How much damage could I have done?
Discussion
So I had a flat battery on Saturday and got a friend round to give me a jump start. It was dark and raining and I stupidly connected up the jump leads on the wrong battery terminals, turned they key - resulting in slow turning of starter motor but no turn over of engine. It didn't sound normal so checked connections and discovered foul smelling fumes/smoke coming from Chimeara battery area. Had leads connected wrong way round for about 2 mins with other car engine running.
Once I swapped the leads the correct way round the engine fired up pretty quickly but when I removed the jump leads from donor car the engine died instantly.
...so what damage could or is likely to have been done?
Could the alternator be screwed? oil light came on, headlights worked, heater works, but unsure how much real damage is likely to have been caused. ICE?, ECU? although engine did start...
Anyone done this themselves!?
Once I swapped the leads the correct way round the engine fired up pretty quickly but when I removed the jump leads from donor car the engine died instantly.
...so what damage could or is likely to have been done?
Could the alternator be screwed? oil light came on, headlights worked, heater works, but unsure how much real damage is likely to have been caused. ICE?, ECU? although engine did start...
Anyone done this themselves!?
Difficult to tell- You have ended up with a battle between the two batteries and had a huge current flowing between them, hence the bad smell. It does not mean however you have dumped minus 12 volts onto the wiring loom, and if the engine still starts the the ECU has taken it OK. You need remove the battery, and try and charge it on the bench. If it wont charge then its likely you have bent the internal lead plates and the battery will be scrap. You wont really tell what else has been damaged untill you have another good charged battery connected and can test everything.
Thanks for the reply Blitz.
The TVR battery was very flat, in case that makes a difference to the "battle" and the potential -13V. I was pleased when the engine actually ran as indicates the ECU has survived. ECU is Megasquirt not Lucas. I hope the EDIS modules and sensors are all ok.
The bolts holding the battery have lost their captive elements so are just spinning and I therefore can't take the battery out, unless the bolts are ground off from underneath. I figure I need to get her towed somewhere with a ramp to provide enough clearance to get a grinder under there. So do you think I would be ok getting her taken to a normal garage or do you think I need to look for a specialist auto electrician?
Thanks.
The TVR battery was very flat, in case that makes a difference to the "battle" and the potential -13V. I was pleased when the engine actually ran as indicates the ECU has survived. ECU is Megasquirt not Lucas. I hope the EDIS modules and sensors are all ok.
The bolts holding the battery have lost their captive elements so are just spinning and I therefore can't take the battery out, unless the bolts are ground off from underneath. I figure I need to get her towed somewhere with a ramp to provide enough clearance to get a grinder under there. So do you think I would be ok getting her taken to a normal garage or do you think I need to look for a specialist auto electrician?
Thanks.
blitzracing said:
Difficult to tell- You have ended up with a battle between the two batteries and had a huge current flowing between them, hence the bad smell. It does not mean however you have dumped minus 12 volts onto the wiring loom, and if the engine still starts the the ECU has taken it OK. You need remove the battery, and try and charge it on the bench. If it wont charge then its likely you have bent the internal lead plates and the battery will be scrap. You wont really tell what else has been damaged untill you have another good charged battery connected and can test everything.
+1Most likely scenario would be a fried battery (and you were lucky really as they have a desire to explode when connected up that way for any length of time). It's also quite possible that the diode pack on the alternator will be damaged, but it's not a certainty. I'd have a good look at the starter cable from the battery too - that would have carried a bit more current than it was anticipating, and in the opposite flow direction too (actually if the solenoid was engaged it might even have TRIED to turn the motor over backwards - although I'd be a bit surprised if it managed it).
like blitzracing said - you won't know until you put a fresh battery on it... Oh and I'd check the 100A fuse(s) too as a first point of call if all does not appear well after putting the fresh battery on - then the alternator..
Fingers crossed...
Bassfiend said:
Blitz is right - it's unlikely to have damaged the car itself but I think your battery will be completely fried and you've probably blown the big 100amp fuse...
