Battery issue

[tindale]

mark:

If it makes you feel any better, my bike is down for the count at present. in no particular order it got very hot and started pressuring the engine cases this last week, I figured at the least I had rings gone bad. on teardown I found valve seals leaking, rings gone and a burned valve. It also looks kinda like the headgasket was weeping a bit? lots of dough in parts later I think I will have it up and running in about a week.

Well that sucks Bill, good luck on the rebuild. I am riding tomorrow with Guido and will be testing battery during ride.

[aj_mariner]

Did you already go over this connection under the tank? What is the reading with this unplugged?

55EA5B02-5106-4263-AA9A-FDEE199FBEDC.jpeg (108.31 KiB) Viewed 7493 times

[tindale]

Did you already go over this connection under the tank? What is the reading with this unplugged?

55EA5B02-5106-4263-AA9A-FDEE199FBEDC.jpeg

With that unplugged I am still getting the 30 plus ohm reading . I had a buddy test his 390 RE and he was getting 3.5 ohms and 0.00 when starter button was depressed. So it was behaving the same as mine but with a lower ohm reading. I have seen temperature effect the ohm reading on my bike ( lower reading with a warm bike ) and my buddy is in Arizona while I am in Canada so maybe that is the difference, plus he has an RE which may have less wiring than mine. Anyways it looks like resistance in that cable plus the drop to zero when you push the start button is somewhat normal ?

[aj_mariner]

It’s like putting that 18-22AWG wire directly across the battery terminals. With that plug disconnected and still a low resistance reading, it either means that your short to frame is between there and the plug on the starter relay...or your diode pack is possibly the culprit. Easiest next step is to disconnect your diode pack and check resistance again. Mine is under the air box cover by the subframe leg. It should be the larger 6 prong plug

[tindale]

Okay will check that next.

[tindale]

Rode the bike on Wednesday with new battery, no problems, battery reading 12.86 volts , 13 volts after ride. Checked battery today still reading 12.8 volts. Pulled positive cable to check resistance and reading was 10 ohms, much lower than before. Disconnected diode pack behind battery and ohm reading went to OL . Plugged pack back in and now reading 6 ohms. Not sure what that all means but lower reading is close to what my buddy's bike is reading . Guess I will continue to ride with multimeter and booster in my pack and check often on the trail . I thought I heard or read somewhere about problems with the diodes or was that only with the OI two strokes ?

[aj_mariner]

Cool. Just to be thorough, disconnect and test the diode pack at its plug. One row of 3 black wired connections and another of 3 red wire connections. Test leads should go on the red and black directly above one another. You will see a very high resistance or “OL” with test leads one way, and a very low resistance reversing the test leads (reversing polarity). Test all three diodes. If a diode shows low resistances both ways (straight and reverse polarity) then it is bad.

If all diodes check out ok, then your plug might be the issue

[tindale]

Okay thanks AJ , I will check today. Checked it just now and looks like the charging diode may be the culprit. Red probe on red wire side black probe on black wire side gives ohm reading of 10 ohms at all three , reverse the probes and I get 95 to 100 ohms across all three.

[tindale]

Just an update, since switching to a quality Yuasa battery and changing the diode pack bike has been trouble free now for 110 hours ( 365 total hours ). Pretty confident problem is solved , just not sure if it was crappy batteries or the diode pack but I would bet on the diode pack being the culprit.

[babelfish]

The way the batteries behaved it sound like batteries that shorted inside due to mechanical failure.
But 3-4 batteries sound extreme. Yausa are good but also prone to failure due to G-forces.
LiFe on the other hand, are not. I make my own LiFe packs from 26650 cells. Work great.