Ken Hall's posts

Posted by Ken Hall on Feb 14, 2011 12:28 pm

#1 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > Re: Situational System
Your post generates a lot of questions.
Have you quantified your wind and hydro resources ? A lot of people think they have a resource until they measure it.   If you have a good hydro resource, that is the first thing I’d put in.  How much head and flow do you have that you can use ?
Why are you insisting on battery backup ? Do you have a lot of outages of long duration ?  Have you quantified what size of battery bank you will need and do you expect it to grow with the rest of the system ?
Have you done a load inventory and executed energy conservation efforts to control the size of your system ?  6kW is a lot of power.  Or are you thinking of “selling the excess”.  Most power companies have different rules for system that produces something near the total annual usage or less, and a system that generates excess power.  The additional requirements to become a power producer often drive the cost up to the impractical range.
Your idea of connecting the pedal bike charger to the system is an un-necessary complication.  Might as well send the kids out to carry water from the creek to the swimming pool with a cup.  Buy a battery and a small 12V TV and keep it as a separate system.
Why locate the solar panels on the shop roof that is so far away ?  How about a nice ground based rack system closer to the house ?

Posted by Ken Hall on Feb 7, 2011 05:01 pm

#2 -  Renewable Energy > RE General Discussion > Re: Solar heat pump
Here are a few links that may be of interest.


Posted by Ken Hall on Jan 24, 2011 04:01 pm

#3 -  Renewable Energy > RE General Discussion > Re: appropriate generators for off-grid photovoltaic system
You seem to be asking an entirely different question from Ed's. He apparently read the installation manual for his inverter and was asking what the smallest generator is, that he can use.  That recommendation should come from Xantrex.

You did not mention what your inverter is. The answer of how to hook up the generator should be in the installation manual for it.

Posted by Ken Hall on Dec 28, 2010 12:56 pm

#4 -  Renewable Energy > Technical Discussion: Other > Re: Adding a battery bank
In an emergency, taking the whole system down until you are 100% positive of what is going on, is the safest route. A hasty decision to try to keep power flowing is what caused the Three Mile Island accident.

But if you are going to do it anyway, you should be aware that the switch you intend to use, is not code compliant for residential use. There are knife switches and other disconnects that can be used for the same function, that have the appropriate UL listing.


Posted by Ken Hall on Dec 26, 2010 03:43 pm

#5 -  Renewable Energy > Technical Discussion: Other > Re: Adding a battery bank
Do not use the selector switch.

Your decision is either that you are going to have one bank that consists of two strings (1092ah total) OR you are going to have two banks of 546AH that will NEVER be paralled.

If you decide to parallel them, the answers are:

Do they need to be at a similar state of charge ? Yes.

Will the stronger bank charge the weaker one ? If by "stronger" you mean higher state of charge, Yes.

Will it harm the batteries to suddenly parallel in another bank at a different state of charge ? Very possible. The greater the difference in state of charge, the more likely damage is to occur.

Should you equalize both banks together ? NO. One bank of two strings, yes. Two banks of one string each, NO.

Now the debate on whether to combine them or not, can start.
Should 2 year old batteries be combined with new ?


Posted by Ken Hall on Dec 21, 2010 02:52 pm

#6 -  Renewable Energy > For Sale > Re: Submersible hydro UW100 for sale
The UW100 is the old "Jackrabbit" generator. Its performance curves are optimistic, particularly when you are trying to use it in a river.  It does somewhat better when mounted on a towed barge.

Bottom line is that he would need to get the flow up to about 3 meters a second to get about 60 watts, and something close to 5 m/s for 90 watts. Depending on that rivers flow rate, the effort/cost is probably not worth it. 

It sounds like he is in the lowlands of Irian Jaya (aka West Papua). Based on PNG lowland rivers, I am guessing that he is starting with a flow of l meter/second, or less.

I think Matthew is probably making the right decision to cut his losses.

Posted by Ken Hall on Nov 9, 2010 07:15 pm

#7 -  Renewable Energy > For Sale > Re: Submersible hydro UW100 for sale
Michael, if you click on Matthew's name at the top of one of his posts, it will take you to his profile.  His e-mail appears on that page.

