building a 12 voltbattery charger

[egbert369]

G,day all from Oz,
No doubt this topic has been covered many times but poor computer and search skills have failed to help me.
I have a modest 12 volt solar system of 875 amphours using donated Agm batteries,The system has met my needs adequately for the last 2 years,however about 3-4 times a year I need to utilize charging back up from another source when the cloud cover decides it needs a 6 day holiday in my part of the stratosphere.
Up to now I,ve used a Xantrex 60 amp charger off my generator to bulk charge,panels do the rest and everythings been fine.
Unfortunately some AC output issues on my Kwaka Ge5000 generator resulted in the Xantrex emitting a bright flash and Loud bang that clearly were,nt within the manufacturers specs.
So here,s my query Folks-I have a very good 13hp?? Kwaka motor(ditching the generator),A Sterling ProB regulator on the way and I,d be appreciative of your advice and wisdom on-
*What size alternator to use(unsure if the Stirlings specs on amps relate to input amps,or output amps?
*What the optimum RPM,s for this motor/alternator/reg setup should be?
*Alternator brand-(leece-neville appears to be favoured on this site.
Bearing in mind thanks that this arrangement will only be utilized 3-4 times per year,The motor though probably oversized,is something I already have and the fuel consumption therefore not overly important.
A great forum from what I,ve read,Knowledgeable and generous contributors.
Thanks all for any replies,Unfortunately,Our 11 hour time difference and my typing speed preclude quick replies on my behalf.
Regards,Andy.

[Mad_Labs]

As you said, that is that is a lot of motor to charge such a small bank. I made that mistake when building mine and my fuel economy sucks. I know you only plan to use it a few times a year, but plans change. And if you happen to run low on fuel when you need it, fuel economy suddenly becomes important! Maybe trade for a smaller motor?

What speed depends on the alt that you use, but most need to be in the 3kRPM range to pull most of their power. The Leece 555 is awesome, I have a ton of hours on mine and I pull max amps of it for a couple hours at a time if the bank is sacked. I do have extra good air circulation though, more than just the fan that comes with it. However, it is much larger than you need. As above though, things change and you may add to your battery bank, so you might want to go for the 555 anyway.

What speed does your motor run at? Mine is 3600 rpm, so I went for a direct drive which has worked out well for me. If you do go belt, make sure to select large pulleys for good belt life. I made the mistake of using too small belts and chewed through belts. IN fact, I came to the (wrong) conclusion that belts sucked, which is why I went direct drive on my last one.

Have fun!

Jonathan

[thomasonw]

Morning,

From my experience I have found the 'rule of thumb' of 5HP per 100A (at 12v) of alternator seems to be a rather good starting point.   Based on your 13Hp motor, and that you are really looking for something KISS (esp with the 3-4 times / year use) I would offer that you would not go wrong using a 200A large frame Leece Neville alternator (4800 or 4900 series), belted to spin it around 4-5000 RPMs.   EBay often has them for under $150, search for 200A leece neville, but make sure it is the LARGE FRAME alternator - 6.5" in diameter and weighing around 30lbs...  ala:  http://www.prestolite.com/pgs_products/n_alt_results.php?item_series_id=100&series_name=4800-4900  

You will need an external brush kit (I have found it under these part numbers: A038100265S, 39-5204 or 100265)  to expose the brushes and allow the Sterling regulator to be hooked up, and make sure you use dual belts.

But for a quick job to use every once and awhile that might just work well for you.  Perhaps in operation you could monitor the charge rate and when the batteries are getting towards full charge (the Amps being delivered are getting smaller), you could manually lower the speed on the Kwaka engine to lower noise??

Best of luck!  It seems most of the challenges are often the physical mounting of the alternator and getting a drive pulley on the engine...

-al-

[Ronmar]

For your needs, 13HP is probably a little more than you need for this task.  But that is the beauty of belt drive, thru pully selection you can de-rate the engine and run it at a lower RPM that delivers enough HP to meet your charging current needs yet still meet alternator RPM needs.  This will save you a bit of fuel, and you can always shift to a more appropriate engine at a later time.

I am not specifically familliar with the controller you mentioned, but The typical main issue with charging large battery banks directly with engine driven alternators, is being able to control the peak current output from the alternator.  The issue is that with a small efficient engine and an alternator sized to do a good job, or an engine derated to be more efficient, without max current limit can be drug down to shutdown by a severely discharged bank.  Or when charging a large bank, an alternator can be commanded to output at 100% which can damage it under a sustained load.  A maximum generator current limit that is adjustable would be basic requirement IMO, with an alternator temp sense/limit circuit being a very nice to have feature. 

