Battery questions.........

Battery questions.........

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Original Poster:

499 posts

191 months

Sunday 20th November 2016
quotequote all
I've had a varta battery sat in a bmw 116d for the best part of 10 months. When i removed it, it was showing 2.80v.

I have it on charge, which seems to be slowly charging. But im just wondering if 2.80v would be too low for it to recover properly? thoughts?.

Also another question..

I removed another 75ah 650cca battery from a diesel mini. If this battery mentioned above recovers, which is 80ah and 800cca, would it be ok to stick it in the mini?

Le TVR

3,092 posts

251 months

Sunday 20th November 2016
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If its a Mini2, then you will probably lose the Stop/Start function. They have to reprogram the ECU with a battery change.

1083 Feedbacks

Original Poster:

499 posts

191 months

Sunday 20th November 2016
quotequote all
Le TVR said:
If its a Mini2, then you will probably lose the Stop/Start function. They have to reprogram the ECU with a battery change.
2004 mini one without stop start.

PositronicRay

27,012 posts

183 months

Sunday 20th November 2016
quotequote all
1083 Feedbacks said:
I've had a varta battery sat in a bmw 116d for the best part of 10 months. When i removed it, it was showing 2.80v.

I have it on charge, which seems to be slowly charging. But im just wondering if 2.80v would be too low for it to recover properly? thoughts?.

Also another question..

I removed another 75ah 650cca battery from a diesel mini. If this battery mentioned above recovers, which is 80ah and 800cca, would it be ok to stick it in the mini?
Most batteries have a 3 yr warranty, take it back. I had an internet cheapo fail after 30 months, the company just sent me another, no questions asked.

1083 Feedbacks

Original Poster:

499 posts

191 months

Sunday 20th November 2016
quotequote all
PositronicRay said:
Most batteries have a 3 yr warranty, take it back. I had an internet cheapo fail after 30 months, the company just sent me another, no questions asked.
This was the original battery from a 2009 bmw 116d. So its 7 years old. It was working fine until i left it sit in the car for 10 months.

I know if i got 5 years out of a battery i'd be over the moon. But seen as the battery was good 10 months ago, i just want to know if charging from 2.8 volts would recover it. Or is it 50/50.

GreenV8S

30,195 posts

284 months

Sunday 20th November 2016
quotequote all
1083 Feedbacks said:
I've had a varta battery sat in a bmw 116d for the best part of 10 months. When i removed it, it was showing 2.80v.
Batteries tend to fail one cell at a tie i.e. in roughly 2V increments. The usual failure mode for a cell seems to be the plates shorting and taking that cell to 0V. They can sometimes be recovered by zapping a high current through them to burn out the short but they're never the same after that.

I suggest that you've lost 3-4 cells there so the battery is scrap several times over. What you're doing now is probably charging the couple of 'good' cells back up. They'll soon be fully charged and will then be overcharged and start boiling as you over charge them trying to bring the overall battery up to voltage so you're likely ruin those too.

1083 Feedbacks

Original Poster:

499 posts

191 months

Sunday 20th November 2016
quotequote all
GreenV8S said:
Batteries tend to fail one cell at a tie i.e. in roughly 2V increments. The usual failure mode for a cell seems to be the plates shorting and taking that cell to 0V. They can sometimes be recovered by zapping a high current through them to burn out the short but they're never the same after that.

I suggest that you've lost 3-4 cells there so the battery is scrap several times over. What you're doing now is probably charging the couple of 'good' cells back up. They'll soon be fully charged and will then be overcharged and start boiling as you over charge them trying to bring the overall battery up to voltage so you're likely ruin those too.
Thanks for that, i guess nothing to lose if i leave it on charge. If it does what you say then i'll have to scrap it.

Should know by tomorrow.

anonymous-user

54 months

Sunday 20th November 2016
quotequote all
2 volts?

Yup, that'll be scrap.....



1083 Feedbacks

Original Poster:

499 posts

191 months

Sunday 20th November 2016
quotequote all
Max_Torque said:
2 volts?

Yup, that'll be scrap.....
On another forum i've this moment read a chap saying that he said he recovered 0v batteries and worked for years. He also said he tried to recover a battery which showed 6v but wouldn't recover.

I guess its also down to the condition inside the battery rather than the voltage reading?.

Le TVR

3,092 posts

251 months

Sunday 20th November 2016
quotequote all
1083 Feedbacks said:
I guess its also down to the condition inside the battery rather than the voltage reading?.
Yes but you may recover the voltage to a nominal reading but the battery capacity will be effectively zero.

