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Comparing L-16 Batteries

Tuesday, February 3rd, 2009

Dear Jeff,

Am assuming you cannot endorse a particular solar battery manufacturer. However, am interested if you are aware of ratings or reviews that have taken place in relation to solar batteries.

In several of your articles it appears you have been quite affirmative of using L16 batteries. I have noted a battery manufacture “U.S. Battery” L16HCXC with diamond plate technology. This battery however has only a one year replacement battery. Then there is the Rolls Surrette L16 that comes in two models with First 24 months replacement, next 60 months prorated. Another is Trojan L16 coming in a couple models with 24 months replacement and next 60 months prorated as well. There appear to be a few other brands as well (i.e. Deka, Magnum, East Penn, Interstate).

Great to hear from you on what perceptions may be on the above batteries or if there are others coming out with new technology that need to be given a serious look.

Thanks,

Jon

Jon:

You are correct that I think the L-16 battery is perfect for most residential solar power systems, and I do avoid indicating brands. However, I will give you some of my own feelings about battery brands.

The main reason I use Deca batteries for most of my smaller projects is there is a regional Deca factory distributor about 15 miles from our offices that always keeps a good inventory of fresh batteries and we do not have to pay for shipping. The East Penn you also mentioned is actually the same as Daca as they are a combined company.

I believe the original “L-16″ size designation was a Trojan model number, and I think they build a really great battery. But I have also heard from other solar installers that Trojan batteries are getting very pricey, and Trojan now makes their “L-16″ battery size in about 4 different amp-hour sizes, so you can no longer compare their battery just by the generic model number.

I have used the Surette / Rolls batteries which have a really long warranty period and are very well made. Some of this added life comes from the chemistry of the lead they use, but this also makes it harder to achieve an equalize charge unless you are still on the grid, so I like them better for grid-tie systems than off-grid systems. I have not used the other brands you mentioned, but this does not mean they are not good.

When comparing battery brands be sure to also check the amp-hour ratings as they are all different even for the same L-16 battery size.

Good luck,

Jeff Yago

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Back-up power for off-grid

Saturday, September 6th, 2008

Dear Jeff,

Having recently bought some land in Missouri that is located out the the sticks and very much at the end of the power grid. I have pretty well deduced that I will need some back up power.

Recently I have discovered the backwoodshome.com website and a number of your articles. As one who is not totally familiar with alternative power like wind and solar, everything I read seems only to confuse me more.

With interest I have read about l-16 industrial batteries for a battery bank in some articles. In an article about adding a solar cell to a truck camper a RV/marine battery is recommended. Since RV/marine batteries are easy to find and will take to repeated charging wouldn’t they be logical choice for a battery bank vice the harder to find L-16?

I have noticed too that with wind power most often suggested is a dc wind generator that requires upwards of 6 or 7 knots of wind to operate. In searching around I have found a source for a AC wind generator that begins operation in the sub 7knot range. AC generators have to best of my knowledge a big advantage over DC generators and that is in size of the cable between the transmission line from the tower to the battery bank. An ac generator can use a standard ac power cord and suffers no loss in current between the tower and batteries.

I have to admit that my understanding of the way a ac generator works is taken from the following website: http://www.tlgwindpower.com/default.htm On the opening page there is a photo of a customer using 9 ac wind generators on his farm in Wisconsin. Although wind power as such is confusing to me I believe that this ac system must be quite good or the farmer who had added to it and bought these generators would not be doing so if they weren’t efficient.

Perhaps you can give some insight into battery banks and DC versus AC generators in a future story. Also the battery bank issue of l-16 versus marine batteries is very confusing to a novice seeking information like myself.

Any information you can provide along these lines would be greatly appreciated.

Thank You

Keith McElroy

Keith:

Lots of questions! Actually you are talking about “L-16″ batteries, not “I-16″. When I suggest using an RV/Marine battery, you will find that it is for a small 12-volt DC system that does not have a large load that would fully discharge it each day. These batteries are much heavier duty than a typical car battery, and most have re-combiner caps and do not need to add water. However, they will NOT hold up to a daily deep charge/discharge cycling like a solar powered home or cabin. For these larger loads and system sizes, the lowest cost battery designed for a heavy charge/discharge cycling each day is a 6-volt golf cart battery ( T-105 size). These are less than $100, and can be found at most big box stores during the summer months. They are about the same size as a car battery, but because they are 6-volt, the plates are very thick and very heavy.

For a 12-volt system you will need two 6-volt batteries wired in series, and for larger systems you will need 4, 8, or 12. When you start getting above 8 batteries of any size, its better to switch to a larger amp-hr battery and stay less than 16, as this can cause problems with un-even charging and dis-charging when you have multiple strings of parallel batteries.

I think you are caught up in the AC or DC debate as a marketing ploy. There is no engineering difference in the amount of wind it takes to turn a wind turbine based on AC or DC output voltage. Wind energy is a “cubic” function of the area of the blades, and below around 7 MPH I think you will find most small-scale generators will not provide any real power, although the blades might turn. There are now both AC and DC wind turbines and each has its advantages, but only in wiring and additional equipment that will be required.

A 24 or 48 volt DC output wind turbine is very easy to add to an existing solar-power system, and some models have built-in charge controllers and can be hooked directly to the batteries. Yes, this will require a larger wire size since the voltage is lower, but the ease of wiring is its real advantage. Also, unless you are talking about some huge wind machine on a 150-foot tower, the difference in wire costs would most likely be less than 50 cents per foot for the larger wire caused by using a lower voltage DC model. An AC wind turbine can use a smaller wire size since the voltage is higher, and these are usually designed for grid-connect systems without batteries. There are a few other issues, but you cannot say an AC unit works better than a DC unit having the same size and blade design, and the reverse is also true.

Good luck!

Jeff Yago

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