Deep Cell Battery Option

Google "uninterruptible power supplies", as these have all the requirements in a complete vendor package. All that remains is to select the sizing required, procure, and install.

Take a minute to check this site; www.powerstream.com I'm in the mid-design phase and of a solar powered flare ignition system with battery backup capability and found it to be informative as well as having a good product line. Check the technical resources link. Good luck and Happy New Year!

the absoloute best batteries money can buy are the type that were used in the edison electric car, and in electric forklifts untill the 1970's. Jay lenno's edison electric car has its original batteries, and they still hold a full charge, and are now over 100 yrs old. There are other instances of them working for over 100 years. Unfortunatly, a product that lasts 100 years does not fit anyones business plan in the united states any more. They are nickel/iron batteries.Only One company imports them every few months from china. The company link is www.beutilityfree.com You will get your feelings hurt when you see the price. Other than that, trojan batteries used for golf carts are the best true,deep cycle batteries you can easily get ahold of for power storage. Make sure you spend the extra money and get a proper charge controler for them, do not just use a typical plug in charger,if you want them to last. And do not discharge the batteries more than 25% between charges. They are deep cycle, but even deep cycle batteries do not tolerate 50% or more discharge between charges very well.

the water pump will be the biggest draw. If the pump uses 500 watts, it may well demand 2000 watts to start it up. Go to cfl or led lights to reduce power draw from lighting. The 12dc yahoo discussion group can help with the inverter selection, and do all the math to help you size the system.

Any product "just around the corner" will probably be snatched up and studied for 20 yrs by the dept of energy, doa, etc.

If you drive, you have a generator. you could just run a line in from your car to power an inverter during outages, instead of having to babysit a bank of 10-12 batteries charging in your home. Batteries have been known to overcharge and explode if not charged properly.

Your cars alt. can only supply so much power for so long. I would not recomend running more than a 500 watt inverter worth of power from your vehicle, unless you have a high output alt.

Thank you for that - very good info that will help me along my path to some energy independence here! It sounds like after the battery selection I had better pay really close attention to the charging system. I wasn't aware of the pitfalls on that level.

Yes, a good charging system is the key. The good ones arent ungodly expensive, between 100-200 us. The 12vdc yahoo group has several schematics and a few people who can build you a good charger for less than retail. I think one of the members also sells a cd, with all the info you need to set up an alternate power system of any size, for about $35. The batteries have to be "overcharged" sometimes, too, to properly keep the plates inside cleaned of buildup. The overcharging does produce hydrogyn gas,aka hindenburg, so you have to have proper ventilation if done inside. Also, the batteries themselves have to be around 75f to charge properly. A cold battery wont charge properly, and can damage the plates and connections inside.

About the best you can get are Trojan T105. With a 5-7 year warranty they are well worth the money. I've been running 8 of them with 8-12 hour blackouts daily.

www.trojanbattery.com

The boaty people have been using these systems for a while. Have a look at the 'Chandlers Sites' for more economic domestic plant. I'd add a petrol genny anyway because it sounds like the supply system is stretched, if something fails it'll take a couple of days to fix it! With a genny you can buy just for base needs, if you want to run a washing machine whatever, start the genny. That saves on battery costs. A flip over switch Mains > BackUp but never both. Don't discharge the batteries below 50%, it will damage them. Boaty stuff protects against this with low voltage cut-offs built in. You can wire around it with a switch if you like. A small solar or wind genny will re-charge and extend service life, but mains charger will do fine. Just needs thought on how to make it automatic. Presumably you want the system to look after itself.

Thanks for your input. I do want a relatively maintenance-free system so the auto-switch to bring the battery back-up on when mains go down and then switch back to mains when power is restored is a must. I've heard that these type of devices can be rather twitchy here in the tropics and am wondering if you know of a well-engineered brand that can withstand the humidity, heat, etc.?

Join the 'cruisersforum.com' free. There is a wealth of information on Boaty electrics there, particularly for the tropics by USA based people. They'll even engineer it for you, just be prepared for their individual opinions. And mention the cost range. This can cover cheap with Ebay used parts OR reliable with warranted parts OR needs to work in a humid atmosphere for months at a time without meddling. It's not a new problem for live aboard boat people.

For the switch over, you could just make a small electromagnetic switch, where the house current lifts a contact off your inverters hot or ground wire, then when the house current goes off, drops the contact turning your inverter back on. Or use a solenoid switch, for the same result. If no one comes up with a cheap soloution for you, get back with me and i will try to draw you up something to work from. cr4's login doesnt seem to be working now. ageniusforhire@yahoo.com

Thank you all for your insights and many useful links. I've had a chance to do some follow-up (although it seems the more I read the more I need to research) and have a couple of questions still lingering; first, as the batteries will be sitting for several days between discharges would it be a good idea to have some type of 'trickle' charger attached to keep them healthy and charged to capacity all the time? Also, I've noted in several forums various battery configurations to accommodate space requirements, A/h needs, etc. Is there any advantage to running a 12v battery array configured in such a way as to generate 24v power for the inverter as opposed to 12v? Or even a 6v array of batteries configured to send 12v to the inverter?

