How To Check A Leisure Battery's True State? (2 Viewers)

[HKF]

Hi everyone

We recently converted to 1 x Lithium (LiPePO4 100ah), after being told our 2 x Bosch L5 013 90ah 800a batteries had had it and needed replacing. However, on connecting them to a charger, they show 14.1v and switch off, presumably because they both think they're fully charged

So, knowing nothing much at all about batteries, how do I know that they really have had it before I scrap them, please?

PS I don't mind if I've been hoodwinked into converting to Lithium. I just want to know that I'm not scrapping perfectly good batteries

 

[Richard n Ann]

Hi everyone

We recently converted to 1 x Lithium (LiPePO4 100ah), after being told our 2 x Bosch L5 013 90ah 800a batteries had had it and needed replacing. However, on connecting them to a charger, they show 14.1v and switch off, presumably because they both think they're fully charged

So, knowing nothing much at all about batteries, how do I know that they really have had it before I scrap them, please?

PS I don't mind if I've been hoodwinked into converting to Lithium. I just want to know that I'm not scrapping perfectly good batteries

All you can do is do a discharge test with a known load and time how long it lasts.

 

[dunnah01]

I just connected a 10watt bulb across my old batteries. They went from 12.9v to 11.0v in a few hours so happyish that they were goosed

 

[Sneds]

We sold our old one to a local metal recycling company, £15

 

[HKF]

We sold our old one to a local metal recycling company, £15

Sorry, yes, that's what I'm planning on doing but not until I know they're done for

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[HKF]

I just connected a 10watt bulb across my old batteries. They went from 12.9v to 11.0v in a few hours so happyish that they were goosed

Can you tell me how I would go about setting that up, please?

 

[dunnah01]

I had an old 12v ceiling light with wires still attached and simply connected them to the battery terminals using half a brick to hold each wire in place. I used a voltmeter to measure the battery voltage before starting (they had been disconnected for a few weeks so very stable voltage wise) and both my old batteries showed 12.9v. They were both 100Ah so if good they should have lasted at least 2 days but one light went out after about 4 hrs and the other light was still working but the battery was only about 11v so not long left.

 

[HKF]

I had an old 12v ceiling light with wires still attached and simply connected them to the battery terminals using half a brick to hold each wire in place. I used a voltmeter to measure the battery voltage before starting (they had been disconnected for a few weeks so very stable voltage wise) and both my old batteries showed 12.9v. They were both 100Ah so if good they should have lasted at least 2 days but one light went out after about 4 hrs and the other light was still working but the battery was only about 11v so not long left.

Thank you so much! Very much appreciated

 

[Emmit]

I had an old 12v ceiling light with wires still attached and simply connected them to the battery terminals using half a brick to hold each wire in place. I used a voltmeter to measure the battery voltage before starting (they had been disconnected for a few weeks so very stable voltage wise) and both my old batteries showed 12.9v. They were both 100Ah so if good they should have lasted at least 2 days but one light went out after about 4 hrs and the other light was still working but the battery was only about 11v so not long left.

"and simply connected them to the battery terminals using half a brick to hold each wire in place."
Priceless!!!
That's made my day. Bodging of the highest order. Well done.

 

[HKF]

"and simply connected them to the battery terminals using half a brick to hold each wire in place."
Priceless!!!
That's made my day. Bodging of the highest order. Well done.

It's probably not going to be far off what I'll do, either!

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[Emmit]

Could go high tech and use a pair of mole grips.

 

[dunnah01]

"and simply connected them to the battery terminals using half a brick to hold each wire in place."
Priceless!!!
That's made my day. Bodging of the highest order. Well done.

Thought a whole brick might have been a bit OTT

 

[Emmit]

Thought a whole brick might have been a bit OTT

But there's two terminals. That's why they use half bricks. One on each terminal.

 

[Spriddler]

You can try fixing the wires on the terminals with cable ties or Jubilee clips. Although terminal posts are usually tapered I've found that ties will work o.k.

 

[dunnah01]

You can try fixing the wires on the terminals with cable ties or Jubilee clips. Although terminal posts are usually tapered I've found that ties will work o.k.

That's how the new batteries are fitted in the van. I've found that sellotape and Bluetac are great for securing the batteries aswell

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[pappajohn]

Can you tell me how I would go about setting that up, please?

Charge batteries overnight.
Remove off charge and let stand for 2 hours.
Check voltage with a multimeter.
Connect a 60watt (5amps) headlamp bulb.
Check voltage after 10 hours with bulb removed and battery stood for an hour.
Should be around 12v if it's good.
10v/11v.....it's knackered

 

[Emmit]

You can try fixing the wires on the terminals with cable ties or Jubilee clips. Although terminal posts are usually tapered I've found that ties will work o.k.

