Help!!! Charging system is pissing me off!!!

[Sundie]

Ah...great......another convert!!....

Well, i don't think i'd wire it to the neutral switch. I think i'd just find a right control with a light switch.

On my '78, i run a city light headlight (so i don't get nabbed for lack of DRL) then just flick the full lights on at night. Also a LED tail. Everything else - meh. Lots of power left.

 

[650Skull]

How much charge is going into the battery when the bike is idling or below the 2000 revs?

 

[650Skull]

It's only my opinion, but i think going to the lengths of hooking up a relay the the neutral switch to turn off the light is a *bit* over zealous, and solving a problem that doesn't really exist.

Well, i don't think i'd wire it to the neutral switch. I think i'd just find a right control with a light switch.

On my '78, i run a city light headlight (so i don't get nabbed for lack of DRL) then just flick the full lights on at night. Also a LED tail. Everything else - meh. Lots of power left.

Obliviously you do think it is a problem or you wouldn't have altered your head/tail light

 

[pamcopete]

How much charge is going into the battery when the bike is idling or below the 2000 revs?

Well, I'd have to do some testing, but I would guess no more than an amp at 2,000 and nothing below that. That's why LED tail lights are so great. The light bulb tail light is 8 watts, or about .6 Amps. The brake light is 27 Watts, or about
2.25 amps. If you are stopped at a light with the brakes on, that's a total of 2.85 amps. The LED draws no more than 100 ma (.1 amp), so you gain 2.15 Amps at a stop light with an LED tail light, meaning that at least some current goes to the battery.

Part of the discussion in this thread is whether or not a PM alternator would do better. We are awaiting some numbers from the PM group for comparison.

 

[81-650chopper]

I've also found that when system was working fine. Like someone was talking about idling at a light for a long period sometimes it doesn't put out enough to recharge the battery fast enough between lights. That's 1 big flaw in this sytem it recharges too slow. Was the battery has been drained, let's say 30%, once your back on the go it seems all the juice needed to run the bike gets it straight from this charging system not the battery. Correct? So really how much is left to recharge the battery? And how long will it take? I don't know the exact numbers like some of you do. But in real life situations I've found it takes a long time. I haven't had this problem highway riding but in the city I have come across it more than once!!!!

 

[Sundie]

Obliviously you do think it is a problem or you wouldn't have altered your head/tail light

Actually, the tail light was a: way better visibility, and b: the regular bulbs kept blowing out due to vibration. Lesser consumption was just a bonus. I wouldn't have spent the silly amount of money for the LED one if it was just a consumption issue.

The headlight - mine came with a on/off switch from the factory, and i got the city light one after the original cracked, because i was tired of people frantically waving at me telling my headlight was out during the day. Technically, i've added another 5w or so back into the system. But i'd probably do that regardless, because city lights are cool.

 

[pamcopete]

81-chopper,

Well, again, it relates to the need to balance the output of the alternator to the maximum charging amps of the battery. You can't just bolt in a bigger alternator to charge the battery faster because that would soon ruin the battery. So, when you say it's a big flaw in the system because it charges too slow, what you are really referring to is that the battery is too small for the load.

If you had a bigger battery, it would carry the load better and you could install a bigger alternator to recharge the battery faster.

Now if someone comes along in this thread and says that they have a PM alternator that puts out 20 Amps and charges the battery faster, well, it doesn't really charge the battery faster. The battery can only absorb so many amps of current over time. Applying a higher amp alternator simply means that the battery will convert the extra amps to heat and boil the water out.

So, the bike could use a bigger battery and a bigger alternator, but as it is designed, it works just fine if well maintained.

 

[Sundie]

That's 1 big flaw in this sytem it recharges too slow. Was the battery has been drained, let's say 30%, once your back on the go it seems all the juice needed to run the bike gets it straight from this charging system not the battery. Correct? So really how much is left to recharge the battery?

According to the graph above, 25% is 20 mins, give or take. So sitting in traffic idling for 20 mins... Not out of the realm of possibility. Your charging is about 3x your discharge, if i'm reading the math right, so around 5 mins of anything over 2500 and you'd be good to go. I think.

Anything over about 2000 rpm is more than enough to charge the battery in a short time, i would think. If you're tootling along at 1500 rpm (which i've noticed the open pipes guys like to do, which is outside design) not so much.

 

[Sundie]

Now if someone comes along in this thread and says that they have a PM alternator that puts out 20 Amps and charges the battery faster, well, it doesn't really charge the battery faster. The battery can only absorb so many amps of current over time. Applying a higher amp alternator simply means that the battery will convert the extra amps to heat and boil the water out.

Which would of course be another argument to run batteryless, admittedly.

Hm. Doesn't the regulator in a PM setup also limit current though? I seem to remember that it does, but i'd have to check.

Edit: Aha! PM regulators regulate *current*, not voltage. Although the effect is the same, since V * A = W. Regulate the current to whatever wattage you need, with the voltage as a constant. But wait, you may say: i need more wattage, thus i'll just get a regulator that regulates to a higher level. Oops, now you're pumping through 17 volts. Which is bad.

