Main fuse keeps blowing

[sportwaiheke]

Hi all
The story - I left the ignition on and flattened the battery.
First push start attempt it sort of fired on one but would not take throttle as it backfired and sputtered for about 20 seconds.
Other attempts at push start got one detonation and then nothing.
Tried recharge with leads on - charger read 7amp and didn't come down in 5 hours.
Took leads off and it took charge.
Reconnected leads and even with ignition off it blows the main 20amp fuse the moment the second lead is contacted.
What do I have to test, in what order, and where do I find them please.
Bike is 1400 Intruder 1996.
In anticipation
Cheers
Rick

[Motu]

If you tried to charge it with the battery connected you have most likely fried the reg/rec,that is where the short will be.Disconnnect the reg and see if that stops the short.Keep unplugging until it stops blowing fuses....the last one is the problem.

[sportwaiheke]

Thanks for that - where is it - on front of battery box at tyhe bottom - device there has cooling fins?
My 800 has it off to port I think - sorry not into electronic stuff.
Cheers
Rick

[FilthyLuka]

silly question, are the leads the right way around?

[Waxxa]

Yep, sounds like your regulator-rectifier (not sure how you would spell that) needs replacing. Buma, they are expensive.

[FROSTY]

I'd go with battery leads round the wrong way

[davereid]

If you tried to charge it with the battery connected you have most likely fried the reg/rec,that is where the short will be.Disconnnect the reg and see if that stops the short.Keep unplugging until it stops blowing fuses....the last one is the problem.

What he said.

Lots of bikes have shunt regulators.

If you attempt to charge the battery without first disconnecting the earth lead, the regulator will try to regulate the battery charger.

If you have a tiny little battery charger (like a "battery tenda") the regulator will win.

But if you have a standard "grunty" battery charger, the regulator will lose.

And so will you, cos you need a new one and they cost a fortune.

[bimotabob]

I agree with the others that it sounds like a case of trying to charge it round the wrong way. Dont do that.
Unplugging circuits does sound like a good plan but if you do that I would hook up a short bulb instead of using new fuses to test.

I disagree with the comments that charging the bike with the leads still connected will damage the reg/rect.
It will if they are reversed as the diodes don't like that on any bikes and cars with field controlled alternators or "shunt regs" - it blows the diodes off the heatsink!

In all my years as an Auto sparky and Motorcycle
owner I have never seen a reg/rect get damaged by leaving the battery connected and I have done it many many times.
Jump starting with the donor vehicle running is like doing the same thing and is okay
- always disconnect the slave battery first and try to use surge protected leads.

A charger is only puttting a 2 volt raise across the battery just like the reg/rect does.
You shouldn't use a heavy duty or industrial charger at any rate as they will destroy your bike battery.

Another thing to watch for is when dealing with a fully flat battery is that if you charge it with the leads backwards
the battery polarity will be reversed and then when you hook it up....

Did you see any smoke?


Cheers