Bandit 400 alternator output? (Watts)

[Squishy]

Hello.

I'm trying to figure out how much output the alternator/ac generator/stator of the b400 has.
It doesn't state anything about the output amps or total wattage in my manual.

On this forum someone mentions 362.5W (http://forums.banditalley.net/index.php?topic=12117.0).
Can anyone confirm this? That would be a lot of output since most smaller bikes only have ~200W. For example 220W for GS500 (http://www.eurospares.com/gsfaq.htm)

Thanks

[greg737]

I don't know what the wattage output is for our Bandit 400 alternator, but I think it's pretty healthy, so that it has a good bit of extra wattage available in the stock/factory setup.

I say this because my fuel injection project Bandit is running the stock alternator with the addition of:

Honda TRX500 Rancher Fuel Pump
Kawasaki Ninja ZX-6R secondary injector array
MicroSquirt ECU
Wide band oxygen sensor + controller
Several additional sensors (Air Temp, Throttle Position, etc.)
and several electrical relays

With all of this extra stuff running in the electric system the battery gets a solid 13.7 volts while the engine idles at 1,400 RPM.

This is a screen-shot from a data-log I took while riding the Bandit last week.  At the moment of this screen-shot the Bandit was sitting in my driveway idling (which is 1,400rpm when the bike is fully warmed up).

The screen is divided into three sections, from top to bottom.  you can see the RPM in the top block (in white) and the battery/electrical system voltage in the bottom block (in red).

(sorry that the picture doesn't fit perfectly, you have to slew it side-to-side to see all the data.  it would be too small to read if I reduced its size.)


In the screen-shot above the Bandit's radiator cooling fan is OFF (I've got it set to come on at 205 degrees F).  When the radiator cooling fan comes on and the engine is at idle RPM the line voltage drops to 12.5 volts.  This shows that when the engine is at idle with everything running, including the radiator cooling fan, my Bandit begins to mildly "draw down" its battery.

[Squishy]

Thanks.

However I don't think sensors and ECUs really draw that much power.
Not even the injector would draw that much.
Only the fuel pump might use a bit more..

Also I'm not sure whether the supplied voltage is really a good indicator.
Are you saying the supplied voltage by the R/R will drop if the load is too high?

[greg737]

Thanks.

However I don't think sensors and ECUs really draw that much power.
Not even the injector would draw that much.
Only the fuel pump might use a bit more..

Also I'm not sure whether the supplied voltage is really a good indicator.
Are you saying the supplied voltage by the R/R will drop if the load is too high?

Yes, thankfully most of the F.I. components are "low draw".  The fuel pump is definitely the big electrical system addition compared to a carb Bandit.

With regard to the system voltage:  The R/R isn't the issue.  The R/R is just a "middle-man".  It just sits there doing its job, turning the 3 phases of alternator AC power into DC power and regulating the upper limit of that DC power to prevent battery damage (13.7 volts is what it uses).

I'm saying that when my Bandit is at idle engine RPM and the radiator cooling fan comes on the bike's alternator output is "overwhelmed".  There's just not enough wattage being produced.  I can actually see this happen in the data-log because the system line voltage will drop below the battery's normal "resting" voltage.  This means that the battery is now discharging to feed into the bike's electrical system to meet demands rather than being charged/maintained.

At idle RPM without the radiator cooling fan my Bandit's data-log shows 13.7 volts, which is above the battery's resting voltage, meaning there's adequate alternator output to power all components + charge/maintain the bike's battery.

[Squishy]

I guess that makes sense.

Only 13.7?
The manual states the charging system must produce 13.5 - 15.5V.

[greg737]

I guess that makes sense.

Only 13.7?
The manual states the charging system must produce 13.5 - 15.5V.

Looking back over a couple of data-logs I'm seeing system voltage as high as 14.2 volts.  And it's indicating 13.8 to 14.0 most of the time.

I'm running an ’07-’08 Yamaha YZF-R1 Rectifier/Regulator which is MOSFET technology. 

The MOSFET R/Rs are designed to be "gentle" on batteries.  They maintain the bike's system voltage within a narrower range.  And MOSFET R/Rs have very long lifespans compared to Thyristor type R/Rs.

Sealed Lead-Acid batteries (SLAB) like to be charged/maintained between 13.8 to 14.0 volts.  This helps a SLAB to last as long as it can and stay healthy.  A system voltage at or above 14.5 volts will shorten the battery's lifespan substantially and when the system voltage gets up to 15.0 or more the SLAB will "boil".

[ventYl]

being short: if you generator was overloaded you should experience drop of output voltage.

