Battery Drain

[nwsavvy]

Hi Folks.

Had a problem Tuesday morning, went to start car,Mondeo mk3 130 diesel, battery dead, checked everything and so ordered new battery as had car now for 12 months without problem (electrics only) I checked the current drain after fitting the new battery and got a reading of 0.10 amps. How does this sound to anyone in the know please? Would this drain a battery that otherwise caused no problems previously?

Many thanks.

BJ

[nwsavvy]

Hi again, to test before I used a multi tester inline. Would this be better then I can check with the battery still connected.

http://www.toolstation.com/shop/Electrical/d190/Electrical+Test+Equipment/sd3348/Digital+Clamp+Tester/p61650

Thanks

[al2052]

I think you will find that meter reads AC current only, you will have to spend a lot more money than that to find a tongue tester to read DC current ie. car electrics, hence is reading correct??

[nwsavvy]

Ok thanks will have to look else where.

Cheers

[BOF]

Well, that meter doesn't claim a DC current range (look at the specs) so Alan is correct. One of the other problems is how you actually do the measurements; it is easy, if you have to leave the doors open/unlocked, the bonnet open and the car 'part on' for it to be drawing a different current than it would be overnight. On a Mk IV, for example, for approx the first 30 minutes after switch off, the power hold relay is still on and the current consumption is quite different from what you'd measure later.

As to 100 mA, if you have a 70 Ah battery, and is down to 35 Ah (half original capacity...capacity of lead acid batteries goes down over life, until it becomes insufficient), it would take an Ah every 10 hours, so it would last 350 hours until fully flat. That wouldn't start the car, being fully flat, so to have any chance of actually starting, so, practically, it would probably more like half that. That's 175 hours (just over a week), which is ok until you leave it at the airport for two weeks, when you had better have other measures in place...

100mA sounds on the high side to me; if that really is the current draw - which it probably isn't - then, are you sure there isn't any aftermarket equipment on the car, putting the current draw up?

[nwsavvy]

Thanks all.

I didn't know about the 20 minute wait for the relay to kick off. I tested it after I disconected the battery and put my multi meter inline and it went up to about 0.3 A. Then it dropped to 0.1A after about 2 mins. I had the meter on 10A setting and it registered 0.1A thereafter. I just thought I would get a better result using a clamp on meter but knowing which one? Maplins have a mini at £15 ish so will borrow one for now maybe and look into buying one later.

No aftermarket radios or anything fitted and I had no idea of the age of the old battery.

Checked the car and started ok this morning so hope it is a one off.

Thanks again

BJ

[stef123]

You can get clamp on meters to work with dc but where low values are concerned don't even bother - stick with using the meter inline.

[nwsavvy]

Thanks for that. will go look for some croc clips then I can leave it connected inline for the draw down time and recheck. it was ok this morning but for peace of mind will check it.

Thanks

BJ

[nwsavvy]

Right, left the car with MM connected for an hour, with the MM set at 10 Amps I got a reading of 0.02 Amps. I assume therefore that is ok? Is this Thanks for all the help everyone.

BJ