Phil
+1 for Phil & Mark you wont know until you refit a new healthy batt Phil
Edited by Bassfiend on Monday 17th December 13:02
it's a bit late now but it's like the old saying measure twice cut once and this includes jump starting cars your also lucky you did not take out the jump/master vehicles electrics big time 
I know plenty of late vehicles that would kick you right up the b
ks for making a mistake like this 
all the best Edited by Sardonicus on Monday 17th December 13:08
I was planning on replacing the battery over Christmas anyway as felt it was pretty knackered.
I feel the alternator could be damaged as as soon as the leads were removed with the engine running - it died instantly as though there was no charge going in at all and the doner car was providing the only power.
I feel the alternator could be damaged as as soon as the leads were removed with the engine running - it died instantly as though there was no charge going in at all and the doner car was providing the only power.
Teetertank said:
I was planning on replacing the battery over Christmas anyway as felt it was pretty knackered.
I feel the alternator could be damaged as as soon as the leads were removed with the engine running - it died instantly as though there was no charge going in at all and the doner car was providing the only power.
You have probably blown the mainfuse I feel the alternator could be damaged as as soon as the leads were removed with the engine running - it died instantly as though there was no charge going in at all and the doner car was providing the only power.
check you have power to the large terminal on the rear of the alt before you panic 
If battery was smelling badly, you've probably boiled off lots of the battery fluid. If it were dead anyhow and you have effectively discharged it even further by reverse energising it. As already said, you were very very lucky both batteries didn't explode or the jump leads / high current wiring catch fire.
I wouldn't even bother trying to charge your old battery. You're more likely to have an accident. It was probably knackered before you started and definitely is now. A voltage test with a voltmeter would confirm that. I would count myself lucky and replace it.
I don't think any of your car's wiring will be damaged as it was only the jump leads that will have seen all of the current. The currents that your car's wiring will have seen will be lower than normal but opposite polarity.
The heavy current wiring / battery / alternator on the car that you were using to jump start yours might not have faired so well though. That car's alternator and battery will have been pushing a lot of current.
The electronics on your car may have seen a reverse voltage but the amount of voltage will have been reduced by your battery's internal resistance being quite low and a large volt drop through the jump leads.
I wouldn't even bother trying to charge your old battery. You're more likely to have an accident. It was probably knackered before you started and definitely is now. A voltage test with a voltmeter would confirm that. I would count myself lucky and replace it.
I don't think any of your car's wiring will be damaged as it was only the jump leads that will have seen all of the current. The currents that your car's wiring will have seen will be lower than normal but opposite polarity.
The heavy current wiring / battery / alternator on the car that you were using to jump start yours might not have faired so well though. That car's alternator and battery will have been pushing a lot of current.
The electronics on your car may have seen a reverse voltage but the amount of voltage will have been reduced by your battery's internal resistance being quite low and a large volt drop through the jump leads.
My 5p worth.....with a flat battery, you started the car by jump starting it.....normally, when you disconnect the donor car, then your car will keep running, as the alternator is supplying enough juice, and the status of the battery won't matter.
On a healthy TVR, if you take out the 100 amp fuse, the car will start on the battery and will run for about 50 miles on the battery alone. You will get silly things like the speedo misreading, and in the end there will not be enough left in the battery to run the car and it will die.
The 100 amp fuse lies between the alternator and the battery, and allows current to pass from the alternator to charge the battery. If you have a dead battery, and the 100 amp fuse is blown, nothing will be getting from the alternator to the spark plugs, and so your jump started car will die instantly.
So, the first thing to check, on the off chance that you have actually done no other damage, is the 100 amp fuse, as they cost about £2. And if you do have to replace it, get a midi fuse off Ebay, as they are so much more reliable,
The 100 amp fuse is tied to the underside of the chassis where the rear arm of the offside front wishbone attaches. Logical.....not!. Except it is roughly where the cable descends from the alternator on its way to the battery. It will be in a cable tied black fuse holder about 2 inches by 1. Easier to get at if you jack up the car and remove the driver's side front wheel.
