Battery Charging (again)

Ok, I have verified that my alternator is sending AC current to my Boyer Power Box.

I have hooked my voltmeter to the black wire coming out of the power box, the one that is usually hooked to the negative battery terminal.

My voltmeter shows 14 volts coming out of the black power box wire when the motor is running.

All sounds good so far?

BUT, when I attach that black wire to the negative battery terminal, with motor running, the voltmeter attached to the battery terminals shows 12.5 volts, no increase to show it is charging the battery. Yes I brought the rpms up to 4000, still no increase in voltage at the battery.

Bermuda triangle in my garage.

The battery is off my Honda ST1300, it is a strong sucker, and it is fully charged, reads 12.5 volts. Any outside chance that because this is a much more powerful battery than the standard
cranking Norton one that it just shrugs of the 14 volts supposedly coming into it from the black wire power box, and won't show any increase in voltage?

When you hook the multimeter to the wires of the powerbox, one is positive"+" and the other is negative"-". Just because the bike is a positive ground does not mean that the battery shouldn't charge + to + and - to -.

If you put a charger on the battery you most curtainly would NOT put positive to negative and negative to positive.

Verify which wire is what and hook it to the battery accordingly. + to + - to -.

I have offered this info knowing it may be a mute point to you but it is easily confused by many as to the nature of positive ground systems.

Hopes this helps......if not you then someone else.

If you keep running the bike, does the battery change voltage? It should gradually charge up to over 13 VDC and hopefully around 14 or more. If not, the alternator may not be supplying enough current. Maybe try another battery if you have one.

Dave
69S

Sounds like a bad battery to me....

Do you have an ammeter ? It has to be able to read +/- 15-20 amps. Wire it into your lead going to the battery. I won't matter which way around it is. With the motor off and the ignition and lights on, the battery will dischage and the needle will deflect one way. When you start the bike and rev it up the needle should move to the other side. If it doesn't, you might have a bad Powerbox or alternator.

I'm not sure how to check a Powerbox or if you have weak magnets in the rotor (other than seeing it a large screwdriver will stick to it). I can't find a wiring diagram for the stator, but generally (with the bike off, and the alternator unplugged), your alternator stator should have about the same resistance between all three leads (or some if you only have 2 leads) and none between any of them and the primary case. Zero or infinite ohms in the coil windings or zero ohms going to ground would be a bad alternator.

If you set your voltmeter to AC, is there a lot of ripple on the power going to the battery ? Do you get the same AC voltage between each alternator lead and ground ? Do you have a spare rectifier that you could substitute ? Are all your grounds good ?

If the Honda battery acts the same, it is probably not the battery.

Greg

Thanks all, good suggestions that I will work on!