96 gsx 787cc battery issue

[DerekI]

I’m having quite the issue with my 96 GSX. I changed the stator and voltage regulator. Had 13.9v on the battery. last year I went thru 4 batteries. They kept only charging to 6volts after running on the seadoo for a bit. Now with the new stator and rectifier I’m back at 6volts again. And the rectifier is blown as I have conductivity between 1 yellow ac and red DC charge circuit. When it was clear when I got it. Is the mpem the cause and I've had no blown fuses??? Please any advice would be appreciated. Seems I'm the only 1 to have had this issue. Can't find any related articles

 

[soccerdad]

I can't help on that one. But the 96 GSX does have an odd issue where it keeps some stuff energized all the time and drains the battery much faster than my GTX of the same year. I have heard some putting a small disconnect on the battery to keep that from happening. So if the voltage is low after sitting, that may be it.

 

[DerekI]

I can't help on that one. But the 96 GSX does have an odd issue where it keeps some stuff energized all the time and drains the battery much faster than my GTX of the same year. I have heard some putting a small disconnect on the battery to keep that from happening. So if the voltage is low after sitting, that may be it.

It's blowing the batteries. Once the cells are cracked I can't get it to charge past 6 volts it's seems the cause is before the rectifier.

 

[jjsinaz]

Have you been jumping the battery with a running vehicle? That will destroy rectifiers and MPEMs. The fact that you say you have continuity between one of the yellow leads and the red one would definitely indicate a bad rectifier. Do you have any additional added on items like a stereo, lights, etc that would be placing additional load on the charging system? These charging systems are designed to keep the battery charged and ignition system powered up and that's about it. Another thing I think I would check is to make sure you don;t have any of the yellow leads coming from the stator shorted to ground. Sorry If I am telling you things you might already know. Just doing some thinking out loud. This is an odd problem.

 

[DerekI]

No to the jumping and yes it's bad I know. I've read the schematic the red goes to the mpem. So I'm thinking something in the mpem that sends a charge to the battery is sending ac current vs DC which it needs to charge. The mpem is working as far as I can tell except with the battery failing? Ive replaced the stator and checked and double checked to ground. I appreciate your comment. You think I'm on right path with mpem? I can get 1 with a rectifier for 175$ which isn't bad but f if it's something else idk

 

[jjsinaz]

I really don't think the MPEM has anything to do with the charging, other than a holder for the 15A fuse. The red wire connects to the one side of the 15A fuse and the Red/Blue wire connects to the other side and then runs back to the rear Ebox and connects to the 15A fuse back there, which is how it charges the battery. I think you might be off base replacing the MPEM. Did you check both of those 15A fuses to be sure they aren't blown?

Another thing, is the VTS working? After you replace the rectifier, try pulling the 7.5A fuse for the VTS and see if the problem clears up

 

[Kris69]

Is it an aftermarket or genuine Seadoo regulator? Aftermarket regs are dodgy. From experience, I bought 2 for my GTI LE RFI and wouldn't charge high enough. Bit the Bullet and went genuine and no drama since.
If your batteries are cracking etc, it's being overcharged to the point of boiling the cells, shorting them internally. That's why you're only getting 6volts.

 

[DerekI]

Well I have an oe mpem and rectifier on the way. I hear what your saying but honestly I took it out the water last year. Maybe 20 min running. It was brand new. Brought the seadoo home and stored it and charged it all winter held a charge. Started the seadoo twice last week after all repairs maybe ran it 15 min max in total. Was gonna put in water so I put the charger on it. Got a fault on the charger and checked the battery for voltage and I was at 6 volts. Really at a loss other than something in the mpem failing the rectifier and battery. Unless it overcharged it within the 15 min. Fuses are OK and all looks good when battery has 12+ volts

 

[DerekI]

If I pull the 15 amp fuse in the rear will the seadoo work just not charge the battery? Basically by pass the charger and plug in the doo after riding.

 

[DerekI]

Turns out that the mpem and rectifier are fine. The 800 is constantly looking for the key and draining the battery and of course my trickle charger is messed up and won't charge past 6 volts. I installed a battery disconnect and now pull it after each use as the seadoo is keeping the battery charged while riding

 

[soccerdad]

Unplugging the connector from the top of the rear electrical box also disconnects the power to the MPEM. No extra disconnect needed.

 

[DerekI]

Unplugging the connector from the top of the rear electrical box also disconnects the power to the MPEM. No extra disconnect needed.

I got the 1 with a key so gives me a little more protection while it sits in the water all year. Thanks