On a healthy TVR, if you take out the 100 amp fuse, the car will start on the battery and will run for about 50 miles on the battery alone. You will get silly things like the speedo misreading, and in the end there will not be enough left in the battery to run the car and it will die.
The 100 amp fuse lies between the alternator and the battery, and allows current to pass from the alternator to charge the battery. If you have a dead battery, and the 100 amp fuse is blown, nothing will be getting from the alternator to the spark plugs, and so your jump started car will die instantly.
So, the first thing to check, on the off chance that you have actually done no other damage, is the 100 amp fuse, as they cost about £2. And if you do have to replace it, get a midi fuse off Ebay, as they are so much more reliable,
The 100 amp fuse is tied to the underside of the chassis where the rear arm of the offside front wishbone attaches. Logical.....not!. Except it is roughly where the cable descends from the alternator on its way to the battery. It will be in a cable tied black fuse holder about 2 inches by 1. Easier to get at if you jack up the car and remove the driver's side front wheel.
Quietlybonkers said:
The 100 amp fuse lies between the alternator and the battery, and allows current to pass from the alternator to charge the battery. If you have a dead battery, and the 100 amp fuse is blown, nothing will be getting from the alternator to the spark plugs, and so your jump started car will die instantly.
So, the first thing to check, on the off chance that you have actually done no other damage, is the 100 amp fuse, as they cost about £2. And if you do have to replace it, get a midi fuse off Ebay, as they are so much more reliable,
The 100 amp fuse is tied to the underside of the chassis where the rear arm of the offside front wishbone attaches. Logical.....not!. Except it is roughly where the cable descends from the alternator on its way to the battery. It will be in a cable tied black fuse holder about 2 inches by 1. Easier to get at if you jack up the car and remove the driver's side front wheel.
Thanks that is good to know and gives me some hope that the damage may be relatively minor - fingers crossed it's only the 100a fuse that got blown. So, the first thing to check, on the off chance that you have actually done no other damage, is the 100 amp fuse, as they cost about £2. And if you do have to replace it, get a midi fuse off Ebay, as they are so much more reliable,
The 100 amp fuse is tied to the underside of the chassis where the rear arm of the offside front wishbone attaches. Logical.....not!. Except it is roughly where the cable descends from the alternator on its way to the battery. It will be in a cable tied black fuse holder about 2 inches by 1. Easier to get at if you jack up the car and remove the driver's side front wheel.
I actually ordered a few 100A fuses from eBay earlier - if I had read your post earlier I would have investigated these midi fuses....They look similar, will they fit in the same plastic housing.
Teetertank said:
Thanks that is good to know and gives me some hope that the damage may be relatively minor - fingers crossed it's only the 100a fuse that got blown.
I actually ordered a few 100A fuses from eBay earlier - if I had read your post earlier I would have investigated these midi fuses....They look similar, will they fit in the same plastic housing.
Not to worry re the fuses, and yes, midi fuses do fit in the same holder. On a more serious note, Sardonicus knows what he is talking about.....I actually ordered a few 100A fuses from eBay earlier - if I had read your post earlier I would have investigated these midi fuses....They look similar, will they fit in the same plastic housing.
I have no Griff any more as I sold it to enable me to move abroad . I still like to view and read the TVR forums though and I would just like to say what a pleasure to read the replies to the OP`s dilemma, not a trace of reprimand or scorn , just a host of informative , good advice . Nice !
.Ribol said:
LuckyLucky said:
Okay, Okay, I'll say it,.......you plum!
So much for comaraderie and 
spirit then ...........
( yes , yes I know well is an adverb too ,in case the grammar police arrive ) mikial said:
Well, since you mention it , what was he thinking, of all the things to do, what sort of message does this send to other TVR owners, or anyone reading the TVR forum for that matter, I mean , starting the sentence with an adverb and without a comer following the offeneder ! ( yes , yes I know well is an adverb too ,in case the grammar police arrive )
Up with this we should not put..... ( yes , yes I know well is an adverb too ,in case the grammar police arrive ) 
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