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What have I buggered up here?

See pic then reference colours.

post-23873-0-62854300-1420340010_thumb.jpg


Green - From Battery.

Yellow- From Alternator.
Blue - Engine harness

Red - Another Engine Harness

Purple - Fuse for car alarm/can be ignored.

In this pic the switch is off, he car will not start, no accessories will turn on, fuel pumps not priming.

However, I can go out after a week and find the car hard to start as battery voltage has dropped.

I had problems with this setup originally and found this setup was the only way to get it to work, with the blue coloured engine harness on the other side the car would continue running when the switch was flipped.

What have I stuffed up? Or should I have used a 3 pole switch and separated those two engine harnesses connections red/blue from each other and the battery.

Here's a pic of the battery setup, pretty sure this problem existed before the surge tank went in, the trigger wire for the relay for the surge tank pump is the existing fuel pump wire, so neither pump primes unless they should be.

post-23873-0-42054500-1420340014_thumb.jpg

Battery is dry cell for car with CCA rating above what's needed for this engine.

Neg terminal corrosion is dissimilar metal spacer used there. AFAIK that shouldn't cause a current drain.

Ok so this drops the battery and the alternator feed? Alarm is still on the hot side of the battery and still active regardless of switch positions.

  • Like 1

No, alarm is on the side that gets disconnected. The switch is in the off position in this pic.

It's been suggested that putting both engine harness connections on the non battery side should be enough, or that the alternator can be pulling amps from the battery, however I'm pretty sure that testing last time (and I'll test again shortly to be sure) showed that having the two engine harnesses on the same side saw the engine keep running when the switch was flipped.

Alternator will kill battery if a diode is cactus or if the reg is faulty. Auto sparky will soon tell you.

Chris is wondering about the alarm. (as am I)

Most alarms will trigger once the car's battery is removed from the circuit.

All my machinery has a breaker similar to yours right at their batteries. First item from the battery is the breaker.

No alarms of course but my battery life has been extended miraculously by removing any chance of drain.

I had an aircon mate of mine around and he had a current tester or something he called it, put it on the alternator wire and got nothing.

The alarm wiring goes to a fuse then off elsewhere, the car used to have remote central locking etc, but most of that has been removed (track car).

I will have to test if that wire can be ditch, either way though it's on the wrong side to be draining the battery when the switch is off.

just measure the current draw each cable consumes with engine off. easy to do with a multimeter. I would move the blue engine harness to the same side as the red one (isolated). I don't see how the engine can keep running with both harnesses connected to the isolated side of the switch.

As per the previous discussion in your other thread. Test current draw with a clamp meter on the blue cable with the switch isolated. Move everything but the battery positive cable to the other side of the isolator. Theres no reason that anything else should be on the battery side of the altenator. Unless you have picked up the battery cable after it goes to the altenator but im assuming the yellow cable is the battery feed to the altenator

If so then it can be on the other side. The altenator is never charging with the switch off so no need to be over there

If you are worried about too many things hanging off one side of the switch, then you can fit a small junction block after the isolator and just run one thick cable from the isolator to the junction block

  • 2 weeks later...

Has the relay next to the battery still got power going to it.

Try taking the battery out of car for a week to see if it goes flat.

Once a dc battery goes flat you will never charge it to 100% again. You will still have 12v it just wont have the capacity.

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