Ken Hall's posts

Posted by Ken Hall on Jan 28, 2009 04:18 pm

#91 -  Renewable Energy > Technical Discussion: Other > Re: What is wrong with my system?
The first question is, how long are you running the light and TV ?
You said until midnight, but you didn’t say when you are turning them on.

My initial guess is that you are drawing the battery down too far and experiencing a low voltage shut off sometime during the night.

If you are leaving the draw switch on, the inverter puts about .6 amps load (about 7 watts) on the battery. Turning that switch off will reduce the load to less than 2 milliamps.

Disconnecting the inverter could allow the voltage to recover to above the low voltage disconnect limit, and would reset the inverter.

What type of solar charge controller are you using ?

You may also be estimating your load a little on the low side.  What make/model of TV do you have and how many watts is that light ?

Posted by Ken Hall on Jan 28, 2009 03:47 pm

#92 -  Renewable Energy > Technical Discussion: Other > Re: Permanent Magnet DC Motor wiring question
If I understand your post correctly, you are probably pedaling the bike and trickle charging a full battery (how big?) at 1-2 amps. You then turn on the inverter with light bulb (how many watts ?).  Sometime later, the pedaling resistance jumps.   Does the amp meter jump at the same time ?

I think your inverter/bulb are initially running off of the battery, while you are seeing the trickle charge load.  When the battery voltage drops down below “full”, your charge controller is kicking from “trickle charge” to “bulk charge”, so you are attempting to run the light bulb/inverter and charge the battery simultaneously.

If you want to test this, try running the battery down a ways with the inverter/bulb.  Then shut it off and start pedaling.  See if you get more resistance and higher amp readings than your current 1-2.

Posted by Ken Hall on Jan 21, 2009 04:03 pm

#93 -  AltE > Discussion > Re: Wind Power
"and the WIND,when it blows,can exceed 30 m/p/h gusts."
That is not what you want for a wind turbine. You want strong steady winds.
Here is the validated 50 meter windspeed map for Washington.

Note that the Seattle-Tacoma area does not even qualify as marginal. Vancouver is better off with a marginal rating.
You might have some wind potential. The map is aimed more at utility sized units.  But you need to start looking at your average annual wind speed and potential generation/pay back. You might be better off investing your "wind" dollars in more solar.
How many wind turbines have you seen in a five mile radius of your house ?


Posted by Ken Hall on Jan 21, 2009 03:23 pm

#94 -  Renewable Energy > Technical Discussion: Other > Re: Check My Calculation
I would take a look at landscape lighting. 5 watt 12vdc bulbs are availible in the MR11 floodlight style, although not every one stocks them. 4 watt and 7 watt wedge base bulbs are extremely common.


Posted by Ken Hall on Jan 20, 2009 03:26 pm

#95 -  Renewable Energy > Technical Discussion: Other > Re: Specific Gravity - are my batteries charged or not?
Good afternoon Sally.

A couple of suggestions for you.

I think you should dial back the charge voltage setpoint (I am assuming that is what you raised to 15.2) to something around 14.5.  That should still reduce the charge time without stressing the battery as much.

Watch your electrolyte levels like a hawk.  Running higher voltages can boil it away. It hasn't really been much of an issue because your panels have been working on a big battery that has generally been in a lower state of charge. Now that you have a charger, they will see a higher state of charge more often, and the higher voltage will actually come into play. 

You have not mentioned the optional temperature  compensation on the charge controller, so I assume that you do not have it.  I think it would be a wise investment for you, particularly with the wide range of ambient temps that you see during the year, and your use of higher than default voltage settings.

Until you get a few more panels, I would opt to run equaliztion charges with the charger.  You dont have enough panels to drive a really effective equalization charge.

Which charger did you decide on ?



Posted by Ken Hall on Jan 20, 2009 03:35 am

#96 -  Renewable Energy > Technical Discussion: Other > Re: Specific Gravity - are my batteries charged or not?

Which voltage did you set to 15.2 ?

I am assuming that your charge controller is a Blue Sky Solar boost.  Either a SB2512i or SB2512ix.  Please confirm the controller model.


