bigger battery questions - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Where does this wire go?
Includes Electrical mods, Lights, Stator,
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post #1 of 18 (permalink) Old 08-09-2007, 05:27 PM Thread Starter
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bigger battery questions

I've been reading with great interest Hizzo3's messages regarding both his Frankenstator mod and his bigger battery mod. I have a few questions regarding the bigger battery install; unfortunately Hizzo3 hasn't been on here lately for me to ask him directly. I don't know if anyone else on here has installed a bigger battery (read larger capacity battery).

I'm wondering if I can just go ahead and install a larger capacity 12v battery with no problem, without having made any modifications to the stator ? I don't know if Hizzo3 added the larger battery in order to accomodate his Frankenstator's higher output.

If I can just add the larger capacity 12v battery then would I still be able to use the same Battery-Tender charger that I use now with my stock wet-cell ?

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post #2 of 18 (permalink) Old 08-10-2007, 03:08 AM
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You could have the worlds largest stator, but the R/R is only going to put so much into the battery, so I don't think stator size would have alot to do with it.

I'm not really sure how the R/R works..... off of Amps, or Volts. That, to me, would be the only issue. Would a stock R/R put more Amps into a larger battery? Same with the Battery Tender.

But then again, I'm a machinist, not an electrical engineer, so I could have my thinking completely backwards ? ?

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post #3 of 18 (permalink) Old 08-10-2007, 09:32 AM
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Battery capacity is rated in Amp / Hrs. A larger capacity battery is like getting a larger bucket. It "holds more" and hence can supply more at a given rate of discharge. Conversely, it take longer to fill back up to full, i.e. fully recharge. I am not up to speed on the charging system (yet) and am not sure if it would be equivalent to an alternator or a generator set. [UPDATE - 13AUG 07 - We have an alternator with a fixed field (permanent magnent rotor). The stator / perm magnet rotor generates a 3 phase AC (alternating current) voltage that is rectified by the diode rectifier bridge in the R/R.]

I have an on going interest, I want to add a Big Pair of driving lights. When I turn on my front lights, I want like it to look like I am working for Speilburg FX :-) and that requires lots of Amps. Power (Watts) =I (Amps) X E (Volts) . 55W+55W = 110W; 110W / 12Volts = 9.2 Amps of additional load. A 10 Amp/Hr battery alone would only run this load for about an hour. After that the alternator set would have to handle this load, plus the standard system load.

Back on track, The alternator set is a constant voltage charging device. The Regulator / Rectifier (R/R) should maintain a maximum voltage at RPM greater than the battery voltage to the battery to charge and in effect, at that max voltage, regulate the nominal amount of current (amps) out of the bikes stator (alternator) to the system. The system, being the load, will include the battery, lights, etc. A larger capacity battery is a larger load on the alternator set, depending on its charge state. If it is fully charged, and there is minimal load on the system, the battery will greatly assist the alternator. BUT, if the battery is heavily discharged, it posses a threat of being a large load. I do not know what the "continuous current" capacity of it is, but it IS limited by the stator and the ability of the R/R to maintain this output without burning up itself or the stator windings / brushes as a result of too much load. And therein lies the rub.

The Frankenstator mod, if it increases the amperage output, will merely charge up a battery faster than the standard stator, and source more current to the system, as it has greater current output capacity. It will not damage anything unless the R/R has failed.

Addressing the Tender, in all likelihood it is a constant current source and it will only output say 1 amp/hr. Simply stated, a 7 amp/hr battery will take 7 hrs to fully charge, a 10 amp/hr battery will take 10 hrs to charge, etc. Using it should maintain the battery in a fully charged state. The limiting factors being the output rating, the capacity of the battery, and how much time you have to let it charge.

I would appreciate all leads and links to additional technical information regarding our electrical system.

Light On Dude!


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post #4 of 18 (permalink) Old 08-10-2007, 09:52 AM
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post #5 of 18 (permalink) Old 08-10-2007, 09:12 PM Thread Starter
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I'm so frustrated...

Its just that I'm so pissed off at this bike's electrical/charge system. I know I'm not the only one and I also know that its an old problem, ie its a recurring theme on this board.

I'm finding I have to put the battery on my Battery-Tender about every 3days. Yeah, I do alot of city driving and it HAS been hot but come on! This is ridiculous.

The other night I conducted an experiment: I went for a long drive. Before taking off my battery read 12.51V. I rode for two hours at a constant 100-120km/h, 4500-5000rpm, all highway riding. At the end of the trip I took another reading: 12.65V. It was cool and the fan didn't really bogg the battery down.

I stoped for about 1 hour. Then I rode some more as before but for about 15minutes. I took another reading: 12.69V.

The other day my buddy, who has a Marauder 800, and I went riding around town all day. We got stuck In traffic a great deal and it was HOT. My fan was on constantly. It was stop-and-go for a great deal of the day. At the end of the day my battery was having a rough time of it, I had to pull out the headlight fuse in order to start the bike. His bike kept on going and going just like the energizer bunny. What the f!!k !?

I don't think this is normal. And I replaced bothe my R/R and the Stator about 3 weeks ago. I tested the charging system according to that electrosport flowchart and it checked out okay.

