I've just been a prize prat. Connecting +ve lead to -ve terminal of battery then -ve lead to positive. Took me a minute to realise, wondering what that electrical burning smell was !!
What am I likely to have fried ?
I'm presuming I will have killed something. Am hoping I haven't knackered the loom as me and my multi-meter only vaguely get on.
It's a B40F Star. 6V Ignition set up - as it would have been originally .
hope nothing serious ,I have just re-wired my Super Rocket and the first thing was to fit a fuse into the earth line(+earth) glad I did as when I tried my new altett horn it blew as it shorted to the frame ,yes a new horn faulty out of the box and over £100, so always fit a fuse !
Connecting the battery wrong polarity will allow current to flow through the rectifier and alternator. The alternator may have been damaged as may the wiring between alternator, rectifier and battery. The rectifier should be ok though.
ALWAYS FIT A FUSE
I'll put the battery in the right way round on Wednesday and see if anything works. Will no doubt then be asking questions about how to check which bits are damaged. I'll not be sure where to start.
Is there a way a to check the alternator wiring without removing the clutch case ? (I've not been in there before) I've just taken the alternator cover off and peered in vainly. Well at least it smells of oil in there and not burnt wiring....too little to see otherwise... very much hoping I haven't killed it.
There was unfortunately no in-line fuse. What Amp rating is sensible on a 6V B40 ? & where do I place it. I can see various bits of red Positive wire around the bike including where it earths at the coil under the saddle & of course the +ve lead to the battery. Quickest place to get to would be in the head lamp cowl or on the +ve lead to the battery. Does it matter where ?
Did you just connect the battery the wrong way and did nothing else eg try and start the bike?
I am not sure what electrics you would have fried - I doubt the alternator would be damaged but possibly the rectifier could have been damaged. Most of the other circuits such as lights/horn will be fine. The alternator is just a big coil of copper wire and if you didn't start the bike should not be damaged. A fuse will only protect a circuit from a short circuit - connecting the battery the wrong way shouldn't cause a short circuit to form.
Sorry just to add - the battery may short to earth via the rectifier.
Hi Hoogerbooger, I was interested to read that you're thinking of fitting a fuse. Firstly, I should stress that I know nothing when it comes to electrics, I am a numbskull, so am definitely in no position to advise you! Anyway, a while ago I was planning to fit one to each of two wires which come from my battery -ve terminal (one going to horn and stop light, one going to other things, so two fuses in all), but I never got round to it. I wasn't too concerned, given that the new B40 had no fuses as far as I know. But people appear to think it's a wise thing to do, so I might do it while I'm sorting out my current electrical problems. Anyway, I remember I was thinking of maybe 15A (continuous rather than blow) fuses, but was advised on this forum 10A. I thought I might fit a little bracket near the battery to hold a fuse holder. Again, I think I got that idea from this forum. I got as far as buying bits but never got any further. If you are interested, you can see the conversations I had on this forum from 19 March 2018 onwards (heading is "Fuse ratings.") Phil.
( Thanks Phil for the thread on fuse ratings. I also have two brown-blue wires to the negative battery terminal .....as the original circuit diagram shows. So will probably try two fuse holders with 10A continuous fuses)
OK then, I put the battery back in. (Battery was nearly full charged - unloaded about 6.25V)
Lights & horn working & got it to turn over briefly. But only briefly ...but this looks like a non-electrical issue ( the reason I took the battery out to top up was because I couldn't get it to turn over at all after a few months standing unused)
[I say it appears non-electrical because it now starts easily when tickled on a coldish day, runs evenly for say 15 seconds then cuts out. Tickle it again and it'll start ...then cuts out...so I'm thinking carburation/fuel supply issue][ I have no separate air valve on my concentric - so can't play with that]
I presume this start up only demonstrates that at least parts of the wiring is ok and the battery has enough juice to start up ? but doesn't necessarily tell me anything about the rectifier and alternator.
I set my multimeter to 10hms and tested all combination of pairs of terminals on the rectifier ( there are only 3 terminals. No continuity on any combination)
I took the battery out and set the ignition switch to the emergency start mode. I got one spit back at the carb. but then got it to fire for 3 or 4 cycles. got it to almost start twice like this ..... before the tickler jammed and fuel started spewing everywhere. !!!! [looks like I'll have to remove and strip down.]
So currently not sure what to think on electrical damage.
Any suggestions on tests I can do to check the electricals for damage without a start up required ?
Looks like rectifier is ok. I've retested with multimeter (as per Rupert ratio vol 2) I have continuity between AC poles and the DC pole each time in only one direction. Also had same Ohm reading from both AC to Dc combinations. Had not pulled leads off before and now realise I had previously had the probes on insulating coating of the rectifier !
Looking to me that I've been lucky and I disconnected the battery before damage. I hadn't tried any switch or starting the bike. However, one minute of the battery the wrong way round, with evident smell of hot wiring and was enough to realise the potential to catch fire.