Posted by Ken Hall on Jan 20, 2009 02:45 am

#97 -  Renewable Energy > RE General Discussion > Re: PV is a sellers market.
I don't know all of the plants. The panels could come from a number of places.  But, Kyocera does have a big maquiladora facility in Tijuana, Mexico. It produces about 35 megawatts of panels a year.  It is currently being expanded. They hope to have capacity for 150MW by 2011. Not sure where they currently are in between those two figures.


Posted by Ken Hall on Jan 19, 2009 03:26 pm

#98 -  Renewable Energy > Technical Discussion: Other > Re: Specific Gravity - are my batteries charged or not?
Meters can lie to you, for various reasons. Idiot lights are even worse. Hydometers generally do not. Trust it.

Were any of the adjacent cells more than 0.05 apart?
Also, what temp did the hydrometer give you when you took the readings?

If your system is still 2x80 watt panels, they are not going to charge that battery in 2 days.  You are probably getting no more than 2 hours of full sun equivelence at this time of year. That means you can only charge about 5-6% a day.  It will take over a week to bring the battery up from 50% to full.

I would suggest you get a charger on them. Get the batteries up to full charge and then monitor them.


Posted by Ken Hall on Jan 18, 2009 06:43 pm

#99 -  Renewable Energy > RE General Discussion > Re: PV is a sellers market.
I guess it depends what you mean by region.
I would break it down a lot smaller than West or Northwest. Oregon and Washington are generally less expensive than California, although in all three states, property within 20-50 miles of the coast tends to be more expensive than properties further inland.  Larger cities also tend to be more expensive than smaller towns. The worst is a large city in the coastal zone.

You can tie a lot of costs directly to real estate, including paying higher wages.

Labor laws and taxes can also impact costs. Some of the large chains find it less expensive to locate their distribution centers in Oregon or Nevada, and truck to California, versus operating a distribution center here.

While there are sellers that are gouging people, you need to look at the sellers margin.  It is quite possible that my local suppliers are operating on a smaller per unit margin than some guy in midwest, even though his listed prices are less.

Paying more to keep the people that you trust and can count on in business makes sense. The cheapest price from whomever, can cost you in the long run.


PS If you want a California on-line store that carries Kyocera, Wholesale Solar. Its on the solarbuzz list.

Posted by Ken Hall on Jan 18, 2009 04:53 pm

#100 -  Renewable Energy > Technical Discussion: Other > Re: Looking for a wind system wiring diagram

I am not sure what you are looking for exists in one document. You usually have to fit several diagrams together.

As far as a turbine goes, take a look at the AirX models.
Read the manual.
It has a pretty good diagram as far as the batteries.
It fits your 400watt size, but there are others available.

An inverter manual should give a good diagram of "Batteries to house". But we cannot recommend "an inverter" without knowing a little more about your idea of a system. What you are thinking about. Is this wind only, or will you be adding PV in the future ? Are you thinking a stand alone system, stand alone with grid backup, or what ? Have you identified the loads that you intend to put on the system ?

Answers to the above would impact recommendations as to what inverter to use.

Do you know what the average annual wind speed is in your location ?


Posted by Ken Hall on Jan 17, 2009 02:28 am

#101 -  Renewable Energy > Technical Discussion: Other > Re: Should I use Trojan or Interstate batteries?

Your question is a good one.
I think that before going into it, I want to say that the numbers we calculate are only as good as the data we have to start with.  We are making estimates, and looking for ballpark answers.  While we might come up with 21% DOD, that answer is often more precise than the data we started with. We often find that the actual depth of discharge does not match the original calculations.  We just hope the real numbers come within a few percent of the estimate.  If it isn’t, the problem will generally be in the load estimates that we are given.

Having said that:
If somehow your load matched the generation perfectly, The battery would not be in use as long as that condition was maintained. The impact of that would result in a DOD that is less than calculated. E.g.  we calc’ed for 20%, but you used 5% worth as it was generated, so the actual DOD would be 15%.  But that almost never happens.

The battery is usually charging or discharging.  If our system is generating exactly 800W, what are the odds of having exactly 800W worth of load during the day?  Usually, we will be under that figure, so the battery is charging, in spite of some of the 800W being used. If we go over the 800W (perhaps using the stove for lunch) we will experience a short minor discharge cycle in the middle of what is normally a “charging period”.  My experience is that the minor discharge cycle either doesn’t count, or you could say that it is somehow averaged into the numbers.  The figure that is going to count the most, is the greatest depth of discharge that occurred during the 24 hour period, or since the last major charge cycle.

