P38A 1.6volts after 72hrs!

Jon Dor · Mar 5, 2022

Just gone to start car and horrified that battery voltage is at 1.62v after being parked up for 72hrs or so! No lights left on, or anything else that I can see.
What's the best course of action to establish what's happened please guys...before I get on blower for Alan to abandon his holiday... Hahaha!
Thanks in advance.
Mike.

kermit_rr · Mar 5, 2022

How old is the battery? Is there a big spark when you connect the terminals to suggest a big drain?
If you fully charge it overnight while disconnected then leave it overnight you'll see how the actual battery is. 12.0v or below is dead as a doornail, 12.2 is still pretty dead but might stay the engine if you're lucky

brianp38dse · Mar 5, 2022

Check battery first but at 1.6v probably beyond recovery then try and find the drain with one of these

https://www.ebay.co.uk/itm/311684520868?hash=item4891d85ba4:g:AlYAAOSwdzVXwD8N

kermit_rr · Mar 5, 2022

A multi tester works too and probably already got one

Jon Dor · Mar 5, 2022

brianp38dse said:
Check battery first but at 1.6v probably beyond recovery then try and find the drain with one of these

https://www.ebay.co.uk/itm/311684520868?hash=item4891d85ba4:g:AlYAAOSwdzVXwD8N

Loaned my mate mine about 3 months ago. Just called to get it back and he's loaned it to someone else who's on holiday... Sod's law!

Jon Dor · Mar 5, 2022

kermit_rr said:
A multi tester works too and probably already got one

How do I use the multimeter to check for a current drain Kermit?

kermit_rr · Mar 5, 2022

Jon Dor said:
How do I use the multimeter to check for a current drain Kermit?

You can measure milli volts across the fuse while it's in place, where 0 means no drain, have a look at this chart, can't remember where i got it from

Jon Dor · Mar 5, 2022

kermit_rr said:
You can measure milli volts across the fuse while it's in place, where 0 means no drain, have a look at this chart, can't remember where i got it from

Thanks Kermit! What a frog/gent

Datatek · Mar 5, 2022

kermit_rr said:
You can measure milli volts across the fuse while it's in place, where 0 means no drain, have a look at this chart, can't remember where i got it from

Unless the drain is large, you are looking for micro volts across a fuse, undetectable with a normal meter.
Most likely cause is the BECM staying awake, do the sleep test. Next most likely is a failed diode in the alternator.
I'm sorry to say that the battery is unlikely to recover. even if it appears to do so it's capacity is likely to be much reduced.
Needs a solar panel to keep it topped up.

Jon Dor · Mar 5, 2022

Datatek said:
Unless the drain is large, you are looking for micro volts across a fuse, undetectable with a normal meter.
Most likely cause is the BECM staying awake, do the sleep test. Next most likely is a failed diode in the alternator.
I'm sorry to say that the battery is unlikely to recover. even if it appears to do so it's capacity is likely to be much reduced.
Needs a solar panel to keep it topped up.

Thanks Keith...the MF-31 1000 is over 5yrs old and, in recent very cold weather had been very suspect, needing jump starting a few times. I bought a decent, but only 900CCA one for the XC90, but terminals are incompatible. Frustratingly, both my solar battery maintainers are aboard Jondor and, with quayside flooded, I've been unable to get aboard to retrieve them. Doing a trickle charge for next 24 hrs, but not at all hopeful it'll recover. On the charger, it has a * setting. Should I set it to that Keith?

Datatek · Mar 5, 2022

Jon Dor said:
Thanks Keith...the MF-31 1000 is over 5yrs old and, in recent very cold weather had been very suspect, needing jump starting a few times. I bought a decent, but only 900CCA one for the XC90, but terminals are incompatible. Frustratingly, both my solar battery maintainers are aboard Jondor and, with quayside flooded, I've been unable to get aboard to retrieve them. Doing a trickle charge for next 24 hrs, but not at all hopeful it'll recover. On the charger, it has a * setting. Should I set it to that Keith?

I do not know what charger you have Mike, * sometimes means a cold weather setting. Batteries fail due to being kept in a semi discharged state, Lead Calcium batteries and not designed to be kept in any state other than fully charged.
My smart chargers will not even try to charge a battery if the voltage is below 11 volts, I have to use a lab power supply, so you are lucky if your charger works.

Jon Dor · Mar 5, 2022

I have a Halfrauds "Workshop" charger, busy charging another battery, but the one I am trickle-charging the MF-31 1000 on is a Lidl cheapo with 6/12/* options. When I put on charge, it started out at 11.5 v, but started charging OK. Halfrauds pic is attached

Jon Dor · Mar 5, 2022

Other charger pics attached

Jon Dor · Mar 5, 2022

Whoooops...part deux...

Datatek · Mar 5, 2022

Jon Dor said:
I have a Halfrauds "Workshop" charger, busy charging another battery, but the one I am trickle-charging the MF-31 1000 on is a Lidl cheapo with 6/12/* options. When I put on charge, it started out at 11.5 v, but started charging OK. Halfrauds pic is attached

OK, you are lucky that the Lidl charger actually started charging, I have 2 of those and they will not start charging below 11 volts.
The star is for winter maintenance charging according to my info.
The Halfrauds charger looks a bit of a beast what is the maximum charge current?
The Lidl charger will take more than 24 hours to bring the battery to a state of full charge unless it has degraded a lot.

Datatek · Mar 5, 2022

Jon Dor said:
Whoooops...part deux...

I have one like your picture and an earlier version with no display, just an LED to indicate when charging is complete.
They are good chargers IMO, but with less than 4 amps output, it takes a long time to charge an MF31-1000

Jon Dor · Mar 5, 2022

Three setting options Keith:

Datatek · Mar 5, 2022

Jon Dor said:
Three setting options Keith:

I would not connect that to a P38 battery that is still connected to the car. The RMS figure suggests that the output is not pure DC

Jon Dor · Mar 5, 2022

Datatek said:
I would not connect that to a P38 battery that is still connected to the car. The RMS figure suggests that the output is not pure DC

MF-31 1000 is off car on charge in my flat Keith. Which setting on the Halfrauds one would you select to leave overnight Keith?

Jon Dor · Mar 5, 2022

Datatek said:
Unless the drain is large, you are looking for micro volts across a fuse, undetectable with a normal meter.
Most likely cause is the BECM staying awake, do the sleep test. Next most likely is a failed diode in the alternator.
I'm sorry to say that the battery is unlikely to recover. even if it appears to do so it's capacity is likely to be much reduced.
Needs a solar panel to keep it topped up.

What's the "sleep test" you mentioned Keith?

P38A 1.6volts after 72hrs!

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