Just switched to LEDs all around

[NorazDad]

I have an '81 H that has been stripped down to simple systems: Kick only, Shorai LIon battery, Pamco, EAdv, HHB PMA. All unnecessary safety switches and relays have been eliminated. Bike runs great. My problem has been with keeping the battery charged while riding. I'm a rider who likes to tool around and cruise a bit, but I rarely keep my rpms up much above 4K for very long. The problem I have diagnosed is that I am not getting enough charging juice on my slow assed runs to keep up with the draw from the Hallogen headlight and the running lights. I would notice that I was on my last leg battery-wise when the turn signal indicators slowed down indicating that my bike would die soon. This scenario has been repeated a number of times with a number of good samaritans helping me out along the way. I had finally had it. I had to reduce the draw from my headlight and running lights.
I read a thread where Retired Gentleman discussed the possibilities and it all sounded like it would contribute to solving my problem. I don't think this problem is unique to me.
Well, I ordered a Safego MC H4 LED headlight. Hi Lo at 40 and 20 for $30.00
I ordered Superbright 650s for my turnsignals at $11.00 a pair and a 2 pin LED flasher relay.
And I happened to have an LED running/brake LED that fit and worked just fine.
So, for about $60.00 I am now pulling a ton less poser from my lighting system.
Hopefully, if I pick up my pace and run some recharging Voltage into my battery, it will no longer die after an hour's ride.
A friend asked me though, "Why doesn't the PMA provide enough power to keep the battery charged at idle?"
Good question.
Thanks and Peace All

 

[retiredgentleman]

The root cause of your problems is due to using a poorly made, inferior Taiwan/Chinese, PMA ,rec/reg system. Your idea to go to all LED may be the wrong thing to do. Your alternator is going to produce approximately 12 amps at 3800 to 4000 rpm. If your LED loads, battery charging and ignition only consume say 5 amps, as an example, then the regulator will have to dissipate the heat from the other 7 amps. I suspect the cheaply made regulator will get very hot and may destroy itself.

If you had a high quality Japanese made PMA/ rec/reg system, then it would be able to handle the above conditions. You should not blame the engine rpm for being less than 4000 rpm. A proper charging system, whether PMA or stock design with an energized rotor, will keep a battery charged even if the rpm never goes above 3800 rpm.

I use a stock alternator, with an automotive regulator, and my rpm seldom exceeds 4000 rpm. Typically my rpm is around 3800 when I drive down the road. My battery is always fully charged, and I always use the starter motor. I have never had to use an external charger/battery tender during the riding season.

If you stay with the Taiwan/Chinese PMA system, your best bet is to use a 55 watt halogen headlight, to help consume some amps or else your poor regulator and/or stator wiring may smoke. You should also have a voltmeter on your bike so you can monitor what is happening as you drive down the road.

The problem with a PMA design is that the amps being generated are uncontrolled. As the rpm goes up the amps go up. Ideally those amps would all be consumed by the loads on the bike. I like the stock alternator design (same as used in cars and trucks), because its a controlled design. If my bike only needs 8 amps, then my alternator only produces 8 amps; its a balanced system. Therefore my regulator has very little work to do, and it never gets hot, and my alternator never gets overly hot.

"A friend asked me though, "Why doesn't the PMA provide enough power to keep the battery charged at idle?" "
Either type of alternator does not charge the battery at idle 1200 rpm. That is quite normal. At 1200 rpm is when your battery supplies current to the bike. At 1200 rpm you are pulling current out of the battery, and as the rpm increases say above 1300/1400 rpm the current flow reverses and amps go back into the battery.

 

[NorazDad]

Thank you for that. Leave it to me to find an unbalanced solution. Yeah, I can do the halogen. But you got me rethinking the charging system and the rec/reg. I probably know where I can find a perfectly good OEM.
Hearing that LED fan humming in a dark garage is kind of creepy though.
I should probably carry a spare Rec/reg or know where to get one in a hurry...and that heat coming from the PMA...
I've never been a fan of that.
OK, thanks
Peace and I'll let you know what happens.
Rob