And here, we are really talking average depth of discharge over many days.  If you run 30 days at a 20% DOD, and then have one to 50%. What does that work out to ?  20.96774% average depth of discharge over 31 days.  (How is that for an overly precise number ?) The bottom line is that you averaged somewhere in the ballpark of 21% over the 31 day period.  (And the 20 percent figure for the first 30 days was also probably bouncing around in say the 18-22% range).

A couple of percentage points really doesn’t matter much. What we do know is that when your “about 20% DOD” drops to “about 30% DOD” your battery life will be shorter. And it get shorter for about every 10% it drops.

I hope that answered your question. 



Posted by Ken Hall on Jan 15, 2009 02:53 pm

#102 -  Renewable Energy > Technical Discussion: Other > Re: Want to build a small offgrid system
You are doing it backwards.
Identify the loads that you are going to try to support.
When you have a total watt hours per day, then you size the battery bank and panels.
Start here:


Posted by Ken Hall on Jan 15, 2009 02:47 pm

#103 -  Renewable Energy > Technical Discussion: Other > Re: Should I use Trojan or Interstate batteries?
Here is an article for you on the life and death of batteries.
Take a look at the section and chart about halfway down, on depth of discharge.

While you may only be getting two hours of full sun now, this summer you should be getting something around 4.5 hours. With your current panels, it is about 6KWh or 125Ah a day. When you increase the panels, it will be closer to 9KWh or 189Ah a day. 

189Ah would equate to a 50% DOD on the 37AH bank of eight batteries. 
I would give serious consideration to increasing your bank size to 16, and limiting the depth of discharge to about 25%.  If you cut your daily draw in the winter to something close to your generation, you would be running less than 10% DOD during winter.  That should more than double the life of your batteries. (Talking about the life of the L-16’s, not your previous batteries)

As far as which battery to purchase, I have had good service with both.  Interstate makes a good battery, but I believe the Trojans are a little better, and give a longer life in identical service. 

I glanced at the info Dave supplied, and question the 3300 cycle life for “Interstates” vs 2800 for the Trojans.  We cannot safely assume that the US battery L-16 listed and the Interstate L-16 are identical. I would also look at the warrantee. USB 1 year, Trojan 7 years (I believe that is 3 years free, and prorated to 7).   

 If it were me, I would go talk to the Trojan dealer and see what type of deal he would be willing to make for me on a bank of 16 batteries.  If you are going with eight, you might as well go with the Interstate and put the “saved” 55 dollars towards your next battery purchase.


Posted by Ken Hall on Jan 14, 2009 07:13 pm

#104 -  Renewable Energy > Technical Discussion: Other > Re: Distance of Inverter from batteries
The unloaded speed of a dc motor is essentially lineal.  In other words you will get X rpm for every volt applied.  However, we don’t know what that unloaded speed is. All we have is the loaded speed, which is some percentage of the unloaded speed.

When you drive it as a generator, the voltage is not directly lineal to rpm. 

In a quick glance of at the images, the flywheel and added bearing appeared when they are driving the generator on an extended shaft, using a light bicycle wheel.  Extending the shaft adds the bearing and the flywheel is (presumably) to cut down on surges from the peddling.

Most of the exercise bikes that I have seen, have a heavier wheel which acts as a flywheel to limit rpm surges, so you probably will not need to add one. If you drive the motor with the current shaft length, it should be designed for the forces. Lengthen it too much, and additional support will be required.

Posted by Ken Hall on Jan 14, 2009 05:41 pm

#105 -  Renewable Energy > Technical Discussion: Other > Re: Should I use Trojan or Interstate batteries?
I am far more concerned with the size of your battery bank, than who makes it. You did not specifically mention size, but I get the impression you are talking about eight batteries.  You should not go smaller. I think you should be going larger, if you want a long life for your battery bank. How much larger depends on where it is located.

Your comment that you just use whatever you make, is bothersome.  How deep of a daily discharge are you planning for this new bank?


Posted by Ken Hall on Jan 14, 2009 02:30 pm

#106 -  Renewable Energy > Technical Discussion: Other > Re: Solar system calculator
If you are using 12V batteries that are 274Ah or greater yes.
But if you are using 6V batteries, each string would be two batteries, for a total of 6.
If you were using 2V batteries, you would have 18.