[mobile_bob]

the amp manager function of the balmar and the xantrex (rebranded or made by balmar for xantrex) really is useful for tailoring the load to the available hp, sorta like an infinitely variable electronic transmission.

i "think" the sterling has a similar capability, but don't recall just now... i do remember being pretty excited about the sterling regulator when i first came upon them a few years ago, and it is hard for me to think i would have been excited about a controller that did not have the ability to tailor the amperage to the available power.

that is something to double check on in my opinion.

another point is the access to the brushes for connection of the controller to the chosen alternator, the leece neville jb series and the 4800-4900 will have to have the special adapter plate so that you can replace the oem regulator and gain access to the brushes.. that is an additional cost albeit not terribly expensive.

the 110-555jho can retain the oem regulator as a cover, and you can simply insert the 1/4inch female spade connectors to the brush holder, and reinstall the oem regulator as a dust cover... the upside is you can tape off the oem leads and retain its function in a back up capacity, and then use the aftermarket controller to control the charging regime.

also down the road should you choose to step up to a 24volt battery bank the 110-555jho will do significantly better in efficiency over the 4800-4900series leece nevilles... you can use either of  the 12 volt alternators to charge the 24volt bank with certain minor alterations.

lastly i am of the opinion that the 110-555jho will handle heat a bit better than the 4800-4900 series units, but i wouldn't pick one over the other based on this criteria alone as added cooling is not a big issue for most diy'ers

bob g

[mike90045]

1) be sure to chose a belt/pulley ratio to keep the alternator in IT's preferred RPM range, and it's cooling fans running properly.

2) You can use the alternator to get the batteries close to 85% charged, but beyond 90%, you NEED a regulator/controller set for AGM battery charge voltages, or you will gass the batteries, overwhelm the gas recombiners, and vent the cells, that are nearly impossible to refill with distilled water. 

[BruceM]

Very good point about AGM charging, Mike.  They are great batteries but can't be treated like wet lead acid batteries.

[egbert369]

Thanks all for your replies,I,m only an occasional user of the net so return answers from me can be delayed at times.
Agree the motors on the large size,It does,nt owe me anything though so I guess I can write off the extra fuel used occasionally against the additional outlay of another,albeit,smaller engine.
I was planning on running it thru the same solar Trimetric so,s I am able to keep an eye on it whilst running.
Also intend to just get the bulk charge in only with it though I guess in prolonged spells of lousy weather,getting the batteries fully charged would be a good principle to abide by.
From the spec sheet for the- Sterling alternator Pro B regulator- that I,ve read,It does have separate settings for Wet lead acid/Agm,s/gell etc.
These voltage settings correspond with the 14.4 volts (bulk stage)   I,ve been running thru the Xantrex C60 solar controller for the last 2 years without issue so far,(touch wood)
The AGM batteries were a donation from a mate who works in UPS rooms,hence why I went with them.
I designed and built the setup myself-In hindsight I,d have utilized 24 or 48 volts instead-A learning curves a good teacher though.
well I,ll read thru this information several times to sink it all in and post some questions to your good advice later so,s I can fine tune the design.
Once again-Thanks for your help!

[glort]

Looking at leece alternators on Fleabay, the cheapest I could see was over $260+ substantial postage for a 12V, 160A unit being here in Oz.

You can buy any amount of Commodore/ Falcon/ Camry 100-120A alternators from the wreckers for $30-40.  For occasional use as you intend, I think I'd go buy say 3 of these ( 2 hooked up to the engine, 1 spare) and use them.
I have 2 80A Mitsubishi alternators off  Subarus and have ran them flat out for hours and never had a problem with the things. They certainly get hot but having a good look at them, they have a fan at the front ( enclosed) for the windings and another at the back I surmise for the Diodes/ regulator.
I was telling my Father who I got them from that runs a wrecking yard and he said no wonder we never sell any of the bloody things, they make them too good.  Apparently they are not an item that often fails on those cars.

I drive them off my 6 HP lister and it will just cope with 2 at full power so your 13 Hp Kwaka engine will eat them for breakfast.
I have a little 5.5 HP kwaka  I have hooked up to a Bosch 65A, 24V alternator. I use a 6" pulley on the engine and can run the thing about 1800 revs and it spins the alt just fine to about 40A. After that I need to give it a bit more stick to keep the speed from dropping at higher load.
If you gear up your engine on the pulleys, you can drop the revs down to use the torque and save a lot of fuel, wear on the engine and noise.  It will pull 2 alternators on a 6" pulley no sweat and you could easily get the same output as a leece for a lot cheaper.
I'd like a BIG leece as well but hard to justify what they go for here when the alternatives are sooo much cheaper.
Sometimes you are better off to accept a shorter life from a cheaper solution and just replace it if and when need be.

I like my little white engine. Certainly a league ahead of those crap garbage B&S things that's for sure.  I once had a brain fade and topped the tank up about half way with Veg oil . I ran the thing for over an hour before I noticed it was blowing a smoke haze and got a whiff which tipped me off to my stupidity. I was running the thing on the alternator to drive a UPS I was using as an Inverter and had a few hours to go so I just kept topping up the thing with the right fuel and it was fine.

