Jon C's posts

Joseph, for some reason, the site would not allow me to reply to your post, so I am posting my reply in this manner.  I have been using solar PV water heat for several years now with excellent results and no problems.  I am using 50vdc from 4 solar panels in series through a 120v/1200W lower element in a standard 30 gallon electric water heater.  The element has a resistance of 10 ohms, which passes 5 amps of current from 50vdc.  This is 250 watts of heating power.  (The upper element is still available for AC usage for emergency heat should the DC heat fail.)  I use a relay operated by the standard thermostat in the water heater to switch the 50vdc in and out of the heating element.   You cannot use the thermostat for directly switching DC power to the heater element because the DC will ionize the thermostat gap and will burn the thermostat contacts.  Thus the use of a switching relay to buffer the thermostat.  Any further questions, feel free to contact me at  JonChristenson @ msn.com   :-)

Ken, I made an error in the last post.  I intended to suggest adding only half the amount of additional panels, or four panels, not two.  This would theoretically produce 50 amps of charging current for the battery bank, and not overload the 60 amp charge controller. 

Ken, there are many variables here, but if I understand the parameters correctly, you have a solar panel power source of 8-200 watt panels which yields 1600 watts of power in full sunlight.  This would produce 33 amps of current at 48 volts.  Since your charge controller is rated at 60 amps, you could almost double the number of solar panels.  Keep in mind that there are surges in panel output when going from cloudy to full sun condition as the panels cool and then reheat (cloud effect), so you might want to add only two more of the same type of panel, instead of four and risk an overload of the charge controller.  Batteries, in my experience, are only 50-75% efficient in returning usable power to your system, but by increasing the number of batteries in the array, you increase their efficiency by drawing less power from each cell under normal load conditions.  So, in my experience, even though you are distributing a smaller charge current to each cell, and requiring more time to produce a full charge condition, you are also drawing less power from each cell and increasing the battery efficiency.   I wish you good fortune with your system.  :-)  Jon C.

Hi Ken.  I am in a similar situation located just south of Manitoba with a 48v system, and limited solar power during the winter months.  Do you have the option of using wind power?  I get most of my electrical power from the strong NW winds in winter and the wind turbines often produce more power than I need to maintain battery charge.  I simply dump the excess power into heating of the residence.  Perhaps increasing your battery capacity would help?  I have doubled my battery bank and found that it helps to reduce the depth of discharge.  I also use a backup generator for extended "down" times of wind and solar energy resource.   Jon C. 

Hello Adam.  I currently use DC to heat water using 50VDC on a conventional 1440 W, 120VAC element.  I am using the lower "trickle" heater, as you call it.  The element resistance is 10 ohms, which produces a current of 5 amps and a heating power of 250 watts.  Since we use little hot water, it works fine for us.  I use a timer to switch power on for 12 hours during the day, and shut off the power at night, since no hot water is being used during sleep time.  This minimizes any safety problem with overheating due to a stuck thermostat.  I did experience a problem initially, however, and wish to share this with you.  The 240vac/10a stat that you mention is the same as the one that I am using, and the contacts will burn from using DC current.  The life span is then very short.  I modified my electrical configuration to use a DC relay to switch the 50VDC to the heater element.  The thermostat then supplies only a small current to the relay coil and so far has operated without fault for several years time.  I am operating my household off the grid, and find this technique to be very efficient.  I wish you good fortune in your endeavors.  Jon C.

Ibraheem, it seems that no one is answering your last question about multiple inverter charging, so I will respond with my experience.  I have two inverters operating from the same battery bank, and they are charge inverters similar to yours.  I operate them in LBX (low battery transfer) mode, which has a programmable setpoint for recharge voltage level.  Invariably, one inverter will switch to recharge first and assume the charging function, thereby disabling the recharge mode for the other inverter.  There is no problem with this arrangement as either inverter can assume the job of charging the batteries, and the batteries don't care which inverter is taking care of them.  I hope that this answers your question.  :-)  Jon C.

You are most welcome, Simon.  :-)

Simon, your line voltage reading is correct.  An AC meter reads voltage in RMS value which is .707 x peak voltage.  So, your meter reading of 9.1 divided by .707 equals 12.87 peak volts.  Your battery is being charged by the peak voltage.  If you connected an oscilloscope in place of the meter, you would see that the peak voltage exceeds battery voltage and that is why charging is taking place.  Jon C.

