Motoscrubs.com

Hello everyone,
I've recently "completed" the restoration of a 1966 250 Scrambler. I added the quotation marks because while the bike looks good, I'm having some issues with the charging/battery system. To begin, I'm using a 120 watt 12v alternator purchased from Lacey Engineering. The kit came with the new stator with 12 coils, a new flywheel, and an Electrix regulator. With alternator isolated and ignition from the 12v Shorai battery, I am measuring approx. 80 watts output. This is reving up the engine a bit from idle. I don't have a tach at this time. The Shorai charges from my Battery Tender and with a full charge I find 13+ volts.

The problem is that after riding the bike with lights on (60 watt 12v headlight) for a few miles, the battery drains and the bike dies and won't restart. At the side of the road, I checked the headlight and it dimmed quickly when the switch was turned back on. Once I had the bike back in the garage, I measured 10 volts at the battery. After a couple of hours on the tender, the battery was back to 13+ volts and the bike started second kick. I should also mention that I had started the bike a number of times today while working on carburation before taking the bike out for a ride late this afternoon. I didn't have the lights on and I don't know how much I was drawing from the battery with the bike close to idle speed.

Since the alternator seems to have a good output, the question seems to be why isn't the battery charging while I'm riding the bike? The possibilities seem to be a short in the wiring that is preventing the battery from holding a charge. (I've checked all the circuits for a short to ground and so far haven't found a problem.) Is the regulator at fault? Since I'm breaking in the engine, I'm keeping the engine speed low - is that the problem?

I would appreciate any suggestions and advice on how to test the 12v regulator and also how to test the circuits to find any ground faults. I've disconnected the lighting circuit and a test for continuity to ground was negative.

Thanks in advance,
Steve

Hook up a voltmeter across battery.

Start bike.

What is the voltage at idle?

What is the voltage at higher rpm?

Turn on headlight.

What is the voltage at idle?

What is the voltage at higher rpm?

The voltage across the battery should be between 13.8v and 15.5v (around 14.5 preferred) in order for the battery to be charged.

I addition to JB's questions...
Have you talked to Nigel about it?
It does seem like a 120w alt at a reasonable rpm should do ok with a 60w hl, even running with a fully charged battery alone should get you more than just a few miles. I mean, if the total load is 7 amps and the smallest battery Shorai offers is what, 7 amp hours...?
Have you measured what the total current draw is with everything on? Seems something other than normal must be drawing it down or there's an output issue.

With alternator isolated and ignition from the 12v Shorai battery, I am measuring approx. 80 watts output. This is reving up the engine a bit from idle.

To measure wattage output, you generally need to know the amperage as well as voltage. What were the numbers? You may be getting 80w at 10v and 8 amps. What were you using for a load?
Also those Shorai's specifically like a lot of voltage and don't take kindly to being drained too low...

Bill

By: ozarkman...
" I've recently "completed" the restoration of a 1966 250 Scrambler.
I'm having some issues with the charging/battery system.
I'm using a 120 watt 12v alternator purchased from Lacey Engineering. The kit came with the new stator with 12 coils, a new flywheel, and an Electrix regulator.
The problem is that after riding the bike with lights on (60 watt 12v headlight) for a few miles, the battery drains and the bike dies and won't restart. "

____ As Bill has already indicated,, with your battery fully charged before beginning your ride, even if your charging-system is not connected-up, you should be able to run for at least a half-hour before your headlight drains the battery enough to rob the ignition of sufficient power to produce ign.spark.
__ Too bad that a (single phase) 12-coil alt produces too high of an AC-frequency to run the ignition without a battery, (so you wouldn't get stuck on the side of the road) !
To cure that from happening, you could install a large capacity capacitor, for such emergency occasion.
In fact, a good test to try-out, would be to see if you can run your Duke with it's aftermarket-system, without the battery & while the lights are kept turned-off.



" I didn't have the lights on and I don't know how much I was drawing from the battery with the bike close to idle speed. "

____ With the lights kept off, such a powerful system should at least break-even near idle,, so this concern of yours ought not be of any actual consideration.


" The possibilities seem to be a short in the wiring that is preventing the battery from holding a charge. "

____ Well if you had any real 'short' anywhere,, then either you'd get a blown-fuse, or some quite noticeably burnt-up wiring somewhere !


" Since the alternator seems to have a good output, the question seems to be why isn't the battery charging while I'm riding the bike?
Is the regulator at fault? "

____ Well my GUESS (on this aftermarket system of which I have no experience), at this point would be that you may've connected-up something as if your Duke had a positive-ground system, (instead of all negative-ground).
Have you double-checked to be sure that you have ALL the (added/special) wiring properly connected according to a negative-ground system ?


" Since I'm breaking in the engine, I'm keeping the engine speed low - is that the problem?

____ Well if your high-power lights are always kept turned-on while also riding in significant stop & go traffic, then it would certainly contribute.


Hopeful-Cheers,
-Bob

How old is the battery? Is it sulfated? Do you have a pulsing battery tender that desulfates the battery? If you put a meter on your charging output, you should get 14 volts. If you're getting that (at what rpm?) and the battery is going flat, try another battery if you have one. As someone said already, check the voltage at rpm with the light on and off. That will tell you a lot.
Stevan

Do you have a pulsing battery tender that desulfates the battery?

You very specifically don't want to use a charger with a 'desulfating' pulse mode with this type of battery (as per Shorai website), these LifePo4 batteries are a very different animal from lead/acid...

BTW, I think the OP has long abandoned us here...

Bill