all cells in all are good, but I know from last year that the bank is getting beyond being able to go much over a day tied up anywhere without running the engine.

 

The problem is that if you say a battery is good based just on voltage and SG, you really don't know if you add it to an existing bank how much it is contributing, (or not).

 

I'll see if I can find the thread on a battery I had that nobody could really explain away - I certainly couldn't!

[dmr]

Alan,

Its a shame that Gibbos gone.

All my batteries die from reduced specific gravity when fully charged but maybe that says something about how I look after them!

A full SG suggests that all the lead suphate is turned bck into sulphuric acid which should be a good battery.

What I am not sure about is what the normal "plate corrosion" does to the fully charged specfiic gravity, maybe this can give a battery that looks good but has very low capacity? Forum needs a new battery expert!

 

.............Dave