Hi Steven.  Yes, I have some thoughts on the electric motor powered generator, or alternator, if you are using it to produce AC power.  You state that after an initial startup by battery, the electric motor will run on its own generator produced power?  This is theoretically impossible, since both the motor and generator have losses in power conversion and one cannot get more power out than is put in to a source.
The monthly electric bill of $15 is likely the utility company rent for having wired their power source into your building, and may not indicate any actual power consumption at your structure.   The previous genius owner must have had some power source to run the electric motor/generator combination that was independent of utility company power in order to have an electric bill which is that low.  The way to gauge actual power consumption from the utility would be to read the watt meter which they placed at the point of entry for the utility power line.
If you have experimented with solar and wind power and have been dissatisfied with the results it may be that you do not have good enough exposure to those sources of energy or you did not commit to an adequately sized installation of solar panels and wind turbines.   I wish you good fortune on your mensa project.  :-)  Jon C.

You are most welcome, Simon.  :-)

Hi Simon.  Yes, increasing the number of turns of wire in the PMG will increase the voltage, since each turn contributes to the resultant output voltage.  If you must decrease wire size in order to accomplish that, or keep the same size wire, there will be an effect of increased resistance in the windings, and a subsequent voltage drop under load due to power losses in the smaller wire, so it is a tradeoff........more voltage out, but more internal losses.  This may or may not work for you, and I think that you will have to experiment with this to determine the results.  I wish you good fortune in your project.  Jon C.

Hello again, Simon.  You simply do not have enough turns of wire on the PMG to generate over 12v at 200rpm.  The only other way to get more voltage would be to DC - DC convert the output to a higher voltage, but then you would suffer losses in the converter and wiring, and realize a smaller output wattage overall.  You could, as I said earlier, put larger, more efficient blades on the turbine, or increase the efficiency of the turbine itself.  If you don't have sufficient wind at your site to spool up the turbine at adequate speed, you might raise the mast height or find a better location for the turbine.  I got the impression that your PMG is homemade?  Might I suggest buying a commercially made wind turbine that may satisfy your charging requirements?  Jon C.

Simon, your question is confusing, because you state that the PMG generates 368 watts under no load.  Since wattage is a product of both voltage and current ( P(watts) = E(voltage) x I (current), you must have a current flow through a load to be able to measure wattage.  So, how can you possibly determine wattage with no load?  Generally speaking, a generator produces an open load voltage that is higher than that when it is under load, but the current is determined by the amount of power that can be extracted from the wind, the efficiency of the PMG, and the losses due to resistance of the wiring in the generator and in connective wires to the load, and the voltage would be clamped at or near your nominal battery voltage, since you are using the battery as a load.  In order to get more power from the PMG, you would need to have less resistance in the windings of the PMG, or increase efficiency of the turbine blades, or have greater strength of the permanent magnets or their coupling to the windings.  Increasing the length of the turbine blades is an easy way to capture more power from the wind, since it is dependent on swept area.  Just my suggestion.  :-)  Jon C.

A simple bench experiment would prove this concept.  If you series wired a C cell and an AA cell (battery neg to pos), and a flashlight bulb, you would have a 3 volt battery pack using the bulb as a load device.  (sub C and AA nicad battery would be a better example of a rechargeable power source and would yield better result).  Assuming a fresh charge on the batteries, the bulb would burn brightly at first, and then, after some time, the bulb would dim as the batteries run out of capacity.  The first battery to go flat would be the smaller AA battery, and the C battery would not serve to charge it further, but rather, would discharge it further.  Eventually, the smaller AA battery would totally run out of capacity and would go resistive, exhibiting a reverse polarity voltage across its terminals.  The battery may or may not recover from this discharge state, and may be permanently damaged by the polarity reversal.  A lead acid battery most certainly would be permanently damaged.  From this test, one can conclude that the capacity of the battery pack is that of the smallest battery, and that the batteries should have been the same capacity rating for best results.  All multiple cell battery packs are, or should be, critically balanced for cell capacity to get the best performance from the battery pack.   If you have had experience with rechargeable battery packs and banks, as I have, you should know this concept. 

Thomas, discharge current flows externally from negative to positive terminal of a battery.  Charge current flows just the opposite, internally from negative to positive in the battery.  In a series string of batteries, if the smallest battery loses charge capacity first, then the other batteries will force a current through it that is reverse to a charging current.  I.E. from positive to negative, internally.  Current is the same in all parts of a series circuit and would have to flow this way through the small battery.  This would, in fact ruin the smaller battery by forcing a current that is in reverse to a charging current.   Jon C.

