How to: Fix your Vmax's low voltage or charging problems

[Littleschipper]

Thanks, Fire-medic! That clearly answers the question about my single pickup. I’m disappointed the Clymer manual didn’t mention the difference since the parts diagram shows one pickup and the photo shows two. If I may ask, what is the source of the two different electrical diagrams? After chasing down many electrical car gremlins I can read them.

 

[Fire-medic]

Sorry as to where that was sourced, I cannot recall. For things like that I usually google a specific word group, trying to narrow the search results. Something like '1985 Yamaha VMax wiring diagram' and then sort through the chaff until I find the best rendition. #1 is the colors make it an easy time of it, following leads and trouble-shooting. Blowing it up as big as possible is necessary for my Boomer eyesight.

 

[Fire-medic]

Here's one I got in about a minute using 'search the internet for this image,; by right-clicking on the schematic I sent you in this post. Note that this is the 1985-'89 diagram and the pick-up lead is 5 wires.



The 5 pick-up coil leads:

• black
• red & white
• orange
• green & white
• grey

 

[Littleschipper]

Thank you for explaining how you found it. Filed for future reference. The boomer statement made me laugh. Count me in for that group, not just the eyes but hearing too! Now, if someone can answer the question about the tab?

 

[Littleschipper]

Finally, after an internet search and deep dive in this forum I finally found a reference to the tab in my first photo, labeled ‘1’, and I did have it on the correct screw but on the wrong side. Refer to the photo here of a cover for sale in the parts for sale section where I circled the tab correctly oriented. Many thanks to this forum for providing all the info I need to finish the job!

 

[Nsubs]

I replaced my AGM battery with a lithium battery. Everything works better and no need to keep the bike on a trickle charger. The lithium battery is guaranteed for 3 years. I ran into a fellow VMaxer at a fuel stop in Albuquerque and he saw me waiting for the bike to cool in order for it to start. He recommended the lithium battery and uses them in a Gen1 and Gen2. Expensive, but worth it.

What size lithium did you use?

 

[Dansmaxresto]

Can you give us the exact make and model number?

 

[Fab333]

I use a ssb lithium battery LH9B

 

[brian hicks]

I use Yuasa led acid batteries. I usually get 10 years out of them with no problems.

 

[Dansmaxresto]

My lead acids last about 3 years max

 

[Littleschipper]

What size lithium did you use?

Sorry for missing your question until today. I bought mine from Amazon:

OPTIMA QUAD14 ORANGETOP​

420 Cranking Amps, 7AH​

The battery also uses a unique charging connector so I had to purchase a new battery maintainer for compatibility. It’s also made by Optima, my Battery Tender trickle charger connector will not fit the Optima connector. All together not a cheap package but my experience with lithium batteries over lead acid and gel batteries makes it worth the expense, for me. YMMV…..

 

[brian hicks]

I find that at tick over speed of 1000rpm the battery will drain because the alternator isn't producing enough power to charge the battery plus run the bike. At Higher rpm the charging voltage goes up to 13.1volts DC. and that will put about 1Amp into a fairly low battery and that should be sufficient. A car battery charges at about 13.8volts but it can take a lot more amps than a small battery fitted in a bike. For an output of 13volts DC from the regulator you need at least 13.8volts ac from the alternator because the regulator always drops at least .8 of a volt through the semiconductors.

 

[Dansmaxresto]

Mine was doing the inverse. When I reved it the voltage would drop. But CaptainKyle has it now and he’s going to fix that…along with a whole bunch of other stuff!!!

 

[sparky4123]

I think you might be mistaken on the charging voltage. I believe with the rpm up you should be reading over 14 volts at the battery terminals and possibly as much as 14.4 Volts. A fully charged lead acid battery should read 12.8 at rest with no load.