Help install battery backwards! - Page 2

Rockmelon · #11 01-12-2010, 03:37 AM

my speculation of what might happen is this: when battery is connected wrongly, all electrical & electronic devices will see the reverse voltage. electrical devices should less susceptible compared to electronics (e.g. bulbs & heating elements are electrical & not electronic). however, some electrical devices can be controlled by electronics. so the latter may fail instead of the former. when engine was started under reverse voltage condition, the alternator kicks in and take over the electric supply to the car. the alternator is connected in the correct way. hence everything that requires electric supply will see an instantaneous change in voltage direction. as power (P) = voltage (V) x current (I) and physics does not allow power to change instantaneously, any instantaneous drop in voltage is compensated by a corresponding instantaneous surge in current. fuses are typically located at the +ive terminal as there is where the current would normally flow. so they may not protect if the surge in current is at the -ive terminal. this instantaneous surge in current via the -ive connection might have caused damages to electronics. having said all these, i dont think that there is much of an option but to bring the car in to the agent and ask them to troubleshoot and isolate/identify the damaged components. good luck.

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powers1 · #12 01-12-2010, 05:11 AM

As rockmelon said,this is the best route to take! Good luck

seanjohnnyc · #13 01-12-2010, 05:15 AM

Hi guys , I checked all the fuses in the glove and the trunk and removed 7 burnt fuses. I currentLy got the nav and radio back to life but the suspension inactive fuse I changed no changed in that. The seven burnt ones I will change tommorrow and I will see what I get.

Is the another fuse location beside glove and trunk locations?

bgsquad · #14 01-12-2010, 07:31 AM

I am not so pessimist about it... I've worked with logical gates and IC back in the engineering school, and believe it or not, those things are not so sensible to reverse voltages... how many times did we connect reverse polarity... the transistors gates just don't work with reversed polarity, but once it's back to normal, i think the physical properties are restored... and about the spike that rockmelon talked about, and that may result from all other power dissipating units on board, well those can be damaging to IC boards, but the fuses might have acted as surge protectors...

So replace all damaged fuses, and give us the latest list of damaged modules... i think it should not be more than one or two unlucky devices...

You learnt the hard way

bchurch05 · #15 01-12-2010, 06:56 PM

how does a car actually start with the battery wires reversed?

ecproductions85 · #16 01-12-2010, 07:29 PM

he swapped the cables back before trying to start I am assuming other it wouldn't have started

bchurch05 · #17 01-12-2010, 08:03 PM

it wont take but just touching the wrong one even a wrench touching the wrong thing during removal or install to really screw things up. most will survive but it is allways going to be something strange that will haunt said vehicle forever.
i am pretty sure it would not start with them reversed as previous poster said it was.

secretaznsauce · #18 01-13-2010, 04:13 AM

Quote:

Originally Posted by seanjohnnyc

Hi guys , I checked all the fuses in the glove and the trunk and removed 7 burnt fuses. I currentLy got the nav and radio back to life but the suspension inactive fuse I changed no changed in that. The seven burnt ones I will change tommorrow and I will see what I get.

Is the another fuse location beside glove and trunk locations?

MAN they hide fuses all over the damn place!!!

remove the back panel that covers the spare and follow the wires from the pump. its an always live ckt. trace that to the source, i think there are more fuses there by the battery

secretaznsauce · #19 01-13-2010, 04:14 AM

once when i was repairing a "theft" e39 I found fuses under the passenger seat!

seanjohnnyc · #20 01-13-2010, 11:56 PM

Good News Guys,

I replaced all seven burnt fuses and every electronic component survived. Im glad i checked everything out myself first before i took it in to the shop and saved a boat load of cash. There is one negative side to this story is that my alternator is fried and dead. Atleast i know what to expect by getting a new alternator bill compared to a whole electrical system repair bill.

Thanks for all your comments and suggestions.

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