Hi Kay.  Looks like no one is anxious to jump on this one, but I will take a stab at it.  I am not an expert on lead/acid batteries, but common sense tells me that this series combination would be a very bad one.  The useful capacity of the string would be that of the smallest amp/hr battery, the Rolls 6v 683amp/hr.........it would be the first one to discharge, since the current is the same in all components of a series configuration.  After it discharged, the other batteries, being larger, would still have charge capacity, and they would be forcing a current through the 6v Rolls that would ruin it for any further use  other than lead ballast weight.  If you are going to wire batteries in series, they should be the same voltage, amp/hr rating, and preferably the same age, in order to avoid a situation where the oldest battery ruins the string and renders the newer batteries useless as well.  Jon C.

Awesome post there, Thomas!  You have certainly done your homework, and you are right that most of us do this piecemeal as we can afford it and learn as we go.  When people ask me about the economics of my system, they are somewhat disillusioned, as they are looking for some kind of monetary reward or payback........that's not the reason we do this......it's to do something for the planet and for our own independence and freedom, and that is the reward.  I also have switchgrass on my farm and was interested to learn that it is a great source of biofuel alcohol when properly processed.  The infrastructure here is only tailored at present for corn processing, and I really don't like to see food used as fuel.....food should be used to feed people and there is less farm land available for that as time goes on.  One can only hope that people eventually adapt to their needs for conveniences in more efficient ways  and stop wasteful consumption of non-renewable resources. I wish you good fortune in your future endeavors.  :-)  Jon C.

No offense taken, Thomas.  Doing the same thing here.......proposing other possible scenarios.  We hear about enough systems that are not working properly, so it's always refreshing to hear about systems that actually do work.  It's senseless to argue about something that works. I use similar redundancy with regard to solar panel capacity, and battery capacity.  Works well for me.  :-)  Jon C.

Gee, Thomas, I was responding to Travis and didn't mean to refute your logic, even though you chose to refute mine.  I think that this technology is very much dependent on location and wind/solar conditions that exist in our individual areas. My whole idea in pursuing this alternative energy concept was to get away from using fossil fuels or anything burnable like propane, natural gas, fuel oil, etc., and I have accomplished that goal.  Expenditures had little to do with that goal.......Independence and freedom from conventional power sources was the primary consideration, and it is hard to put a price on that.  I am pleased that you are happy with your system, and was only sharing my experience with others.....that is what this forum is for.  I appreciate your input as well.  :-)  Jon C.

Hi Travis.  I would agree with Thomas that mounting wind turbines on a building may be unsatisfactory from a structural and noise standpoint.  I tried mounting one on the side of a garage, and found the noise rather unsettling.  The mounting brackets tend to loosen up from vibration and perhaps a shock absorbing mount would offer some relief from these problems.  I am using SWWP Whisper 200's on guyed poles and am very pleased with the performance of them for the last 4 years.  I chose SW over Bergey at the time, because SW offered a 48v wiring option that matches my battery backup system for off grid operation.  I do however prefer the redundancy of three smaller turbines over one big turbine....If you have turbine failure, it will likely not affect all three at once, and you will still have two operational turbines to get by as you repair the third one.  I also had a lightning strike on one turbine which destroyed an insulator on the brushes, and it seems that lightning only strikes one turbine at a time, so I was still able to run on the other two before springtime and the opportunity to repair the defective one. (SWWP was very helpful and speedy in sending me a replacement part)  If you oversize your wind generator capacity, you could probably get by with a shorter turbine mast and not have such a large ground footprint for the cable anchors.  I am using 40 foot masts and have no problems with the reduced output, since I am using one more turbine than required to satisfy my electrical consumption needs.  I wish you good fortune in your project.  :-)  Jon C.

Travis, I am pleased that your project is living up to your expectations.  I do not see any fuses between the capacitors or between capacitor and battery, and quite frankly, this scares me.  I know you do not have a death wish, but you are tempting the electrical demons as I see it.  Just a friendly reminder?  :-)  Jon C.

