Minimum Voltage Needed To Start Fat Lady?

[Valkorado]

Big Bertha came with a voltmeter that keeps beeping at me and driving me nuts.  It usually reads around 10.5, drops if I turn on aux lights, but so far the bike starts again at gas stations, etc.  I've changed out batteries with the same result.  I'm trickle charging the battery after riding in case it's not getting any charge on the road.  I'm hoping it's a bad voltmeter and not a bad alternator.  I don't have a multimeter (on my wish list).  Would a Valkyrie even start at 10.5 volts or less?  I thought I read they need at least 11.5 or more to start.

[pancho]

Hey Valkorado,, any one can tell you anything, but the only way to get to the bottom of this is to beg, borrow or steal a voltmeter for five minutes and check the voltage across the battery when the bike is running. A cheap voltmeter can be found for under $10 that will work for situations like this, or go to a NAPA auto parts,, they will probably have one you can use to check.

[rhinor61]

Val....

 1) It's not voltage that determines whether you can start the bike, it's the starter's ability to deliver amperage. A volt meter will only give you a rough idea of the state of charge assuming that the battery is known to be in good condition. The volt meter will tell you nothing about the condition of the battery.

2) A known-good battery is "dead" at 12.0 volts and fully charged at 12.6 volts.

3) Depending on the battery condition, the voltage that will allow the engine to turn over changes. A battery with 5 good cells and one bad cell may only read ~10 volts but still be able to turn the starter. A battery with all six cells in good shape that reads 11 volts, however, would almost certainly not be able to spin the starter.

4) Yes, when the bike is running the alternator puts out more than 12.8 volts.

buy a decent DVM... vs a better volt meter for your bike................ and enjoy your ride.


John

[Chrisj CMA]

When I installed my volt meter, I could not get it to read 14 V (or near that) unless it was connected straight to the battery.  You may not have a faulty meter, just less than ideal connections.  Doubt she would start if that reading was accurate.

[Valkorado]

Thanks for the info, guys.

[indybobm]

This has been a problem for Wing riders, you can read about it here: http://goldwingdocs.com/forum/viewtopic.php?t=31554#ixzz3yvOaqp4K.

Basically, The voltage path to the coils have a number of connections that can drop the voltage from 12vdc to a much lower value. If it gets too low, the bike will not fire.
The starter has a relatively straight shot to the battery, the coils not so much.
One solution the Wing guys tried was to install a relay supplying voltage directly from the battery to the  coils. The relay is energized by the original coil wire. This way there is virtually no voltage drop to the coils.
Something to think about.

[Firefighter]

Chrisj cma, I had the same problem, you need to ground your frame to the battery negative. I used a seperate wire and BOOM I have over 14 volta at idle.

[indybobm]

The voltage losses through the wiring and connections is the reason that Bon's Headlight Smart Switch results in a brighter headlight. The same losses affect the firing of the sparkplugs.

[Chrisj CMA]

Chrisj cma, I had the same problem, you need to ground omyour frame to the battery negative. I used a seperate wire and BOOM I have over 14 volta at idle.

I may do this just to ward off future ground issues.  Did you go from battery to frame or engine block ground point to frame?  TIA

[Firefighter]

Battery negative to frame, very short maybe #10 wire, right side I think pin bolt that the side cover attaches to. Will look soon as I can. I had problems of low voltage through the frame as frame ground was not doing it's job. I never found that ground either. Ing. coils and I dont know what all get their ground through the frame not the battery. Caused me to have gauge problems and engine running problems at low speed, the engine starter always worked fine as it has its on ground. Hope it helps you!

[indybobm]

When I installed my volt meter, I could not get it to read 14 V (or near that) unless it was connected straight to the battery.  You may not have a faulty meter, just less than ideal connections.  Doubt she would start if that reading was accurate.

Chris, you might have more than a ground situation. Using a good DVM, put the negative lead on the negative post of the battery. Place the positive lead on the supply line to your voltmeter on he bike. If the DVM still shows less than battery voltage then you have voltage losses through the wiring and connectors.
The losses are due to resistance across the various connections from the battery to whatever is being powered.. Voltage loss due to bad connections generates heat. For example, it is this heat that destroys the red connector on top of the starter relay. Many of us have already been witness to that.

[Firefighter]

When I was checking my problem, the bad ground would come and go while I was riding. I ended up mounting my test meter to the gas tank and and the leads attacked to the battery. The battery voltage remained constant, but the volt gauge would drop a volt or so. Now after repair my frame voltage is the same as my battery voltage.

 Yes Indy,  your voltage read from the positve to battery ground, frame ground or gauge ground should be the same as if you checked it at the battery, if not there is a connection or wire problem.

[MarkT]

As I've said in other threads, just move the battery ground from the back of the engine block to the left side drivers footpeg bracket mount on the frame.  For extra credit add a ground strap between engine & frame.  (I didn't bother on Jade, did add a strap on Deerslayer.  The engine has several contact points to the frame so IMHO the ground strap is redundant.)  I discovered this problem on a road trip when the bike wouldn't start and it took me a while to ID the problem & move the wire with minimal tools.  While cussing out Honda for a stupid problem.  They should have grounded the battery to frame in the first place, and failing that, used a star washer on the aluminum block engine ground.

[MITCHO]

Maybe that chrome cover isn't making a good ground either.                                                                     Sorry Mark I couldn't help my self.