V-Star 1100 charge voltage w/o tachometer

[wellsc1]

How does one test the charging voltage without a tachometer to know when the engine is at 5000 rpms? I don't have a tach to hook up inline with the rear spark plug wire.

I'm thinking about just testing the voltage while revving up the engine high enough to feel good about it. At least I can see if any voltage is coming out of the rectifier.

I was driving home at night when the speedometer began jumping around with dim headlights and driving lights. Switching to high beams (one light now), it quit jumping, but only for a while. Then back on dims it was at zero. By the time I got home speedo zeroed on high beams also. Before that I was wondering if the headlights were a bit dim. Arriving home, I tried to restart but battery would not even honk the horn.

I'm charging the battery to start up the bike and test charging system, but will have to guess at 5000 rpms.

Any suggestions?

[Motorcycle Forum]

[Easy Rider]

I'm charging the battery to start up the bike and test charging system, but will have to guess at 5000 rpms.

Any suggestions?

Yes. Guess at it and don't obsess !!

At the very least it sounds like you are going to need a new battery.......soon.

Depending on the exact condition of the "old" battery, it can sometimes throw your charging system test off.....if you are simply measuring the voltage across the battery.

[mas3386]

I would go with testing the charging system first, and find a manual on it to help you out. You probably don't need a new battery, but you can charge it up and have someone check it for you. ER, just because the battery is dead, doesn't mean you have to get a new one. The charging system could have failed or been on its way to failing, so it was just running off of the battery. Then, he might of had just enough juice to get home. I have seen it before where guages will turn off, but the engine will keep on going, but usually not for long

[Easy Rider]

ER, just because the battery is dead, doesn't mean you have to get a new one.

That is true BUT regardless of the reason, a battery that has been in service for a while.....like 2 years or more....that is allowed to go REALLY dead just once has likely lost a significant portion of it's capacity. This is especially true in the case of a failed charging system which may have left the battery not fully charged for a LONG time.

You don't HAVE to get a new one, and if money is really tight, I probably wouldn't......but the odds are really good that you WILL have to fairly soon.

AND unless and until you get the old battery fully charged and load tested, it is NOT A GOOD IDEA to test the charging system with an old battery in place whose condition is largely unknown. You could end up forking out hundreds of dollars on charging system parts when the real problem is a shorted cell or two in the battery giving you low readings even when the charging system is working to the max.

I have been at this electronic "stuff" for a LONG time and those are just two of the many lessons I have learned the HARD way......and were later confirmed by folks who have been at it even longer.

Of course, you don't have to take my word for it. Do as you please.

[mas3386]

i've seen many batteries go for 5 or more years, so 2 years really isn't that long. If you charge a battery up, and then see whats it reading for a voltage, it should read close to 12.6v. Might be a tad lower if it's an older battery. If it does have a shorted cell, your going to know it right away when you check the voltage. So if you would of checked the battery first, you wouldn't be forking out the money for the charging system. That's why its called testing. It's just that simple. Maybe, you shouldn't tell everybody they need a new battery.

[Easy Rider]

Maybe, you shouldn't tell everybody they need a new battery.

OK, I see that only one thing will end this "discussion":

I am wrong and you are absolutely right.

There, does that make you feel better ???

P.S. A simple voltage reading of 12.6 tells you virtually nothing about the ability of the battery to provide sufficient current to do it's job..............oops, I forgot, I know nothing about batteries. Sorry.

[wellsc1]

All,

Thanks for the input. It's all valued toward making an informed decision. I charged the battery, then watched it slowly drop in voltage as it set for a while. It never reached 12.8 volts like the manual says.

I tested the charging system also. It provided 14 volts or higher before revving up engine very high. Yep, I guessed at revs, but never took it close to what sounded like 5000 rpms.

Took battery in for load test. It slowly dropped in voltage immediately upon initiating test. While it may have worked a while longer in the bike. The few dollars saved stretching it beyond the approx. 5-yr. life wasn't worth getting stranded on the road, ruining an enjoyable ride. It got a new sealed, lead acid battery. I take same philosophy with boat battery. Walking back to shore is not possible to get help, and traffic on the water is not like on the road.

Again, thanks for the advise...wellsc1

[mas3386]

at least you had it tested first. The last thing you want to do is to throw parts at a problem