Testing for 12v current drain

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Testing for 12v current drain

Post by Billy Ruffian on Mon Sep 11, 2017 9:25 pm

I want to see if I've got a continuous drain on the habitation 12v.   I assume I can do this by disconnecting the battery from one of its terminals and using an ammeter between the battery terminal and the disconnected wire.    Does it matter whether I disconnect the positive or negative?

Also I've not been able to locate a fuse on the 30w solar panel (factory standard fit) - any ideas about where it will be?   It's on  2012 Nuevo ES.
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Re: Testing for 12v current drain

Post by brodco on Mon Sep 11, 2017 9:58 pm

Hi  wave

Billy Ruffian wrote: I assume I can do this by disconnecting the battery from one of its terminals and using an ammeter between the battery terminal and the disconnected wire.    Does it matter whether I disconnect the positive or negative?

Yes - you assume correctly - and you can use either terminal (whichever is more convenient).
Don't forget to change the meter lead back to the voltage terminal immediately afterwards to avoid the classic mistake of inadvertently connecting the meter across 12V with the leads in the current socket! shrugg

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Re: Testing for 12v current drain

Post by dbroada on Mon Sep 11, 2017 10:04 pm

brodco wrote:
Don't forget to change the meter lead back to the voltage terminal immediately afterwards to avoid the classic mistake of inadvertently connecting the meter across 12V with the leads in the current socket! shrugg

Brod
Who would do such a stupid thing? confused3


blushes  Oh yes, I remember, me.

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Re: Testing for 12v current drain

Post by Peter Brown on Tue Sep 12, 2017 6:35 am

DONT do this on the main vehicle battery.  The multimeter will usually take a max of 10A and if you, say, open an electric window that will draw a much larger current.

For the habitation battery, make sure your battery charger is off.  There is no fuse for the solar panel, you need to unplug it from the Sargent PSU.

Elsewhere on the forum can be found information for ammeters designed to plug into blade fuses that are available from Maplins and a multimeter with a none-intrusive loop that can measure current safely.  If you can't find them, I can find the details later today.

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Re: Testing for 12v current drain

Post by Billy Ruffian on Tue Sep 12, 2017 7:51 am

Hi Peter

Thanks for the warning about the engine battery.   I can't find the links so if you could have a look for them I'd be greatful
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Re: Testing for 12v current drain

Post by Peter Brown on Tue Sep 12, 2017 11:01 am


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Re: Testing for 12v current drain

Post by Billy Ruffian on Tue Sep 12, 2017 11:34 am

Many thanks Peter
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Re: Testing for 12v current drain

Post by brodco on Tue Sep 12, 2017 12:55 pm

Hi wave

Peter Brown wrote:DONT do this on the main vehicle battery.  The multimeter will usually take a max of 10A and if you, say, open an electric window that will draw a much larger current.

The original question was about the leisure battery but you can use the same technique on the engine battery if you just want to measure the parasitic drain. I can’t think why you would open an electric window or (switch on anything else for that matter) while you were measuring current drain. scratch head

You'd hope it would be obvious, never the less just to be on the safe side it’s worth making the point that any high current equipment should be turned off and there’s no point in measuring the current drain while the battery is charging. Normally you get a clue if there is any significant unknown drain because there is a spark when you disconnect / connect the battery terminal.

I agree that a clamp meter is excellent if you want to measure current on a regular basis but I’m not sure it’s worth the expense if you only want to measure low currents occasionally. If you’re worried about it you can always put a fast blow 10A fuse in series with the meter lead (or buy a set of fused meter leads). From the safety point of view it's a good idea to do that on an un-fused meter anyway.

dbroada wrote:
brodco wrote:
Don't forget to change the meter lead back to the voltage terminal immediately afterwards to avoid the classic mistake of inadvertently connecting the meter across 12V with the leads in the current socket! shrugg
Who would do such a stupid thing? confused3
 blushes  Oh yes, I remember, me.

It wouldn’t be so bad if I’d only done it once! Problem is I tend to put the meter back in the case with the lead still in the current socket. Next time – well it’s another ten quid fuse! think_smiley_46  tap_fingers

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Re: Testing for 12v current drain

Post by Peter Brown on Tue Sep 12, 2017 2:29 pm

brodco wrote:I can’t think why you would open an electric window or (switch on anything else for that matter) while you were measuring current drain. scratch head

You'd hope it would be obvious, never the less just to be on the safe side it’s worth making the point that any high current equipment should be turned off
Brod

I don't disagree with the points Brod makes but....

I regularly lock/unlock the van just by bending over with the keys in my pocket - I reckon that would pop a 10A fuse. Not everyone has the concept of how large the currents can be in vehicle 12v circuitry and we've no idea who is going to read these posts.


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Re: Testing for 12v current drain

Post by Billy Ruffian on Tue Sep 19, 2017 1:32 pm

Thanks for all the responses.    I bought the clamp meter suggested by Peter and sure enough when I switch on the control panel there is a 0.3 amp current through the battery leads.    Doesn't sound much but in 24 hours that's 7 amps.    I can't find anything on in the van and as I spend a lot of time off 240v its very relevant to me.

Do all Nuevos have a current draw like this?
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Re: Testing for 12v current drain

Post by Peter Brown on Tue Sep 19, 2017 2:02 pm

I would think that 300 MA is normal. There is the power used by the control panel and PSU and a permanent supply to the circuit board in the fridge. If yo have Whale fresh water fill system, that will also draw a little current.

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