Mercedes SL280 R129 Battery Replacement

[Hans Solo5]

Hi

Has anybody got any experience of changing the battery in the R129 SL 280, very large oblong type battery which holds its charge but for precaution Im topping her up via trickle charge (CTEX MXS) every 2 weeks which works fine.

Im having the intermittent fault in starting the old girl where the key seems to take an age to talk to the immobiliser for it to come to life, I don't think its a Immobiliser issue, Ive had the key battery changed by MB in the key.
The battery is original and has been on the old girl since 1997 and 55,000.00 miles.

Can you change the battery yourself without upsetting the on-board computers, in the past I've had to pay MB to reset the hood lights and roll bar due to a dead battery etc.

I don't want to dance with the ECU -M-tech brain.

Would appreciate any help as always.

Thank you and Happy New Year.

 

[LostKiwi]

I disconnect /reconnect my battery on my 129 regularly and never have an issue.

 

[Hans Solo5]

I disconnect /reconnect my battery on my 129 regularly and never have an issue.

Both terminals ? Thanks

 

[mimile]

I disconnect /reconnect my battery on my 129 regularly and never have an issue.

So do I... Not very different than a 2cv...

 

[LostKiwi]

Both terminals ? Thanks

Makes no difference. Disconnect the earth first, reconnect last.

 

[Nigel Hewitt]

Pulling a battery for replacement is usually not a problem. What electronics really hates is a slow fade out.

 

[brianbrian]

Same as Lost Kiwi, I also put the battery on charge every 6 weeks if car not used, but if battery fully charged, I turn the lights on for a few minutes before starting the car.

 

[tiswas]

Having had flu for a couple of weeks I got in my R129 today only to find it flat.

I have never used jump leads before but intend borrowing a set over the weekend, anything a non diy person like me should be aware of? Online guides refer to earthing to a solid metal bolt on the car engine but not sure what there is in the boot that is suitable?

If I need a replacement Yuasa batteries come at a reasonable price with decent reviews, any thoughts?

Thanks as always and a happy new year.

 

[LostKiwi]

Be careful to connect leads right way round, ignition off. You may want to turn on headlights before connection too to remove any spikes.

 

[tiswas]

I have just noticed I am a "Senior Member", can anyone know less about cars than me, lol!

Had battery checked, it is fine just not doing enough miles.

Bought a charger. Going to charge in situ. Says if battery pos pole grounded then connect black clamp to neg pole if not clamp to vehicle chassis.

Is the + grounded, if not where on the car in the boot do I clamp the black?

Many thanks as always.

Rob

 

[Wearsafoxhat]

I have always just connected my battery conditioner to our 129, pos(red lead) to pos on the battery and the negative (black lead) to the stud that the neg battery lead goes to under the light cluster. Have never had a problem.


Sent from my iPad using Tapatalk

 

[LostKiwi]

Black charger lead goes to - on battery. Red charger lead goes to + on battery.
On a 129 the - lead from the battery goes to the bodywork so you can connect the black lead to the bodywork to a solid earth point (one that's not covered in rust or paint). Personally I use the battery terminals. Do not rely on lead colours on the car as they can both be black.
Always connect the correct way round or you may damage the vehicle, battery and charger. For safety sake connect the battery charger to the car before connecting to the mains. Disconnect from the mains before disconnecting the charger.

 

[tiswas]

Thanks guys.