Flat battery - cannot open boot

[Swotty]

2003 W215 600TT

Don't know if there is a drain on the boot lock but had to put a charger/conditioner on the battery. However, it is now flat and cycling between 3 and 4 volts.

Used the metal key to try and open the boot - has worked several times before - but this time, although the key turns and the lock depresses, the boot doesn't open.

Opened the driver's door with the metal key so can access the bonnet area.

Is there a way of charging the battery or attaching a slave? Have also read that these cars don't like jump starting.

Ideally I'd settle for getting the boot open and changing the battery.

Any ideas gratefully received!

 

[Londonscottish]

I've no experience with 215's - only 211's a 212's.

But, FWIW, on my 212 I can jump start from under the bonnet - in fact that's the way you're supposed to do it on one of those.

There's a +ve terminal (covered by a sliding red plastic shield) and a -ve one (which is a copper post).

Maybe it's the same on yours?

 

[Bobby Dazzler]

I've no experience with 215's - only 211's a 212's.

But, FWIW, on my 212 I can jump start from under the bonnet - in fact that's the way you're supposed to do it on one of those.

There's a +ve terminal (covered by a sliding red plastic shield) and a -ve one (which is a copper post).

Maybe it's the same on yours?

+1 that’s what I’d be doing. You could charge using the same +ve terminal and ground post.

 

[Swotty]

Thanks guys, I'll check. Would check the handbook, but it's locked in the boot!

 

[m80]

Modern electronic chargers will see 4 volts as deep discharge, and fail to attempt to charge.
You would need to bring the voltage up with an old style charger before trying to condition charge.

But it may be goosed and beyond reliable.

 

[MikeInWimbledon]

Call me “old fashioned”….

Have you tried soaking the key in WD40 before inserting it repeatedly into the lock?

Don’t know if it works on a C215 (not W215) but it used to work on older vehicles going back as far as The Ark.

We all stiffen up as we get older. Not necessarily in a good way.

(Oh, and Plus one on recharging via the terminals in the Engine compartment. It’s the only way to charge a battery in a modern car). Always charge a flat battery rather than just throw it away - if only for Greta.

 

[Flyinspanner]

How old is the battery? Terminals are usually stamped, week and year - more than 5? Just get a good quality new one, Bosch/Yuasa/ etc.
(I went through all the next bits - with a 9month old battery- which I assumed was ok…….. many hours later/swear words/ …. Turned out battery had an ‘intermittent’ internal fault.

Get battery stress/load tested.

Get alternator checked, if the diode pack fails, the battery can discharge through it.

if that’s ok, then look at YouTube for parasitic drain tracing/check. For either W215 or W220, basically the same.
It’s a slow and laborious job, but satisfying if you track it down.
At each stage, give car 10mins to ‘fully shut down’
IIRC you are looking to have a drain below 60mA, after 10mins, - there is always a tiny drain as it’s active to look for remote key being used.

best to get a dc mvA clamp meter, and be methodical.
Sometimes it can be the head unit not shutting down correctly.

check the PSE pump area, and the CD player/amp in boot for dampness.

Any aftermarket bits? Check and maybe temp detach them.

Tracker Unit,? Remove fuse.

It’s infuriating, but wishing you success

 

[Londonscottish]

Thanks guys, I'll check. Would check the handbook, but it's locked in the boot!

Hmmm.....I just looked online (because I'm trying to defer my morning run....). It looks like 220's/215's don't have a charging terminal/post set up under the bonnet.

I've seen a couple of YouTube vids with this technique instead.

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[MikeInWimbledon]

Back to the key issue.....

You do know that when you turn the key (anticlockwise), you then ALSO have to press it IN after it has turned, don't you?

I didn't mention it before because you seemed to know that you need to do this, but I thought I'd just double check.

(I know the mechanical lock seems to be working perfectly, but it's always worth double checking things like lubrication and precise movement)

 

[Bendo]

Thanks guys, I'll check. Would check the handbook, but it's locked in the boot!

There is a handy app in the Play and Apple store called Mercedes Benz Guides which has all the manuals. Much better than the paper copy as its searchable.

 

[Swotty]

Back to the key issue.....

You do know that when you turn the key (anticlockwise), you then ALSO have to press it IN after it has turned, don't you?

I didn't mention it before because you seemed to know that you need to do this, but I thought I'd just double check.

(I know the mechanical lock seems to be working perfectly, but it's always worth double checking things like lubrication and precise movement)

Yes, it turns and depresses fully but the lock doesn't release.

 

[Swotty]

Thanks to everyone for your replies.

I found a similar video to Londonscottish dealing with a CL55 and the charging posts are indeed under the carpets on the passenger side floor. 2 layers plus a plastic panel and then the metal cover with screws. Will have a go later.

Yes, I reckon the battery was on its way out and is now so discharged that is basically useless. It is a Varta silver 100ah and about 4 years old.

But before that I'll try the WD40 plus pliers plus a bit of heft on the boot lock ... just in case!

Thanks again for all the help ... this is a great club!

 

[MikeInWimbledon]

Thanks to everyone for your replies.

