Is my battery kaput?

[presta]

@presta
When a starter motor dies it trickle drains the battery when it's not being used.

220mA isn't a 'dead short' as you suggested.

If there is a parasitic drain of more than 10A the meter won't last. The battery would be flat in less than a day.

It's normally 1-2A after locking the car, then a quick fall into milliamps, then less than 50mA a minute or so later

The point I was getting at is if the electronics take more than 10s booting up they might overheat the meter.

 

[CXRAndy]

Well, I never heard of shutdown processes, but now I have I went out and redid the check, exactly as above, an hour or so ago, when I got the 0.22 readout, and...

Much lower. Also, arguably interestingly, all over the place. Fluctuating constantly, between about 0.06 and 0.12. I'm curious about the variation - I would have thought if there was a drain it would be consistent. Apparently not. But assuming it averages out at about 0.09, that's around twice what I've heard is 'to be expected'/acceptable. And would probably account for the battery losing its grunt over a few days.

I'm thinking, as a quick & dirty solution, fit the solar panel, hard-wiring it to the battery terminals so it's isolated from the battery isolator, as per Gwylan's tip up-thread, then simply add 'bip battery' to the regular startup routine. Sounds a belter, eh?

The battery drain is on the high side .

Now to test where the draw is going Put the meter to read milli volts DC. When the car is totally asleep check voltage across the top of each fuse and note it down. Fuses have a small resistance which allows you to measure a voltage. There should be zero volts reading across most fuses. But you may find that one or two have a few millivolts readings.

Once you have narrowed down offending fuse, pull the fuse. Recheck the current draw on the battery to see if it's less.

Only pull one fuse at once. Or you may start chasing your own tail.

It's a methodical process to track down the parasitic drain.

Another thing to bear in mind, is the meter accurate, cheap meters will not be as accurate as a for example a Fluke multi meter

 

[Biker BoB]

Starter motor... 50p....

 

[CXRAndy]

Is the variation in current draw rhythmic, like a flashing LED on the dash (security light). This would account for the fluctuation.

 

[CXRAndy]

I can give you a similar example. I got a car, that would flatten the battery in around 1 week. I found the draw was 150 mA. I found a wired in black box, so removed it. That halved the drain, but still too high. I called the previous owner and they told me that he thought that the car had two black boxes fitted from different insurance companies. I eventually found the second device buried deep under the dash. Once removed the car can sit month without needing a charge and the drain is now 10mA

 

[swee'pea99]

When the car is totally asleep check voltage across the top of each fuse and note it down. Fuses have a small resistance which allows you to measure a voltage. There should be zero volts reading across most fuses. But you may find that one or two have a few millivolts readings.

Once you have narrowed down offending fuse, pull the fuse. Recheck the current draw on the battery to see if it's less.

Thanks, that's really helpful. So basically first I eliminate most fuses from my enquiries by finding zero voltage between the ends (with the car absolutely dead), then having identified any that are registering a reading, I pull one out and test the draw. If it's less, I have the culprit. If not, put it back and try the next 'possible', until I find one that, when it's removed, the draw drops . Yes? Sounds like a plan!

Oh, the meter's nothing flash but I think it's quite a reasonable one. Uni-T UT30B. Not a fiver down the market.

No thoughts on the battery isolator? I thought that sounded quite promising...

 

[CXRAndy]

Yes that's the process.

If you can't find the issue or it becomes expensive to repair, a battery isolator is a good cheap idea.

Have you checked the forums for the vehicle to see if there is common cause?

 

[swee'pea99]

Yes that's the process.

If you can't find the issue or it becomes expensive to repair, a battery isolator is a good cheap idea.

Have you checked the forums for the vehicle to see if there is common cause?

There is a so-called 'notorious relay', but I don't think it really matches the symptoms.

I mentioned this all to 'er indores over dinner. Who said, 'so if you can fit this remote isolator and it will stop the battery draining, but it will still get topped up every time we drive, why do you need all the solar stuff?' To which I of course replied 'Um...'

 

[Richard A Thackeray]

Mine's playing up too
it'll do the long, dragged out, start up
Oddly though, if I turn it off, even a couple of minutes later, it'll start fine

 

[Biker BoB]

Mine's playing up too
it'll do the long, dragged out, start up
Oddly though, if I turn it off, even a couple of minutes later, it'll start fine

Had a problem on my 4x4 recently.
Was dead as a doe doe trying to start. I finally worked out that the glow plug timer wasn't cutting off until it timed out.
So if I didn't wait for the glow plug circuit to complete it charge it was drawing the starter power and the glow plug power at the same time

 

[Richard A Thackeray]

Had a problem on my 4x4 recently.
Was dead as a doe doe trying to start. I finally worked out that the glow plug timer wasn't cutting off until it timed out.
So if I didn't wait for the glow plug circuit to complete it charge it was drawing the starter power and the glow plug power at the same time

It's got a daft push-button start, so it all happens automatically

 

[Biker BoB]

It's got a daft push-button start, so it all happens automatically

I think it's definitely a petroleum spirit fix ...

 

[CXRAndy]

Mine's playing up too
it'll do the long, dragged out, start up
Oddly though, if I turn it off, even a couple of minutes later, it'll start fine

Could be numerous causes, worn starter motor, crank sensor iffy, spark plugs, fuel supply. Need a scan to see if there are any codes pointing in the direction of fault