Posted by Ken Hall on Jan 13, 2009 01:28 pm

#107 -  Renewable Energy > Technical Discussion: Other > Re: Distance of Inverter from batteries
I am not following you.
You say you want 100 watts at 12VDC.
You then talk about driving the motor at rated rpm. That is a 24VDC 250 watt motor. Driven at 2500 rpm, it should produce about 200 watts at 24VDC.
Your 100 watts at 12VDC should occur lower in the RPM range. You might want to find someone that has a good lathe (or variable speed drill press).  Spin the motor at various RPMs with a load on it, and find your target RPM.


Posted by Ken Hall on Jan 12, 2009 11:37 am

#108 -  Renewable Energy > RE General Discussion > Re: Solar vs. Wind
There are plenty of free sites (no registration required) that provide info on solar and wind.  So, I am not sure what "secrets" are being promoted by the site you linked to.

There are many areas of the country that do NOT have a decent wind resource. Since you gave no details as to where your installation site is, or what the wind resource is there, the probability says you will have a better solar resource.  So, go solar.

Posted by Ken Hall on Jan 9, 2009 03:40 pm

#109 -  Renewable Energy > RE General Discussion > Re: function of a voltage regulator
3-4 hours of winter sun, particularly if it is near mid-day can still give you a surprising amount of heat gain for a hot water system.  Mid summer, even more.
You might want to spend a little time on the subject. If you are in a cold climate, possibly something like this.
In warmer areas, you can get by with a less expensive option.

At the very least, you will have learned something and have another bright idea for your pile.  But you may find it to have a fairly short payback, particularly since you seem to be all electric on your hot water.


Posted by Ken Hall on Jan 7, 2009 01:32 pm

#110 -  Renewable Energy > RE General Discussion > Re: function of a voltage regulator
Oh my gosh,  it’s the “Jack Rabbit” in stream generator. I didn’t realize that they were still available.  The US distributor quit handling them some time ago.

If the company hasn’t tweaked the machine or redone their production curves, you will find that they are optimistic.  Don’t be surprised if your actual production is about 15% lower than published.
Also, are you working with measured stream speeds, or are you estimating them ?  If you are estimating, I would suggest you measure, now.

You are building a complicated system to gain the heat of about a 75 watt light bulb (maybe 60W ?).
It is not enough to heat your house, or your domestic water. So it will take coordination with the 110v system in both tanks.  By removing the second element of each (to install the 24V) you are dropping the recovery time/ultimate daily capacity of both systems.

I don’t like generating electricity to heat water, at least not when direct solar heating is viable. But if I was too far north or had some other compelling reason to do it, I would install a 10-15 gallon tank in front of my domestic water heater as a preheater. Use all my generated power there. If the tank ever reached max temp and the thermostatic switch opened, a diversion load controller (or other relay scheme) would shunt the power to a second heater element in an outside water tank.  With normal hot water use, the diversion would never happen. It would only kick in when you are gone more than a day. If you are going to be gone longer than a day or two, shut down the hydro.

By using all the power as preheat to your domestic hot water heater, the hot water heater will automatically, use that much less energy.  You will get full benefit of the energy, without the complications of trying to transfer it between two systems, or coordinate it with the 110V systems.   


Posted by Ken Hall on Jan 6, 2009 08:15 pm

#111 -  Renewable Energy > RE General Discussion > Re: Airbird Wind Turbines
Here is the Calif. CEC List of approved small wind turbines.
If the Mfg isn't on this list, I would suggest you steer clear of them.

If your state has a rebate program on wind, you should look for a similar listing.


Posted by Ken Hall on Jan 6, 2009 11:59 am

#112 -  Renewable Energy > Technical Discussion: Other > Re: Calculate number of panels needed
The calculators you need are located at


Posted by Ken Hall on Jan 4, 2009 01:11 pm

#113 -  Renewable Energy > RE General Discussion > Re: function of a voltage regulator
I think Roger needs to clarify what he is attempting with the two water heaters.  How much water is he trying to heat, How much of a temp rise is he looking for, how much water is drawn out per day (and replaced by cold water), etc.
Assuming 60 degree F. water to be heated to 120 degrees, there is only enough power for roughly 15 gallons/day.
The second water heater may be out of the question.