I found a similar video to Londonscottish dealing with a CL55 and the charging posts are indeed under the carpets on the passenger side floor. 2 layers plus a plastic panel and then the metal cover with screws. Will have a go later.
Yes, I reckon the battery was on its way out and is now so discharged that is basically useless. It is a Varta silver 100ah and about 4 years old.
But before that I'll try the WD40 plus pliers plus a bit of heft on the boot lock ... just in case!
Thanks again for all the help ... this is a great club!

Four years old !! Mon dieu, mine are usually more than a decade old.

 

[E55BOF]

Agreed. A Varta should last longer than that. I've changed several, and the youngest was seven years old.

 

[Swotty]

It's odd, as the battery on the XKR never goes more than 3 years and the CL more than 4. I have been buying battery conditioners and have one on the Jag, and was trying to unlock the CL to do the same. The CL had started to drop the passenger window on start up which is an indication battery change time is coming. Both have Varta Silver 100ah and the Jag was changed a couple of months ago, just a month or so outside the warranty.

The Jag has always had a quiescent drain - quite common on those - and I think the CL may have a dodgy boot lock (solenoid?) as I have heard it cycling from time to time. Hopefully conditioners will now extend battery life.

The Corvette had a new battery just before I bought it and that's on its way out, too, after just over 3 years ... and less than a thousand miles. Going to replace the AC Delco with an Optima Redtop for its imminent putting on sale.

I don't drive any of them enough, really, as I've become really fond of the C6, which is spacious, comfy, has all the toys and is far more economical. I must be more disciplined ... but the classic car scene will be restarting soon.

 

[Bobby Dazzler]

It's odd, as the battery on the XKR never goes more than 3 years and the CL more than 4. I have been buying battery conditioners and have one on the Jag, and was trying to unlock the CL to do the same. The CL had started to drop the passenger window on start up which is an indication battery change time is coming. Both have Varta Silver 100ah and the Jag was changed a couple of months ago, just a month or so outside the warranty.

The Jag has always had a quiescent drain - quite common on those - and I think the CL may have a dodgy boot lock (solenoid?) as I have heard it cycling from time to time. Hopefully conditioners will now extend battery life.

The Corvette had a new battery just before I bought it and that's on its way out, too, after just over 3 years ... and less than a thousand miles. Going to replace the AC Delco with an Optima Redtop for its imminent putting on sale.

I don't drive any of them enough, really, as I've become really fond of the C6, which is spacious, comfy, has all the toys and is far more economical. I must be more disciplined ... but the classic car scene will be restarting soon.

Perhaps not driving them enough is the clue to why the batteries don't seem to last.

Have you had to jump start them? In my experience discharging a battery so low that you have jump start the car - especially an AGM battery - can prematurely age it.

 

[Swotty]

Perhaps not driving them enough is the clue to why the batteries don't seem to last.

Have you had to jump start them? In my experience discharging a battery so low that you have jump start the car - especially an AGM battery - can prematurely age it.

Yes, the Corvette battery is on a conditioner and shows 13.6v and yet more often than not I now have to jump start it.

I believe jump starting the CL could fry some of the electrics, so have always used a charger when necessary.

I agree ... I think the lack of regular use is the main factor and, after replacing the CL and Corvette batteries, they will now be always on a conditioner. The Jag seems to be doing fine, so far.

 

[Londonscottish]

It's odd, as the battery on the XKR never goes more than 3 years and the CL more than 4. I have been buying battery conditioners and have one on the Jag, and was trying to unlock the CL to do the same. The CL had started to drop the passenger window on start up which is an indication battery change time is coming. Both have Varta Silver 100ah and the Jag was changed a couple of months ago, just a month or so outside the warranty.

The Jag has always had a quiescent drain - quite common on those - and I think the CL may have a dodgy boot lock (solenoid?) as I have heard it cycling from time to time. Hopefully conditioners will now extend battery life.

The Corvette had a new battery just before I bought it and that's on its way out, too, after just over 3 years ... and less than a thousand miles. Going to replace the AC Delco with an Optima Redtop for its imminent putting on sale.

I don't drive any of them enough, really, as I've become really fond of the C6, which is spacious, comfy, has all the toys and is far more economical. I must be more disciplined ... but the classic car scene will be restarting soon.

My previous and present E Classes have munched though batteries on a 3 to 4 year basis. Lots of sitting on the drive.

 

[MikeInWimbledon]

My previous and present E Classes have munched though batteries on a 3 to 4 year basis. Lots of sitting on the drive.

On a family car, it'll be too much sitting on the drive AND short runs that barely scratch the surface of putting enough charge back in.

For a "collector" like Swotty, or a used car dealer, the answer is to charge or condition regularly, and maybe even trickle charge. Walk into any big private collection, and you'll see CTEK's and connectors hanging around to keep batteries topped up.

For the family car / garden ornament, the answer is to just charge it up if you've left a car pretty much unused for a month or two. It sounds like a faff but it's better than being caught out by a flat battery and better than just throwing batteries away every four years.

I'm "lucky" in that I do 12,000 a year across my three cars these days, so it's less of an issue for me, but I do consciously switch cars so that one doesn't get left unused for more than three weeks. Not just for the battery, but just to keep the whole car "limbered up:" from oils to tyres etc etc.

 

[MikeInWimbledon]

My previous and present E Classes have munched though batteries on a 3 to 4 year basis. Lots of sitting on the drive.

How's your little Italian flirtation working out? Is she keeping you "limber?"