SL350 R230. What happens when you connect the aux battery up the wrong way?

[H1 NPW]

Well, I can tell you, as almost exactly a year ago, that's what I did... One of my 3 most expensive mistakes, ever....

How??? I hear you ask... I really don't know... I must have changed well over a dozen car batteries over the years. But the terminals are different sizes! Yes, I know.... I used a mallet to get the small wire loop onto the big terminal. Pure muppetry...

It caused the car alarm to go off alerting me to the fact that something was seriously wrong. I realised what I'd done straight away. It was probably connected for about 5 seconds before I disconnected it. Immediate diagnosis was that the engine started (phew), but the dash was lit up like Blackpool with the news that the braking system was inoperative. On a tow truck to Mercserve in Nottingham.

To say it gave Nathan & Rodger at Mercserve a few headaches is an understatement... They said it would be a big and probably expensive job, but they would keep the cost down as much as poss by working on it in when they were quiet. I wasn't in a hurry as the good weather was over and I have another car so that was OK. They replaced loads of different relays and fuses that had blown - in the boot, in the car, under the bonnet - everywhere - this is one complicated car when it comes to electrics. First major repair was the fried battery control module in the boot - £300.
After months of trials and tribulations and visits from Auto electricians they informed me that the brake control module could not be repaired and had to be replaced - could only be done by the main dealer as it needs coding to the car. £3K later and outstanding problems were the cooling system fan had blown (£140 off eBay) and the SRS airbag system control module needs replacing. This is proving to be problematic as apparently it's a special order part and again has to be fitted by a main dealer and Germany can't say when they will be able to supply one.... I'm currently investigating an outfit called Crash Data in Liverpool who say that can transfer the data from the fried module and transfer it to an undamaged second hand module.....

Has anyone had any experience of Crash Data? I was surprised that they sounded so confident about being able to do what they said they can do, as I'm surprised anyone else could be as stupid as I was to actually fry the module (as opposed to it having deployed airbags)

 

[Botus]

patching up Airbag / crash modules is well known..

the idea the manufacturers peddle is the system pushed mega current through it and possibly damaged things so next time round something may fail before the safety system go off correctly.

so now a few things to think about

1) the takata air bag crisis where for 20 years nearly every air bag fitted to every car ever made is a death trap waiting to kill you

so it might be helpful they fail to go off !!!
https://www.caranddriver.com/news/a14499263/massive-takata-airbag-recall-everything-you-need-to-know-including-full-list-of-affected-vehicles/

2) the manu's like the idea of a quick scare to incur ways to extract silly money from you

3) the engineers like a laugh studying how you crashed and what happened, so they like the idea of getting the modules back to extract the data

 

[EmilysDad]

Ouch! That was a kick in the wallet. But you would think that Mercedes should have built some kind of safety into the car for when someone does as you've done. I can't think that you'll be the last person to connect a battery up harris about face ..... though quite how you managed it I'm not really sure

 

[LostKiwi]

Ouch! That was a kick in the wallet. But you would think that Mercedes should have built some kind of safety into the car for when someone does as you've done. I can't think that you'll be the last person to connect a battery up harris about face ..... though quite how you managed it I'm not really sure

A simple diode on the feed to every module would prevent damage. But that's 5-50p per module....

 

[Uncle Benz]

It is possible to recode a secondhand airbag module for an r230, but it isn’t easy. You need developer mode and a reasonable knowledge of technical German. I have even managed to recode an American airbag module from LHD to RHD for use in a UK SL500. Took me a good few hours though.

 

[mioba]

Sometimes one learns the hard way...........I feel for you, really

Mercserve are great for mechanical absolutely spot on, but electrical is not thier forte, I have used them for 15 years. They were even not comfortable changing the capacitor (like second battery on my C Class). So I had that done at the dealer.

This is compounded with modern cars with amazing amounts of CPUs (look at the new S class).

Good luck with crash data, you are making progress and I am sure will get there in the end.

 

[Craiglxviii]

A simple diode on the feed to every module would prevent damage. But that's 5-50p per module....

In this case the designer put in a poke yoke feature to prevent accidental battery misconnection. Unfortunately the owner decided to deliberately force the misconnection with a 4lb Glasgow spanner

 

[peterws1957]

In this case the designer put in a poke yoke feature to prevent accidental battery misconnection. Unfortunately the owner decided to deliberately force the misconnection with a 4lb Glasgow spanner

Never heard of a poke yoke feature - not on the spec of my stuff. I'll check Ebay.

 

[Craiglxviii]

Never heard of a poke yoke feature - not on the spec of my stuff. I'll check Ebay.

 

[H1 NPW]

Thanks for all your replies guys.

I'm not sure of the relevance of the post about Takata airbags as the SL is not on the list of cars fitted with the dodgy ones?

Uncle Benz - would you be interested in recoding a module to my car?

Cheers

 

[Uncle Benz]

Thanks for all your replies guys.

I'm not sure of the relevance of the post about Takata airbags as the SL is not on the list of cars fitted with the dodgy ones?

Uncle Benz - would you be interested in recoding a module to my car?

Cheers

lol! Where are you located?

 

[joderest]

cor blimey, i really feel for you, such a simple error to make (the error, not the execution of it !!!!). Perhaps some simple electronic device in the negative battery cable that detected positive currant and blows would have prevented this, but as lost kiwi states, it costs.