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Main 30A battery fuse blowing

14K views 3 replies 4 participants last post by  Tbirdnz 
#1 ·
Looking for some assistance here. I recently accidentally let my battery run down to completely dead, on my 08 Bonnie. I attempted to jump start the bike and get it running from my car battery.

My first attempt at this worked fine, i let the battery charge for about 10 minutes then started the bike, all lights worked as they should and bike started as long as it was connected to jumper cables.

As soon as i disconnected the cables and gave bike any throttle at all it died. I then reconnected the jumper cables. When i went to start the second time, i found that no electrics worked on the bike.

I took off the side cover and found the fuse box, the main 30A fuse was blown, i replaced the fuse and as soon as i hooked up the jumper cables it blew again.

I then purchased a 15a trickle charger to charge the battery. I left it on the charger for 48 hrs and i don't believe the battery is charged at all, because the bike battery will not blow the 30a fuse and if i put the jumpercables on, it still blows.

At this point i've disconnected the bike wiring to the battery and am trying to let the trickle charger charge the battery that way.

I haven't dug out my voltmeter yet. Does anyone have any ideas that would explain why my fuse blows immediately. I'm pretty sure i'm not doing anything obvious like shorting the jumper cables to the frame, but passed that i can't figure anything out.
 
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#2 ·
It would help if I could see the schematic for the 08 Bonneville, but, assuming it's basically similar to the 07, I'll offer the following: The 30 ampere main fuse feeds the rest of the fuses in the fuse box, which are all of a lesser rating.......if none of those are blown (which is what I'm guessing) then the overload is occurring between the 30 amp fuse and the rest of the fuses.....the one thing that's tied in between these 2 points is the output from the charging system, specifically the rectifier/regulator unit. You might try unplugging the rectifier unit, replacing the 30amp fuse, charge your battery (and note whether it WILL charge and load test properly) and retry to see if the 30 amp fuse blows. It's possible that the order of failure here is the rectifier/regulator unit output shorted to ground (blown internal diode).....this will cause your own battery to blow the fuse and especially the booster battery from the car. Alternatively, your bike battery may have one or more shorted cells.....this will cause the rectifier to dissipate a LOT of heat as it tries, in vain, to pull the defective battery voltage up.......which can, if severe enough, cause the rectifier to fail - same scenario as the first above.

Charge and verify your bike battery as good first.....and as I mentioned, disconnect the rectifier and reinstall the battery 'n fuse......additional testing can be done on the rectifier (not sure of your own experience or capability here.....you may need help or the use of your 2 year warranty ;)

Hope this helps.
 
#3 ·
A 15 amp charger is a trickle charger for a car battery, but is a pretty heavy-duty charger for a motorcycle battery. As a rule of thumb, usually 1/10th of the amp-hour rating of a battery is a good trickle charge rate. I'm not sure what 48 hours at 15 amps did to your battery, unless the charger you have meters the charge rate. As always, opinions may vary...
 
#4 ·
You should never try to 'charge' your bike battery with a car battery.

You can jump-start a bike battery with a car battery as long as the car's engine isn't running. If the car engine is running you will fry your battery and/or the bikes electronics.

To jump start from a car battery simply connect up the positive of the car battery to the positive of the bike battery and negative of the car battery to an earth on the bike, part of the frame will do, then restart the bike. Disconnect the connections as soon as the bike starts.

First get your battery tested to see if it is OK after attempting to trickle charge it, one or two cells may be shorted out causing the 30amp fuse to blow. If the battery is OK then follow Sparkss advice on the regulator.

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Ride on ! :)
 
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