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Rectifier problems

Posted: Wed Jul 27, 2016 6:52 am
by slyngej
Hi
I have upgraded the diode regulator system on my /5 to a combined rectifer/regulator unit from Motoren Israel. I have had a few charging problems. I thought i was due to bad battery and old wires, ive went through all these, but today i tested the rectifier/regulator unit. I tested the continuity and resistance over the phase wires and the positive red wire. The continuity was 203 in two of the phases while only 139 in the last. The resistance was 100 ohm in the two phases and 70 ohm in the phase with low continuity. The rotor resistance was 7 ohm resistance. I bought a new stator with phase resistance of 0.55 on all phases.
When the bike is running at idle, the output is jumping around between 9 and 12.5 volts, so i think its the rectifier/regulator unit which is fault. What do you guys think?
I needs to run above 2100 rpm to charge, and to get a steady 14.3 output.

Re: Rectifier problems

Posted: Wed Jul 27, 2016 7:33 am
by Gibson
Could be a bad cell in the battery. I don,t think you should not be seeing 9V even with engine off. How old is the battery?

Re: Rectifier problems

Posted: Wed Jul 27, 2016 9:43 am
by slyngej
The battery runs flat with because of the bad charging, Its <1 year old. With a newly charged battery, it slowly drains, unless running more than 2000 rpm. But could the variation of the outout volts be due to different continuity of the phases?

Re: Rectifier problems

Posted: Wed Jul 27, 2016 10:44 am
by jagarra
If you have the original system, it may be worth while to install that unit again. Reaching charging voltage at that high of RPM may indicate problems with new rectifier/regulator unit. Just out of curiosity, how many wires does the new unit have, 2 input, 2 output?

Re: Rectifier problems

Posted: Wed Jul 27, 2016 5:57 pm
by slyngej
Its described here in the installation guide: http://www.motoren-israel.com/Shop/Engi ... hic1945cq6

Theres the 3 phases and the DF wires to the stator.
From the rectifier unit, theres the positive wire, directly to the starter moter/battery.
There a ground, which i have connected with three seperate nuts.
And then theres the wire going to the starter relay, going to the battery charge bulb.
So theres no D- or Y wires from the stator.
Im using a new stator, from the same producer, fitting the rectifier unit.

Ive mailed with the seller of the unit, they have described a adjustment screw on the unit. I have adjusted so the charging starts a bit lower rpm, but still not passing 11 at idle (900-1100 rpm). If the unit is adjusted lower, the max output passes 15 volt...

But the continuity and resistance should be the same over all three phases right??

Re: Rectifier problems

Posted: Thu Jul 28, 2016 11:17 am
by slyngej
Can anyone recommend an other rectifier unit? Ive considered the enduralast or a electrosport ESR450?

Re: Rectifier problems

Posted: Thu Jul 28, 2016 6:47 pm
by pat76r90
I used this ( I think) in my 76 r90/6
http://www.thunderchild-design.com/diodead.html


Worked good, actually looks like the rectifier/diode trio from an old Delco alternator, on a custom board. I was happy with it.

Re: Rectifier problems

Posted: Wed Aug 03, 2016 5:35 pm
by mattcfish
MI sells good quality stuff. Strange though, that they recommend mounting the Reg./ Rect. under the front cover.
They need to be kept cool,...that location can be a very hot place. Lots of chat on the Ducati forums about RR failures because there wasn't enough airflow on some of the stock configurations.
Warranty?