Far too sensible for this thread.

 

[jonasw19]

dont bother, you are now a lithium convert weigh them in.
OR keep them in the shed, periodically moving them, sometimes charging them and three years later take them to the scrapyard where they will be worth about the same as now only they will definitely be stuffed.
Wise advice is worth just what you pay for it Jon

 

[Tombola]

Am I missing something...can't we just fully charge, check after an hour..leave overnight and check that they are still 12.7 -12.8 ? In the morning..if they were goosed wouldnt they lose more

 

[Burgo]

Am I missing something...can't we just fully charge, check after an hour..leave overnight and check that they are still 12.7 -12.8 ? In the morning..if they were goosed wouldnt they lose more

Not really. It's not just the voltage that matters. The Amps are the "oomph". You could have a 12.7v battery with 150A capacity, and one with 0.5A capacity. Both are 12.7v but only one of them would start your car.
Or you could stick 8 1.5v AAA batteries in series to give a 12v battery. That wouldn't start your car either.

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[dunnah01]

Am I missing something...can't we just fully charge, check after an hour..leave overnight and check that they are still 12.7 -12.8 ? In the morning..if they were goosed wouldnt they lose more

My goosed batteries were still reading 12.9v after about 5 weeks sitting in the garage

 

[dunnah01]

Can you tell me how I would go about setting that up, please?

This was the laboratory test conditions

 

[berni109]

Just as well you were using non conductive bricks.

 

[dazandandrea]

I dont have any bricks like that . Which builders merchant did you get them ( it ) from .
Thanks

 

[PhilandMena]

Hi everyone

We recently converted to 1 x Lithium (LiPePO4 100ah), after being told our 2 x Bosch L5 013 90ah 800a batteries had had it and needed replacing. However, on connecting them to a charger, they show 14.1v and switch off, presumably because they both think they're fully charged

So, knowing nothing much at all about batteries, how do I know that they really have had it before I scrap them, please?

PS I don't mind if I've been hoodwinked into converting to Lithium. I just want to know that I'm not scrapping perfectly good batteries

You may find the following posts usefull.

From autorouter :

1. Fully charge the battery, leave it to settle for a couple of hours.
2. Attach a load that draws an amps value of Capacity/20. (for example for a 100Ah battery, 100/20 = 5A.
3. Run the load for 5 hours. The amp-hours taken from the battery is Amps x 5 hours. (for the same example, 5 x 5 = 25Ah. For a brand new battery this would be 25% of the capacity, so it should be down to the 75% level.
4. Let the battery settle for a couple of hours
5. Measure the voltage.
6. Use this voltage, referring to the battery charge/voltage scale (In Lenny HB's post #32) to estimate what percentage charge is left in the battery. For this example, let's suppose it is 12.28V. If it's a Sealed Lead-acid type, that represents a level of 60%. Since you drew 25% of the label capacity, you would expect the voltage to be at the 75% level on the charge/voltage scale. However because the battery has aged, it is now at the lower level of 60%.

7. If the battery is actually at 60% when you expect it to be 75%, its capacity when full is
(60 / 75) x 100 = 80% of the original capacity.

So the battery capacity has reduced due to aging, and is now only 80% of its original capacity.

The test I tried:
OK! I have now started my test. At 09.00 this morning both batteries were found to be 12.96 V. They were disconnected at 14.00 hrs yesterday and both at 13.66 V.
I have put a 4.6 Amp load on to one of the batteries at 09.00 and it dropped immediately to 12.33 V (which is meaningless information !) I'll leave the load on for 5 hours then remove load allow to settle and calculate remaining capacity. I'm only going to do this one on one of thee batteries as they have both been linked as a pair from new and the readings up to the point where a load has been applied have been identical. Watch this space.
So First update. Test is now completed. I measured the voltage with the load of 4.6 Amps still applied and after 5 hours the voltage reading dropped from 12.33 to 12.25 a drop of 0.08 of an Amp what does this mean. I don't have an effing clue
I will measure battery in an hour to see where its at. A picture of the battery at the the end of the test.

Test is more or less finished but my maths do not make sense.
After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery)
So! 90/77 x 100 = 116 ?
But if I do this 77/90 x 100 = 85.5 This would indicate I have used 14.5 % of my total battery capacity which I think makes sense !
Very happy with that, if it is correct ? I will measure again after two hours resting.

