tolsen

Battery drain

22 posts in this topic

Starter battery in my 2002 Cabrio runs flat in about a week. Current draw whilst car is locked and no consumers on is 0.15 A, equivalent to 25 Ah in seven days. 

Obviously a fault somewhere and a potential fire risk. 

 

I have as a temporary measure fitted an ingenious, dead cheap and well made China battery pole screw down isolation switch so can no longer lock the car overnight but no problem here.  

 

The master plan is to start at the rear end and go over all wiring. 

 

Must sort out this soon as planning to go mackerel fishing. 

 

 

 

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Load test your battery could be weak or a plate shorted out.

A brand new battery can be NFG freash off the shelf or any day in use from then on.

25 ah shouldn't drain a battery enough to not start a Smart

When I bought mine it hadn't been started in 6 months and It fired right up on about it's 3rd revolution about the same still for cold starts it was a bit slow as I'm sure the it wasn't at full charge we also had to dig it out off the snow bank it was parked in to open a door so it had sat a while.

Diodes in alternator are the most likely culprit for battery drain.

Disconnect the leads off of the alt and recheck your load draw.

Next is to start pulling fuses one at a time to see which one stops the load draw

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Condition of starter battery has nothing to do with the amps drawn by the car when it is partked, locked and all consumers turned off.

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i agree with Mike.  try unplugging your radio.  my was doing the same thing.

after the SAM shuts down  (usually 3 seconds after you turn off the key)  the radio is the only drain on the battery.

the battery in my car with the radio plugged in would go flat in 3 days,    i can leave the car sit for weeks with the radio unplugged,  and have no issues.

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Radio when turned off only draws 20 mA according to my uncalibrated Fluke multimeter.

 

It looks now like the fault is intermittent because battery drain measured a few minutes ago appears normal at 0.013 A.

 

I have locked the Smart with both side windows open and the multimeter reading amps between battery negative pole and chassis.

 

The culprit may be a sticking relay.  When switching on and off parking lights the amps go back up to 0.15 A, sometimes drops to the normal 0.013 A but sometimes stay constant at 0.15 A.  So getting nearer to homing in on the cause I think.

 

There also appears to be a fault in wiring to my trailer socket.  A fantastic trailer light test tool arrived recently all the way from China.  This tool tests both trailer lights and trailer light socket on the car.  All trailer lights work when connected to the car but tool tells me there is a fault with brake light.  Testing brake light on its own is OK but trailer brake light does also indicate on tool when I turn on parking lights so need to check that out further.

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A NORMAL radio only draws that much.  A faulty one will drain it overnight.  I know of two diesel fortwos that had mysterious drains that ended up being a faulty Grundig unit.

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1 hour ago, MikeT said:

A NORMAL radio only draws that much.  A faulty one will drain it overnight.  I know of two diesel fortwos that had mysterious drains that ended up being a faulty Grundig unit.

nothing about my smart is normal..  including the driver.    lol

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My Smart is behaving just now:

8CA99FF8-A839-4CA3-9D8D-D882B58AB16E.jpeg

Note the green hand knob on negative pole. Another dead cheap quality product from China. Will soon become expensive for the Americans. 

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Standard diagnostic procedure for locating an electrical component that has a parasitic draw is the following.

1. Disconnect the positive terminal from the battery and hook up the ammeter in between the cable end and the positive battery post. Your meter is now in series with the battery.

 2.  Make sure the car is fully turned off and observe the current draw. It should  be below .05 amps.

3. If it draws quite a bit more than that you start removing fuses one at a time until the current flow drops to something like .05 amps.

4. You have now isolated the circuit with parasitic draw component on it and you should be able to disconnect the few components on that circuit and further narrow the search down.

5. Sometimes you have an intermittent fault that could be hard to isolate. It could be a component, wiring or a computer. Selectively removing the suspect part could also help find the culprit.

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I measure amps between negative pole and chassis as nearer and easier access.  Otherwise I have followed same procedure but since this appears to be an intermittent fault it may take some time to sort it out. 

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Got an intermittent problem with my thirty years old microwave too. Got that one sorted. Found turning off and on contact breaker fixes it. 

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Help! I have the opposite problem! i just bought a 2015 451 Electric Drive and everything so far as know is working fine EXCEPT THE RADIO it was "mysteriously not working" from day one at first i thought it might be a fuse then i thought maybe previous owner swapped out and back in a after market radio but didnt plug it back in BUT NOW after reading the comments here i suspect that whoever disconnected the radio ON PURPOSE ! because maybe they were having the battery drain problem which i dont seem to be happening with a dead radio. Now i dont really want to listen to the radio at all but i do want to be able to hook my phone or other mp3 and use the cars speakers, so anyone got any ideas? ones that wont lead to draining the battery? Thanks! in advance

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On 9/12/2019 at 4:55 PM, tolsen said:

And to ensure battery won’t go flat I have decided to fit a PV solar panel. 

oddly unrelated to my radio issue i was looking into this too as i dont drive often maybe once a week for short distances i was concerned about 12v bat issues and Amazon has lots of 12v 10watt solar chargers to maintain batteries not used often claiming they have no overcharge and no backwards charge safeguards and all under $90 I keep my 451 electric under a car cover due to the blazing CA sun and cold wet mornings here for the week so thinking of glueing the solar panel to the top of the car cover and running cables down and in.

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If your Smart has a solid roof, just stick a suitable 100 watt solar panel to it and connect to battery via a cheap PWM charge controller. 

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54 minutes ago, tolsen said:

If your Smart has a solid roof, just stick a suitable 100 watt solar panel to it and connect to battery via a cheap PWM charge controller. 

Hi thanks for your answer yes it is a solid roof solid all glass moonroof! but im sure there are areas that are not the glass see thru areas

well to keep the 12 v bat from draining while i have its car cover on it for a week or two at a time I was just thinking of putting a solar panel on the cover on the roof of the car glue it or something then run cables to the 12v bat but of course its a pain to have to disconnect etc added to having to fold up the cover all this while I can barely stand or walk due to disability ugh  there must be a solution other then just unplug radio permanently i mean i want a sound system in the car other then using my phone only

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Today I unseized alternator on a 1999 Smart City Coupe.

Had quite a surprise when I checked its starter battery. Original from 1999 meaning it is at least 20 years old. Tested battery with my load tester and confirmed still good. Amazing. 

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Another fact about this 1999 Smart. Only done 30,000 miles since new. 0.6 petrol engine. No cracked exhaust manifold and no split in lower seam of muffler. 

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