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

Thanks for the Guide.
I cut my RED (pos) R/R wire just below the connection and crimped in a 12 Ga. /30A inline fuse to the + side of the Battery and my Voltage went
from 12.6 - 12.8 @ Idle to 13.5 - 13.6 @ Idle and 13.5 - 13.6 @ 2500 to 14.3 - 14.5 @ 2500.
I was going to direct wire the Black (ground/neg) R/R Wire to the battery but after seeing those Numbers I didn't bother.

I just found the Sticky, thanks for the write up RA. I recently performed the R/R sanding and additional ground per the Vboost artical and had 13.4 volts at idle. Since you have me covered I am going back in for more voltage.

I started with 13.4 volts at all RPM, performed the new ground wire, deleted the stator to R/R connector, and cleaned all grounds Now I am at 13.8 volts. Much better!! Stator checked out i guess this is as ggod as i can get. Thanks again.

I read the post above from RaWarrior regarding "low voltage or charging problems" and I "think" I may be able to do most of it, with no problems. However, I'm not an electrician, and am hoping I won't need to understand it. Now, let me explain......The battery on my 2005 Vmax was at the point that if it didn't start on the 1st few cranks, then the battery was too dead from then on. I placed a charger on the battery and could only get it to charge to 50% after about 8 hours. So, I checked the acid/water level in the cells and all of them were very low, so I purchased some distilled water and filled them up and then attempted the charge cycle again, all to no avail (would only charge to 50%). It was the original liquid lead/acid battery that came with the bike, so it managed to last for about 6 years which is not bad considering the type of battery. So, I went all out and purchased a Panasonic battery (the one recommended on Vmax Outlaw) and also purchased an Odyssey PC680 battery (the one recommended by almost everyone else). Checked each of them new when they arrived at my house with a multimeter and each was just low enough to put a boost charge on them. The Odyssey charged up to a full charge in about 20-30 minutes with no problems. The Panasonic would only charge up to 75% even after leaving it on the charger for almost 12 hours (and it's a brand new battery!!!). So, I think it's a no-brainer which battery I'll be installing in my bike! I'll keep the Panasonic on a battery tender as an emergency backup only. So, why did I write all this? Because after I install the Odyssey in my bike this weekend, and ride it a day or so, I will make all the checks listed in RaWarrior's post to see if all is well, and if not, will attempt the mods he mentioned................but if I run into a brick wall and get stuck, hopefully I will be able to post my problem on here and get someone to steer me in the right direction. In the meantime, thanks for the info............and I sincerely hope I won't need to use it.

6 years is not bad at all for a stock lead acid. The Odyssey cell will probably be the last battery you buy, they're famously durable. Pricey, but a case of you get what you pay for.


The steps I detailed are probably easier than they appear and I wrote it trying to be as explanatory as possible so pretty much anybody could do it. I would have got more pictures, but I did the mods mentioned months before I did the write-up and didn't have the foresight at the time to snap loads of pictures of what your stock setup looks like to point things out. By all means if you have questions let me know I'll be glad to help out either here or on the phone.

Use my general voltage guidelines to see how well your system is working and go from there (why I put that bit first!)

I finally fix my charging issue following ryan how to. Big jump from barely 12.8v to 14+. I just didnt make the check when hot.

Thanks ryan, even I could do it

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Well I seemed to find that my battery was at 38% and would not start the mighty max. I have pulled my battery out not know the age to have it fully charged and load tested to find out if it is any good or not. I do not know the age of the battery it was in the bike when I bought it. It looks new but you never know. After It has been tested and I know the battery is not the issue I will be checking the rest of the system with your guild. And if the battery is the problem, I guess I will be installing a new one.

I must say that RaWarrior's write up was on the money. After testing the everything, it was the R/R that was the mean effing gremlin that was the real root, oh but the little monster got into my wires, After the install of a new R/R it was better but not right. I jumped the ( + ) connection to the battery and same for the ( - ) and at engine 1k we are over just over 13 volts and anything over 2k we are 14.05 volts so all is right in my charging system and all the Gremlin's are dead. And you know what I have more power at the wheel the bike feels a bit stronger. I bet I was not getting full spark power and as the battery was getting killed off while riding. Thanks RaWarrior for the write up.

+1 with that. One of the best mod i did with an immediate result. I don't get stuck because the battery is discharged anymore
Thanks again for the write up.

