“There are hot water coils designed to fit inside traditional free-standing woodstoves, and hydronic water jackets designed to fit inside a conventional masonry fireplace”

Brad

Brad,

I have answered this question before.

Stricter Federal government regulations and easy lawsuits against manufacturers have driven all the manufacturers of this type equipment out of the US market.

Back in the 70′s and 80′s there were many manufacturers of wood-fired hot water heaters, hydronic fireplaces, and hot water coil inserts for wood stoves.  Some moved to Mexico and are selling lots of these products in Mexico and others just went out of business.

There may be one or two left, but about the only water heating wood stoves made now are the outdoor wood-fired boilers you see advertised in this magazine that pipe the hot water into the house.

Hope this helps,

Jeff Yago

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Bob Kruckenberg

Bob,

The solar module you are considering is a 24 volt module, and cannot be connected to a 12 volt battery system unless you purchase a $400+ MPPT solar charge controller that allows a higher voltage solar array to charge a lower voltage battery. If you use a standard charge controller, it will force the solar module to operate at half its normal voltage which cut its watts output in half.

Although I do not buy or install any solar hardware made in China for more reasons than I can discuss here, I will say that SunTech is one of the oldest and best respected solar manufacturers in China, but I was not pleased with workmanship on the few that I have purchased.

If you stay with a 24 volt battery to match the 24 volt solar module, you will need four (4) golf cart batteries, and I think you will find the lower cost voltage converters to be very light-duty for this application. We have had several fail when loaded near their advertised ratings.

Since this is a small cabin, I would keep the batteries and all wiring 12 volts DC as you can find almost anything in an RV or boating supply store that will operate on 12 volts DC. You cannot find much of anything to run directly from 24 volts DC unless you use the voltage converter, but then if it fails you lose everything.

Good Luck and buy a good LED flashlight!

Jeff Yago

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Kristi

Kristi,

Several companies make a 12 Volt DC powered air conditioning unit for truck cabs that can be powered from an alternator charged battery. They are not cheap and they usually require adding a heaver dual battery power system, but you can buy these.

I think you will find the cost will be so high that its not worth the trouble, but give it a try.

Good Luck,

Jeff Yago

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I own land on a river and want something simple that will pump a small amount from the river to the water trough on the other side of a fence about 50 yards from the river and at an elevation of about 10 feet.  Nothing fancy.  Simple and small is fine.

David Mayfield

David,

Check out this article from a past issue that covers this topic:

http://www.backwoodshome.com/articles2/yago91.html

Good Luck,

Jeff Yago

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SharLynn

Sharlynn,

You guys are in a tough place.   I have talked with many folks from there and your choices are limited.

The first thing you need to do is really limit your electrical usage.  I assume you will be using a wood, oil, or propane cook stove, space heater, and water heater.   I would not have any heating system that requires operating a central fan or air handing unit as these require lots of power.

I would use only a few low wattage compact fluorescent and mostly LED lights for lighting, and buy only very energy efficient short wave radio, flat screen TV, computer, and video equipment.    You must lower your energy needs first, and it’s worth paying extra for the higher efficiency devices.

Batteries do not like the cold, so they need to be above freezing.  Diesel generators do not start when it drops below freezing unless you use crankcase and carburetor heaters, and you cannot run these high energy loads 24/7 on battery power.  This means you need to find ways to keep the generator area above freezing.

Solar systems can work that far north for the periods of the year when the sun shines, but a generator-battery system will be needed the rest of the year.

I would check with neighbors to see how they deal with this.

Good Luck!

Jeff Yago

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Bob Libbon

Bob,

You should never run a large generator like this just to use the battery charger circuit. Some generators offer this small DC charging power to trickle charge a battery while you are running the generator to power other loads, but you would use up a tank of gas just to charge a small battery like this.

You want to buy a high quality 120 VAC battery charger and plug it into the AC outlet of the generator. Select a charger that lets you select different amp charging rates to match the battery. You could easily power a large capacity charger with this size generator, so the charging process would be much faster and will save fuel.

One caution – cheap battery chargers will not work from most generators as they require the higher peak-to-peak voltage of a generator output, and if the generator voltage drops while under load the charger will stop charging. Be sure the charger specs indicate it can be powered from a generator.

If you have a half-full basketball with 30 PSI pressure inside, you will never add more air to fill it up if your air pump only goes to 20 PSI, even if you ran the pump all day. You cannot charge a 12 volt battery with 8 volts. Regardless of charger type – solar, generator, wind, grid, the charger voltage must be higher than the battery voltage. A 12 volt battery will require a charger that puts out 13 to 14 volts. At 12 volts the battery will be almost discharged.

