does my sprint hate its battery?

[enos]

I bought the bike 3 weeks ago. I had to push start it 10 minutes after buying it, as the battery died.

Anyway, it seems to charge while riding, but occasionally the battery would still go completely flat. I thought this was suspicious, as the PO put in a new battery in February (Interstate Battery, good brand). But I bought a new one anyway (Yuasa).
So far so good, though it's only been a couple days. HOWEVER, when I was putting the new battery in, I borrowed a multimeter and checked the voltage:
12.8 V just sitting there, engine off (good, like a new battery should be)
13.2 V when running at 2000+ rpm. Goes up higher while the rpms are changing, but then it settles on 13.2V no matter how fast the engine is turning.

Can someone please verify what your Sprint does? I have the service manual but I can't find any sort of spec in it. My older bikes would go up to 13.8V, occasionally over 14V. Is my Sprint undercharging?

[dmulc]

I just checked mine and I'm getting similar numbers. I don't have any battery issues.

[enos]

Originally Posted by dmulc

I just checked mine and I'm getting similar numbers. I don't have any battery issues.

Awesome, thanks!
I guess it was the battery, then.

[DaveM]

As a reference;
I have an '04 955 Sprint ST from new, last year I replaced the battery.

I only ride weekends and used to have a Triumph Datatool S3 Alarm on it which was a constant drain on the electrical system. But I never had a starting issue ever in almost 60,000kms.

cheers,
DaveM

[Spodman]

12.8 V just sitting there, engine off (good, like a new battery should be)
13.2 V when running at 2000+ rpm. Goes up higher while the rpms are changing, but then it settles on 13.2V no matter how fast the engine is turning.

I had a battery that seemed normal, other than it only ever needed a small load without charging and it didn't have enuf oof to turn the bike over. Eventually it let me down 200km from home in the rain, just outside a battery shop! The electrician did what I had done and check the charging, and got number simial to yours. Then he turned the headlight on high beam, and the volts went down to 12.9. I ride a lot at night, and leave the lights on in the daytime anyhow so my battery was never getting enuf charge, and it was discharging every time the bike was idling.

I had a bad (as in black & crispy) stator, do a search on charging problems for a popular mod to increase the effectiveness of the system if your stator is good.

[jeffro]

I got the same numbers. Tine thing about the 05+ Sprint is it does all its main charging at 1200 rpm aka Idel. I put a accuman ammmeter on mine. See attach

[jeffrichards1966]

Hi

Once it loses charge, is it then flat or can you start later?

Either way, the alternator and wiring to it could be culprits?

Jeff.