Battery Charging Problem

[Methane Bloke]

Help Guys.

I've got a problem with the battery on my NC30 going flat. On start up she charges fine 14.5 volts and 13+ with dipped beam on. Over a few hours riding though the battery volts drop to around 10-11 and of course she won't start. Any ideas?

[Methane Bloke]

The bike lives on an Optimate when in the garage, so always starts no problem from cold.

[Methane Bloke]

Bike had a new alternator before Christmas. I have new reg/rec and one of three years old, both work fine. I have new battery and one of three years old which charges fine and holds it on the bench for weeks. If anybody tests the bike, all appears OK, no apparent problems. It's only after a few hours riding that the battery is flat and there's no charge. It seems to be related to heat as it's fine when cold.

[Methane Bloke]

Temp gauge is fine, hardly above 80C all Sunday.

[Methane Bloke]

mojitomax said:

I had a similar problem. After a short trip the bike would start immediately. After long trips though, the bike would not start immediately, but after resting for an hour or so, she would start up again. It turns out it was a dead battery. Seems to be ok after changing battery

New battery just before Christmas, although as it happens there was nothing wrong with the old one which is now being used on another bike. Using CBR6 battery which has larger capacity than the NC30 one (thank goodness).

[Methane Bloke]

mitzy said:

I would take it to your local friendly bike garage, let them give it a good check out.

Now here's the rub, I used to be a Honda Motorcycle Mechanic and have a 3300 Diagnostic Unit in the garage and it all checks out fine. Take it for a decent ride and it fades away.

[Methane Bloke]

10-11V is with the engine running, so it is a battery charging problem. However new alternator, choice of two reg / recs and two batteries all produce the same results, so where is the fault?