Auxiliarly Lights - How big is my alternator?

bcarter · Sep 26, 2003

I've been doing my homework regarding the installation of additional lighting on my 1999 Kubota B2710... There are tons of great ideas in the various threads on the subject but one thing that was mentioned several times and not discussed in detail was the required size of the alternator. Obviously the "current" current load plus the "new" current load must be less than the output of the alternator, but how do you determine the output of the alternator?

I've checked the docs that came with the tractor and I've done some searching through the threads here but I haven't found anything on how to determine how "big" my alternator is. Does anyone happen to know what size alternator comes standard on a B2710? Alternatively, does anyone know how to determine alternator output?

For folks with a B2410, B2710, or B2910 - how many watts of auxiliary lighting have you added?

Thanks in advance...

RichNJKubota · Sep 26, 2003

Look in the specs section of the Kubota brochure or it is usually marked on a plate on the alternator. My L4310 has a 40Amp alternator. More than enough for lites. A 55watt lite draws about 4.5 amps.

Rich

bcarter · Sep 26, 2003

> Look in the specs section of the Kubota brochure or it is usually marked on a plate on the alternator.

Thanks for this feedback... I actually thought of both of these, but didn't find what I was looking for. The alternator itself had no markings on it at all...and I don't have a Kubota brochure (although I thought I saved the one I got when I bought the tractor...)

I was hoping that another B2710 owner might already have this information. /forums/images/graemlins/grin.gif

> My L4310 has a 40Amp alternator.

I figured that a 40Amp alternator would be more than enough for what I want to add... My guess is that I have a 20Amp alternator and if so, I'd be pushing the limit if I added 3 or 4 55 Watt lights.

Mikemas · Sep 26, 2003

Bill,

The standard alternator (dynamo) on a B2710 is probably more in line with 10-15 amps. I can't remember the exact output, but it isn't much. I was in the same quandary as to how to add additional lighting. The first thing I did was upgrade the factory headlamp bulbs with 55 watt bulbs. For my auxiliary lighting, I used two 55 watt magnetic worklights that can be attached to just about any metal surface on the tractor. (top of rops, under rops, side of rops, loader arms, etc) I used the factory auxiliary hot wire (on the right rear fender wiring harness) to install a cigarette lighter in the plastic toolbox under the seat. Now I can plug in my auxliary lights separately and not overload the electrical system. The other choice is to purchase the optional 40 amp alternator from Kubota ($150.00-175.00?) if you want to add more than just two additional lights.

Good luck on the project,
Mike

jpr62902 · Sep 26, 2003

Just check the fuse in the circuit you want to tap into. Mine was 15 amps. Multiply that by 12 volts and you get the total watts that circuit can handle (i.e. 180 watts). Since my headlights are only 24 watts each, I still had plenty of amperage to power two 55 watt lamps on my ROPS.

Soundguy · Sep 27, 2003

If the alternator that kubota is sticking on those tractors is only 10-15 amps... they are a ripoff... heck.. dc generators kick up to 20 way back from the 1950's.. and If I were in that low output range.. i would much prefer a dc gen to a low output alternator.

Glad my stock NH alternator isn't in that same class of charging units.. reminds me of those little jobs on bikes for running a headlight or something.

I realize that they only need to charge a battery, and run some lights.. but considering everything else on a tractor is usually beefy and 'over-rated' for its designed purpose.. you would think they could have pony'd up for a hary chested el-cheapo 30 amp job.. heck.. probably the cheapes alternator you can buy is a delco 10si... and that is waht 40-45 amps?

Things like companies scrimping in areas they think you wont notice is what really burns me these days.. that 'just get by' attitude... In the old days stuff used to be 'value added'.. guess those days are gone...

Soundguy

MadReferee · Sep 27, 2003

According to the WSM the dynamo output on the 2710/2910 is 14-15 amps at a dynamo speed of 5200 rpm. The no load voltage should be 14-15 volts.

Based on this it would appear that a full load of lights plus normal electrical loads just might drain the battery faster than it can be recharged.

The manual also quotes "This dynamo produces higher voltage in slow speed rotation, and charges electric current to the battery during engine idling."

rbarker · Sep 27, 2003

( According to the WSM the dynamo output on the 2710/2910 is 14-15 amps at a dynamo speed of 5200 rpm. The no load voltage should be 14-15 volts. )

It is the same for my BX2200.