 

[inxs]

- i imagine that if they regulate the voltage, then, as the resistance is more or less a constant, the current is also regulated

 

[pamcopete]

Well, confusion is starting to develop.

inx...the effective resistance is not constant. Hi beam low beam as an example. The battery internal resistance changes as its charge condition changes. Tail light on or off, turn signals etc. all change the effective resistance of the load.

The PM regulators are voltage regulators, the current increases as the RPMs increase, so it is by definition, unregulated.

and Sundie, "you seem to remember that the current is also regulated?" How could this be when there are no current sensors, shunts etc. to feed some sort of current dependent signal to the regulator?

The regulator in a field excited alternator simple looks at the voltage and adjusts the current to the field (rotor) to maintain the desired voltage up to the limit of the currant capability of the alternator. Beyond that, the voltage will decline as the load increases.

In a PM alternator regulator, the regulator shunts the excess current to ground to maintain the set voltage, so as the alternator produces more current with higher RPM's, more of the current is simply converted to heat. It's not regulated. It's wasted.

 

[81-650chopper]

Why would you wanna cruise along at 2000-2500 rpm's and waste gas instead of 1000-1500 puts less effort on the motor, less heat build up, and more fuel efficient. Name 1 other bike that cruises along at 30 mph @ 2500 rpm's?????

 

[inxs]

Name 1 other bike that cruises along at 30 mph @ 2500 rpm's?????

- my SR500 and in fact many of my old brit thumpers

 

[pamcopete]

81-chopper,

Running in a gear higher than the optimum does not produce less heat. It produces more heat and puts a real strain on the drive train. It can also induce preignition and does not result in better gas mileage. The term for this operation is "lugging".

The problem is the heat created by the burning fuel is not being exhausted fast enough and replaced by cool intake air. The hot gasses transmit more heat to the valves heating them up. The end result is that it's hard on the valves.

It's also hard on the bushings and crank because they take a beating. At low rpm the burnt gas expands, but has no place to go.

Think about riding a ten speed up a hill in a higher gear than you need. You get hot, but most of the generated heat is just wasted.

 

[81-650chopper]

Well duh!!!! I'm not an idiot!!!! Maybe my bike is geared just right. I'm not talking about cruising at 30 in 5th gear I usually cruise 30-35 in 4th gear turning 1000-1200 rpm's and no I'm not lugging! With just a little crack of the throttle and I'm right up to 40-45 no problem! Oh believe me I've rode next to some "stock" bikes twisting 3000 rpm's at 30-40 mph. I just laugh and wanna yell "shift buddy shift" I think some people need a shift light on their bikes! Lol. I build my own motors for either my drag car, or circle track car. I build motors for friends anything from stock motors to mud trucks, high performance anything so I know what is loading the motor and what's not. And my bike at 30-35 and 1000-1200 rpm's isn't any effort. No offence but maybe if they rider is 250+ lbs but not with my 160 lb ass. And not all motors are equal. They may all be built the same but every single motor is different. Example, I built 3 circle track motors exactly the same. One for me and two buddies. Exact same parts everything. All produced equal hp + torque but once on the track all motors were in identical cars set up the same. But no matter who the drivers were in what car. One motor always out performed the other 2 putting down much noticable faster lap times. we don't know why and nobody does. So just cuz your bike will lugg doesn't mean mine does. Like I've said before I don't know why but mine is very fast!!! I will pull away from any stock 88 or 91 inch Harley. I even hang with 1300 Honda VTX's. I've also took off next to 2 diff other XS's and I left them in the dust!!!!! Very proud of the performance of this bike just not completely satisfied with the unreliability of my charging system!

 

[pamcopete]

81-chopper,

Well, to each his own, but I always stay above 2,000 RPM except when starting out in first gear. I can also see the oil pressure and battery voltage with my gages and the numbers are better above 2,000 RPM. Maybe it's just a comfort thing....

 

[retiredgentleman]

Wow, nothing like a good healthy discussion.

If you like a PM alternator, and it works on your bike, then enjoy it. The stock alternator works just fine...............give it a little maintenance once in a while.

I have to agree with Pamcopete, running much below 2000 RPM (except in first gear) will eventually damage these engines.

 

[81-650chopper]

How does running in 1st gear make any more difference than any other gear at under 2000 rpm's? Let's say your riding down a flat road, no traffic, no wind, just a steady speed, at 1500 rpm's, the bike isn't lugging or struggling to maintain speed because once your at a certain speed it takes very little to maintain it. Unless of course you have brake drag or some other sort of resistance. Why does it matter what gear your in the motor is in? It's still doing 1500 rpm's.

 

[pamcopete]

81-650chopper,

If you regularly run your engine cruising at 1,000 - 1,200 RPM, then that may explain why you are unhappy with the charging system. Not much happens with the charging system until 2,000 RPM and above.

 

[xstwin]

From charging system to this,I think cabin fever has melted everyone's brain. You guys keep on lugging I"m gonna go build an engine for my latest project and 81-chop just get a PMA setup and you"ll be fine,if u want pm me with any questions about one please do or go to the 650 garage there"s a bunch of stuff on pma"s over there.