Electrical Drain

EskimoPie

Supercharged
Joined
Dec 1, 2020
Messages
439
Location
Sahuarita, AZ
Ride
2021 Rocket 3 GT
I had a post a little while back wondering if I had a bad starter or a bad connection somewhere due to my bike being unwilling to crank the starter. I picked up a bluetooth battery monitor that you leave connected to the battery and it keeps an eye on your battery and reports to your phone. On a fully charged battery measuring 12.9V as soon as I turn the ignition on (and not the starter), voltage starts rapidly decaying and stabilizes at ~12.4V. When I hit the starter from there the bike does start but the monitor reports the voltage dipping as low as 9.4V during the crank.

Any thoughts on what this might be? It can't be a bad connection to the starter as the voltage decays just when the ignition is switched on. Seems like I have a short somewhere. It just doesn't make sense to me though as any short able to drag a fully charged battery down to 12.4V would be making some really hot wires I'd assume.

 
It is not uncommon for a battery to drop a few tenths when ignition is turned on.
I think that when it drops to 9.4
So either dirty/loose terminals
bad batter
Starter drawing to many amps
I have an amp gauge if you would like to borrow it.
Also for test purposes you could jumper from battery to starter solenoid and that would compare going directly versus going through the starter relay but probably not this.
Check battery terminals first.
Hth herman
 
, mine does this after 6 years. This is new 2500 battery YTX12-24 Hi-Power Lithium Battery the new rockets use a different battery than the old models. Yours dropping to 9.4v tells me if its not what turbo suggests then the battery is just not heathy, dead cell possible, and top loading meaning bike thinks battery is full when charging but battery actually doesn’t fully charge. When youre running what are the voltages doing at idle and at 3000rpm ? Batteries gave me fits before i bought the 900 cca beast from antigravity, this winter it was torture tested, outside in a truck for a week in freezing conditions tuning and it did great.
 

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Kevin, my screen shots are from a fully charged battery that was only 4 months old (the OEM AGM Yausa battery). Based off my screen shots I convinced myself (and Revzilla) that the battery wasn't able to source enough current and got a warranty replacement. The new battery behaves in exactly the same way.

I was considering going the Antigravity route but the 900cca batteries are ~6.7" long and the battery box only seems to accommodate a 6.0" battery. Which model do you have and did you put it in a 2020+ Rocket?
 
Brand new battery.
Clean tight terminals.
I don't know how to define what "too many amps" for the starter to draw means. Other than testing another 2020+ rocket and comparing it to mine.
The bike used to instantly blip to life, especially after I moved from premium fuel to mid-grade. Nowadays the bike often likes to crank for a second before it fires. Perhaps it's completely unrelated and I'm making a mountain out of a mole-hill but I'm trying to avoid what happened to be prior by being stranded because the bike wouldn't crank using a battery that was ridden daily and only 4 months old and I now believe to be a perfectly healthy battery because the new battery behaves the same. It just feels to me like something has changed on the bike but I'm struggling to identify what it is.

On a mildly frustrating note, in order to warranty replace the old battery, Revzilla made me cut the battery terminals off and send them a photo. Seems I ruined a perfectly good battery. Oh well.
 
verify with someone else cranking amps, I have this DC amps meter, I can measure cranking amps if that is going to help you but then you would need clamp meter to measure yours(?)

 
If you went antigravity route you would need this one i believe. , let us know what its doing voltage wise at idle and 3000 or so rpm. Ive replaced many powersport batteries on cleaning equipment like floor buffers and such and its a crap shoot, how long was battery on shelf etc, a tool like this gives some good info some have had great results with yuasa, i did not.
 
Last edited:
sunny said:
verify with someone else cranking amps, I have this DC amps meter, I can measure cranking amps if that is going to help you but then you would need clamp meter to measure yours(?)

Click to expand...
yes please measure for the forum, others will come across your post as well and it would be nice for information gathering.
 
as an estiment it takes 1 amps per cubic in like a 350 motor will take 350 amps when it turns/cranks over.
as best as i can remember my 2007 was about 200.
the new r3 have a compression release built into the motor so i would assume it would take less amps to turn it over.
my tester is a simple antolog starter gauge that reads 0 to 600 amps on a bad starter i have seen it go futher and peg the gauge.
it would be nice if the group would give us a few readings so we could establish a normal value.
 
the older i get the worse my memory gets
i think (i may be wrong) that there was a thread where the compression release was messed up on the late rocket and that would increase the amps it draws.
maybe someone can confirm?
 
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