Velocity (ft/s) x Area (ft^2)= volume flow rate (ft^3/s), not (gal/min).
If you want gpm, you have to multiply the cubic feet per second by 448.83 to obtain gpm.

Matthew, Where in PNG are you ?

Posted by Ken Hall on Aug 8, 2010 11:51 am

#8 -  Renewable Energy > Technical Discussion: Other > Re: Windmill with rotating sails
Your description "a vertical axle around which three sails spin around" is a Savonius wind turbine. There have been hundreds of these made since 1922.

So, you need to give us a much better description of it.  Or, provide a link or reference to where you heard of it.  Otherwise, we cannot tell what is new or revolutionary about it.

Posted by Ken Hall on Jul 28, 2010 06:42 pm

#9 -  Renewable Energy > Technical Discussion: Other > Re: backup generator hookup
Don’t tie the generator to the charge controller, a generator will burn up a solar controller.

You didn’t say what model inverter you have, or are considering.  Some off grid inverters have a good charging circuit in them. You can run house loads and simultaneously charge the batteries from a generator.

Depending on the size of your bank and what inverter you choose, you may want to consider a large battery charger run by the generator.

Posted by Ken Hall on May 18, 2010 03:13 pm

#10 -  Renewable Energy > Wanted > Re: Wanted, used deep cycle batteries in CT
GC2 is a battery group number.
They are golf cart batteries with max dimensions of 10 3/8 Length x  7 3/16 Wide x 10 5/8 Height.
They fall somewhere in between 200AH and 300AH depending on specific model or mfg.

Posted by Ken Hall on May 14, 2010 03:08 am

#11 -  Renewable Energy > Technical Discussion: Solar Water Pumping > Re: Newbie needs help with small solar water pump
The flow reduction is based on a couple of things.  The first is the height you are pumping. If the pump is pumping 40gph at 1 foot, it will do less at two, less at 3 and less at 4. In this case 4 feet is the Mfgs upper limit.

The second source of flow reduction is the pressure drop in the pipe or tubing.  Every foot adds to it, as do the different fittings. What that drop is, is affected by the length, the diameter, and how much water you are attempting to move through it. You can think of it as being similar to friction. 

Trying to move 40gph through the small tubing would be like having to pump the water an extra 15 inches higher.  By upsizing the tubing, the extra work is equivalent to about 3.5 inches.  So, we are saving almost a foot of pumping.

That one foot may be come important if your heights are slightly off.

If the Mfg is comfortable with the pump working many hours a day at a 4 foot lift, and we stay below that height (real height plus height equivalent losses), I wouldn’t worry about the motor. 

The thing that will kill it is if it becomes plugged with debris and cavitates or runs dry for long periods.  What are you planning to protect against that in the stream ?


Posted by Ken Hall on May 13, 2010 04:43 pm

#12 -  Renewable Energy > Technical Discussion: Solar Water Pumping > Re: Newbie needs help with small solar water pump
The Aquajet will NOT work for you, it only has a 1.5 foot lift (or head) capacity. So, you need to look at something larger.

The waterfall fountain kit has a lift of 4 feet, so it should work for your purpose.  Although they list the pump at 40 gallons an hour (gph), I would expect less than that.

It is common to list the gph at a low head.  It drops off with increased height and with longer tubing runs.  I would buy a 1/2 to 3/8 reducer and 1/2 tubing to extend the 3/8 tubing that is supplied.

You should also look at creating some type of overflow outlet for your trough and either return it to the stream, or pipe it some distance away from the trough before letting it flow out in the pasture.  Otherwise it may get real muddy around the trough.

I assume you have animals. Have you given any consideration to mounting the panel out of their reach and still having it in the sun without it being shaded ?  The supplied cord is 10 feet.



Posted by Ken Hall on May 5, 2010 02:05 am

#13 -  Renewable Energy > Technical Discussion: Other > Re: New to Solar Power - Beginner Questions
Sounds like the system will work, based on the numbers we have discussed.  A 40watt panel, 60ah battery, and a controller. 

I haven’t used any small controllers for years.  Maybe James or one of the other guys will jump in with a better  recommendation. 

