Battery earth strap.....

Nik_L · Post by **Nik_L** » Wed Mar 06, 2013 9:42 pm

Ok, today while working on the car, i accidently snapped the end off the earth strap that goes to the car body (slam panel) from the negative side of the battery.

I couldn't get to the motor factors in time so have had to wedge the remaining part under the bolt. Its not very secure though. Will it do any damage if it falls out while driving etc??

sc_001 · Post by **sc_001** » Wed Mar 06, 2013 9:51 pm

OH MY GOD THAT WILL MAKE THE ENGINE EXPLOOOOOODE!!

Post by **paul bristol uk** » Wed Mar 06, 2013 9:56 pm

There will be a bloody big flash and bang if the earth strap touches the positive cable.

Nik_L · Post by **Nik_L** » Wed Mar 06, 2013 10:05 pm

Its not long enough to reach that far i don't think.

What i mean is, if it comes loose, will the car cut out or anything??

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Wed Mar 06, 2013 10:07 pm

Doubt it very much - it's not the only earth return path.

I wouldn't run it like that for ages though.

Nik_L · Post by **Nik_L** » Wed Mar 06, 2013 10:14 pm

Ok bud cheers.

Just wasn't sure as ive heard of running problems with cars due to earth straps not being attached and what not.

Start work at 3am and last thing i want to do is break down at that time

sc_001 · Post by **sc_001** » Wed Mar 06, 2013 10:17 pm

The ECU might die eventually.

Post by **Gayno** » Wed Mar 06, 2013 10:39 pm

You don't actually need a battery at all. Try it, start the car, then remove the negative terminal. The alternator puts out enough power to run the electrics on the car

Supermarine Blues · Post by **Supermarine Blues** » Thu Mar 07, 2013 12:01 am

The battery's more to damp electrical surges, which is why ECUs sometimes fry if the lead drops off.

If you can clamp it with a body washer or something metallic, it'll be fine. Spare wheel locator, maybe?

PerformanceAutoworks · Post by **PerformanceAutoworks** » Thu Mar 07, 2013 9:17 am

Gayno wrote:You don't actually need a battery at all. Try it, start the car, then remove the negative terminal. The alternator puts out enough power to run the electrics on the car

Not very good advice at all !!!!!

This can and often does lead to alternator failure and voltage spikes frying ECUs !
This is why a PROPER FIA type electrical isolator is more than just a simple 2 terminal "wire disconnect swith". It is relayed and has resistor to dampen out any voltage spikes on switch off.

In answer to original post - this small earth wire off the battery isn't long enough to reach the positive (well not easily anyway) and it sounds as though the wire has been secured to body under the bolt head. Fair enough it's not ideal but it at least keeps it out of harms way. Its not a main earth more a subsidery one but do get it fixed properly as soon as you can.