JS550 not charging battery - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

jleuck64 · 10-07-2009, 12:44 PM

Hello,
I am hoping some of you could lend me a hand figuring out why my son's JS550 won't charge the battery. Starts and runs fine until the battery voltage drops to low. I have checked the coil resistance as per the manual and those readings compare to the specs. I also have checked the AC voltage coming out of the coils with the engine running as per the manual. The highest value I could measure was 1 volt AC while reving the engine. The Manual suggests this may be due to the magnets in the flywheel becoming weaker and I just wanted to run this by you guys for a second oppinion before I start looking for another flywheel... If I am missing something on checking this out please let me know.
Thanks in advance,
J

prickofmisery · 10-08-2009, 01:40 AM

Ohm the charge coil wires back all the way to ebox and insure a path back to battery.

OL JS Rider · 10-09-2009, 01:32 AM

I doubt that the flywheel magnets have weakened to the point that it will not charge. I think you have a broken wire at the stater coil. It prob touches enough to pass resistance checks but becomes detached while running. Thats my guess!

LASERMAN · 10-09-2009, 10:47 AM

There are two coils behind the flywheel. One supplies the timing\voltage for the spark, and the other supplies the voltage to charge the battery.

You say it runs until the voltage gets too low -

It should run all day, even with a dead battery. the starter would quit, but the battery is not used for "running" the engine. The battery is only used for the starter.

The above statements apply to a stock configuration.

There is an aftermarket flywheel system known as a "total loss" system.

It doesn't charge the battery at all. The advantage of this is a much lighter flywheel, which gives increased performance.

So if you are sure you have the stock system, then it is probably the coil under the flywheel.

It could also be the voltage regulator. That is a small metal box inside the electrical box. It is in charge of regulating the voltage to the battery.

One thing I recommend to everyone who has these old JS skis, is to run nice thick ground straps between the engine and the electrical box, and from the electrical box to the neg terminal on the battery.

These skis were built using a tiny wire to provide ground for the system. I had a lot of electrical issues until I did this. I haven't lost a component since!

OL JS Rider is correct about a coil sometimes passing a resistance test but failing under operation.

jleuck64 · 10-09-2009, 09:31 PM

Yea, it would run for a couple of days during our camping trip this summer until the battery was too weak to start it. That was probably due to the starter motor pulling the battery down not the ignition, I understand that now thanks.

I ohmmed out the charge coils at the eBox as suggested:
Gr - Gr = 2.1 ohm
Gr - Blk = 1.2 ohm and on the other G - Blk it would read 2.2 ohm ( would think those readings should be closer to the same?)

I agree 100% that an ohm test is not the same as a live circuit under load. think I will pull the cover off the flywheel and inspect the connections down there. Tell ya what I find when I get the chance.

Thanks for the input!

jleuck64 · 10-31-2009, 12:30 AM

So I had some time tonight to dig a little deeper into my charging system problem. When I removed the flywheel cover it was pretty obvious the o-ring had been damaged previously. It's been letting moisture inside for quite some time now...

I also noticed the charging coil windings were loose around the core. My ohmmeter readings would jump all over the place when I wiggled the coil windings. I also found one wire on the windings were just hanging on by a thread (literally!) to the ground terminal, looks like the solder joint failed.

Any one have a good used charging coil they would be willing to sell to me?

Besides obviously cleaning up everything, is there anything else I should take care of while I have the front cover off?

Thanks for the replies, I have really appreciated your help on this one.

OL JS Rider · 10-31-2009, 01:26 AM

I would hit ebay there are a couple on there. look under ebay motors, parts and acess., personal watercraft, kawasaki jet ski 550. beware! you will be here alot! It is addicting.