Good luck,

Jeff Yago

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Tom
Indianapolis

Tom,

I am not sure why you want to do this but I am going to assume the on-board 36 v charger is dead, and you have this other charger around but it is a 72 volt charger (6 x 12)??.

My first suggestion is call or stop by a used golf cart outlet.  There is usually at least one in all larger cities having several golf courses.  They have tons of these used chargers around and will either give you one or sell you one very cheap since many people are paying to have these old carts re-furbished for use in RV parks and they usually include a new charger with each cart sold.  Be sure to get the right model as many of todays golf carts use six (6) batteries @ 8 volts each which require a 48 volt charger.

If your charger is really a 72 volt charger designed to charge six (6) batteries of 12 volts each, then you cannot use it.  It is possible to use a 12 volt charger and connect to two batteries at a time in series which makes 12 volts.  You would connect to the positive and negative of each set of 2 batteries, then move to the next set of 2 until all 3 sets are charged, or you could use a 6 volt charger (some 12 volt chargers have a 6 volt switch) and charge them one at a time the same way, but do not connect a higher voltage charger to a lower voltage battery set.

Good luck,

Jeff Yago

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Louis

Louis,

There are lots of manufacturers of water pumps that do not require a pressure pump, but I do not recommend you putting one of these on a home.

This type of pump is designed for an RV or boat where you have a holding tank full of water, and the water flow rates, pressures, and piping system are all small. These pumps include a very sensitive and fast-acting pressure switch which turns the pump on and off when you open and close a nearby faucet. If you tried this with the larger pump sizes and flow rates of a typical home, the water hammer alone would soon either cause a fitting failure or damage the pump.

In addition to absorbing the pumping shock of quickly stopping the water flow, the expansion tank also saves wear and tear on the pump because any single toilet flush or short hand-washing most likely can be supplied from water stored under pressure in the pressure tank and will not require cycling the pump every single time.

On smaller RV and boat systems with a holding tank as the source, these problems are not that big a deal.

Good luck,

Jeff Yago

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Rodger Newgreen

Roger,

Although it’s always best to match all solar modules in any array for the best performance, it’s possible to mismatch wattages in smaller systems under certain conditions.

The key is not the “wattage” of each module, its the “voltage”.  You want all modules to have the same nameplate voltage ratings under open, short, and peak power.  If the voltages match and they are all wired in parallel, the current for each will be based on each module wattage.

If wired in series, you may have problems if the smaller wattage module cannot handle the amp current passing through from the larger modules.   There is also the possibility that the lower wattage module in the circuit will “draw down” the other modules so and reduce their output, much like what happens when you install one old battery in series with two new batteries.

Good Luck,

Jeff Yago

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Sam Allen

Sam,

Your question is actually more complex than you probably thought since there are several different charging issues involved. If you read the fine print on any new deep-discharge battery, it will give its warranted life in a fixed number of total discharges. In other words, a battery with a 6 year warranty may only last 2 years if deeply discharged more times in the shorter period than warranted. This means a battery that is discharged 25% every day then recharged will normally last much longer than the same battery that gets discharged 75% one day each week. However, on the other side of this debate, a deeply discharged battery can take a huge charging rate which charges much faster if using a generator or solar array without out-gassing which will increase the need to add more distilled water more often.

The other re-charging issue relates to a large battery capacity matched to a small solar array. Typically what happens is the first day the battery starts out at 100% full, then is discharged 20%. The next day the solar brings it back to 90%. Again, the next day the battery is discharged another 20% so it now is at 70%, and the days solar adds another 10% leaving it to start the next day at 80%. This cycle continues until the battery keeps cycling in the 30 to 50% charged state and never gets fully recharged. This type situation will damage the battery because when the lead plates are never brought back to 100%, the surface area will soon develop a layer of calcium or other minerals which become insulators between the acid and the lead which reduces the plate area exposed to the acid and this means battery capacity is reduced. In many cases, this damage cannot be reversed.

The real answer to your question is based on how the battery is being re-charged. If you have a quality 3-stage battery charger that will “back-off” the charge rate as the battery reaches full charge to avoid gassing, then you should get the best battery life by shallower daily discharge and re-charge cycling regardless of battery capacity.

Hope this helps,

Jeff Yago

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