[T2098]

My experience so far mirrors what greg737 has found in that the electrical system seems to be barely okay for a stock bike.  I have a '91 JDM VC model with the headlight switch, and I have found a couple of times when I forgot and kept my headlight on while in stop and go rush-hour traffic, the combination of the headlight and the cooling fan running constantly was enough to flatten my battery and require a few bump-starts and cursing under my breath.  Granted, the battery in my Bandit is getting on in age and really should be replaced soon, but even still, the output voltage does seem to drop a lot at idle with the lights and fan on.   I'm running a North American H4 bulb (55/60W) instead of the 90/100W Japanese one, so I can only imagine it would have been worse out of the box.

I just received a couple of Shindengen regulators and assorted wiring bits in the mail, so I'm going to try to do some quantitiative testing of the charging system with the OE reg/rec and wiring, versus the modern Shindengen MOSFET shunt model (FH020AA) and their new SCR series model (SH775) - I've heard rumours that the series SCR model likes to drop out of regulation at very high revs, so we'll have to do some testing on the B4 and my VTR250 Interceptor. :)

[Squishy]

Weird for me votlage is highest at idle.. at 5000RPM it drops

[Rare-Renegade]

Hi guys. I'm new on here and have searched without luck to my related issue as this thread. I'm having a very hard time starting my 400 bandit and when/if i finally can, it's on producing 12.6V at the battery at any RPM's. Sure seems like a weak spark as well. It's a almost new battery as well. Checked connections, etc. Thanks for your responses!

[T2098]

Hi guys. I'm new on here and have searched without luck to my related issue as this thread. I'm having a very hard time starting my 400 bandit and when/if i finally can, it's on producing 12.6V at the battery at any RPM's. Sure seems like a weak spark as well. It's a almost new battery as well. Checked connections, etc. Thanks for your responses!

That's basically the way my '91 VC has been since I got it too.   Especially when cold, the battery seems to have plenty of voltage to crank the engine over, but very weak spark makes it rather hard to start.   I've tried two different OEM CDIs and one Chinese aftermarket replica, and one of the two OEM CDIs is slightly better, but the Chinese replica is actually significantly more difficult to get the bike started with.

One thing I noticed is that the +12V at the CDI drops almost a full volt from the battery/charging system voltage while the bike is idling, and since my charging system is rather weak at idle to begin with, that's probably not helping my spark energy.   I measured ~12.7v at the battery at idle (with the light off!), and when back-probing the +12v connector at the CDI, I measured `11.7v.  Now the CDI sure doesn't draw a ton of current, and for it to drop a full volt is less than ideal.  I've been busy with other things, but after I upgrade the reg/rec on the bike, I'm also going to be either running a separate 12ga +12v wire to the CDI to a known 'strong' switched 12V source, which should at least keep the voltage at the CDI about a volt higher and right at the battery/charging system voltage.

Might be worth seeing what yours is like.  I also noticed that while cranking, even though the engine was spinning over just fine, the +12v connector at the CDI would drop as low as 3-5V!

The caps in those CDI modules get weak over time as well and will greatly lower your spark energy over the years.  If you're lucky enough to have a non-VC Bandit, the CDI modules are relatively easy to crack open and replace the caps for very cheap to restore them to like-new status.

Unfortunately, both of my '91 VC CDI modules are potted solid in epoxy and I haven't found a good way to open 'em up yet without destroying the PCB and components inside.

Lots of good info in the stickies in the 250/400 FAQ forum about the CDI repair/rework:
http://forums.banditalley.net/index.php?board=59.0

[greg737]

Hi guys. I'm new on here and have searched without luck to my related issue as this thread. I'm having a very hard time starting my 400 bandit and when/if i finally can, it's on producing 12.6V at the battery at any RPM's. Sure seems like a weak spark as well. It's a almost new battery as well. Checked connections, etc. Thanks for your responses!

From reading your description it sounds pretty likely you've got a problem in the charging system.

  It could easily be something simple like a connector plug that has begun to corrode or possibly overheat, they are well over 20 years old after all, or a bit of wiring that's going bad.

Or, one step worse, you have a failing Regulator/Rectifier which would easily explain the 12.6 line-voltage you're seeing (it should be something around 14.0 volts from a healthy R/R).

Or, even a step further toward the worst possible scenario, you could have an alternator problem but that's unlikely because they're very robust and long lived.

[Chris H]

Yep, sounds like the reg/rec is duff, should be 14v across the battery, 12v would indicate problems.
The vcc cdi is a pain and is full of foam or something, as mentioned maybe acetone would melt it out.