I know Morningstar makes a 4.5 amp controller that ahould work (I’ve never used it),  but it would not leave any room for expansion if you decide to add another panel.  You will have to weigh the decision to go minimal and getting a new controller if expansion becomes necessary versus going with a somewhat larger controller now, that would allow a second panel if it becomes necessary or desirable.


Posted by Ken Hall on May 3, 2010 02:30 pm

#14 -  Renewable Energy > Technical Discussion: Other > Re: New to Solar Power - Beginner Questions
The big question is, How many hours a day are you expecting to run the pump/waterfall ??  We can’t really give good answers until we know that.

It would help if you would tell us the makes and models of the pump, battery etc.  It lets us tell you whether they are right for the job, and allows us to look up specific info that you may not have provided.

That being said, you have a miss-match between your pump and battery.  Your pump is going to draw about 3 amps. So it will be operating at a C4 discharge rate (would draw the battery flat in 4 hours.)  That is an extreme rate that would result in short life for the battery.  You should be discharging at something near a C20 rate for longer battery life. So that would mean a battery/bank of about 60 AH. (That size is subject to change based upon how many hours you are going to use it.)

I am guessing that your battery is most likely a rechargeable battery that is generally used for standby or electronic use.  If that is true, it is the wrong type to use for daily cycling with a motor load. 

Posted by Ken Hall on Apr 14, 2010 05:49 pm

#15 -  Renewable Energy > Technical Discussion: Other > Re: Backfeeding existing circuits
While you can reuse the wiring, you will need to replace the breakers with 15 amp breakers.

The wiring will be greatly oversized. So if it isn’t going real close to where it needs to be, I think I would abandon it in place and just make some new home runs with more appropriate sized wire

The first ac connector in each branch circuit (a connector in the enphase supplied connector cable) is approved as your ac disconnect.  However, your local building inspector or your local utility may require some sort of separate AC disconnect closer to your breaker box, because they are used to seeing it on other solar systems. If either of them wants the additional disconnect, it will save both time and money to put it in, rather than to argue the point.  When you go in for the permit, discuss the issue with them.

Posted by Ken Hall on Apr 13, 2010 04:42 pm

#16 -  Renewable Energy > Technical Discussion: Other > Re: How to connect a generator with a battery(12v) or with a lamp?
Great !
Please post your results with it.  We like to hear how things work out.
Best of luck,

Posted by Ken Hall on Apr 13, 2010 02:56 pm

#17 -  Renewable Energy > Technical Discussion: Other > Re: How to connect a generator with a battery(12v) or with a lamp?
If your speaker cables are a full 2 mm, that would make them about #12AWG.  So you should have been good for at least 5 amps or so. Probably not the problem, right now. 

I have been trying to find the specs on the Ametek 60, but have not found them.  Do you know what the rated rpm is ??

From the comments that I have seen, The rpm is most likely the problem, even in winds of  6-8m/s (15-18mph). 

If the rpm problem is as big as I suspect, I would NOT try cutting down the blade length.  The marginal rpm gain will not help. 

You may be in the position where you have two choices.
1)Get a different motor to use as a generator.
2)Increase your blade length for greater torque, and then use a step up gearing to spin the generator faster than the blade rpm.



Posted by Ken Hall on Apr 12, 2010 12:45 pm

#18 -  Renewable Energy > Technical Discussion: Other > Re: How to connect a generator with a battery(12v) or with a lamp?
Your cable might be a problem now, it will definitely be one later.

You said that you checked the output voltage when the wind was "high". What is your best guess of the windspeed.

Where did you take your output voltage measurement?  At the generator
terminals or over near the battery/controller ?

Were the controller and battery online, or were you measuring open circuit voltage ?
What is the wire gauge of your speaker cables and how many feet of it are used from the generator to the battery/controller.

Posted by Ken Hall on Apr 2, 2010 02:00 pm

#19 -  Renewable Energy > RE General Discussion > Re: Rodent protection
I haven't had the problem with PV. If I did, I would try using spiral wrap.
I've had good luck with it in other "chewing" applications. I would use a larger size than the above,probably 1/2 to 1 inch. I selected the above page for the photo.
You could also try split tubing.  But with either one, make sure it is a UV resistent type. The indoor stuff won't last very long outdooors.


