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BarryM

Battery reading 1.06v

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Not used the car much recently but went out to the garage today and remote wouldn't work so after unlocking it manually I stuck a multimeter on the battery and it reads 1.06v.....I did drive it a week ago but reckon it must have suffered some kind of major failure!

 

It's a Bosch S5 0120 from 2016 and spent lots of time on a CTEK battery tender but today the CTEK just has a flashing green light which apparently happens at <2v

 

Thinking I might go for one of the AGM batteries as the car has spent quite a lot of time sitting in the garage recently! 

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17 minutes ago, BarryM said:

Not used the car much recently but went out to the garage today and remote wouldn't work so after unlocking it manually I stuck a multimeter on the battery and it reads 1.06v.....I did drive it a week ago but reckon it must have suffered some kind of major failure!

 

It's a Bosch S5 0120 from 2016 and spent lots of time on a CTEK battery tender but today the CTEK just has a flashing green light which apparently happens at <2v

 

Thinking I might go for one of the AGM batteries as the car has spent quite a lot of time sitting in the garage recently! 

 

Yeesh; what's drawn it down to that?!

 

Have you checked for any of the usual suspects draining it (interior lights, boot light, FSAU, HVAC control panel, heater valve, stereo etc)?

 

As you said though; old'ish battery, but would it drain like that on its own?

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32 minutes ago, d_a_n1979 said:

would it drain like that on its own?

 

tbh I'm not sure anything would take it down to 1v - surely if it was a drain the battery would be at 0, although I've never really thought of checking a battery voltage when it was flat before. I guess I did it because the car was fine only last week so was a bit confused.

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13 minutes ago, BarryM said:

 

tbh I'm not sure anything would take it down to 1v - surely if it was a drain the battery would be at 0, although I've never really thought of checking a battery voltage when it was flat before. I guess I did it because the car was fine only last week so was a bit confused.

 

Something constantly running in the car would; like the fan in the HVAC control panel maybe; or the fans running due to the FSU failing?

 

Just ideas; but something doesn't sound right with me with the battery being drawn down to that much

 

Re the AGM battery; not sure it's needed really as if you're not using the car, you can always just leave it on trickle charge etc

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Not sure you will ever recover that battery.  If they go completely flat then they sulphate up and are ruined i think.  In my view they dont last much over five years anyway.  Looks like a new battery then immediately chase down the drain.  Plenty of posts on that with things like dan mentioned.  You might need an ammeter.  I would not leave the battery connected for long until the drain has been found.  Alternatively if you can get hold of an old fashioned battery charger you might recover the battery for finding the drain with less risk of flattening a new battery, but it will never be the same or reliably hold a charge.  Modern battery chargers won't charge a battery that flat.  That is why i didn't bin my old charger from the 80s when i bought a ctek. I think you might be able to fool them into starting a charge by connecting another battery in parallel just to start them off.

Edited by Dbcrd

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Maybe it's just batteries failure because of age or being on charge for too much time. 

 

Long years ago my mate's nissan just stalled while idling. After getting towed back to garage measured voltage was couple volts only. Another battery in and that car was running faultless for few more years. I believe it's something to do with cell plates failing themselves or something like that. 

 

I would take new battery and for being sure it's not car's issue, get current draw measured, just remember to wait 16 minutes until car goes into sleep mode. Up to 0.05A was acceptable limit. Mine is taking about 0.02A after sorted front electric ventilator parasitic drain issues.

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Thanks for the replies. I connected my battery pack which managed to put a bit of power into the Bosch and then connected the CTEK which was tricked into thinking the battery had enough charge so started charging it - currently on led 3 of 7 so I'll have a look tomorrow. I immediately used my remote to turn off the alarm in case the charging failed and set it off. My FSU failed years ago so I know about that and being the paranoid type I often check the charging rate whilst driving so I know the alternator is doing its job. 

 

I'm keeping my fingers crossed the battery just had a massive failure as off for a few days towards the end of next week with a 4hr drive each way, my little battery pack always starts the car if I've been tinkering about on the drive for too long with the doors open etc so I know I have a way to start the car if it has developed a parasitic drain.

 

I've been thinking for a while the battery was past it's best and the CTEK has just masked it by always keeping it in good condition so I'll give some thought to what to replace it with. I had a Varta before this Bosch so that's 2 batteries in 10yrs which isn't too bad I guess.         

