Commando on fire

Ron L said:

It should have blown with a short like that

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No. Think about it. The pigtail has a fuse in the positive lead because it is made for a normal negative ground system. The bike's fuse is on the negative side. When the exposed pigtail lead touches the frame, the path is closed from the frame thru the negative lead on the pigtail to the battery and from the positive wires of the bike's harness back to the frame. No fuse in the circuit!!

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I had the exact same thing happen to me a few years ago and the fuse blew instantly. Now I remember to put that cover on the pigtail as soon as I disconnect the Battery Tender.

But I repeat, the fuse blew instantly. No other damage whatsoever.


Edit: But I'm not sure I didn't change the fusing arrangement when I rewired the bike. I did substitute a modern fuseholder/fuse for the old "canister" type. Maybe I changed the location too.

Yep, first time i put one on one of my bonnevilles, I saw it spark, then swapped the tender and pigtail mating ends for positive ground use.

When I bought my Trident last year, I noticed it was wired kind of strangely. The feed and ground wires from the harness that go to the battery were connected to a battery charger plug and it was plugged into another battery charger plug that was wired with short jumpers to the the battery terminals. To charge the battery you disconnected these two plugs and plugged the charger into the one going to the battery. Once charged, you unplugged the charger and plugged the connection from the harness back into the one from the battery.
I really didn't see the point of it at the time and actually did away with it doing the routine harness connections to the terminals and a lead and plug for the charger. But after reading this thread I can start to understand what the po was trying to do. There is no chance of a short this way because for the wiring to be hot the two plugs have to be connected.

AGM battery = Battery Tender ELIMINATOR
(they hold charge much better than old style LA battery)

tomspro said:

AGM battery = Battery Tender ELIMINATOR
(they hold charge much better than old style LA battery)

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I agree.. occasionally my Mk 3 might not get started for 6-8week or so. After i've exhausted myself on 5 kicks i push that green button it spins like puck and instantly starts thanks to the AGM battery.. But if i kick it every week-10 days just to smell the fumes its a 2 kick scenerio.. Maybe/probably its cos the AGM has good volts and never seems to bleed out to 12.7v or less over 4 weeks.

But i do also attach a "solar powered" tender occassionaly to both bikes (AGM)... Works for me!

If it doesn't correct polarity, then just swap the leads to the battery, then cut the end off the charger, flip it to reverse the polarity. Then solder the end back on it. Problem solved.

I had a chat about my fun with fire experience with an old friend yesterday over a couple of beers. He is the best moto mechanic I know and he told me he ALWAYS wires a second fuse on positive ground Brit bikes so that BOTH sides of the battery are fused. Fire problems from a shorted battery eliminated. My fuse, a 20 amp, did not blow nor did the fuse on the Battery Tender pigtail because both were on the same side of the battery. I will be adding that second fuse when I rewire my fried harness and I think I will drop down to a 15 amp fuse as well. And I will ALWAYS remember to use the rubber cap on the pigtail. Also I am very happy to hear that several of my Norton Brothers here have learned from my mistake. It's a good feeling to pass on knowledge gained thru tough circumstances and maybe save the unnecessary destruction of a Commando. I am sure that if I was not standing right by my bike when this happened it would have gone up in flames.

flyboy49 said:

I am sure that if I was not standing right by my bike when this happened it would have gone up in flames.

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Just had to add this :wink: Okay, so I'm a sick bastard! I'm also very happy to know you were able to save your bike from the worst death imaginable.