astra h - battery voltage

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Tue 27 Dec 2022 19:04
astra h - battery voltage - sim-sim

Hello

If I put + probe from multimeter on battery + post and the - probe on bodywork should I see battery voltage as I'm only seeing 5v.

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Tue 27 Dec 2022 19:18
astra h - battery voltage - elekie&a/c doctor
You should see the same voltage as if you put your probes directly across the battery. If it’s showing 5volts , either your battery is flat or the meter is reading incorrectly. Does the engine start ?
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Tue 27 Dec 2022 20:50
astra h - battery voltage - sim-sim

I have been having battery drain problem even though I can't find a drain. Battery is 12.25v using battery earth and is same if I use engine as earth but earth with body work I get 5v.

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Tue 27 Dec 2022 21:06
astra h - battery voltage - elekie&a/c doctor
Are you testing the body earth at bare metal, not painted metal ? Battery drain on these is very often radio related . Does it turn off when ignition key removed ?
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Tue 27 Dec 2022 21:39
astra h - battery voltage - sim-sim

I have tried various earth points like bolts going into bodywork. I even tried doing the drain test from battery earth to earth lead then putting meter on dc amps but it stayed at 0. Altenator is charging at 14.5v and after switch off battery reads 12.75v after two days of no use battery reads 12.25v but can sit a week and still start easily but get can bus errors on some modules as I guess it's low voltage. I have removed radio and screen fuse. I thought it was odd that I was not getting battery voltage on bodywork I will check the earth strap.

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Tue 27 Dec 2022 21:55
astra h - battery voltage - elekie&a/c doctor
What meter are you using ? Usually you need to move the red positive lead to a different port to measure dc Amps . Often the maximum is 10 amps .
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Wed 28 Dec 2022 14:01
astra h - battery voltage - sim-sim

It's digitek dt 3800. I have tried in the fused and un fused ports with black lead in com port.

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Wed 28 Dec 2022 14:36
astra h - battery voltage - elekie&a/c doctor
I’m all confused now. Do you actually have a problem with the car ?
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Wed 28 Dec 2022 17:15
astra h - battery voltage - sim-sim

Losing volts and eventually flat battery. All ready kill one battery and as there is a sticker on battery saying no lower than 12.40v it sits at 12.25v won't be long before this one goes as well. I have pulled fuses and relays but still voltage drops.
Can't as yet check earth strap as wet day today.

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Wed 28 Dec 2022 18:39
astra h - battery voltage - elekie&a/c doctor
You can’t do a battery drain test on these by pulling fuses and relays. I would suggest you get a decent multi meter that can accurately measure dc current . Connect in line between negative battery terminal and earth lead .
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Wed 28 Dec 2022 18:48
astra h - battery voltage - Crickleymal

Silly question but are you measuring DC amps or have you got the meter on AC amps?

I confess I'm a little lost as to how you're seeing 5V when measuring to the chassis unless it's insulated somewhat. If the battery earth strap was high resistance the car wouldn't start. I wouldn't worry too much about the battery being 12.25V. It's when it gets down below 12 then you start worrying.

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Wed 28 Dec 2022 22:27
astra h - battery voltage - bathtub tom

I had weird electrical problems on an albeit much older car. The earth lead went from the battery to the engine. It had a crimped tee off to the body. That tee was a bad connection, so I simply fitted another lead direct from the battery to an adjacent suspension turret.

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Thu 29 Dec 2022 00:14
astra h - battery voltage - Big John

The earth lead went from the battery to the engine. It had a crimped tee off to the body. That tee was a bad connection

My neighbour had the same crimped tee issue with a Fiat Punto

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Wed 1 Feb 2023 14:29
astra h - battery voltage - sim-sim

Earth was ok. I managed to get meter working,was blown internal fuse. My meter has 200u,2m,20m,200m,2 and 20u20 dca settings. I can only get a reading of .650 on setting 2 dca is this the correct setting and does that mean 650mv? All other settings show -1 or 1 did not use 20u20. Did not let car sleep as unsure if what I'm doing is correct.

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Wed 1 Feb 2023 14:39
astra h - battery voltage - sim-sim

Also no reading from 10 amp only from 2 amp socket.will the meter handle the amps if I lock it with alarm or should I have a earth strap on until modules start to sleep.

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Wed 1 Feb 2023 15:18
astra h - battery voltage - elekie&a/c doctor
Lock the car with battery connected . Then disconnect the earth lead and put the meter in between the lead and the battery post . On leave it for 30 mins to settle and check the reading on the 10 amp scale
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Wed 1 Feb 2023 15:55
astra h - battery voltage - sim-sim

I can't get a reading on 10 amp plug only 2 amp plug with dial on 2 dca, this gives me .650. Evrey other setting gives me 0, -1 or 1.

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Wed 1 Feb 2023 16:07
astra h - battery voltage - elekie&a/c doctor
If the reading on the 2 Amp socket is accurate, then .650 is way too high. Battery would be flat within 2-3 days. Reading needs to be .050 or less
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Wed 1 Feb 2023 16:23
astra h - battery voltage - sim-sim

Was just testing as not sure what I was doing was correct. Tomorrow I will lock car and let it go to sleep mode.

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Thu 2 Feb 2023 10:57
astra h - battery voltage - sim-sim

So 10 minutes into the test I'm getting a reading of 0.72.

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Thu 2 Feb 2023 11:54
astra h - battery voltage - sim-sim

Exactly 1 hour into test reading went to 750ma for around 5 seconds then 350ma for another 5 seconds then back to 0.72ma is this normal?

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Thu 2 Feb 2023 12:02
astra h - battery voltage - elekie&a/c doctor
If the reading from your meter is accurate, then those figures are not normal. The reading should stabilise around 0.050 - 0.060 mA .
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Thu 2 Feb 2023 19:27
astra h - battery voltage - sim-sim

So I'm looking for a 13ma current draw. I Guess pull fuses and see what happens. Any fuses I should not pull?

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Thu 2 Feb 2023 19:46
astra h - battery voltage - elekie&a/c doctor
It’s not possible to locate a current drain on cars that use a can bus network by pulling fuses . I would start by disconnecting the radio . Is it a factory fit unit ?
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Thu 2 Feb 2023 19:50
astra h - battery voltage - sim-sim

Even with the meter connected?. Alarm,radio and screen fuses has been removed. It is cd30 mp3 standard unit.

Edited by sim-sim on 02/02/2023 at 19:55

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Thu 2 Feb 2023 20:17
astra h - battery voltage - elekie&a/c doctor

Re fit all the relevant fuses and re-test the system . leave the radio disconnected .

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