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Are these normal voltages while riding?

4K views 24 replies 11 participants last post by  smokeyfish 
#1 ·
I finally got my voltmeter working again today and wanted to test another thing that I had repaired. I had worn my 10 yr old battery down flipping the bike on while not starting it during trouble shooting and it was at about 77% charge per my smart charger. I didn't wait for it to charge fully but took a ride and while on the highway at 83 mph my voltage slowly dropped to 11.8 volts. When I slowed down to 50 the volts went back up to 12.8. Nearing my friends house and going 30 it went up to 13.5.
On the way home I was doing 85 and it went down to 11.8 again. Thought it might have something with the cruise control so I shut it off. That made no difference. Slowed to 70 mph and voltage went up to 12.4. Slowed to 60 and volts went up to 13.3. Went 50 in a gear where revs were 4000 like at 80 but volts didn't really lower. Got home and sitting in the drive way I revved the engine to 4000 a couple of times and volts went to 14.2.
Turned it off and put the smart charger on it to see the percentage to see if the battery was charged up by my charging system. In 65 miles it had gone from 77% to 90%. I am not running any auxiliary lights or aftermarket bulbs. I have a power source that was switched off and the cruise made no difference whether it was on or off.
I do plan on getting a new battery too.
Normal? Thought volts should go up the higher the revs.

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#8 ·
Stock, 2001

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#4 ·
BUT. i recently had an odd experience similar in some way to this. I found voltage was dropping off at high revs. I ended up connecting the output of the RR directly to the battery because i figured that something in the loom was causing the problem. Hasn't glitched since. You might want to consider that ... it's easy to do and cheaper than a new battery.
 
#7 ·
Easy? How so? I am not real good with that. Someone points me in the right direction and I can go do it. Just snipped and soldered in 4 wires as I put in new divider on the cruise control. But Beestoy pointed me in the right direction!

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#6 ·
It is a cheap Ebay voltmeter. I also have it connected to keyed power going to the fan relay. It is mounted on the left black fill panel just to the left of the tank. I also found out that when in town going slowly or sitting at a light it heats up and quits working. As soon as I take off from the light and air flows by to cool it, it starts working again.

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#14 ·
So do I after it heated up and quit working then cooled down and started workingagain. Do you have a link to the one you put in the upper left part of your dash? I loved how that looked sitting there.

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#15 ·
Man
It's been so long since I picked those up. I'll have to see what I can find. I bought 3 of them originally for each of our BB here. I can't find the other 2 right now I'll do some searching when I get back and see what i can find out. I bought them off of Ebay. They were a 3 wire DC miniature meter in green.
 
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#17 · (Edited)
:hmm:........ where did I read the post about old batteries not accepting a full charge after a few years and eventually cooking the RR/alternator coils....... I think it was posted way back in 2006.......

Are you sure your 10yo battery isn't the problem? I have never got more than 4 years out of any battery with regular use (I also have never had to replace a RR, but my alternator coil did fail at 73,000kms and I had it rewound with heavier wire).

Have a look on the technical thread...... it was a very informative article....... if you run a standard AGM battery then it's got to be knackered now..... probably only accepting 30% of it's capacity. The RR will be working overtime to dump excess volts out as heat.

If you have an Odessey or similar super battery, then maybe it is still ok........ do you have access to a battery load tester to check your old battery?

Might be cheaper to just slip a new AGM in before you burn up a Reg Rect or alternator (which might also be failing due to the ancient battery or oil contamination etc etc).

PS The only way for you to test your battery is to put your voltmeter across the terminals and test the 'cold cranking volts' on 1st start (after battery left off a charger for 12hrs minimum). If the meter reads under 9.5v while cranking the motor....... that battery is toast.

It's no good just testing the standing volts as batteries are tricksters..... but a fresh battery will have above 13v standing...... and your charging system should be pumping 14.5v in on fast idle. I've had mates tell me "oh the battery is ok, it reads 12.4vs but the bike won't start"...... when i turn up with an old battery that is still ok, the bike jumps into life........ trickery eh?
 
#18 ·
Ok, new LiFePO scorpion stinger battery ordered. After running for long enough to charge the battery the suspect meter is saying that the battery voltage is 11.8 prior to start and goes down to 7.4 when cranking. Battery was 10 yrs old so I got a new one and plan on finding a better quality meter and putting it somewhere on the dash. This one is blue and I cannot see it during bright sun. If anyone has a source for a compact voltmeter please post it up!!

Guy

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#19 ·
My battery just showed up on the front porch! Will put it in tonight... if nothing else comes up.

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#20 ·
I just replaced Stator to RR with connections after the team here schooled me through the troubleshooting. Melted connections and burned up Stator. With my voltmeter on the dash it's now hanging at 13.7 majority of the time. After losing some faith its once again feeling bulletproof! hope its just your batt!
 
#21 ·
The voltage was going lower and I never got the chance to replace the battery. I was chasing an electrical gremlin on the daughter's Rebel. Found and fixed it. But the battery on the XX is dead. Was going to replace the battery and the rear tire on the XX but the son had a mishap with my tractor and I have to repair a section of fence now instead. Will let you guys know what the results are. My 10 yr old battery is a X2POWER sold at batteries Plus. They said that that battery is now sold under the Duracell name. Just in case you're wondering.

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#22 ·
Well, finally got around to replacing the battery. Here are pics of my new LiFePO battery. I like these Scorpions and have had no bad experiences with them. The one in my ST1300 sat all winter and fired the bike right up as if I had ridden it yesterday instead of 4 months ago. Had to vacuum out the battery compartment as a mouse had stored a bunch of mouse/rat poison I had put around the corners of the garage. Put the spacers on the bottom of the new battery and slid it in and the fit was very, very good. Plan on changing the tire tonight. Then will start doing diagnostics on the charging system as you guys suggested. This is my 3rd scorpion lithium ion battery plus 1 shorai for the Rebel. Really like them and for around $140 from battery-stuff.com don't see why I should buy a good quality lead acid battery for the same price or a little less. I took some ear plugs and cut off the ends then put them inside the battery terminals then depressed the foam and placed the battery nut on top. This holds the nut in place and makes it easy to attach the bolt with a few extra leads connected for heated clothing or other things.


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#23 ·
Got the tire changed and fired up the bike and put a voltmeter on it. Voltage drops from 13.4 to 11.9 or slightly higher on start then back to 13.4 at idle. Rev it to 2000 rpm and voltage climbs to 14.2. Bike was charging just fine. Went for a ride and the voltages are fine. Old battery must have been the problem.

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#24 ·
Ok it is still at higher revs cruising around 70 mph or higher it is dropping down to just above 12. Will be figuring out the best way of hooking up a voltmeter and going for a ride.

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