Topic: Testing the Charging system?

[noelocol]

Hey Gents,

Im sure that that this topic has been brought up in the past but I cant seem to find it in the search.
If anyone could point me to a thread Id greatly appreciate it!!

Anyhow here's my question:

Facts:
- 75 cb550f
- new wet Battery (Interstate 12N12A-4A-1)
- Fully charged on the trickle charger/maintainer at 13.2v & stablizes at 12.6v
- Battery drains after a few weeks to 11.5v after a few rides.

I suspect that that my charging system (regulator/rectifier), is not charging the battery as it should
I understand the very basics: - Rectifier converts AC to DC & Regulator maintains a constant voltage level by comparing the the actual voltage output to some internal fixed reference then adjusts.

My question, how do I test which piece is not working properly to determine what I should replace?

I also know that our bikes are known to have weak charging systems. Has anyone built their own regulator/rectifier from aftermarket components to replace or compensate for the old weak charging technology?

Ive included a pic of the tester that I have.

Sorry for the noobie question and any help would be greatly appreciated!

[OldSchool_IsCool]

Use your meter to measure battery voltage at the following engine RPMs:

- engine off, key off
- idle (1000 to 1500 RPM)
- 2500 RPM
- 3500 to 4000 RPM
- 5000+ RPM

Report results back here.

[Frankenkit]

google oregonmotorcycleparts.com for new reg/rect units if you need one...

[TwoTired]

Very good position statement, noel.  You are well positioned for successful outcome.
Oldschool's requested data is what I'd seek as well.

The 550's charging system can output 150 watts at 5000 RPM.  At idle its only about 50 Watts.

However, whenever the key switch is on, the bike uses about 110-120 watts, stock bike.   If you have coils and/or Headlight "upgrades", the base power consumption goes up.

Might be informative to repeat the Batt voltage vs/ RPM test with the headlight fuse removed.

Cheers,

[noelocol]

Use your meter to measure battery voltage at the following engine RPMs:

- engine off, key off
- idle (1000 to 1500 RPM)
- 2500 RPM
- 3500 to 4000 RPM
- 5000+ RPM

Report results back here.

Thanks guys... Here's the results:
I wired up a headlight & lights kill switch so it was easy to test the with the lights on & off:

Headlight Off
- engine off, key off = 13v
- idle (1000 to 1500 RPM) = 12.5v
- 2500 RPM = 13.2v
- 3500 to 4000 RPM = 13.8v
- 5000+ RPM =14v

Headlight ON:
- idle (1000 to 1500 RPM) = 12.1v
- 2500 RPM = 12.7v
- 3500 to 4000 RPM = 12.6v
- 5000+ RPM = 13v

So what do you guys think?

[martino1972]

i think that not bad...
charging system seems to work fine....
from what ive read here,the 550's run a fine line between charging or draining the battery..
make sure you keep the rpm's up high enough,don't bog the engine to low rpm's when your riding..
unless your in slow traffic of cource,dont wanne overheat the engine...
slow city driving will drain your battery,and fast highway driving should charge her back up,with a healthy battery you should be fine....just make that baby scream here and there,its a sohc,they love that..

[TwoTired]

Looks like your charging system is working as expected.

And, from the looks of it, you now know that when the engine is operating below 2500 RPM, your battery is draining.

I suspect you simply need to spend more of your operational time above that speed.
If you can't, then you either need to charge the battery more frequently when parked, or make changes to the bike to lessen its electrical load.

Cheers,

[noelocol]

THanks guys... Good to know that everythings OK.
What else can I do to ease the electrical load when riding in the city.
Like I mentioned, Ive already put a kill switch for the headlight so I can ride around with it off during the day.
I'll disconnect the turn buzzer. Anything else?

[martino1972]

i'm not sure if you wanne turn off your headlight...the better they see you the longer you will live..
you could go to some led lights for signal and/or brake lights,theres some good posts about that here..
but i dont think you need it..

[WFO]

THanks guys... Good to know that everythings OK.
What else can I do to ease the electrical load when riding in the city.
Like I mentioned, Ive already put a kill switch for the headlight so I can ride around with it off during the day.
I'll disconnect the turn buzzer. Anything else?

I have a kill switch on my headlight that helps a whole lot in keeping the battery charged.

[TwoTired]

Does your bike have stock electrical components?

[noelocol]

Does your bike have stock electrical components?

Bone stock..except the kill switches to the headlight & running lights!!

[WFO]

Does your bike have stock electrical components?

Bone stock..except the kill switches to the headlight & running lights!!

Mines kills just the headlight not the running lights.

[noelocol]

Does your bike have stock electrical components?

Bone stock..except the kill switches to the headlight & running lights!!

Mines kills just the headlight not the running lights.

yep...
I got a kill switch for each: the 2 red Missile switches between the bar mounts

[TwoTired]

Ok.  Then it is quite possible the all the interconnects and switch contacts have gained resistance.  There are hundreds.  The entire electrical system then becomes less efficient.  The math work like this.
Say the are 100 connections and contacts, and each one gains 0.1 ohm resistance since the day it was put together.  Further, lets say the average circuit current through these connections is 2 amps.

100 times 0.1 ohms is 10 ohms.  Passing 2 amps current through 10 ohms dissipates 40 watts as heat distributed throughout the wiring in the bike.  This lost wattage comes right from the alternator and cheats the battery from getting the charge currents it deserves.  Now the resistance may not have increased that much and the average current may not be that high in all the connections.  Still, if you send 10 watts away as heat, your alternator then behaves as a 140 watt device rather than the 150 watts it ought to have available for system use.

Cheers,

[OldSchool_IsCool]

I think what Lloyd is saying is it may be worth your time to go through your wiring harness and clean up the connectors so that any resistance due to corrosion is reduced.  Repack the connection with dielectric grease to slow the corrosion process such that your grandkids will be the next to clean the contacts.

The biggest load on the electrical system are coils and lighting.  Check your headlight, tail light, brake light and turn signal bulbs to make sure they are stock parts.  An uninformed repair tech can easily substitute a higher wattage bulb by mistake.

To check your coils, open up your points cover (points, right? you did say bone stock settup).  With the key off, slip a piece of electrical tape or plastic between the points to make sure they aren't making contact.  Now, with your ohm meter, measure the resistance between the blue wire and ground.  Then measure the resistance between the yellow wire and ground.  Do you get close to 5 ohms?  If you get less, then your coils aren't stock or they may have some internal damage dropping their resistance and efficiency.

[TwoTired]

I'm sorry to inform, Oldschool.   But, the coil check procedure is wrong to obtain the data you specify.

The points provide a ground for the coil primary.  The other end of the primary is attached to the Battery POS terminal after some switches.
If you want to check the coil primary resistance, measure between the blue or yellow and the black/white wires of the coil.  You can insert an insulator between point contact to keep bike grounds from interfering with measurements.  However, both the coil leads have connectors which allow isolated disconnection and testing without external interference or involvement of the points.

Cheers,

[tom8Toe]

I'm bumping so I can keep track of this post as I'm also having an issue with my 400/4. After replacing the regulator, rectifier, stator unit, and complete wiring harness, +/- battery cables & fuse box, I still haven't been able to rid my bike of this ghost.

[OldSchool_IsCool]

Learn something new every day!  Thanks for the correction Lloyd.