( Based on this it would appear that a full load of lights plus normal electrical loads just might drain the battery faster than it can be recharged.)

Sure seems that way! I wonder what the normal load without lights is on these tractors? Probably not too much.

( The manual also quotes "This dynamo produces higher voltage in slow speed rotation, and charges electric current to the battery during engine idling." )

Yeah, isn't that an interesting quote. It raises more questions than it answers. It would be nice to know how the 5200 rpm corelates to actual engine rpm. /forums/images/graemlins/confused.gif

At any rate, I'm going to be pretty careful with my use of lighting during snow removal this winter. Or maybe I'll just splash out for the optional 40 amp alternator. /forums/images/graemlins/frown.gif

bcarter · Sep 29, 2003

Mike,

> The first thing I did was upgrade the factory headlamp bulbs with 55 watt bulbs.
> For my auxiliary lighting, I used two 55 watt magnetic worklights that can be attached
> to just about any metal surface on the tractor.

If this is what you are currently running for lights then the total is 220 Watts (2 55W headlamps and 2 55W auxiliary). Mr. Ohm says that this is 18-19Amps if you run everything at the same time. Do you run everything at the same time? If so, have you had any problems keeping the battery charged?

I'm looking at adding 3 35W auxilary lights which should be about 9 Amps plus what ever the stock head lamps draw. If you have no problems with 18A, I shouldn't have a problem with 9.

If you only run the headlamps OR the auxiliary lamps (mutually exclusive) then I think I'd still in pretty good shape as far as current draw from the alternator...

Thanks,

bcarter · Sep 29, 2003

Jim,

> Just check the fuse in the circuit you want to tap into. Mine was 15 amps.

This will only tell me if I've got enough "room" in that particular circuit. The alternator may not have enough "umph" (that's a technical term... /forums/images/graemlins/grin.gif) to drive all of the circuits that I have access to (or even "all" of one circuit). If, as has been suggested in other posts, I only have a 10 amp alternator, this theory wouldn't hold true...

However, if you're running the stock alternator on your BX22 and you can run the stock headlights plus 110W of additional lighting with no problems keeping the battery charged - I should be OK as well.

Thanks for this feedback...

Soundguy · Sep 29, 2003

( This will only tell me if I've got enough "room" in that particular circuit. The alternator may not have enough "umph" (that's a technical term... ) to drive all of the circuits that I have access to (or even "all" of one circuit). If, as has been suggested in other posts, I only have a 10 amp alternator, this theory wouldn't hold true...
)

Not exactly... just beacuse you have a 10 amp alternator doesn't mean that the 'theory' is wrong.. just means that while running that load, your storage battery is discharging the the remaining amps in excess of what the alternator can handle... just like it would do if you were not running, but had the lights on. Duration at that load would be determined by the amp hour rating of your battery, at that load.

It is quite possible to have a fused circuit that has a fuse rating higher than the max output of the alternator.

Soundguy

Mikemas · Sep 30, 2003

Bill,
You are correct about drawing 19 amps with the headlamps, tail lamps, and auxiliary lights. I do not run them simultaneously due to the possible current drain on the battery. Soundguy makes a good point about circuits being within their fused limits, but the overall system not being able to keep up with the demand of the combined draw of the circuits. Therefore, I wouldn't recommend running all the lights at one time, unless you make some other plans to replenish the charge in the battery. I also agree with Soundguy about the charging / lighting issues on the B-series Kubota. It is a weak link in an otherwise bulletproof machine. I have expressed my opinion to Kubota via letters and questionaires, but I doubt they'll change it on the assembly line. They're getting by with what has become acceptable, and then making a little more on parts when somebody does decide to upgrade to a 40 amp alternator.

Mike

Soundguy · Sep 30, 2003

( about the charging / lighting issues on the B-series Kubota. It is a weak link in an otherwise bulletproof machine )

I think you hit the nail on the head. The mechanicals on the machine are good from what I've seen.... and as you point out.. it is doubtfull that they will upgrade the charging unit from the factory... as it meets the minimum needs of the tractor, as shipped. After the owner gets it.. it is up to him to get it upgraded to do more work etc.

Soundguy

bcarter · Oct 1, 2003

Not exactly... just beacuse you have a 10 amp alternator doesn't mean that the 'theory' is wrong.. just means that while running that load, your storage battery is discharging the the remaining amps in excess of what the alternator can handle... 

