1999 Volvo S70 Improper jump starting.

SIDELINES

MEMBER
1999 VOLVO S70

1999 Volvo S70 115K miles

Hi, A neighbor has a vehicle which in the past year, we've gone over to give him a jump start probaby 6 times. No problem until last week. He connected his cables to both batteries, while making the last connection, lots of sparking, I was alarmed and questioned whether he was connecting them right, but he went ahead and connected. Nothing happened. He was surprised, nothing at all turned on in his car. Well, something did happen, as I saw smoke coming from the cables- which were HOT - connected to my battery. Thinking his cables were fried, I got my heavy duty cables out, he connected those, opposite connections made, and this time his car did start. Our Volvo was driven later that day for about 10 miles, the next day for 40 miles, then it sat for 2 days. It was then attempted to be driven for a 400 mile trip, but, lights came on, the speedometer went to 0, and it died completely. Towed, from out of state, to local shop, where they say the alternator, battery, fuse box cables, battery cables, all need to be replaced. Q: Did the improper battery cable hook-up cause this? If so, why did the car run at all afterwards? Was it just using the residual charge the battery had in it, and not recharging because of being fried? I'm just feeling this is too coincidental, yet don't know how to deal with it. Thanks!

1 Reply

JIS001

MECHANIC
3,408 POSTS

One thing is for sure and that is you got lucky you did not damage a control module. Now for your other question. The positive battery cable on this type of car does go bad and usually build up some resistance inside causing the battery to not get sufficient charge. You can check that by doing a voltage drop test on the cable. On this car you could squeez and twist the cable while checking voltage charge at battery with a volt meter. If you see the voltage get higher and lower then you know the cable is bad. The relay box cable if you open the cover up and look inside where the nut holds it down you will see lots of corrosion and sometimes break off there because of it. Loss of power there your car will die out for sure. If I were you I would just have the cables replaced first, recharge the battery and then recheck the alternator because like I mentiond earlier with the cables, any kind of resistance and it will effect your chargin system and also your starting issue. Good luck and hope this helps.