Ironically, I won a 13 HP Brand new Chonda for a silly price on evil babe Tonight so I might put a couple of Alts on that yet. Dunno whether to take them off the lister and just run a 240V head on that or get a couple more and have a 12V/ 3 phase option on the Roid.

So may engines, so many ways to make power. 
I love it! :0)

[Ronmar]

I think the Leece's get the reccomendation because, besides being durable, they are easier to adapt to external regulation, or swap back and forth between internal and external regulation relatively easilly.  I am sure the Subaru alts are durable, but how easy would it be to access the field contacts(brushes) directly to connect an external regulator, and disable the internal regulator?  On a lot of auto alternators, the regulator module and the brush pack are one module, and not easilly hacked into to connect an external reg...

[mobile_bob]

there are several reasons i have always like the 555 alternator

it started out life some 35 years ago, maybe further back, as a motorola product
and it had some interesting characteristics

1. it has large ball brgs front and rear, no tiny stuff or needle brgs
2. it has a nice brush holder that has 1/4"spade terminals, making it very easy to control the field
3. the stator stack is narrow, which equates to shorter conductor lengths, making for lower stator resistance
4. it has more poles which make for higher output at lower relative speeds

prestolite/leece neville carried forth all the previous stuff and did a few more things
like
5. replaced the iron end housing with aluminum, which made it ligher weight
6. increased the amp capacity from 90amps in the motorola units to 160amps today
7. they cut the over the counter price in half, making it so friggin inexpensive and requiring no
core charge.

then in testing the units in charging 24volt battery banks, it was found they are very efficient, it just became a no brainer for those that want to buy a new alternator and build a charger to go with this unit.

over the last 15 years or so we see many marine aux. generators being built with the 555 alternator or a derivative, so... why look elsewhere?

having said that...

if i were in an area where the availability and cost was such that they were so much more expensive than what they are here in the states, i too would be looking at alternatives.

its hard to pass up an alternator that is proven to be good at 80-100amps and is fairly easy to adapt to external control, which can be bought used for 30-50bucks each.

at that price point, it might well be i would give up some efficiency to keep costs down, at least for some systems, notably such a system that is used as a backup for a solar or wind system that  is likely not be get a lot of use over the year.

alternators such as the delco's, some fords and imports (as Ronmar mentions rightly so) have their brushholders and regulator integrally mounted, or mounted internally in such a way that it is either very difficult to modify them or making them questionable in reliability, have little to be said for them... in short i would never recommend using one unless you are on a deserted island and there is no other option.  if there is another options i would use a 300dollar alternator before i would use a 10 dollar delco!  all else being equal.

while i have no real experience with the foreign offerings, i have heard some good things about the bosch and some of the japanese alternators, as being very durable units, i got no idea how hard they are to adapt to external control?

bob g

[glort]

I think the Leece's get the reccomendation because, besides being durable, they are easier to adapt to external regulation, or swap back and forth between internal and external regulation relatively easilly.  I am sure the Subaru alts are durable, but how easy would it be to access the field contacts(brushes) directly to connect an external regulator, and disable the internal regulator?  On a lot of auto alternators, the regulator module and the brush pack are one module, and not easilly hacked into to connect an external reg...

I think it would be a no brainer to use one of these alts and an external controller if you were reliant on it to any great degree for your power.
In the context of the question though, Being use 3-4 times a year, Here I think they are real hard to justify.

In oz a 555 is going to run $500+ delivery on a good day. I have seen them for plenty more. Add in the external controller, $400 if you are lucky and that's some bloody expensive  power even if you run it in total for a week a year.

Given the purpose of said setup would be the very occasional use of the genny, I think any efficiency  gain with the Leece and the controller in fuel savings  would never be recovered.  If the std alts are 50% efficient and the leece/ controller setup is 85?, what would that be in yearly fuel consumption savings for this very occasional use?
!0L per year? 20? it is only the diff between the std alt and the more efficient one which is 35%.
It's pretty hard for most people to justify spending $900 plus when you can set something up for under $100 and it will only cost you $30 a year more (MAYBE) to run than the alternative.

As far as longevity goes, I really don't see it being an issue. Car alts run thousands of hours in a vehicle in all sorts of horrific heat, dust, moisture and other things that a standby Genny would never see.  I think even if you replaced the alts once a year, you'd still be ahead in this situation.
Others have more money than I but I always find it a lot easier to Find $50  every so often that a lump sum of  $500 or $1000 even if it is once in a blue moon.

