Porsche 964 c2 battery replacement

[jhfozzy]

gilbo said:

DO NOT disconnect the positive first. If you allow the live lead to touch the bodywork (which will be earthed out through the battery, as you haven't disconnected the negative/earth lead) you can very easily cause an electrical fire. At best you'll blow a few fuses/relays and melt some wiring loom but you'll be amazed how quickly a fire can start from this simple mistake. And the same for reconnecting, make sure the positive is the first to go back on.

^This.

Always remove the neg lead first so that the spanner doesn't arc if you touch the body accidentally when undoing the clamp on the positive terminal. You wouldn't blow fuses though, you'd melt your spanner, I've seen it done first hand.

I wasn't impressed with the guy who borrowed it.

[jhfozzy]

gilbo said:

DO NOT disconnect the positive first. If you allow the live lead to touch the bodywork (which will be earthed out through the battery, as you haven't disconnected the negative/earth lead) you can very easily cause an electrical fire. At best you'll blow a few fuses/relays and melt some wiring loom but you'll be amazed how quickly a fire can start from this simple mistake. And the same for reconnecting, make sure the positive is the first to go back on.

^This.

Always remove the neg lead first so that the spanner doesn't arc if you touch the body accidentally when undoing the clamp on the positive terminal. You wouldn't blow fuses though, you'd melt your spanner, I've seen it done first hand.

I wasn't impressed with the guy who borrowed it.

Edited by jhfozzy on Friday 27th May 09:02

[gilbo]

jhfozzy said:

^This.

Always remove the neg lead first so that the spanner doesn't arc if you touch the body accidentally when undoing the clamp on the positive terminal. You wouldn't blow fuses though, you'd melt your spanner, I've seen it done first hand.

I wasn't impressed with the guy who borrowed it.

Edited by jhfozzy on Friday 27th May 08:57

I watched an apprentice drop the live lead on the inner wing of a car he was disconnecting the battery for welding, without first disconnecting the earth. The main engine loom and fuse box went up in flames and locked the doors. The garage owner had to cut the handbrake cable to push it out the workshop and watch it burn to a crisp. This is one of the reasons any vehicle that comes into my workshops have their driver's window down, keys out the ignition and handbrake off!

[Ozzie Osmond]

jhfozzy said:

How are you going to get the battery terminals snugly down on the new battery posts with wires connected to them?

With a crocodile clip onto the upper parts. Easy stuff. You don't need big fat wires and hefty connections - it's only maintaining voltage, there's no demand for significant current.

[jhfozzy]

Ozzie Osmond said:

jhfozzy said:

How are you going to get the battery terminals snugly down on the new battery posts with wires connected to them?

With a crocodile clip onto the upper parts. Easy stuff. You don't need big fat wires and hefty connections - it's only maintaining voltage, there's no demand for significant current.

But the terminal slides down over the upper parts, how will you maintain contact?

Not putting you down, genuinely interested as I change batteries every day.

[jhfozzy]

gilbo said:

I watched an apprentice drop the live lead on the inner wing of a car he was disconnecting the battery for welding, without first disconnecting the earth. The main engine loom and fuse box went up in flames and locked the doors. The garage owner had to cut the handbrake cable to push it out the workshop and watch it burn to a crisp. This is one of the reasons any vehicle that comes into my workshops have their driver's window down, keys out the ignition and handbrake off!

It must have had a secondary battery as there is nowhere near enough residual power in the circuits to cause a fire. What vehicle was it? Not a newish Merc by any chance?

[TooMany2cvs]

jhfozzy said:

Ozzie Osmond said:

jhfozzy said:

How are you going to get the battery terminals snugly down on the new battery posts with wires connected to them?

With a crocodile clip onto the upper parts. Easy stuff. You don't need big fat wires and hefty connections - it's only maintaining voltage, there's no demand for significant current.

But the terminal slides down over the upper parts, how will you maintain contact?

Not putting you down, genuinely interested as I change batteries every day.

Most of the "radio code savers" I've seen plug into the ciggy socket - obviously, you'd then need to make sure that the ignition was turned to a position where the socket was live, which'd increase the risk of a voltage spike to ECUs etc.

But you could croc clip onto the battery terminals, if there's sufficient exposed metal.

[jhfozzy]

TooMany2cvs said:

Most of the "radio code savers" I've seen plug into the ciggy socket - obviously, you'd then need to make sure that the ignition was turned to a position where the socket was live, which'd increase the risk of a voltage spike to ECUs etc.

But you could croc clip onto the battery terminals, if there's sufficient exposed metal.

We have a cig socket one but don't use it for the ECU spike reason.

We croc clip onto the terminals (not the posts) and use a small slave battery.

Just interested on how he does it only using the new battery.