GreenV8S

30,195 posts

284 months

Sunday 20th November 2016
quotequote all
1083 Feedbacks said:
I guess its also down to the condition inside the battery rather than the voltage reading?.
Part of the problem will be that the individual cells will now be in a different condition and will need different treatment to restore them to a working state. Part of the problem is that some cells are likely useless and will probably not be possible to get working again in any case. Bottom line is that it's very unlikely IMO that you will get the battery as a whole back up to fully working voltage and anything like it's original capacity. Nothing to stop you trying, but I wouldn't plan on that working.

S0 What

3,358 posts

172 months

Sunday 20th November 2016
quotequote all
Ignor all the above, the only way to test the battery it to fully charge it, let it rest for 24Hrs then load test it with a propper load tester.
2.8v could meen you have only 1 good cell or that all the cells only have 0.4 of a volt in them, charge, rest, test, i've bought many, many a battery back from below 6V and had many a dead battery with 10V (before a charge cycle).

bmwmike

6,947 posts

108 months

Sunday 20th November 2016
quotequote all
I've got a 1999 BMW battery which was sat in a dead megane for 2 years is now sat on my workbench and happily retains 12.6v. Wouldn't trust it to run a car but is fine for 12v lights and so on.

Edit as above charge it leave it 24 hrs and see what happens. I wouldn't use it in a car though especially going into winter.


eliot

11,429 posts

254 months

Monday 21st November 2016
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I recovered a battery from 0v recently after the kids left the rear interior light on in my p38.
I thought it was shagged as i've tried to recover batteries before with no success.
It was so low that even my ring dsc smart charger wouldn't even recognise that it was connected to a battery. So i fed it 10v for few minutes to get it up a little bit, then the smart charger slowly recovered it.
I then left it connected to a current limited bench power supply at 13.5v for about a week until the current draw was just a few hundred milliamps.

I think it's taken life out of it, but it still starts my p38 in the cold after standing for a couple of weeks at a time which is good enough for now.

jas xjr

11,309 posts

239 months

Monday 21st November 2016
quotequote all
there are a few videos on youtube about restoring duff batteries. must be worth a look. seems to be about adding various householdchemicalsto the battery and then charging it.

1083 Feedbacks

Original Poster:

499 posts

191 months

Monday 21st November 2016
quotequote all
jas xjr said:
there are a few videos on youtube about restoring duff batteries. must be worth a look. seems to be about adding various householdchemicalsto the battery and then charging it.
That would be the older style batteries that are not sealed. I have topped them up with distilled water before and brought some back to life after a charge.

This battery in question is a sealed for life battery. So unable to top it up and must rely on charging only.

1083 Feedbacks

Original Poster:

499 posts

191 months

Monday 21st November 2016
quotequote all
Started the charging at 2.80v and now it is on 4.02v. So just over 1v charging every 24 hours LOL.

This will take 8 days or so...eeeek!

GreenV8S

30,195 posts

284 months

Monday 21st November 2016
quotequote all
1083 Feedbacks said:
Started the charging at 2.80v and now it is on 4.02v. So just over 1v charging every 24 hours LOL.

This will take 8 days or so...eeeek!
I suspect that means you have two cells which are good enough to come up to around their nominal voltage after charging, and the rest are dead. How many amp-hours of charge have you put through it now?

1083 Feedbacks

Original Poster:

499 posts

191 months

Monday 21st November 2016
quotequote all
GreenV8S said:
I suspect that means you have two cells which are good enough to come up to around their nominal voltage after charging, and the rest are dead. How many amp-hours of charge have you put through it now?
I tried a smart charger, but it seems they don't pick up the battery unless its on at least 8v i think. So i dug out a 15 year+ old absaar charger 11amp RMS and its been on for 27 hours and charged to 4.07v now.

GreenV8S

30,195 posts

284 months

Monday 21st November 2016
quotequote all
1083 Feedbacks said:
So i dug out a 15 year+ old absaar charger 11amp RMS and its been on for 27 hours and charged to 4.07v now.
Presumably it hasn't been running at 11A during that time, or you'd have boiled the electrolyte dry on the 'good' cells by now.

I still think it's a lost cause, but if you're determined to see some volts out of it and don't mind wasting your time I suspect your best bet will be to put a massive current through it for a fraction of a second. This is often enough to burn through the lead whiskers which are shorting the two plates together and allow the cell to start taking a charge again. Briefly connecting another car battery to it via heavy jump leads would be enough. I just mean a fraction of a second, not long enough to start smoking the leads, and if it doesn't work at the first go you're probably just making things worse (as well as damaging the other battery) by trying again.

Note that the two 'good' (it's all relative) cells are now in a completely different state to the rest of the battery so any current you put in to try to recover the bad cells is now overcharging (and damaging) the 'good' ones. The lower the current you use, the less damaging it will be.