Some of the 6 volt batteries may actually work better. I think they still sell them for golf carts. Once again, the trojan brand is about the cheapest locally available? battery you can get that has reliably been used for off grid and alternate power setups, other than the nickel/iron type. They can be wired in series for 12 or 24 volt operation, yet can be set up to charge with only 7-8 volts of input, which is easier to create via solar, wind or hydro power than the 14-15 volts needed to properly charge and maintain a 12 volt battery system. As far as a 12 or 24 volt inverter goes, i believe the biggest advantage is you have to have a 24 volt inverter system to grid tie your system into, if you choose to sell power back to the utility, or even be dumping excess into their lines, which is kinda silly to do, anyway. There may be other advantages to a 24 volt inverter, but i just stick with 12v units.

A trickel charger wont fully charge batteries, as they need excess voltage to top off that the trickel cant provide. The charge controler will keep the batteries fully charged, as long as there is power going in to it.

Thank you again. Over night (late one) I managed to find some more info regarding nickel iron batteries and although they certainly come at a dear price, look so much better for overall performance and battery life. Aside from the price, is there any reason why these would not be suitable for a system like the one I have in mind?

There is one more question regarding the Ni-Fe batteries that you may know as I've not been able to see documentation regarding this. Are there any issues with depleting these batteries beyond the 50% level as there are with lead-acid batteries? I'm thinking that if I can utilize most of the capacity (say 80%) of these batteries over 4 - 6 hours, it means carrying far less capacity in the battery bank than I'd have to with lead-acids and therefore the cost becomes much less prohibitive. Any thoughts on this?

Check with the guys at www.beutilityfree.com From my research, deep discharges did not affect the battery. Also, long periods of sitting around discharged also seem to have no effect. There are a few people who scavenge junkyards and old wharehouses, searching for some remaining edison cells (nickel iron) batteries. Electric forklifts used them into the 1970's, then the company making them got bought out, and the nickel/iron battery did not fit the new companies business plan.

"... then the company making them got bought out, and the nickel/iron battery did not fit the new companies business plan." Sadly, there are a lot of great technologies that fall into this category ... not enough profit down the track to sustain the corporate profit projections or several fat cat execs lavish lifestyles so blink ... they're gone! Fortunately there are companies in China that 'don't quite see it that way' so we do have the option of going with these superior batteries. For my part I feel compelled to do so despite the increased cost for the system, particularly in light of the robust performance that appears to be inherent in them. Thanks for the great information and for helping me to make a very key decision in putting together the best possible system for my needs.

Lots of good input so far, so I won't belabour... I would look at the loads you are considering adding to your battery bank - do you really need to run the well in the four-hour period you are without commercial power? I ask because a motor load like that would eat your amp hours faster than lighting, etc. Is it possible you can pump your well on commercial power, then have enough stored to outlast your commercial power outage? I have seen well systems that because of water in the table had to pump very slowly so a pump ran almost continuously to draw water over time, and dumped it into large tank/cistern setup that could then be drawn upon for a short period but large quantity at a time. Also, consider how deep you want to discharge your batteries before you can recharge - the deeper you discharge, the shorter the life of the batteries. Discharging to 50% depth of charge will drastically shorten the life of the system, costing more batteries in less years. Better to have larger battery bank that you only have to discharge to 80% or maybe 70% depth of charge - you'll gte much longer battery life. Also, less discharge means shorter re-charge time, but I guess it equals out because you have to charge more batteries.

Appreciate your additional thoughts, particularly concerning the pump usage. This would only be used occasionally during the outage period for toilet flush, sink tap, maybe a quick shower (it's really hot here this time of year), etc. So the drain on the back-up system would periodically be higher, but for the most part this could be left off. (Just need to be sure no leaky washers anywhere.) Same would be true for the television or a couple of the other loads I anticipate using now and again rather than the entire down-time. I think its more about efficient management of the resources during the outage and leaving off what is not absolutely required at the time. I have LED lighting system so the one main load that would be continuous only adds up to about 200 watts at any given time, including pool and garden lights. Regarding your comments on battery drain and charging, I believe from all I've now read that what you were referring to is lead acid battery characteristics and not the nickel iron battery. However, if you think I've overlooked something and there still is a reason to take care with loads and how much I use on the system before recharging, please address this one more time as it relates directly to the Ni-Fe battery type?

After some more digging, I've found that the same discharge parameters are in effect for the Ni-Fe batteries and lead-acid types. Here is part of FAQ on the BeUtilityFree site: Q: How long will a nickel-iron battery last? A: These batteries are a lot like a solar electric module. No one knows how long a PV module will last, but they have been working since the early 1950's when they became commercially available. The original batteries that were manufactured by Edison's company are still in use today in applications such as mines, railroads and home power systems. We have access to the coding that the company used and, therefore, by the markings on the top of the cell, we can determine the manufacture date and also the amp-hour capacity of the battery. Many of the original batteries are still in service after over 50 years! Some cells that were 50 years old still produce 100% of their rated capacity! The new batteries that we have been importing from China since 1995 are still producing 100% of their rated capacity 16 years later. The manufacturer claims that their batteries will last up to 20 years with a regular discharge of 50% of the battery's rated capacity. Our guess is that they will last up to 40 years with a few electrolyte changes and less discharge. Electrolyte repalcement is inexpensive when compared to battery replacement! So, I guess my question about discharge percentage is answered fully and while they may be less impacted than lead-acid batteries by greater than 50% discharge, one must take care not to push that theory too much and operate within safe percentages. This also means, of course, that I'll be spending considerably more on the battery bank to get the amount of power required over 4 - 6 hours of continuous operation. I still think it's worth it considering the reduced maintenance and safer operating conditions of these batteries. If they do in fact last up to 40 years with proper care, then the costs amortized over those years will probably work out to be comparable or even better than going with lead-acids - just a bit more up front cash required ...