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Hawker 6TAGM batteries
Posted: Sun Jan 02, 2011 3:47 pm
i think i found my batteries. they are military spec. used in the humvee. im running one in my rv right now with good results. but am thinking of getting a few more. question is how many should i get. i figured 4 would be all the power i would need for all day use. i dont have any panels yet but have been looking at the 45 watt kit from harbor freight to start out with and building from there.
ok guys point me in the right direciton. i have very limited funds and have to build this cheap. really cheap. the batteries i can get for free. but the rest i have to buy.
Posted: Sun Jan 02, 2011 4:54 pm
If you mean "cheap" as in "inexpensive', then Harbor Freight panel kits are NOT the way to go. I don't have the numbers in front of me right now, but all of these PV sets are ~much~ too overpriced from my observations. Do some simple math and figure what the price per watt is. If it's anything over $2.50-3.00/watt, you've getting ripped off big time.
Look through Home Power magazine, or any other reputable RE wholesaler and you'll see PV's for anywhere from $2.25 to 4.00 a watt. And these are panels that (mostly) all carry a 25 year warranty. What is HF offering if your panels go dead or perform poorly in a year or two?
Also, if the Hawkers are AGM (I assume that they are) you ABSOLUTELY have to have an effective charge controller. These batteries will NOT tolerate overcharge conditions. They will vent and be destroyed if the panels continue to charge them once they are full.
Also be aware that AGM batteries don't like to sit around partially discharged, they sulfate particularly quickly. Be sure to build your system with the load and DOD in mind and provide sufficient panels or backup charge sources (AC power, etc) to keep them topped up and happy on a regular basis.
Any more than two batteries in parallel is asking for trouble, it's very difficult to properly balance three or more batteries in a parallel string. If they are free, I guess you could afford to kill some by experimenting.
Posted: Mon Jan 03, 2011 2:38 am
The last time I checked in with my supplier here in N.Y. which was only about a month ago my price on Sharp 220 watt panels was $2.10 per watt and theres some great panels coming out of Canada of $1.75 per watt both come with 25 year warranty. Shipping is a little steap but you have to pay shipping anywhere.