Baffling battry drain issue.

jackbombay

2003 158" shc
So I got a new battery for my sprinter recently as I though the old one had a cell go bad, but the new one, after getting a full charge, went dead in 8 hours. This battery has to be at least an 80 Ah battery, to get that to 11 volts in 8 hours we're talking about a draw of 5+ amps.

So I hooked up my multimeter to the neg terminal of the battery and the negative lead to measure amp draw, the first time I did this it blew the 10 amp fuse in my multi meter, the second time it spiked to 8ever so briefly and then settled to .02 which is in the range of normal. According to my manual normal is .005 to .035. SO I hooked the battery back up after charging it again, and it was drained right quick again, how?

So today with the battery charged once again I hooked up my multimeter and let it set for several hours and checked it every 15 min or so, it was at .02 for a while and then dropped to nothing. I then unhooked the multi meter and checked voltage, 9 volts, how is that possible?

How is the battery getting drained so quick when supposedly only .02 amps are being drawn from it?

I let the battery sit after a charge for a day without the neg lead hooked up to it and ti held a charge fine, fwiw.


Anyone have any ideas?
 

Altered Sprinter

Happy Little Vegemite
Soft start:Check the battery condition.
Bulk:Bulk charge>
Absorption: Charge.Peak charge with minimized fluid loss.
Analysis:Tests whether the battery retains the energy.
Recond:Reconditioning of a drained battery.
Float:Maintenance for maximum performance.
Pulse: Maintenance for maximum battery life .
Based on suitability of your chargers charging capacity.
Irrespective of what ever your manual or information comes from.

The facts are :If your battery is low on power voltage.
Spikes: on first test to ign you will drop into a multiple-spike fluctuation on rapid second voltage digital variants.
8 v is less than one second followed by rapid build to 10.2 to 11.4 v
Start will record after one second 12.2 to 12.4 v
Upon alt normalization at rpm under 4 seconds your alt will rapid charge to show 13.4 v normal 14.4 full charge.it will only show 14 volts with zero acc's running 13v range is normal with heaters radio etc
Acc's/ill show variations depending on the main battery positive line to end of //ACC'S LINE TWO SEPARATE VOLTAGES WILL SHOW DEPENDING ON LOAD OR LOADS As to how many accessions are running especially on aux lines.
If in doubt as to amp drop measure the distance between the positive mains battery cable to where it is leading to! if connected to aux battery supply ground loss is due to both cable voltage loss and live connection to aux.
Suggest you place a Kill Battery switch as close as possible to your main battery to prevent power voltage loss when not in use.as the Mercedes kill switch is absolutely useless if your running non Mercedes powered accessories or units.

If you use a digital volt display cheap as chips to buy, you will be able to see the VOLTAGE fluctuations including temps of battery .
 

Eric Experience

Well-known member
Jack.
If your multimeter is digital it may not show the true current if the load is a switch mode power supply. I suggest you connect a globe about 50 watts in place of the meter, the globe will indicate the average current. Just a tip to find an intermitant load, use a blow fuse with a small car horn wired across it, it will sound if there is a heavy load, to test it plug it into the head lamp fuse and then turn on the lights.
Eric
 

sikwan

06 Tin Can
So today with the battery charged once again I hooked up my multimeter and let it set for several hours and checked it every 15 min or so, it was at .02 for a while and then dropped to nothing. I then unhooked the multi meter and checked voltage, 9 volts, how is that possible?
Does the battery hold its charge (not connected) after an hour?
 

mendonsy

Member
It sounds a lot like a bad battery. The plates take a "surface charge" so the battery appears to be fully charged but really isn't.
Here's a fairly good description: surface charge
Auto parts stores (Advance, Auto Zone, NAPA) have a high current tester to check for this problem.
 

kkanuck

LUV my T1N
I too just put a new battery in my ride, thinking it was bad, as 5-6 days of not driving it, it would crank very slow, or would not crank enough to start. Now having put in a new battery, it seems like the symptoms have not gone away.


Is an electrical issue like this with some kind of intermittent draw when off a warranty item? I am still in powertrain and engine warranty, but the original 3 year 36K warranty is over...


Thanks for any clarification
 

jackbombay

2003 158" shc
My battery drain issue did end up being a bad glow plug relay, sticking on. Well, I have not replaced it, but I have been driving around with the GP relay unplugged for ~6 weeks and have not had the battery go dead once. I will be getting a new GP relay this fall sometime.
 

kkanuck

LUV my T1N
My battery drain issue did end up being a bad glow plug relay, sticking on. Well, I have not replaced it, but I have been driving around with the GP relay unplugged for ~6 weeks and have not had the battery go dead once. I will be getting a new GP relay this fall sometime.
Did you diagnose it yourself? Are you sure there are no glow plugs that are bad causing the relay to go bad? Was it hard to unplug?


I just put a new alternator in and want to make sure I do not re FRY it if GP's or relays are causing it.
 

pgr

Active member
I had a similar problem in the winter. I discovered the LED's on my back up camera were on all the time as I hadn't wired it through the ignition switch. I only noticed it when I happened to be outside one cold winter night. It was just enough power to drain the battery on a cold winter night but fine in warmer weather.

pgr
 

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