SLS battery draining
Discussion
I know some others have had issues in the past, and wondered if anyone has found an answer?
My SLS coupe battery drains overnight from time to time, at random. This week I put it in garage fully charged and it was dead the next morning (showing 5v).
Car is locked and everything off, and I replaced the battery in November after it happened 3 or 4 times before. I've already fallen out with local dealer who told me there's no problem, and charged £59 for diagnostic to do so. It now goes 40 miles away for service!
I'd say it's happened 6 or 7 times so far, and Merc assist have sorted each time, but also can't identify fault. Any ideas..?
My SLS coupe battery drains overnight from time to time, at random. This week I put it in garage fully charged and it was dead the next morning (showing 5v).
Car is locked and everything off, and I replaced the battery in November after it happened 3 or 4 times before. I've already fallen out with local dealer who told me there's no problem, and charged £59 for diagnostic to do so. It now goes 40 miles away for service!
I'd say it's happened 6 or 7 times so far, and Merc assist have sorted each time, but also can't identify fault. Any ideas..?
That is a heavy drain to empty the battery over night, the only thing that I can think of is the diode pack in the alternator, the only thing against this is the semiconductors are either good or bad, and never intermittent.
To empty the battery over night means a draw of around 8 amp if the battery was fully charged, there is nothing in the car that could pull that much when turned off, so my thoughts are something around the alternator.
To empty the battery over night means a draw of around 8 amp if the battery was fully charged, there is nothing in the car that could pull that much when turned off, so my thoughts are something around the alternator.
television said:
Trackers only draw milliamps.
When all working well yes but not if there is a problem with it. On the experience I had I agree that they are an expensive waste of time. Even when it was flattening the battery every couple of days the tracking company had no record of it going "off air".Edited by JimmyR1 on Friday 15th May 11:36
I've (touch wood) never had a problem with my 2010 SLS Coupe.
I ensure she is always locked when I put her to bed. So far she's only been 3 weeks between useage and started first turn of the key. I have fitted an trickle charger but I doubt I'll ever use it.
I wouldn't bother with Mercedes dealers for diagnosing this - find a decent local Auto electrician and find out whats causing the battery drain and take it from there.
I ensure she is always locked when I put her to bed. So far she's only been 3 weeks between useage and started first turn of the key. I have fitted an trickle charger but I doubt I'll ever use it.
I wouldn't bother with Mercedes dealers for diagnosing this - find a decent local Auto electrician and find out whats causing the battery drain and take it from there.
Merc tech suggested it might be because doors were left open, so that must be a known issue. I don't think that was the cause last time, as I had to use physical key to get in to open bonnet so I know door was locked.
As an aside - i bought mine second hand and don't think it has a tracker. I take it they weren't standard? Need to get one for new insurance co.
As an aside - i bought mine second hand and don't think it has a tracker. I take it they weren't standard? Need to get one for new insurance co.
Merc tech suggested it might be because doors were left open, so that must be a known issue. I don't think that was the cause last time, as I had to use physical key to get in to open bonnet so I know door was locked.
As an aside - i bought mine second hand and don't think it has a tracker. I take it they weren't standard? Need to get one for new insurance co.
As an aside - i bought mine second hand and don't think it has a tracker. I take it they weren't standard? Need to get one for new insurance co.
I had an Audi that was a bugger of a thing to find.
If you are planning to look for it yourself - it's generally pretty easy, but time consuming, fit an ammeter either in line, or a clamp meter so you can see what's going on.
When you have found a current drain (will normally be about 3 - 4 amps to drain overnight (not 8) you can pull the fuses out one by one, and see if it makes any difference.
If you have a current drain, and the individula fuses have made no difference it's either through the alternator (disconnect alternator and check), or through the CAN system.
The later is a bugger to check, and will need an auto electrician (I know one....
) with some sophisticated kit.
If you are planning to look for it yourself - it's generally pretty easy, but time consuming, fit an ammeter either in line, or a clamp meter so you can see what's going on.
When you have found a current drain (will normally be about 3 - 4 amps to drain overnight (not 8) you can pull the fuses out one by one, and see if it makes any difference.
If you have a current drain, and the individula fuses have made no difference it's either through the alternator (disconnect alternator and check), or through the CAN system.
The later is a bugger to check, and will need an auto electrician (I know one....
) with some sophisticated kit.The CAN bus is easy to check to see if anything is staying awake, if the CAN is the same as the 230 the CAN H would be 11v dormant and 4.6v active, CAN H would be 0.025 dormant and 0.65 active. I can check if you do need the voltages exact.
On average most memories when leaking only draw 100ma.
A DC clamp meter that can resolve down to 1ma would be the best tool to use as the path of any leak would not get broken.
On average most memories when leaking only draw 100ma.
A DC clamp meter that can resolve down to 1ma would be the best tool to use as the path of any leak would not get broken.
Had similar problem with mine last year and it turned out to be the tracker which was draining the battery. New unit fitted by Cobra and no issues now. The people from Cobra actually said there was no issue at first but during the testing at Mercedes Newcastle the unit had an intermittent fault show up. Hope you get it sorted.
Had similar problem with mine last year and it turned out to be the tracker which was draining the battery. New unit fitted by Cobra and no issues now. The people from Cobra actually said there was no issue at first but during the testing at Mercedes Newcastle the unit had an intermittent fault show up. Hope you get it sorted.
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