Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
Parasitic battery drain - clamp meter recommendations ?
I have a parasitic battery drain.
Logged battery voltage dropping over a 24 hour period.
Checking for amps to identify the leaking circuit, I disconnected the negative lead from the battery and connected my cheap multi-meter across the gap. The multi-meter only has a max. of 10amp (unprotected/unfused) and the probes spark when I make the connection. I'm concerned I'll blow the meter !
Can anyone suggest a decent clamp-style meter which can be used to safely detect this leakage ? The likes of FLUKE meters would be wasted on me.
Thanks for any help.
7th Aug 2021 4:33 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4871
You'd be better to use the DMM or other device on a specific circuit rather than trying to take on the full residual load via the battery terminals. As you have identified, the clamp meter is ideal for that and there are decent a number of devices on the market via Amazon, Eblag, et al without the expense of something like Fluke which I use myself.
Then there's something like this, it's a only a one trick pony but it's simple and this one is fused at 15A
Click image to enlarge
Here it's being used to continuously run the lpfp whilst monitoring the current draw at the same time.
It can be plugged in via the fuse or adapted to whichever test point you require. That said, I'm sure when member GStuart reads this will be along very soon after with every possible clamp meter and DMM option known to mankind. yµ (idµ - eAµ) ψ=mψ
7th Aug 2021 6:44 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8154
Before parting with your hard earned cash disconnect ALL add on electrical mods you have fitted AND check the centre console fridge is is switched OFF, they kill batteries on D3s when left switched on, if that cures the problem connect the mods back one at a time, auxiliary battery solenoids can be another culprit.It can when others can't,
It will when others won't,
It goes where others don't.
7th Aug 2021 7:31 pm
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
PROFSR G wrote:
Then there's something like this, it's a only a one trick pony but it's simple and this one is fused at 15A
Click image to enlarge
Here it's being used to continuously run the lpfp whilst monitoring the current draw at the same time.
Thanks. They look to be about £20. Looks like the resolution doesn't go down to 1mA on the ones I've seen. I've found the clamp which Robbie uses in his excellent Battery Drain Testing post (DiLog DL6506) for £70, which is tempting given the extra functionality.
8th Aug 2021 9:15 am
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
M3DPO wrote:
Before parting with your hard earned cash disconnect ALL add on electrical mods you have fitted AND check the centre console fridge is is switched OFF, they kill batteries on D3s when left switched on, if that cures the problem connect the mods back one at a time, auxiliary battery solenoids can be another culprit.
Mine doesn't have the centre console fridge.
It all kicked off when I added the Audio Connectivity Module into the radio (low line) harness.
The boot release latch was also corroded/not working and I replaced it.
New battery installed at the same time.
Haven't checked the aux battery solenoids ... thanks.
8th Aug 2021 9:20 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10485
I wouldn't be spending £70
You don't need 1ma resolution. 50-100ma ish should be fine
8th Aug 2021 10:15 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10485
One way you could try with the parts you have.....
Put your volt meter on 200mv (yes volts)
leads in com & V
Put the 2 probes on either side of the fuse.
If you get 0 no current is going through the fuse.
If you get a value, a significant amount of current is going through the fuse, indicating a problem.
you need to shut all doors, latch the bonnet catch and wait 10 mins before starting this procedude.
There are even lookup tables on line to convert the voltage you get to a current (taking into consideration the fuse value and type).
Also do this for the larger fuses with plastic lids. (remove the lids)
You can use you 10A meter if you want. You just need to make a link between the 2 leads, so all the current goes down the link at first. Wait 10 mins. Then remove the link and the current will go thru meter, and should be a lot less than 10A at this point.
It's interesting to know which of the 2 red + battery leads its going down.
ie is it the alternator or something on the fusebox
8th Aug 2021 10:20 am
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
Thanks Pete.
When you say "make a link between the 2 leads", which 2 leads are you referring to ?
Do you mean link the ends of the 2 test meter probes together with the meter already in position to test the current ... then remove this link-lead after 10 mins and just let the current flow through the meter instead ?
Have I understood this correctly ?
Thanks for the tip on testing voltage across the fuses. I understand this one
8th Aug 2021 10:53 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10485
yes that is correct.
Have the link and meter in circuit at the same time, so the meter doesn't get all the massive current when connecting up.
have two paths, and then remove the one so it all goes through meter after 10 mins
8th Aug 2021 4:03 pm
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
So following Robbie excellent guide I have the following results.
Once all switched off, doors locked, bonnet switch shorted out and I rested it for 60 mins ...
... the main positive lead from the battery to the BJB reads 1.25 Amps
... the positive lead from the battery to the alternator reads 1.14 Amps.
Alternator (new Denso unit fitted Nov 2017) sounds like diode(s) have gone ?
Still a difference of 1.25 - 1.14 = 0.09 Amps, so perhaps I have a secondary leak ?Chris
11th Aug 2021 9:33 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4871
Did you have the test equipment connected during the 60 mins rest, or did you only connect them after that?yµ (idµ - eAµ) ψ=mψ
11th Aug 2021 9:39 pm
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
Equipment only connected after the 60 mins rest.Chris
11th Aug 2021 9:41 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4871
OK so have you then triggered the vehicle to partially wake up when you made the connection?
Try connecting again the test equipment via the BJB/Batt but with the equip switched in the off position. Wait until the vehicle is asleep (5 min) then switch on the test equip. Hopefully that won't trigger a "wake up" and see what the drain is.
If it does wake up try it with the equip switched on!yµ (idµ - eAµ) ψ=mψ
11th Aug 2021 9:52 pm
ckra1000
Member Since: 16 Aug 2010
Location: Sheffield
Posts: 165
Sorry, I should have been more specific .... I decided to buy the Di-LOG DC Amp clamp meter and this is what I used for the tests.
Hopefully, this wouldn't wake the system up ?
Also, 1.14 Amps on the Alternator positive leads seems wrong awake or not.Chris
11th Aug 2021 9:57 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4871
Ah OK, sorry my misunderstanding I thought you were using direct a contact tester.
In that case you could try popping fuses one by one and see if you get lucky? Start with the BJB and then move on to the CJB with the help of a COMPETENT assistant for the latter!!
Oh and check thoroughly your earth points! (all of them!!)yµ (idµ - eAµ) ψ=mψ
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