I did pull an old Bosch alt apart a few weeks ago and it wasn't at all hard to get to the Diode output which could be tapped into to feed to an external 3 phase controller and the field input is right there when you pull the brush pack out which also makes it easy to tap into.
Dunno about newer or different brand alts but for a long term, heavy use setup, it wouldn't be a lot of work to re jigger one of these alts. 

[mobile_bob]

Glort

i agree,

there is no way i would spend 500 bucks for the alternator and another 400 for the controller for something i am to use for maybe one week per year.

not even sure i would do so for something i am to use on a weekly basis either.


here in the states, the 555 can be had for about 160bucks if you catch them on sale at a hd truck dealers monthly sales flier, which is not that hard to do as someone usually has them on sale somewhere.

the controller on the other hand, such as the balmar can be 400 or more dollars, for me i have been searching for them for years and buying them on ebay when i can get them for 150bucks or less.... and the sterling regulators are available here for less than that on ebay too.

with good shopping i can pair the two (alternator and controller) for less than 300bucks, which i find acceptable for my use where they will be called upon to do serious charging on a weekly basis if not a daily basis.

even at 300 bucks there are less expensive ways of getting there,  i have picked up many 555 core alternators for 5 bucks each out of the scrap bins of truck dealers,  most need brushes and a regulator (the latter which i am not going to use anyway), and there are other means of control of the charging process should one be handy with some of the microcontrollers available today.
my bet is one so motivated could put together a functioning pair for less than 100 bucks with little effort.

failing that option, then by all means head out to the scrap yard and see what is available to work with and use that!  no shame in doing what works!

besides there may very well be another option out there that works out to be a better solution than the 555 has proven to be? 

there may very well be one!

bob g

[thomasonw]

I think a few good points to remember is the OP

1) Already HAS the 13hp motor
2) He is looking to use it 3-4 times a year, at up to a 6 day stretch
3) Sounds like his Solar system is able to treat the batteries well, he just needs a crutch to get over the 'Solar Holidays'.

With that in mind, one could make a very valid point that just about any robust alternator (or alternators) that are available locally would be the best choice.  I know if I could not have picked up my large 4884 - 200A alternators for under $150 delivered, I would be looking elsewhere.  And to be honest, if indeed this is a 'Solar Holiday Special', perhaps just using the built in fixed voltage regulators would work just fine.  It might only get the batteries up to 80% recharge, but for that 3-4 times a year, a KISS approach does not seem the wrong way to go - the Solar system can treat the batteries right once the sun comes back.  (Make sure the target voltage is not over the max volts for the batteries, but I think they are often set for 13.8v or so...)

I also noted he called out he has AGM batteries,  I would suggest looking into the MANUFACTURES spec on the max bulk acceptance rate for the batteries - I have seen spec sheets range from 30%c to 400%c, all for "AGM" batteries - clearly they are not all made the same.  But if he has one of the larger % acceptance rate batteries, piling on 200A or so of  alternators (in one package, or 2 or three) would load the engine down well - no wasted efficiency with it loafing along. 

In sourcing Alternators I would point out that many 'small frame' ones just are not designed to provide their rated current for hours on end.  (or even an hour??)  But more to support a large surge that quickly tapers off.  This is not as true in modern autos - which have larger continuous DC loads, and hence maybe the comment about the Mitsubishi  alts??

Let us know where you end up!

[SteveU.]

Hi All
I will comment from an experience standpoint on the later model small case automotive dual fan alternators versus the earlier front fan pull through designs.
It is true they are designed for much higher contious output loads. The vehicle electrical loads demanded this. They are also so much more efficient than any older small case unit like the Delco 10SI or any Ford three bolt small case that it would be rediculous to use one of these now for anything.
Remember inefficnecy will be expressed mostly as waste heat. Underhood of vehicles now reducing heat is important and all vehicle manufactures are having thier feet hung over many fuel effiency fires so these later alternators since the late 80's are no longer the cheapest/lightest that can be slapped togather. The best of the dual fan small case units are of the same conversion efficiency as the best of the older developed large case units. They have to be or they would overheat, cook and die early deaths. Best of the bunch for toughness and longevity in my expereince are the dual fan Nippondenso's. North American Chrysler usage ND units were already set up as offboard externally regulated.

Any of the onboard regulated units can be hacked around. Just think of this as the learning expereince to be able to do your own breakdown repairs. If the alt is a cheap wrecking yard take off then it is cheap learning even if it takes you 2-3 units mechanically ruined and smoked to get it right. How anyone of us done this the first time all had to learn. You could afford to do this much easier than any one of the supposed small case permanet magnet conversion wonder units!!

So a couple of these oppossed belted later model internal fan units internal regulator bypassed into a multi stage contoller (were to spend the money!) spun at a minimum or ~4000 Rpm with the engine loaded at a downed Rpm of 2500-3000 RPM would be what would give the best bang for the set-up bucks overall fuel efficiency useage.

Regards
Steve Unruh