Agreed... My assumption was that I didn't want to run a load that would drain the battery and I didn't make this assumption clear.

bcarter · Oct 1, 2003

Mike,

 ... I do not run them simultaneously due to the possible current drain on the battery... 

OK...this at least partially answers my question. If you can run 2 55W loads (either your primary or auxiliary lights) with no problem, then I should be able to run with 3 35W loads (my auxiliary lights) and not have a problem since my current draw would be slightly less than yours.

...or suppose that I could just pony up the $$$ for a 40W alternator /forums/images/graemlins/frown.gif and then I could light up the whole neighborhood... /forums/images/graemlins/grin.gif

Thanks...

Junkman · Oct 1, 2003

( ...or suppose that I could just pony up the $$$ for a 40W alternator /forums/images/graemlins/frown.gif and then I could light up the whole neighborhood... /forums/images/graemlins/grin.gif

Thanks... )

That is amps, not watts........ and 40 Amps isn't that much.... about enough to power 480 watts at 0.3 Ohms. To keep the resistance down, use the finest stranded copper wire that you can find.

WATTS ÷ AMPS = VOLTS.........Voltage
WATTS÷VOLTS = AMPS...........Current
VOLTS x AMPS = WATTS..........Power
OHMS=Resistance

PS.... no I am not that smart...... just looked it up........ the Junkman /forums/images/graemlins/shocked.gif

Rick Jay · Oct 1, 2003

bcarter and all,

I'm not sure how many hours of continual use you are planning on using your lights, but there is one factor I haven't heard mentioned yet, and that is the reserve capacity of the battery. You can draw more current out of the battery than you put into it, you're just limited on how long you can do that.

I just checked my manuals for my B2910, and I'll be danged if I can find the battery reserve capacity (amp-hours) in the published documents. I'll have to check the actual size of the battery in the tractor. Anyway, assuming the amp-hour capacity of the battery is at least 20 amp hours, that means the battery could "theoretically" run 2 55 Watt lights (about 9 amps) for more than 2 hours without fully discharging. (20 amp-hours divided by 9 amps = a bit more than 2 hours.)

Everything I say here is based on a 20 Amp-hour battery.

This means that if you initially have sufficient current draw from all the lights such that the dynamo is "just keeping up" with the current draw, you can run indefinitely. If you have extra lights that draw, say another 10 amps, you can still run them, but the battery will slowly discharge...in this example, over a span of about 2 hours. If you occasionally shut down some of the lights, the battery will regain some of it's charge.

So...if you're going to be out working at night for extended periods, you need the bigger alternator. If you just want the "extra lights" for short periods of use, I don't think you're going to be putting too much at risk by exceeding the charging capacity.

I guess another option is to find a place to mount a second battery (a biggun'...like a car battery) and run the auxiliary lights off of that. During the day, charge the battery up with a 120 volt charger and it'll be ready for the next night.

I'll admit it's not the "self-contained" solution of a heavy duty alternator (and I also feel that such a critter ought to be standard equipment), but I guess it might be a viable alternative for those of us that are fortunate enough so that we don't generally have to work in the dark. Plus, during the day, you could use the "extra" battery to power an inverter for those that might need limited 120 V.A.C. power out in the field.

Well, in my case, with the standard dynamo, I've got 2 additional 55 watt halogens mounted on the ROPS...one pointing front and one back...and it's sufficient for my use. And on my small property, I can run an extension cord to anyplace I need from the house. /forums/images/graemlins/crazy.gif

To each his own, I guess.

~Rick

Soundguy · Oct 2, 2003

( there is one factor I haven't heard mentioned yet, and that is the reserve capacity of the battery. You can draw more current out of the battery than you put into it, you're just limited on how long you can do that.
)

Actually at the top of page 2, I addressed exactly that point... any load over the capability of the alternator is taken care of by discharge from the storage battery.

Soundguy

Rick Jay · Oct 2, 2003

Sorry, Soundguy, I read that but forgot about it after reading the other posts.

The main point being, that it is O.K. to discharge the battery a bit if people only need the extra lights for short periods of time.

~Rick

Soundguy · Oct 2, 2003

( The main point being, that it is O.K. to discharge the battery a bit if people only need the extra lights for short periods of time.
)

Sure.. otherwise cars wouldn't have an 'accessory' option on the ignition switch.

It is a pretty universally recognized that the storage battery for a vehicle is used to start it, and run loads when the charging system is not runnning.

Soundguy