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Hello all,

I just want to thank you for the sticky, I have been having hot start and low charge issues along time. Replaced the stator and r/r. I did the first part to this, by cutting out the plug and direct r/r to battery, it went from.

Before,
before start 12.6
after start @ idle 12.4 and continued to fall.
2500 rpm no maybe 12.5-12.6
then hot start/well no start.

After
before start 12.6
after start @ idle 13.7
2500 rpm 14.0+
And no hot start problems.

The plug between the stator and r/r was completely melted, I honestly don't know how it worked at all.

rhoke said:

The plug between the stator and r/r was completely melted, I honestly don't know how it worked at all.

Click to expand...

Careful with that - I had the same on mine. I thought I was charging good after replacing my RR (measured fine), but then I started having battery problems. In the end, the stator was fried and needed replacing, I guess the melted plug = a short and did it.

The weird thing was, when I measured AC voltage between the stator wires they all worked, but were actually showing a much higher voltage than they should have done in higher revs (70V+ instead of about 50V)..

If your battery suddenly goes flat you'll know why. Fingers crossed yours is ok!

Thank you for the heads up, I have a new stator and r/r. So I will def keep an eye out for this situation. Fingers Crossed.

rhoke said:

Thank you for the heads up, I have a new stator and r/r. So I will def keep an eye out for this situation. Fingers Crossed.

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Do not wait just do it, It only takes 15 minutes tops to do this. Get yourself a inline fuse 30amp - 2 eyelets and wire them in below the plugs to r/r. It will only make sure that you have a good path to the battery. I used a jumper to tap into R/R wire below the plugs.

Looks like the weak point is the connection from stator to the RR. My end plastic connector was corroded and ended up coming out in pieces before I wired it. I believed fixing the connector was the main fix but i went for a full update. Now no more charging issues so far.

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I did just over 200 miles of riding today and no charging issues at all, lots of power all the way.

Diablotin said:

Looks like the weak point is the connection from stator to the RR.

Click to expand...

These old fashioned (i.e non sealed) connectors tend to be a problem on any older bike. The stator/RR connector was melty on my '85 Magna as well, I just cut it out and spliced the wires together, and viola! no more charging issues.

From that experience, it's why I just suggested eliminating them altogether. Yamaha sucks at wiring. Dealt with electrical gremlins in quads, bikes, jetskis, and outboards. In fact the only problems I ever seem to have with Yamahas are with wiring.

And you're all welcome. Glad so many people are finding this helpful.

RaWarrior said:

These old fashioned (i.e non sealed) connectors tend to be a problem on any older bike. The stator/RR connector was melty on my '85 Magna as well, I just cut it out and spliced the wires together, and viola! no more charging issues.

From that experience, it's why I just suggested eliminating them altogether. Yamaha sucks at wiring. Dealt with electrical gremlins in quads, bikes, jetskis, and outboards. In fact the only problems I ever seem to have with Yamahas are with wiring.

And you're all welcome. Glad so many people are finding this helpful.

Click to expand...

Mr. Warrior -
I agree that connectors are often a weak point, but in this case, doesn't eliminating the connector make testing of the stator output more difficult?
Wouldn't you have to cut the wires, test, and then re-solder?

Thanks for taking the time to post that, I've been fighting electical problems for ever.

Hi all
I had an electrical problem with my stock RR and decided to swap it for a FH010 from a Kawasaki. I connected the RR to the stator and started the bike and i got a reading of 15.2v either at idle or 2500/3000 rpms with little fluctuation while revving (this was read at the RR terminals). The RR was NOT connected to the battery, just to the stator. My question is does the battery work as a buffer and lowers the RR output to the 14s when connected to RR? This reading i got is a bit high and im worried it may be bad. Stator is within specs with 1.3 ohms between phases and outputing 50ish vAC at 3000 rpms.

Somewehere I read that >14.5V is slowly eating your battery away, so you could connect the new system to the battery for a short amount of time and measure Voltage on the poles to see if its like 14.5V max.
If so, your done, if still too high you can't use that RR
imho. B)

Problem solved. It was lacking the battery to even things out. Readings below

Idle, lights out - 14.45v
3000 rpm - 14.5v
Idle, light on (50w) - 14.3v
Idle, light on, fan on - 13.5v

Looks good to me. Thanks all