Need help setting up a 24VDC gas powered charger

[bigshotdadz]

Hola a todos,

DISCLAIMER: I tend to be kinda long-winded, so consider yourselves forewarned!!  

I have a rather anemic 1KW solar array trying to charge a 1,000AH battery bank with limited success due to periodically overcast skies.
I actually have 3KW of panels and a wind turbine, but cannot deploy those due to landlord issues - A relocation is in the pipeline.

I currently use a B&S Wheelhouse 5550 with a Prosine 3.0 to periodically charge the batteries at 60A max, which depending on the DOD, TAKES FOREVER - Not to mention the noise!!

After much reading I happened upon and joined this site, and after much more reading I decided to ask for your help.

I'd purchased a Niehoff C626 alternator (prior to joining) and plan to mate it to the 10hp B&S engine from the genset for faster charging.
The Briggs has a tapered shaft of 0.872 (7/8) inches, and I need a pulley that can be mated to this shaft.

The C626 came with a A3-229 eight-groove pulley which takes a 28mm wide belt, and I'd like to use a slightly larger pulley for the engine.
By my calculations, with a 1,800rpm engine speed, I'll need a 4.44inch pulley to spin the C626 at 2,000rpm.

However, I'm in Jamaica with no access to wide selections of pulleys and belts, so my offline component sourcing has been less than fruitful.

Instead of running the risk of purchasing the wrong thing, I humbly request some guidance re: what belt and pulley to acquire.



P.S.
As I only plan to use this rig for bulk charging, is the onboard A2-141 regulator sufficient?
Or, do I need to replace it with a Balmar (MC624?), or a Sterling unit?

[Ronmar]

Well first off, the specs on that alternator show 28V @260 amps...  My math says that is 7280 watts...  That is going to need 14HP to drive for any length of time.  Is that 10HP B&S 10HP at 1800RPM?  That sounds a little low, and am guessing that 1800 RPM will be derating it considerably...  2000 alternator RPM also sounds a little on the low side for full alternator output, but I am not familliar with this alternators output curve. With that large a bank, and low HP, hooking it up with the stock regulator which has no output limit, will probably stop the engine due to overload...  

IMO, you either need a bigger engine, or you need a programmable regulator that has current limiting to allow you to taylor the alternator load to your available HP.  You also need to run that engine at it's peak output RPM, and size the pullys to deliver an alternator RPM near the peak of the alternator's output curve. Higher RPM also enhances alternator cooling airflow.  With a full 10HP available, you should be able to get nearly 180A out of the alternator. So a programmable that will limit the alternator output is prettymuch a necessity to make this thing work with only 10HP available. The current limit along with appropriate alternator RPM will also enhance alternator life by keeping the heat down.  And a programmable regulator is just plain a good idea when charging batteries via alternator IMO.  

[mobile_bob]

i concur with Ronmar

you need to talk to balmar and see if their mc624 will handle the alternator field requirements you have, i am reasonably sure it will, but check before buying one.

the balmar program-ability in my opinion is worth the money

sterling has a unit that is significantly lower priced, but i have not tested one as of yet, so i would reserve comment on its ability to do what  you need to do, given what you have to do it with.

with the size of your alternator, and the limited power available from the briggs engine i would strongly recommend using a controller, otherwise i am not sure you will get any use out of this thing.

and yes i would set the rpm of the engine to its rated speed, which might be 3000 but likely 3600rpm,,, it will need to run at that  speed to get to its best efficiency and provide for adequate cooling given the load requirements of your project.  the last thing you want to do is overheat and burn up an otherwise good engine all for the want of a decent controller.

bob g

[bigshotdadz]

Thanks for the speedy response.

The motor normally runs at 3,600rpm, but I was thinking to reduce both wear & tear and the annoying noise.
But if 3,600rpm is recommended, that's what it'll be. Hmmm, I wonder if 3,000rpm makes less noise?  

Re: the alternator, its peak output comes at 8,000rpm, but as far as I can tell it'll generate 240A at 3,500rpm.
I don't see myself needing 280A anytime soon, and at the expense of revving it another 4,500rpm to achieve this seems rather inefficient.


The idea to spin the C626 at 2,000rpm was born from the need to perform some rudimentary current limiting. I've contacted C.E. Niehoff about this, and they've said it can be done, but will require large amounts of torque, so the higher revs on the engine might indeed be the ticket. That said, the problem now becomes the lack of current limiting as pumping 240A into a 1,000AH battery bank sounds like a recipe for destruction.

So I guess, I'll go do some more reading on the Balmar and the Sterling units.

Any recommendations on sourcing the pulley and belt??

[vwbeamer]

I would encourage you to look at serpentine pulleys, often called micro groove.  The initial cost is more than cheap aluminum Vee pulleys, butthat they will pay for themselves if you use the system a lot in fuel savings alone. Not to mention they last forever.

I got mine at Utterpower.com. Great quality and fast service.  http://www.utterpower.com/products/pulley/

On the motor, if your gen set still works, I would sell it whole and buy a 13-14 hp engine with a non tampered shaft. it's my fear you will spend more time and money getting a pulley for that tampered shaft than what you would spend on a proper engine.

[Ronmar]

Bulk charge(about 80% of the recharge cycle) on wet cells can use up to 25% of the battery bank capacity in amps.  So your 1000AH bank can use up to 250 amps as long as battery temperature is not allowed to exceed limits(a good controller monitors this as well as alternator temp).  AGM batteries can use even more during bulk, upwards of 40% if I recall correctly...  So I don't think you will have any problem with 180A doing damage to the bank with proper management.

You of course will not have the HP with that engine to reach 25% of your AH capacity in charge current.  But if you did, and temps are maintained, it will drastically shorten your recharge times from a deep discharge and mean less time you have to put up with the noise of the engine running at full output RPM:). 

   

[bigshotdadz]

Darn it!! I was so hoping this engine could do the job. 

It'll be easier to find a 800cc car engine than it is to source a beefier engine!
Shipping and customs duty alone will take all the joy out of this project.

Fuel injected small car engine. Is it feasible to use such an engine btw? 
Or, do I just bite the bullet and go find a V-Twin online?

Let's take Listeroids etc off the table entirely, as I'd most likely go broke importing one.

What kind of gas engine would you recommend for QUIET & RELIABLE operation??