R129 600 limp home after charging flat battery?

[1380]

I have a 1996 R129 SL600 and I wonder if anyone has experience of the following problem.

The car was garaged for about 2 months the battery was totally flat, not even a warning lamp. I could not open the boot but manage to find the main power cable up in the drivers foot well (RHD car), I charged the battery in place overnight, I did not jump start the engine.

The following day the car started first time but now the dash is displaying the EPC and ESP warning lamps it also seems to be in a limp home mode as there is no power and is hunting on idle.

The ABS warning was on for a while but has now extinguished it's self.

Any ideas chaps?

 

[AndyRan]

Have you tried to move the car? The ESP and EPC may need to see movement on the wheel speed sensors to re-calibrate.

 

[CabrioDave]

ABS light coming on is consistent with low voltage. It would go off again once the voltage is high enough to operate the system.

Is the battery now fully charged? If not, get it fully charged.

If it is, I'd be tempted to drive it, carefully, a few miles, then stop and turn off. Wait a few minutes and try again. It's not guaranteed, but it can reset a few of the reasons for limp-home.

 

[1380]

Thank you both for taking the time to reply.

I drove the car only a mile, stopped for five minutes then a mile back again, I will try a longer run tomorrow, I will also check the battery voltage running.

 

[Oldlae]

I would call MB about the problem, you may need the computer reset.
If you spend more that 30 minutes changing the battery on a BMW Z4, the car goes into 'Transport Mode' and costs £££'s at the dealer to reset.
Tony

 

[alabbasi]

I experienced a similar problem with my old 97 E420 several years. I did not charge the battery and the car started without problems, the weather was just cold.

When I it took it to the dealer, they indicated that all systems were throwing low voltage codes and suggested that I replace the battery. You may have enough amps to crank the starter but not to run all the systems. I would put a new battery in it first. It usually costs less than paying MB to do the diagnostics.

 

[BTB 500]

If the battery has been standing discharged for any length of time it's probably had it.

I had rollbar and window faults on my 500 due to low voltage - these had to be cleared via STAR. A maintenance charger is a great investment if you've got mains power where the car is parked - mine is kept on one permanently now.

 

[190]

Is the battery now fully charged? If not, get it fully charged.

This is a good question.

It depends on the battery charger. A small charger will not fully charge a flat battery overnight. It could easily take 2 or 3 days depending on the size of the battery. Driving the car won't fully charge it either unless it's a very long run. Once the battery is fully charged and rested for several hours it should have a no load voltage of 12.7 volts or more depending on battery type.

When making a judgement of the charge voltage while driving, the battery should also be fully charged. If it isn't that will tend to drag the charge voltage down and the lower reading may make you think there is a problem when there isn't.

 

[1380]

This is a good question.

It depends on the battery charger. A small charger will not fully charge a flat battery overnight. It could easily take 2 or 3 days depending on the size of the battery. Driving the car won't fully charge it either unless it's a very long run. Once the battery is fully charged and rested for several hours it should have a no load voltage of 12.7 volts or more depending on battery type.

When making a judgement of the charge voltage while driving, the battery should also be fully charged. If it isn't that will tend to drag the charge voltage down and the lower reading may make you think there is a problem when there isn't.

I have just got in from checking the batter voltage, after an engine off period of 3 hours I am seeing 12.6v, running I have 14.7v.

One other observation is that the MPG gauge is stuck on maximum with ignition off and engine running?

EPC and ESP light are still illuminated, LHM, and erratic idle over around 1000rpm.

 

[LvR]

Battery seems to be ok then. I would disconnect the battery (remove pos or neg terminal) and let the thing sit while you have a beer. Come back and reconnect the terminal and see if anything changed.

Charging from totally flat, the battery voltage would have gradually increased iso being above an expected minimum level. During the increasing stage you may have tripped a lot of funky settings that just need to get reset

 

[1380]

Solved!

I left the charged battery disconnected overnight, before reconnecting I touched the negative terminal to the for several seconds. The engine burst into life with all warning lamps extinguished and full power.

Thanks to all the above for your kind help.

 

[LvR]

:bannana: