So, during yesterday's ride, I went to restart my bike and found the battery was completely dead. as is wouldn't light up my led gauge lights dead. bump started bike, all lights came on but flicked constantly. got out of the woods and trailered home.

When I put the battery on charge, the voltage went right to 15v, charger turned off, voltage down to 12, charger on again. ON,OFF,ON constantly. I believe the battery is internally shorted. I checked the output of the bike. 14v @ idle but ONLY 13.4v @ 4000RPM. so... that different. the alternator is making 38v (A/C) at idle and 80v at 4000RPM on all three legs. All three are within resistance specs (0.8 - 0.9 OHMS) but are on the high side. So i believe the Regulator/Rectifier is cooked.

Can Someone with a meter check their voltages at the battery both at idle and at 4000RPM? My gut says 14.4- 14.6 is good and under 14v is bad. R/R are expensive, I would like to be 100% sure before I pull the trigger.

Any testing idea's / instites are welcome.

thanks in advance.

 

I think battery is bad. stator voltages look good. the regulator looks to me like it is probably working, but you can't really test it without a known good battery. get the battery tested first. or at least try this.... measure voltage of the battery, and then measure the voltage while cranking the engine. if it drops more than about 2 volts from what first the reading was, then its bad

my bet is it will drop way down under load, and maybe not even turn the engine. modern chargers kinda suck. really dead batteries fool them.

 

Okay, i guess I forgot this originally.
the original battery is definitely no good. It wont even run a test light for more than a few seconds.

I got the above readings on a known good, full charged battery. I got very similar results with the lights unplugged and plugged in.

Sorry I forgot that bit, you are 100% correct the battery is dead. RIP June 9th 2019

 

charge your your battery and note what it reads after a couple hours (so that the float charge is stabilized). it should be 12.7 or so. then put a modest load on it, like headlights and watch the voltage. it shouldn't drop more than a volt os so in a couple minutes. hard to give exact numbers but that might give an indication

13.4 volts will still charge a 12v battery

 

New battery is working correctly. Retested and found no A/C voltage on the outputs, so that's good. A fully charged battery is 13.6V so I need 13.8V+ to get a full charge. My meter started doing strange things last night, so I'm going to recheck with a good one once more.