Posted by Ken Hall on Jan 12, 2010 02:19 am

#20 -  Renewable Energy > Technical Discussion: Other > Re: Charge controller needed for mini hydro
PV is an exotic form of generation.  The controller is trying to coax more power out of the panels for better efficiency. It then turns around and simultaneously looks at protecting the battery. That is why you have solar charge controllers.

With your hydro set up, the generator is going to produce a certain power level based on the current flow and the excitation logarithm. That power will come charging out like the bulls of Pamplona.  It is active generation, not the passive generation of PV.

Until you are in a hydro unit large enough to justify the expense of flow control and excitation control to back the production down, you just have to take the full amount and do something with the excess.

You seem to be thinking that because solar works better with complex control, the same complex control is needed on hydro.

With diversion control, all it needs to worry about is protecting the battery. When the battery voltage hits the preset level, it starts diverting enough wattage to maintain the appropriate voltage.  When the battery is full, all the wattage will be diverted.

Something you said gives me the feeling that you think dumping power is bad.  Question for you.  What is the difference between dumping excess power off of a hydro, and not producing the same amount of power with a PV panel because the controller choked it off?

To me, they are both equally wasteful.  The difference is that if you choose the right diversion load (e.g. preheating hot water or pumping water to storage) you can have more efficient use of your generation. (Higher capacity factor)  You may also be saving some other form of energy.

Posted by Ken Hall on Jan 6, 2010 02:21 am

#21 -  Renewable Energy > Technical Discussion: Other > Re: Charge controller needed for mini hydro
It really depends on your battery bank size and your usage pattern.

A lot of the manual is written for marine applications where the battery banks are smaller than RE battery banks. In the marine application, there may not be a daily draw on the battery. So, there may be long periods of full battery banks and high voltage.

In a RE application with daily usage, the full battery period will be fairly brief, or may not even exist. Usually, a diversion controller is all you will need.

Don't be surprised if your actual generation is less than you are figuring. The "Jack Rabbit" is known for it's optimistic performance curves, particularly for an in-stream application.


Posted by Ken Hall on Jan 5, 2010 01:10 am

#22 -  Renewable Energy > Technical Discussion: Other > Re: Charge controller needed for mini hydro
Diversion control is the way to go with small hydro (or wind) turbines. If you try putting a PV type charge controller on it, you will burn something up.

If you don't like the high low choice of the ampair, you could use a Xantrex C series controller instead. (as a diverion controller, not a charge controller.)

Posted by Ken Hall on Dec 14, 2009 02:23 am

#23 -  Renewable Energy > RE General Discussion > Re: Hydro power from 60 foot water falls
Here's another site that may help you.


Posted by Ken Hall on Dec 13, 2009 01:33 pm

#24 -  Renewable Energy > RE General Discussion > Re: Hydro power from 60 foot water falls
The most applicable page is

Note the quote in the last box at the bottom of the page.
“A waterwheel is really designed to do mechanical work”

It is far easier to generate power with high head and lower flow, than to give up the available head and be forced to use a much greater flow.  The less water you divert from the stream, the lower your impact will be.

Water wheels do not like changing water levels.  The headgates, flumes, millraces, or other methods to protect the wheel from the changing levels/flows can be major projects in themselves.

Water wheels do have a certain majesty about them.  I love them(just like steam engines). But they are way down the list when it comes to generating electricity.   

Posted by Ken Hall on Dec 10, 2009 06:41 pm

#25 -  Renewable Energy > RE General Discussion > Re: Hydro power from 60 foot water falls

The biggest question is how much power are you talking about ? How many kilowatt-hours a month (or a day) are you currently using ?

If you are looking at around 18 kWh a day or less, you might be able to do it with a Stream Engine and some 4 inch pipe. In round numbers you would be looking at about 130-140gpm for about 750 watts. It could be done with PVC pipe.
If you are using significantly more power, you would need a larger turbine and larger pipe.

I don’t think flow is a problem, but hear is a link to how you can measure it.
I would pick a spot upstream of the falls to do your measuring.

