About this time last year, the wife of a friend of mine found their 1991 VW Passat (55k miles, fvwsh and in excellent condition) had a flat battery. RAC were called and jump started the car. Battery was found to be faulty, so was replaced. Fair enough. Unfortunately, immediately after this had all happened, my friend found that some of the dash electronics had failed. On examination, it was found that the printed circuit controlling the milometer etc. had burned out. Seems logical to surmise that the actions of the RAC patrolman had caused this, and understandably my friend approached the RAC for recompense. They, sadly, denied everything. My friend is now mid- small claims court case with the RAC to claim back the £800 (!) that the repairs cost. Basically, my question for this sea of knowledge is this: has anyone heard of this kind of damage happening before? Any court cases decided? Some evidence would really help! At the moment, it's down to proving that 1) the patrolman acted negligently, and 2) that the negligence caused the damage. All help very much appreciated!
Thanks in advance!
Dr Alex Mears
Seat ibiza Cupra
Yamaha RD350YPVS
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My Citroen Xantia can suffer from poorly executed jump starts. I understand that the ECU for the ABS can be blown out in this way. Apparently, the initial current surge can prove too much for the delecate electronics.
Your friend would be well advised to, either look in his handbook for correct jump starting procedures, contact his local VW dealer for the same, or seek an auto electrical engineer's opinion in this area.
I am no legal expert, but I suspect that to prove neglegance on the part of the RAC patrolman, he would have to demonstrate that there is a correct method of jump starting this car without damaging the electronics, which the patrolman should have known about (they are of course professionals) but did not follow.
I think that these days they should use surge protected leads that may have some sort of capacitance to earth to protect both vehicles from damage.
I wish your friend the best of luck
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I have heard of damage being caused to the car doing the jumping, but cannot see how damage can occur to the jumpee.
The current surge surely can only pass down the cable carrying the current, which is jump lead itself and the starter cable? Jump starting is really only like having a heavy duty battery instead of a small one - the voltage is the same, but the combined capacity to carry current is increased.
Standard advice is that it is important NOT to leave the jumper car's engine running, because the electronics are not designed to cope with a sudden voltage drop when running. Special circuits come into play when starting, which are bypassed if used to start another car.
If a car is jump started with another battery which is not itself being charged, eg from a running engine, then I cannot see how damage can result.
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I will go along with Cliff on this.
The only scenario that I can think of causing damage is if the earth connection between battery and block in the jumpee is high resistance. (Possibly the cause of not starting in the first place?).
The natural reaction is to rev the jumpee on starting, possibly then causing the voltage applied the in car electronics to rise above the nominal 12v (to maybe 15v), altho this is unlikely to cause problems to well designed electronics.
Sequential failure of voltage regulator and other units on instrument panel could possibly result in pcb damage but I would consider it unlikely.
Other possible causes of failure could be static electricity, with a very high potential difference between the 2 car bodies. If the jumpee is grounded (anti static strap, or conductive tyres for example) and the +ve connected first, this could have the ability (I hesitate to say potential) to wipe out electronics. However well designed electronics should have static protection. Once again no burnt out tracks or pcbs would would occur as result of the primary failure.
I am aware of many apocryphal stories of failures, but wonder how many result from incorrect (but not admitted) incorrect polarity connection. Many cars will even withstand this!
pmh (was peter)
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If the faulty battery was open circuit, then reving the engine after having been jump started could cause a significant over-voltage from the alternator to damage some electronics.
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This is an extreme case of high resistance scenario I outlined.
What is the max voltage an alternator could produce under no (orlight) load conditions? I suspect that it is not high enough to destroy pcb tracks. Altho possible catastrophic failure of a voltage regulator or similar may result in secondary damage. However fuse protection would then come in.
Maybe there is a case for having lights turned on when jump starting to help damp any transients.
Power Engineers out there? What sort of voltage transients do you see when switching high current DC starter motor loads? on the end of long jump leads? Particularly problematic if the jumpee battery is disconnected or HR? This could get very technical!
pmh (was peter)
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old vw`s suffer from main earth lead breaking down. change it now. also if 8valve engine has earth strap from bulkhead to rocker cover area. this is the main earth for dash binnacle if missing damage as happened could happen. remember current iks lazy and will find path of least resistance is this case through dash binnacle and down earth strap as mentioned earlier not through main earth strap. this is a common mistake by inexperienced fitters on golf2 when changing clutch. forget to reconect main earth to gearbox and when tries to start car fries ecu by same method as happened to passat.
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This info (from 'the conductor') goes a long way in explaining the mechanism of failure giving the problems explained in the initial post.
My first thoughts are that to prevent this sort of problem with jump starting, the jumpee should have its earth jumper connected directly to the engine block. I suspect however this conflicts with Manufacturers specific instructions (which are written for a car in good order). It may also give other problems of the 'reverse current' flow from the jumper to jumpee battery via low current wiring if the jumpee battery is very flat and some earth wiring is defective. (ie before starter is operated).
(The following presumes that Passat has similar wiring to earlier Golfs).
To answer the initial post, it means that the failure was probably directly attributable to a defect that already existed in the car. This defect could have been the original cause of car not starting, and damage could have occurred during attempts to start the car before the jump starting attempt.
However it could possibly be argued that the experts (RAC) have a duty of care to check the earth wiring before attempting to jump start the vehicle. This would undoubtably be in the RAC interest as it could minimise the opportunity for claims from disatisfied customers. It woukld be interesting to know if this sort of check is common or recognised practice in the car trade. It would be interesting if the initial poster can discover if the the repairs included any comments on earth straps etc.
pmh (was peter)
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I have just reread all the previous posts, including my own, and make the following comments.
Once again if this only applies if the Passat has similar wiring to the older Golfs…
You will need to seek both professional technical and legal help, but I believe a possible sucessful strategy would be to show that older Passats can suffer from both battery failure and an age related defect that can cause the vehicle not to start with slow cranking, both showing showing in laymans terms similar symptoms, , ie a 'flat battery'. In your case the RAC have told you that you had a defective battery (so they probably sold you a new one), therefore the damage to the pcb could not have been caused by your attempts to start the vehicle just prior to the call out. Since there is a known problem (by the trade) with older VWs resulting in damage as you have described, the RAC should be asked to demonstrate that they have a check process in place that requires that fitters follow a set checking procedure (which may be vehicle specific) before attempting a jump start. Following the manufacturers handbook instructions is probably not adequate for an older vehicles which could have acquired defects over time.
The damage therefore occurred because either the RAC have not issued correct process, or the fitter failed to follow them. If he had investigated fully before jump starting he could have identifed the defect and refused to attempt a jump start that could result in damage.
The RAC could argue that attempts to start the vehicle just prior to the jump start have caused the damage (following failure to the earth strap due to continuous cranking) AND also resulted in flattening of the battery to the point where it could be described as terminally failed. This would require that 2 failures (ie battery and earth strap) had occurred at the same time, - not impossible but less likely. (As an aside remember that the RAC have targets for the sale of new batteries by mobile fitters. This can result in batteries being condemned prematurely).
Best of luck with the claim, I believe that you have a small chance of winning because
1.it is unlikely that the RAC will demonstrate a robust proceess that shows adequate checks necessary before jump starting were carried out. This is particularly likely if a Sub contract call out was used.
2. and by condemning your battery it is unlikely that the damage was pre existing, therefore it must have occurred when they did the jump start.
pmh (was peter)
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