abrescia

Just to put a bow on this thread, I received and installed my new ground strap from Roger tonight- and of course the car fired right up! I’m giddy. Thanks again Stan and everybody, I’m driving my car tomorrow no matter the weather (no snow in the forecast)!

Petza914

I love a happy ending 👍

Alan

If you do ohm it out it could really be anything... get the strap positioned right (wrong?) and it may be hundreds of ohms... twist it a bit and it might then be close to 0 ohms... that's the way theses things work and why battery strap issues can seem intermittent. The act of taking a battery out to test it and reinstalling it can change the behavior of the ground strap significantly. As can just yanking on it while installed. However once the problems start they will only ever get worse... BTDT

Alan

Wisconsin Joe

While I don't disagree with anything above and am really hesitant to go up against Alan in anything electrical...

There's also the fact that a ground strap can show 0 ohms, and not be able to carry the amount of current needed to power the starter.

The corrosion can limit the ability of the strap to carry large amounts of current, while still showing continuity at the levels a meter would use.

This can be checked by looking at the voltage at the battery and at the jump post when cranking. If the ground strap is bad, but still 'continuous', the voltage at the battery would be good, but the voltage at the jump post would be down significantly when cranking.

dr bob

^^^^ This ^^^^

Take the word of a victim of this. I spent effort spread over months, with test leads and meters wired to measure voltage drop through primary wiring sections and that ground strap. Even then, identifying readings didn't show enough voltage drop in normal service to indicate a problem in that strap. I was chasing a battery charging issue, but all we are talking about is which direction the current isn't flowing well enough.

The Good News is that the upgraded ground strap is amazing cheap and amazingly easy to install. Even if you think that you don't really need one, replace it anyway. I grabbed a handful of them when I bought mine, and spread them around among our local SoCal group. Rob Edwards shared back that cranking speed improved noticeably with just that change.

Alan

I think you misunderstood my comment. Once the ground strap starts causing issues - messing with it can seem to make it work (if only adequately) for a bit... At this point its behavior is compromised and will deteriorate to complete failure in a short time. Usually by this point it will look rather ugly in places under the sheath, but you usually cant see that - outside the sheath it will likely look completely normal.

Trying to measure the resistance is a bit futile - because to measure it you have to disconnect the ground strap - which means you have to move it, and this alone can change the behavior. Indeed you are right having a low ohms reading in this case is plausible but that may be through a few small strands that act like fuse when you try to pass >>100A for starting or even just a few amps for ignition. The problem with diagnosis here is that the conditions are constantly changing as you try to measure things.

If you can measure the battery directly (lug to lug) as good under these conditions with no vehicle power, or vehicle power that disappears as soon as you turn the ignition on then the ground strap would always be my first suspect. Measuring voltages while cranking sounds easy but unless you have a meter that does min/max readings you likely can't get a meaningful reading with a DVM (here an old school analog meter would actually work much better - at least indicatively - but who has those now...?)

Best way to diagnose here is what Stan said: use 1 lead of a booster cable pair to bypass the ground strap in parallel: Battery Lug (clamp on the existing ground strap battery connector) to any clean ground point (the bolts at the top of the shock tower or the GP under the plastic cover in the wheel well are very convenient). If this makes everything work AND without it its dead - then you have your answer.

I would say that in installing a new ground strap - I like to wrap mine in a transparent thick wall heat shrink tube and I double seal the battery end using more thin wall heat shrink tube. I want an airtight seal at the battery connector end and I want to be able to see the condition of the strap. Not a stock look - but this is usually hidden away and it make strap issues developing much easier to see.

Alan