What is the high water that you are worried about ?  Are you worried about the intake ? Or is it that you would need to locate the turbine up the bank (reducing the available head) to keep the water pool below the falls from flooding out the turbine ?  Or both ?

Speaking of high water, how much silt/sand/mud is suspended in the water during peak flows ?  Many times it is enough that the turbine should be shut down during peak flows to prevent excessive wear on the turbine wheel. This item could impact whether you go off grid, or stay grid connected and produce some, but not necessarily all of your power. 


Posted by Ken Hall on Oct 28, 2009 01:27 am

#26 -  Renewable Energy > Technical Discussion: Other > Re: Do I need to charge a new battery before I install for a PV system?
Sounds reasonable.
Good luck with it.


Posted by Ken Hall on Oct 27, 2009 01:49 am

#27 -  Renewable Energy > Technical Discussion: Other > Re: Do I need to charge a new battery before I install for a PV system?
You might want to give us a full description of your solar system.
How many of those batteries do you have ?
How many watts of PV ?
What type of charge controller ?
What loads do you plan on supporting with the system ? (how many watts for how many hours)

Those are very small batteries. They are designed for wheelchairs. With anything larger than an extremely small system, you will overwork the batteries.  Overworked batteries have an extremely short lifetime.

Posted by Ken Hall on Sep 28, 2009 12:53 pm

#28 -  Renewable Energy > Technical Discussion: Other > Re: PV panel on wheelchair
What are you trying to achieve ?
What is the amp hour rating of your batteries ?

If your chair is using the 35AH batteries or larger, the 5 watt panel is not going to provide any significant contribution to range or length of use.

Is it worth the cost/trouble just for novelty value ?

Posted by Ken Hall on Sep 26, 2009 12:49 pm

#29 -  Renewable Energy > Technical Discussion: Other > Re: question about switch panel and fuses
Cigarette lighter plugs and receptacles are not code compliant. If you want to be totally compliant, you will need to use different receptacles and then make an adapter to the cigarette type device.

You can use a number of 125V or 250V receptacles for your DC system, as long as they are not used elsewhere in the house and they are labeled.  The NEMA 6-15r is one that is a good one. It is rarely used in households.
It is also available in a duplex configuration, but the single is generally easier to find. It is available at Lowes or Home depot.

I’ve seen a few people use the NEMA L5-15r or L5-20r twist lock receptacles.

Finding light switches is a problem, if you want them to look like light switches.  If you don’t mind metal toggles switches, then they are easier to find. Code requires an AC-DC General-Use Snap Switch.

A code compliant, 12VDC motion switch, that is fluorescent compatible ?? Good luck.

Posted by Ken Hall on Sep 23, 2009 12:43 pm

#30 -  Renewable Energy > RE General Discussion > Re: hebco wind generator newbie quetion
You have a museum piece. You should restore it, or sell it to someone that will. I would hate to see it reduced to just a generator, hooked to a Chinese diesel.

Dave's history is a pretty good one.  The one clarification is that Hebco was definitely not the first to generate from wind power.  Hebco (or the Herbert E Bucklen Corp./ Bucklen himself) is credited as being the first to use an airplane type propeller, instead of the windmill type multiblades (with huge step up gearing), for wind generation. So, it would be the first modern wind turbine versus earlier windmills.

I would try contacting the Elkhart Historical Society and the Elkhart County Museum.  They should have old newspaper clippings, advertising flyers,etc.  They may have some old-timer that has more knowledge.  The Bucklens are an old family in the area.  Your interest is in HEB II.  His father made a fortune in “patent medicine”.

If you know which airfield that unit came from, searching the local museum and newspaper files might give you more info.

I am not sure what became of HEBCO.  They either folded or got sold off in the early 30’s.  The depression, completion from Jacobs, and the Rural Electrification Act probably did them in.  HEB II founded the Durakool Company (Makers of switches and relays) in 1935.

You might try contacting Wind Turbine Industries.
They are the supporters of the old Jacobs units.  They may have some knowledge of the HEBCO units. They would also be a good candidate to supply a prop for your machine.


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