 

 

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Really top 3 names people go with are Bosch, Varta and Yuasa. Tayna batteries provide quite good service with competitive prices and next day delivery. For E39 if you get 5 years out of battery, that's already a fair lifespan, these cars have quite a bit electrics, which obviously takes it's toll. Irregular driving doesn't help either. 

 

Even if you will managed to get that battery charged, which is little doubtfull, I would replace it ASAP, because it's definitely been damaged being this far discharged, and you don't know when it will fail completely. 

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1 hour ago, Ray112 said:

Really top 3 names people go with are Bosch, Varta and Yuasa. Tayna batteries provide quite good service with competitive prices and next day delivery. For E39 if you get 5 years out of battery, that's already a fair lifespan, these cars have quite a bit electrics, which obviously takes it's toll. Irregular driving doesn't help either. 

 

Even if you will managed to get that battery charged, which is little doubtfull, I would replace it ASAP, because it's definitely been damaged being this far discharged, and you don't know when it will fail completely. 

 

Banner Power Bull is also a good choice and one of the OEM brands.

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CTEK was showing a full set of LEDs this morning suggesting battery was all good.....13.34v after disconnecting the charger and then down to 12.85v an hour later. I'm off out until this afternoon but gonna see what happens to it after I try starting the car! I will definitely be ordering a new battery before I use the car in anger again, have read some interesting stuff about how you have to be careful not to overcharge an AGM battery and as the E39 has no electronics to regulate the charge going back into the battery I'm not so sure getting one is a good move. I recently bought a used motorbike that had a duff AGM battery and the chap had been using a regular battery charger instead of a dedicated AGM type charger which I think killed it so I need to look into AGM a bit more yet. 

 

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1 hour ago, BarryM said:

CTEK was showing a full set of LEDs this morning suggesting battery was all good.....13.34v after disconnecting the charger and then down to 12.85v an hour later. I'm off out until this afternoon but gonna see what happens to it after I try starting the car! I will definitely be ordering a new battery before I use the car in anger again, have read some interesting stuff about how you have to be careful not to overcharge an AGM battery and as the E39 has no electronics to regulate the charge going back into the battery I'm not so sure getting one is a good move. I recently bought a used motorbike that had a duff AGM battery and the chap had been using a regular battery charger instead of a dedicated AGM type charger which I think killed it so I need to look into AGM a bit more yet. 

 

I would take just good quality lead acid battery, if you get another 5 years of it, it will be cheaper than buying AGM type battery. 

I would suggest two things: first one -  definitely get parasitic current drain check, make sure it's not excessive. And second thing - if you don't drive it regularly, like at least once a week for half an hour or more, because it's been kept in garage maybe it's worth considering disconnecting battery when not used for long time. That'll definitely help to extend batteries lifespan. I know it's a paint in butt to reset everything every time again, but might be an option over winter period maybe, because I believe it's not your daily car.

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12.85v after charging is just fine (the 13.5ish volts just after charging is called a surface charge which will dissipate after the charging ends, it can also be removed by placing a load on the battery like turning the lights on for a few seconds). Still, it doesn't mean the battery will actually provide enough power to start the car repeatedly, the capacity is permanently reduced by a deep discharge and not recoverable. Definitely do as suggested above and go on the hunt for a parasitic draw as it's about certain you have one to get the voltage down to 1v in a week. FSU being the prime suspect.

 

If it's your only car, I'd not risk it with winter coming up and I'd replace the battery. Lead acid will be just fine if kept charged. I store my E46 convertible over the winter and just putting the CTEK on it for a few days every 3 weeks or so will keep it alive just fine. Going on 7 years on the same battery on that car, with the car off the road for 5-6 months each year. I don't even disconnect it, these CTEK chargers are little miracle boxes.

 

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'you have to be careful not to overcharge an AGM battery and as the E39 has no electronics to regulate the charge going back into the battery'

 

This is nothing to worry about;  AGM do not need anything more than your alternator and its regulator working correctly: _

 

The reference to charge monitoring aplies only to cars with stop-start technology - these usually incorporate charge monitoring , 'coulomb counting' to ensure the battery does not get too far discharged in all the time it is not being actively charged, to maintain terminal voltage at acceptable levels while this is the case etc. and the regulator is controlled by a monitoring circuit to ensure this in/out balance is maintained.  That's pretty much standard for any car with stop-start btw, not just BMW. also why such cars need that ecu telling what type of batttery is fitted ('coding') !

