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Weird power cutoff/electrical issue when battery low

Post by Ties » Subscribing Member » Wed Oct 31, 2018 9:25 pm
Joined: Tue May 27, 2014 12:17 pm
Posts: 53
Hi,

back again with a new problem... Since a few days, my van has been acting weird when the battery runs low.

When starting the starter motor turns just fine at first, slowing down as the battery gets lower, but then suddenly it will just stop, and I can only hear the solenoid clicking repeatedly. This happens way before the battery is dead, i'v heard the starter motor turning much slower then it does now when it start to click.
If I keep trying the starter and drain the battery further, the starter only gives one or two clicks, then stops and the ignition light will just turn off. If I turn off the ignition, wait a few second, and turn the ignition back on, it turns on normaly again and the light looks normal (not dim or anything). If I try starting again it just clicks and turns of again.

At first I suspected the brushes on the starter, thinking maybe they where starting to wear out and combined with a lower voltage when the battery starts to run low wouldn't turn, but it's not just the starter! When I turn on the ignition and switch on the headlamps for example with the battery low, it would do the exact same thing! The headlight would very briefly turn on (barely visible) and then turn of along with the ignition light.

I started to suspect maybe the battery was just bad although its pretty new, but when I connect a jump lead from the battery positive directly to the starter, it would still turn normally and I could start the van without issue when it was just clicking and turning off all ignition power before, so the battery still has plenty enough power in it to start the engine!

I'm really confused now, it it almost feels like there is a short in the starter, only its not just the starter!
And if it was as simple as a short-circuit, the battery charge should not effect it, and why would the ignition light go out and come back after turning the ignition off, waiting a few sec, and turning it back on again...?

Anyone any ideas...?

Re: Weird power cutoff/electrical issue when battery low

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Post by Phil Bradshaw » Club admin » Thu Nov 01, 2018 2:19 am
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3875
Connect jump cable between battery earth (ground) and engine. If starter now operates then fault is on the earth side.

Possible faults -

1. Battery terminal/s loose or connection/s affected by corrosion.

If battery terminals are screw type for taper post then check security and condition of cables under screws.

Terminals should be 8mm type for cable normally used for petrol engines, 10mm for diesel engines -

Image

If a cable is slack inside a terminal then crimp a ferrule on the cable strands -

Image

Ferrule can be cut from central heating pipe. Position crimps to align with screw ends for best security.

2. Battery cable connection at starter solenoid loose or defective.

Includes brown wires connected to the same terminal post: check condition and security of wire in each eyelet terminal.

3. Engine and, or, battery earth (ground) defective.

Engine earth should be connected to the engine near the oil filter and to the body floor panel below the brake master cylinder; the latter connection can be affected by corrosion.

Flat braid cable that is crumbly (or worse) can be replaced by similar or by stranded cable at least the same thickness as the battery cable to the starter motor.

4. Starter loose on engine or solenoid faulty (end cap contacts defective) - starter clicks instead of running.

Normally this fault doesn't affect anything else but can exist alongside a wiring fault.
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  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

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