AGM OR LEAD BATTERY

Test is more or less finished but my maths do not make sense. After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery) So! 90/77 x 100 = 116 ? But if I do this 77/90 x 100 = 85.5 This would indicate I have used...

www.motorhomefun.co.uk

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[Stealaway]

Could go high tech and use a pair of mole grips.

You must be a proper mechanick with two pairs of mole grips

 

[pappajohn]

My goosed batteries were still reading 12.9v after about 5 weeks sitting in the garage

But it needs a load on it to tell how good it is.
I have 3 100ah batteries of varying age. The oldest being 15 years.
They all charge to 12.6v and hold for months ..... But put a load on and they last an hour or two at very best.
I use them to jump start, alongside the original battery, the ride on mower......once.
That reminds me, I must get a new rectifier for the mower

 

[Emmit]

You must be a proper mechanick with two pairs of mole grips

Thanks to my late FIL I inherited loads of stuff.
He was a Pre-war time served spray painter/body repairer who finished his working life working for 'Superwinch'.
They took him on as a handyman and he finished up making and installing ducting all over the factory. A very talented man.

 

[pappajohn]

Test is more or less finished but my maths do not make sense.
After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery)
So! 90/77 x 100 = 116 ?
But if I do this 77/90 x 100 = 85.5 This would indicate I have used 14.5 % of my total battery capacity which I think makes sense !
Very happy with that, if it is correct ? I will measure again after two hours resting.

AGM OR LEAD BATTERY

Test is more or less finished but my maths do not make sense. After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery) So! 90/77 x 100 = 116 ? But if I do this 77/90 x 100 = 85.5 This would indicate I have used...

www.motorhomefun.co.uk

Without sounding thick, what is the 90 in your equation?

 

[bigtwin]

You may find the following posts usefull.

From autorouter :

1. Fully charge the battery, leave it to settle for a couple of hours.
2. Attach a load that draws an amps value of Capacity/20. (for example for a 100Ah battery, 100/20 = 5A.
3. Run the load for 5 hours. The amp-hours taken from the battery is Amps x 5 hours. (for the same example, 5 x 5 = 25Ah. For a brand new battery this would be 25% of the capacity, so it should be down to the 75% level.
4. Let the battery settle for a couple of hours
5. Measure the voltage.
6. Use this voltage, referring to the battery charge/voltage scale (In Lenny HB's post #32) to estimate what percentage charge is left in the battery. For this example, let's suppose it is 12.28V. If it's a Sealed Lead-acid type, that represents a level of 60%. Since you drew 25% of the label capacity, you would expect the voltage to be at the 75% level on the charge/voltage scale. However because the battery has aged, it is now at the lower level of 60%.

7. If the battery is actually at 60% when you expect it to be 75%, its capacity when full is
(60 / 75) x 100 = 80% of the original capacity.

So the battery capacity has reduced due to aging, and is now only 80% of its original capacity.

The test I tried:
OK! I have now started my test. At 09.00 this morning both batteries were found to be 12.96 V. They were disconnected at 14.00 hrs yesterday and both at 13.66 V.
I have put a 4.6 Amp load on to one of the batteries at 09.00 and it dropped immediately to 12.33 V (which is meaningless information !) I'll leave the load on for 5 hours then remove load allow to settle and calculate remaining capacity. I'm only going to do this one on one of thee batteries as they have both been linked as a pair from new and the readings up to the point where a load has been applied have been identical. Watch this space.
So First update. Test is now completed. I measured the voltage with the load of 4.6 Amps still applied and after 5 hours the voltage reading dropped from 12.33 to 12.25 a drop of 0.08 of an Amp what does this mean. I don't have an effing clue
I will measure battery in an hour to see where its at. A picture of the battery at the the end of the test.

Test is more or less finished but my maths do not make sense.
After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery)
So! 90/77 x 100 = 116 ?
But if I do this 77/90 x 100 = 85.5 This would indicate I have used 14.5 % of my total battery capacity which I think makes sense !
Very happy with that, if it is correct ? I will measure again after two hours resting.

AGM OR LEAD BATTERY

Test is more or less finished but my maths do not make sense. After resting the battery for one hour it measured 12.56 Volts. I have taken 23 Amps out of the battery leaving 77 Amps (100 AH Battery) So! 90/77 x 100 = 116 ? But if I do this 77/90 x 100 = 85.5 This would indicate I have used...

www.motorhomefun.co.uk

You have used 23Ah and your resting voltage after consuming 23Ah is 12.56V. Using the chart below, 12.56V represents a SoC of approximately 70%. Therefore, you have consumed 30% of the battery capacity. Since you have consumed 23Ah and this represents 30% of your capacity, you can now calculate that your true battery capacity is (23/30)*100 = 77Ah.

Ian

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