Fluctuating Voltage to battery

[Penguin74]

I'm building an Ironhead chop and I'm using a cycle electrics generator and an 8 cell antigravity battery. I just got the bike cranked for the first time and wanted to check my charging system to make sure all was good. I put my volt meter on the battery while running and it was fluctuating between 1-2 volts and then like 14.5 volts. Is this normal behavior? Should I be seeing a steady 14 volt reading?

Just want to make sure my charging system is working correctly especially considering all the warnings antigravity has about their batteries catching on fire if it isn't getting charged properly.

[Revelator]

Yes The output should be steady or stable, around 14 to 14.5 volts, and Not dipping
down to 1 or 2 volts. maybe your voltage tester is going wonky.
Or a loose connection.
Check the plug/Connector that attaches to the alternator, make sure it has a
nice snug fit & pushed in all the way, or is not loose.
also make sure that the regulator is mounted secure so that It has a good ground to
the bikes frame.

[Penguin74]

Will do, appreciate the help

[Penguin74]

I've checked all the connections and also tried a different volt meter. Still seeing the same thing Voltage fluctuating between 14 and 1, back and forth.

Just some more information on my setup. Its a cycle electric 65A generator with the C540 regulator on the end. I'm running a 14 gauge wire off the regulator directly back to the positive terminal on the battery.

Any other thoughts or anyone seen something like this before?

[JBinNC]

If those are your voltage readings at the battery, I think you have a battery problem. I would call the mfg. and ask them.

Jim

[farmall]

Is all the charging wiring new? Are any ground connections new?

Are any connecting lugs fully crimped or soldered? Precisely how was each connection tested?

How is the charging system wired? (Power to battery should not go through the key switch or any switch which often fail intermittently.)

The battery could be tested off-bike by clamping the test probes with the battery bolts (lightly snugged, be gentle) then shaking and slapping the battery to see if the intermittent reading duplicates.

Intermittent readings are by far most often caused by an intermittent connection. An old circuit breaker can fail intermittently but that's not super common. You can eliminate that by replacement or temporarily by swapping with one of the other breakers.

Sketch your charging circuit and post a photo of the sketch.

[DustyDave]

That cyclic fluctuation is the first stage of regulator failure on the Nippon Denso regulators I use. As the manuals always say substitute a known good part and observe.
Dusty

[farmall]

Interesting. Which Denso model do you use with generators? Denso make quality parts so I'd like to expand beyond my Denso starter fetish.

Cycle Electric have a two year guarantee so if swapping fixes the problem and the regulator was bought recently enough they may warranty it. Either way they can test it on their bench and verify what if anything failed.

[DustyDave]

Interesting. Which Denso model do you use with generators? Denso make quality parts so I'd like to expand beyond my Denso starter fetish.

Cycle Electric have a two year guarantee so if swapping fixes the problem and the regulator was bought recently enough they may warranty it. Either way they can test it on their bench and verify what if anything failed.

The internal regulator that goes in a Toyota forklift alternator or more recently the mini Denso hotrod alternator. Any time I see one cycling like he described after warmup its gonna die soon. Most of the self exciting ones tend to do that until revved once.
Dusty

[JBinNC]

If the battery voltage is fluctuating from 1V to 14V, as stated, it ain't the voltage regulator.

And I wonder if that is indeed the case, because the ignition won't function at 1V (unless it's a magneto).

Jim

[farmall]

Good point JB.

It's common when probing vibrating components for meters to read intermittently if probes are not in FIRM contact with clean metal. Dropping to ~1v instead of cleanly going to zero during voltage checks is no surprise on (cheap) digital meters. My medium price Mastech doesn't do that but some low dollar units do sometimes. Beats me why.

That's one reason my mentor kept his old USAF PSM-6 analog meter as their natural dampening avoids deceptive readings.

[DustyDave]

I always assumed that the output or power transistor was going dead short cyclically. But was never interested enough to de-pot and test since a new regulator was always a cure.
Dusty

[Penguin74]

I've tested it with two different multimeters and am getting the same results. Yes they are both cheap meters, but they've always worked alright in the past. The generator light is also flashing in sync with the fluctuation I'm getting at the meter so makes me think the regulator really is sending fluctuating voltage back to the battery. I'm running just a 14 gauge wire straight back from the regulator to the positive terminal on the battery, not going through any switches or anything like that. I've got another battery I was going to try and see if its possibly a battery issue, but the battery checks fine on the bench, reading over 12 volts. The generator/regulator from cycle electric is nearly 20 years old, so it wouldn't surprise me if it had an issue, just haven't ever run across an issue quite like this before.

[pansshovelsandknucks]

The multimeter is measuring the differential between probes. Just something to keep in mind in case your ground is getting some power. If the battery is reading 12v on the bench, it shouldn't read 1v in the bike even if the generator is not putting out any voltage

[JBinNC]

The multimeter is measuring the differential between probes. Just something to keep in mind in case your ground is getting some power. If the battery is reading 12v on the bench, it shouldn't read 1v in the bike even if the generator is not putting out any voltage

EXACTLY

Jim