 

 

It's no concern at all on cars like ours where the alternator is running if the car engine is. HTH.

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59 minutes ago, Huff said:

This is nothing to worry about;  AGM do not need anything more than your alternator and its regulator working correctly: 

 

It's no concern at all on cars like ours where the alternator is running if the car engine is. HTH.

 

I guess my concern was the knackered AGM battery on the bike I bought had been charged on a regular battery charger and potentially killed it, and then I figured it could be overcharged by the alternator constantly charging it without electronics to monitor charging rate but I might be over thinking it all!

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11 hours ago, BarryM said:

 

I guess my concern was the knackered AGM battery on the bike I bought had been charged on a regular battery charger and potentially killed it, and then I figured it could be overcharged by the alternator constantly charging it without electronics to monitor charging rate but I might be over thinking it all!

 

Depends what charging voltage your charger can go upto. These older vehicles have a constant voltage regulator 13,6 - 14,4 V which itself is not a problem to AGM battery. Newer vehicles like E6x has IBS so the charge voltage can go over 15 V if the charge state and temp of the battery allows, but will restrain the voltage lower if needed. In any case AGM battery can withstand total drainage much better than normal batteries without permanent damage to cell structure or composition.

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On 13/09/2021 at 23:17, Clavurion said:

 

Depends what charging voltage your charger can go upto. These older vehicles have a constant voltage regulator 13,6 - 14,4 V which itself is not a problem to AGM battery. Newer vehicles like E6x has IBS so the charge voltage can go over 15 V if the charge state and temp of the battery allows, but will restrain the voltage lower if needed. In any case AGM battery can withstand total drainage much better than normal batteries without permanent damage to cell structure or composition.


Thanks for your input Clavurion,, too late I’m afraid as I went with another Bosch S5 020:on the basis the last one had done ok (no more than ok though in my opinion).

 

I installed the battery on Tuesday evening and noted the voltage @ 12.36v and purposely didn’t charge the battery or lock the car. 48hrs later and the battery reads 12.35v so I think that points to a seriously failed battery instead of a parasitic draw.

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12.35 indicates the new battery is discharged a fair bit, fully charged you'd want to see around 12.75. Have you measured voltage with the engine running? 13.5-14v at the battery clamps is good.

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You'd only see that voltage totally unloaded i.e. not connected. Draw even very small currents ( its something like c 30ma installed in a car, up to several amps if th body modules have turned on once unlocked and doors open) and it will drop somewhat in response - so 12.3-12.4v in use looks fine to me.

 

eta -here's a handy chart I've posted before: note - open-circuit voltage

 

SLA terminal voltage capacity.PNG

Edited by Huff

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6 hours ago, Carlton said:

12.35 indicates the new battery is discharged a fair bit, fully charged you'd want to see around 12.75. Have you measured voltage with the engine running? 13.5-14v at the battery clamps is good.

 

I was trying to demonstrate that the battery voltage had barely moved over 48hrs which indicated no parasitic drain, I'm doing a 400mile round trip this weekend so that should give it a charge :)

 

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I tell you one thing - this thread has made me go look at the state of health of the battery in mine!

 

Voltages look good on and off load; , it's seeing a healthy 14.0v at idle, and using a DC clampmeter, there's no massive charging inrush after starting (which is quick and prompt) - drops from c.20A down to 1-2a in under about 20s. which also to me suggests the starter is likely okay, not drawing excessive current.

 

Incidentally -with the car unlocked, only bootlid open- there's a 1.0A draw for whatever body electronics are active at that point. Thats lower than I expected.

 

The battery is BMW unit, and a 110Ah behemoth - and as such has the date code stamped in the -ve terminal: Week 27 ...2007. Oh..!

 

I might think about replacing this soonish on the precautionary principle (or at least -start saving to do so!)

This lump would still be useful as a jump pack/ power source in the lock-up for the toy afterwards..

 

IMG_7993_600px.jpg

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