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Discussion Starter #1
Hello All,
I just had a quick question to follow up on my recent modification. When I fire up the bike I'm getting 14.3 volts at startup and after the bike gets to temperature. The reading is consistent whether at idle or around 3k rpms. I had topped off my battery when I first parked it with my maintainer and the battery voltage reads 12.5 with the bike off. I have the new R/R wired directly to the battery and while I'm very excited to see this output. I'm worried about overcharging my battery.
Any thoughts?
Thanks in advance, Yuma.
 

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Sparky!!!
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umm, i thought that was the whole reason to put the MOFSET on.. it keeps the voltage at the needed 14.5 volts through all rpm ranges. The voltage is needed higher at idle more than any other time, because the cooling fan generally comes on when you are sitting at traffic lights
 

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Hello All,
I just had a quick question to follow up on my recent modification. When I fire up the bike I'm getting 14.3 volts at startup and after the bike gets to temperature. The reading is consistent whether at idle or around 3k rpms. I had topped off my battery when I first parked it with my maintainer and the battery voltage reads 12.5 with the bike off. I have the new R/R wired directly to the battery and while I'm very excited to see this output. I'm worried about overcharging my battery.
Any thoughts?
Thanks in advance, Yuma.
My setup (in my signature) functions exactly the same way. You are good to go. If you had an AGM type battery, that would be even better since evaporated electrolyte is recycled back into the glass mat, they apparently cannot be boiled dry as a wet cell can. AGM = Absorbed Glass Mat

edit: I can see your signature now. It wasn't visible while posting.
 

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You're good. 14.3v is a safe charging voltage for a 12v battery. the results you are seeing after your upgrade are normal and typical.
 

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You're good. 14.3v is a safe charging voltage for a 12v battery.
Yup. However a vn will overcharge. The manual states as high as 15v. I now understand why, but it bothered me back when I discovered this fact.

Would be hard on the conventional OEM batteries.
 

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Since installing this voltmeter:

http://www.vn750.com/forum/showthread.php?t=37922

I've noticed the charge rate is 14.5v at first, but after 10-15 miles or so, the charge rate tapers down to around 13v, changing when the fan runs in slow traffic or at stoplights and then occasionally going up to about 14v for short periods at cruise. It doesn't stay at 14.5v the entire time it's running. I would say it spends more time at 13v on a long ride.

That's the regulator doing it's job.
 

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I've noticed the charge rate is 14.5v at first, but after 10-15 miles or so, the charge rate tapers down to around 13v, changing when the fan runs in slow traffic or at stoplights and then occasionally going up to about 14v for short periods at cruise. It doesn't stay at 14.5v the entire time it's running. I would say it spends more time at 13v on a long ride.

That's the regulator doing it's job.
Yup, if it did not reduce, you would overcharge the battery. Your figures are measured at the battery. The R/R could be 'seeing' 15v. It is designed to shunt higher voltage/lower amperage to ground. A lot less heat.
 

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Discussion Starter #9
Thanks to all for the input. Looks like I'm good to go. I really like the numbers just didn't want to risk blowing anything.
 

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Discussion Starter #10
Thanks I'll have to add a volt meter on next . Is it still working well?
 

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Hey, would it be possible to get the brand and, part number from you on that MOSFET R/R you are using?
 

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Thanks for the link. I also found the official site for them and, there appears to be a newer model. The FH020AA. I'm thinking of going with this one.
 

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1986 VN750
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Model / Output / Source Bike
FH001 / 35A / FJR 1300
FH008EB / 40A / BR 600 RR
FH010BA / 50A / ZX-10R
FH012AA / 50A / FJR 1300, R1
FH012BA / 50A / ZX-14R, ZR1400, GTR1400
FH014AA / 50A / CBR 1000 RR
FH016AA / 40A / ZX-6R
 

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1986 VN750
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I used FH012BA. 14.3v @ all RPMs :D

The 020 is not a 'newer model' and there is no benefit from using it over one of the others on the list (aside from the 40A models).

Find the cheapest you can find on eBay.
 

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the reason I went with the setup I posted a link to, is that it included everything needed to hook it up. I didn't have to go hunt down the r/r, then the plugs, get an inline fuse, wire, ect. Just made it easier for me since I was in a time crunch to replace mine (ie, didn't have to wait for all the parts to get to me, they all came in 3 days from same source).
 

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1986 VN750
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the reason I went with the setup I posted a link to, is that it included everything needed to hook it up. I didn't have to go hunt down the r/r, then the plugs, get an inline fuse, wire, ect. Just made it easier for me since I was in a time crunch to replace mine (ie, didn't have to wait for all the parts to get to me, they all came in 3 days from same source).
I bought the kit from roadstercycle for the wiring, and the R/R on eBay. Saved $60!
 
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