In my years of experience living off the grid (since the late '90s), I have found batteries to be the most expensive and troublesome component of a renewable energy system over the long run. With that in mind, I knew there must be a better solution than the standard "go-to" batteries such as Trojan L-16's and T-105's or even the high-end Surrette's or super high-end Solar One batteries. While the high-end batteries mentioned often work very well, they are quite expensive. So for years, I have kept my eyes open for a better solution.
When our small bank of Trojan L-16's bit the dust, we had been hearing rumblings of another option from friends. It was relatively inexpensive, often available locally, and was incredibly heavy-duty and long lasting. We decided to try it out, and so far our experience has confirmed what many others have been experiencing.
A Cheaper Quality Option
You may be thinking of new technologies involving sealed batteries of different materials. However, from what I have seen, the prices are still too high for these units. What I would call your attention to is still the standard lead-acid deep cycle battery, but one of a different variety. They are sometimes right under our nose and for some reason we don't even think of them as an option. What could this possibly be?
The lowly forklift or industrial battery used in electric forklifts or pallet-jacks. It is simply an incredibly heavy-duty, incredibly large, and surprisingly cost effective lead-acid deep cycle battery. Forklift batteries come in a variety of voltages (12, 24, 36, or 48) and sizes (from 1,000 pounds to several thousand pounds). They are available at local industrial battery suppliers or in at least one situation, from the manufacturer.
The lead plates on a forklift battery are far thicker and should last much longer than any L-16 battery made for renewable energy. The battery is composed of 2 volt cells, all packed in a heavy-duty metal case and tied together with metal bars in the proper configuration to add up to the labeled voltage. When used with a forklift every day, these batteries typically last no more than seven or eight years, but expected life-span is up to 15 or 20+ years when used with a renewable energy system, properly maintained, and not deeply discharged.
This is the "zinger" for me. Let's take an example. Say you would normally need 8 Trojan L-16 batteries (this is not to indicate that 8 would be sufficient for you, this is simply an illustration). At $300-400 per battery, we will take an average of $350 x 8 batteries = $2,800. This would be around 740 amp-hours of batteries at 24 volts. Now let's take a forklift battery that we have experience with--GB Industrial Batteries. There are a variety of sizes but let's take the 24 volt battery that is 804 amp-hours and weighs almost 1,100 pounds. A little larger than those 8 L-16's. How much does it cost? Expect to pay around $2,500. Now, bear in mind that this battery should last at least twice as long as those L-16's if properly cared for. That is what I call a good deal!
Where to Buy?
Forklift batteries are readily available from industrial battery dealers in most large cities. And while it is certainly worth checking those local sources, it is very possible that your best deal may come from an out-of-town source.
In addition, anytime you buy a battery for off grid purposes from a forklift dealer, you have to expect that the dealer won't be much help. They may be very well versed in forklift batteries for use in forklifts, but we have found them to not only be clueless about off grid usage, but to actually give information that is just plain inaccurate. You see, what may be good advice for a forklift user could be positively bad advice for an off grid user. We use our batteries VERY differently.
Length of Battery Life?
While a forklift user will most likely wear their battery out in 7 or 8 years by wearing the plates out, an off grid user can get over 15 years and the battery will likely succomb from sulfation rather than the plates wearing out. What this means is that the way you use and maintain an off grid battery must necessarily be different than the way you operate a battery on a forklift.
With that said, you might consider looking at the few off grid dealers who carry forklift batteries and give them a call. You'll not only get the longevity and economy of a forklift battery, but you'll also get the support of an off grid dealer. This is very important unless you are an experienced off grid user or have support from another source like Off Grid Boot Camp. A couple dealers that carry the very good and affordable GB Industrial Batteries are Quality To Last (it's not on their website, so call them for info) and Stoves & More.
The other option is to purchase straight from a manufacturer or local industrial battery dealer, with the most economical one being GB Industrial Batteries. Just remember, they don't have much experience with off grid power systems, so I would recommend seeking advice from someone very familiar with off grid battery use.
How Do You Move A 1,000+ Pound Battery?
The only drawback I am aware of when purchasing a forklift battery for use off grid, is the logistics of picking up and installing such a large heavy battery. This can certainly be done if you have a tractor with a front loader to unload it.
But here is a tidbit that should be very helpful. It is possible to order the 12 volt GB Industrial Batteries with removable cells. That means that a 600 pound battery could be temporarily broken down into 100 pound pieces. It costs extra to do this, but could be well worth it if you have a difficult location to install the battery in. And if you system voltage is 24 or 48 volts (for most people it should be), you can wire 2 of the 12 volt batteries in series to make 24 volts or you can get up to 48 volts with 4 batteries wired in series.
Oh, and by the way, learn from our mistakes...don't put your battery room in the middle of your house! Put it in a location that is easily accessed from outside.
Lower Cost Alternative
Still too expensive? Try a lightly used forklift battery. I usually do NOT recommend used batteries as they could have been damaged by abuse, but if I had to buy a used battery, these forklift batteries are so heavy-duty that they can withstand some abuse. Don't expect to get 20 years of service from a used battery, but I have found a good used forklift battery to run around $500 and even if it only lasts 5 or 10 years, it is still a good deal.
If you go that route, make certain you know your "stuff" to check out. Check all cells with a volt meter and hydrometer (to check specific gravity). You are looking for any dead cells (much lower voltage or specific gravity than the rest of the cells. You are also looking to see that the specific gravity looks good when fully charged as this is an indicator of the battery's health. I have heard of guys buying a 36 volt battery so they can eliminate all dead cells and combine all good ones to hopefully add up to 24 volts.
For More Details
If you are looking for more details on batteries and how to set up a cost effective off grid power system, we have a lot of really helpful training for you. But I think the best place to start is a free video series that everyone interested in off grid stuff should watch. The first video in this series is all about batteries! To get free access to this thorough yet simple training series, visit this page.