So I'm thinking maybe a larger capacity battery would allow me more time between Battery-Tender sessions, you know what I mean ?

I love this bike but I'm not feeling any love back, man. This is NOT a beautiful relationship.

Last edited by ktullu; 08-10-2007 at 09:19 PM.
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post #6 of 18 (permalink) Old 08-10-2007, 11:29 PM
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The big problem is the bike was designed for cruising rather than stop and go. Not very comforting, I know. You might consider installing a switch so you can turn off the headlight when you're in the stop and go traffic, that would help a lot. Another good thing would be to get the LED board from Clear Alternatives . I've noticed that my LED voltmeter hardly flickers when I put the brake light on now. With the old lamps it would dip 1/2 volt. A bigger battery would help keep you going longer in the stop and go, but the question is whether you could ride far enough to recharge it before you stopped the bike for the day. Putting the bike on a battery tender isn't quite so painful if you use Anderson Powerpoles for the connectors, . I have a pair attached to some zip cord that runs to the battery terminals and another pair on the battery tender. And another pair that go to the driving lights. When I'm parked at home, the battery is hooked up to the tender, on the road I hook up the driving lights. Pretty painless and the beauty of the design is there is never any exposed conductors to short out. Here's a good articl on them

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post #7 of 18 (permalink) Old 08-10-2007, 11:49 PM
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Damn, I haven't experienced that with my 2000 I have a Big Crank:

and use a Battery Tender Plus:

The battery tender came with one Clamp Harness and one Lug Harness which I use after every ride to bring the battery back up to full charge. Never has taken more that 30 min. though. When it's fully charged, I disconnect untill next ride.

I don't have a volt meter nor have ever checked any voltages or any such electrical. But I swear by that AGM battery.

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post #8 of 18 (permalink) Old 08-11-2007, 01:49 AM Thread Starter
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yeah...oh well

I forgot to mention I also have the new Clear Alternatives LED tail/brake light. It has made a huge difference. Charging up my battery using the Battery-Tender is not a painful process for me because like you I also have the extra plug attached to the battery. I have the "socket" tucked neatly into the little space beside the coolant tank.

Its the fact that I find myself needing to charge my battery at all that gets me. The bike should do it, just like my buddy's Marauder 800. If I need to charge my bike every three days then I might as well get an electric scooter and save on the gas.

I've thought about adding a headlight switch but I'm a bit reluctant because of legal/insurance issues should I get into an accident. In Ontario (I don't know about other parts of Canada) its illegal to ride without the headlight on day and night, for one thing.
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post #9 of 18 (permalink) Old 08-11-2007, 03:45 AM
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Originally Posted by ktullu View Post
Its the fact that I find myself needing to charge my battery at all that gets me. The bike should do it, just like my buddy's Marauder 800. If I need to charge my bike every three days then I might as well get an electric scooter and save on the gas.
Have you checked for the possiblity of a current draw (short) somewhere, while the bike is shut off? Sounds like there's something discharging the battery that shouldn't be.
This was a method for checking for a current draw from the Vulcan Verses...

Originally Posted by Vulcan Verses
Electrical shorts are usually due to a pinched wire where the crushed insulation of a "hot" (positive) lead is touching the metal frame components and draining off the battery, even when the bike is turned off. It's not enough drain-off to overheat and burn the fuse out, though...Typical crushed-wire points are: under the seat, under the gastank and behind the headlight. You can test for battery drain, even with the bike not running. Hook up a multimeter (analog or digital) that has at least 5 amps of DC Current-measuring capability (most do). Be sure to hook-up the leads to the multimeter properly--most Analog (older type) Multimeters require you to move the red lead to a special jack in the panel. Then with the battery NEGATIVE lead disconnected, touch the red probe of the multimeter to the battery harness wire and the black lead of the multimeter probe to the negative lead of the battery ("in series")--battery still disconnected from the harness--. IF you have any measurement of current at all and the needle moves, either something has been left turned on or you have an electrical short. Finding it is a patient process of elimination. Try pulling one fuse at a time from the junction box or wherever else you have installed aftermarket fuses and watch the meter to see if the current drops to zero. If that doesn't reveal the problem circuit, try pulling each wiring harness *connector* from components around the bike--start at junction box, then ignition module, etc. Sooner or later you'll discover what cicuit/where the short is and then you can focus on that area of the electrical system.

AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC

"When life throws you curves,
Aim for the apex."

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post #10 of 18 (permalink) Old 08-11-2007, 08:19 PM Thread Starter
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anyone in Canada been able to source a MF battery ?

I haven't done that specific test, no but I have been keeping my eye on the electrical system ever since I replaced my r/r and stator.

After I tuck my bike in for the day I take a reading across the battery terminals. Next morning before I ride I take another reading across the terminals. Same numbers come up; I conclude there is nothing draining the battery.

Its a **** wet cell battery. I've been searching for a MF battery here in Toronto, where I live, but for some reason I haven't been able to find one. Both Canadian Tire and my favourite motorcycle super-stores have none in stock.

Which capacity MF battery would you guys recommend: 12AH, 14AH, 18AH ?

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