Travis.  Any resistive equalization would represent a power drain on your system and would be counterproductive in my opinion.  You have already seen a sample of the kind of fire you are playing with when you dropped the wrench across capacitor terminals, but do you realize the worst case scenario......The 2.5 volt rating on the capacitors is an indication of the dielectric strength of the separator material in the capacitors, and if this voltage is exceeded, the capacitor may experience a separator failure which usually means instant death for the capacitor.  Capacitors do not die quietly however, and discharge all of the stored energy instantaneously along with fire and smoke.  If one capacitor in your string shorted, the next ones would see an elevated voltage and would not be far behind, setting off an avalanche effect through the string.  You would see a virtual lightning storm with explosions and the likelihood of intense fire.  I have seen lead acid batteries explode as a result of heat igniting the hydrogen gases, and they are very messy.  So, that being said, I wish you success with your project, but you may want to consult an expert about this.  My knowledge about this is very limited, but I do know about smoke and fire.  Jon C.

This is an interesting post, Travis, and it caught my attention.  A couple of practical factors also occurred to me.  Since the operating voltage may not exceed 2.5 volts for each capacitor, If you are trying to match them to a 6 volt battery for example, you would then need to place 3 capacitors in series before wiring them in parallel with the 6 volt battery, so that each capacitor doesn't see much over 2 volts across its terminals.  As with any series capacitor arrangement, equalizing circuitry must be used to maintain an equal voltage across each capacitor.  This is done simply by wiring a resistor of equal value across each capacitor, or by some other more complex means (the sophisticated control circuitry mentioned in your first link).  Resistors represent a power loss since they would tend to drain the capacitors (and battery) without any other load on the cells.  And, when you place three capacitors in series, the net overall capacity is reduced to one third, so the 2600 farad rating would drop to 867 farads at a rating of 6 volts......for a 48 volt system with 24 capacitors in series, the rating would drop to 108 farads of capacity. At this reduced capacity, would they actually help the batteries with surge current problems, or just add a lot of expense and complexity to your system?  I'm not trying to rain on the parade, but rather, just expressing curiosity at this concept.  Jon C.

I am not using any remote charge controller metering devices, Scott, if that is what you are asking? I have analog ammeters that read charging current for my battery backup power for both solar and wind, and a battery voltage meter inside the house to monitor state of charge condition. I am operating in an "off grid" status. It seems that I have no need for any further metering resources.  Jon C.

Hello Scott.   I have an experience share........also using a 30 amp PV plant with a Trace C40.  The unit has been working reliably for almost 5 years now.  It exhibited overheating during the hot summer months when ambient temp climbed to 100 F, since it is located in a non-air conditioned garage environment, but I remedied the problem by installing a cooling fan on the unit. Hope this helps...I wish you good fortune.  Jon C.

Wow, that's a long lifespan, Tom.  Thanks for the input.  Based on the price of a L16 battery by comparison to the price of a Surrette though, I could replace the L-16's 5 times and get a minimum of 20 years lifespan for the same amount of money.  I guess we get what we pay for, huh?  ;-) Jon C.

The longest warranty that I have seen on lead acid batteries is 7 years, Ashven.  So, I think that your expectation of over 10 year workable lifespan is unrealistic. Lifespan is much dependent on how the battery is treated in usage.  Jon C.

Hi A.A.  I have two banks of the L16 batteries in my system.  They have been working well for the last four years.  The lifespan will be greatly dependent on your DOD (depth of discharge), and the environment in which you keep the batteries.  I would suggest using hydrate caps since it is a flooded cell type battery.  I optimistically project a 7 year lifespan, but time will tell.  I wish you good fortune.  Jon C.

Interesting query, James.  I have an off grid system for household, with 2kw of solar, and 2.5kw of wind.  In the summer, the sun rises and sets on a sweep of over 180 degrees, so I have a bank of panels on the east for morning sun, a bank to the south for midday sun, and a bank on the west for evening sun.  For year round optimal angle, the panels are set to the same inclination as my latitude........44 degrees. I have no generator, but use twice as much battery capacity as i would normally need. I am located in the midwest and get most of my power from wind, however, being next to the Dakota's.  I have often wondered if a solar tracking system would give me better performance or simply be another load circuit to drain my resources.  Anyone have some input about that?  Jon C.

Tom, the Ironridge kit does bolt directly into the frame of the solar panel, and is not a fancy clip.  Sometimes convenience is worth more than the frustration of trying to scrounge around for a suitable piece of hardware that fits the bill.