How can I tell if my accessories are too much for charging system?

[BloodMoney]

1999 Road Star
I am installing a Boss MC720 amplifier. It's on a 7.5A fuse. I'm running it through a relay.
How can I test if the amps is pulling too much wattage/ current for stock charging system?

[Duke]

The "99" thru "03" have a 21 amp charging system.

The best way to figure out your power usage is to add all of the watts that is being used, then divide that number by the voltage and that would give you the amps you are using.
I.e., headlight on low beam is 55 watts, tail light with running lights is, (3 lights at 7.5 watts),= 22.5 watts + 55 watts = 77.5 watts -:- 12.8 volts = 6.5 amps.
It's always best not to run the charging at 100%. Most electricians will say to not run over 80% of the system rating. That being said, you shouldn't run over 16.8 amps continuously.

[BloodMoney]

So oem conditions only pull 6.5 amps? My amplifier can't pull more than 7amps. So I should be good?

[Duke]

You are pulling more than 6.5 amps as it was a example of watt to amps. You have to add all electrical devices used.

[Duke]

After 03, I believe the charging systems went to 30 amp.

[BloodMoney]

Also, my tail light, and rear turn signal bulbs are LED.
front signals and headlight are still incandescent.

[BloodMoney]

What about fuel pump current draw?

[BloodMoney]

I plan to. I was looking on Amazon. Haven't picked one yet.

[Mr. Miyagi]

I would stay away from the cheaper ones and get one with good reviews, but even the middle of the road LED headlights seem to be ok.

[Duke]

I would call the fuel pump a 1. amp draw.

[BloodMoney]

What I still haven't been able to determine is how will I know it's too much?
will the lights dim?
Will I smell burning?
Will it run funny?

Does running with too much draw damage the rectifier or just not charge the battery?

[Duke]

Running to much draw on the electrical system can cause failure in the rectifier, and or, the generator.

[Druegeme]

Sweet!

Wireless charger on the bike. just pop the phone in the mount. Love it.

[BloodMoney]

So I should be able to hook the meter in series with the battery and turn on the key. Then enable the amp and do it again.
I don't think the meter will withstand the engine running, but the amp load shouldn't change whether the motor is running or not. I wouldn't think

[davej]

with everything on and rpm at around 1500-2000 how much voltage do you have at the battery? and how much at idle with everything on?

[BloodMoney]

14.1v idling. It didn't really change much when I blipped the throttle. I didn't try to hold it steady, and no tach so it was a guess.


I put the meter in series with the negative battery leads with the key on, engine off.

I got 6.1Amps without the AMPLIFIER on. I turned the amp on and played music. The highest it goes is 7.2Amp with music turned all the way up.

I hooked the battery back and put the meter in place of the FUSE for the AMP. The highest it read was 1.2amp, but mostly stayed around 600mA.

[davej]

imo you are just fine.

[Tcontrol]

this DC clamp on meter is $45.00

bike not running… all accessories on…. Take a reading…
then start bike and hold rpm about 1500-1600… try to be steady…. Take a reading…

beats adding everything up…. And relatively cheap too….

[jd750ace]

A good induction type meter like that is best, because it will show all losses, which math cannot do without making assumptions.

As Dave was getting into, as the current increases toward the capacity limits of the system, the design voltage will begin to fall. The design limit point for the regulator is 14.25 volts. As you see your running current increase, that voltage will drop. Typically a 13.9 to 14.2 indication is good to go. You see your running voltage drop to 13.8 or below, you’re losing capacity to maintain a full charge on the battery.