Posted by Ken Hall on Jan 3, 2009 06:32 pm

#114 -  Renewable Energy > Technical Discussion: Other > Re: basic inverter wiring question
Romex is not approved for use as a flexible cord.
Cord caps (male plugs) are not approved for use with romex.

Why don't you get a short length of SJ cord (or some other approved power cord) ?   Use a Junction box and connect the romex and the SJ inside the box.

Posted by Ken Hall on Dec 11, 2008 12:03 pm

#115 -  Renewable Energy > RE General Discussion > Re: What will replace oil wells-?
The engine/generator/electric motor drive is not as efficient as a mechanical drive system.  It is used on trains because it gives them great tractive force for starting, without having to slip a clutch.  It also allows dynamic braking (where they waste the electricity as heat, instead of storing it).

The currently available hybrid drives are much more efficient than the “train system”, for automobiles.  Yes, they could be even more efficient if they used a small diesel hybrid (or biodiesel) drive.

Fuel cells hold the "promise" of greater efficiency, as they eliminate the IC engine/generator (and associated losses) from the equation. But they are not fully developed yet.

The only way the “train system” will be more efficient, is if we use it for trains and dramatically cut back on our use of cars.  (Gee whiz, public transportation)

An even better system is to electrify the major rail lines and use stationary power plants.  With a 3rd rail or overhead wire system, the energy from dynamic braking can be put back on the system, rather than being wasted (regenerative braking).

Posted by Ken Hall on Dec 7, 2008 02:15 am

#116 -  Renewable Energy > RE General Discussion > Re: can conservation be immoral?
The only thing that sounds crazy or too extreme is "100% electric" and "33 degrees outside".  Unless the building isn't plumbed for gas, or some other reason, that is crazy.

I lived in Germany as a GI. I heated my apartment with coal. No Refrigerator. We cooled our bier with cold water from a well (hand pumped, the well was colder than the city tap water). In the winter, you would set it out on the windowsill or balcony. Had to bring it in before it froze.

Extreme is only a matter of perspective.

It is always “warm” in California. Felt a bit chilly today. Midday temp was only 52. But that is cold for us. I may have had to scrape ice off the windshield one or two mornings so far this fall, but I really don’t remember if I did or not. Usually, a squeegee will take care of the condensation.

Take care,

Posted by Ken Hall on Dec 6, 2008 07:43 pm

#117 -  Renewable Energy > RE General Discussion > Re: can conservation be immoral?
I don't see a problem. If there was, your apt would probably be warmer than 60 and cooler than 90.

The neighbors above and below you and the ones on either side would be the ones bearing the injustice (if there is any).  It would not affect "everyone in the building".

If your door opens onto a common area where the bill is shared and you were proping the door open to get your heat or cooling, he would have reason to complain.

Is your heat actually electric ?

Posted by Ken Hall on Dec 3, 2008 01:54 pm

#118 -  Renewable Energy > RE General Discussion > Re: What will replace oil wells-?
"plenty of room for all, and them some."
Are you sure about that ?

The physical space problem is the easiest. It is just a little more density per sq mile.
But we have a problem of feeding the world's current population.

We also have an energy problem. Even without any more population growth, as the developing nations make progress, their per capita energy use is going to go up dramatically. Currently China's per capita use is skyrocketing.

We in the US, have the one of the most abundant food supplies in the world. We also consume a substantial portion of the world’s energy.

How much of your food and energy use are you willing to sacrifice, to provide a more equal distribution around the world ? (a: for the current population, b: for an increasing pop.)


Posted by Ken Hall on Dec 3, 2008 01:26 am

#119 -  Renewable Energy > RE General Discussion > Re: What will replace oil wells-?
"Solar thermal is an efficient way to heat water."

Solar Thermal is also a great way to make electricity on a industrial scale.  Most of the current solar power plants being built in Calif. are not PV, but some form of solar thermal. 
The one I am waiting to see is the solar/stirling engine project, which is in progress.

Posted by Ken Hall on Dec 2, 2008 12:27 pm

#120 -  Renewable Energy > RE General Discussion > Re: What will replace oil wells-?
Why are you limiting it to PV panels ?
Haven't you heard of solar thermal ?

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