Greetings, fellow Energy Techs~<br><br>A client has a nice new set of 2v Concorde AGM sealed batteries: 915 amp hours in one 24 volt string. His cabin is often unoccupied with only the refrigerator running. During those "idle" days the battery is called upon to deliver an average of 90 amp hours every night...about 10% discharge.<br>
<br>The client wishes to rev up some more loads to run during these idle times. Coincidentally, those loads would also require an additional 10% discharge from the battery each night. The added loads surely have a cost in terms of decreased battery lifetime. I wish to do the math to amortize the battery cost and arrive at a "dollar value per month" for the additional loads.<br>
<br>The pack plus installation cost about $4,700. I don't know the number of "lifetime amp-hours" which could be expected from these batts, but <i><b>I hope one of you can help me get that number.</b></i> Could we then divide $4,700 by the lifetime amp-hours to get the cost per amp hour? If so...I could do the rest of the math from there.<br>
<br>*************************************************************<br><br>Side note: I realize that various factors such as shallow cycling, repeated overdischarge, repeated overcharge, etc. can affect the number of amp hours which any battery can deliver. In this case, let's assume the following:<br>
<br>* No repeat overcharge because I'm strictly following Concorde recommendations and I've even calibrated the Outback charge devices<br><br>* No repeat overdischarge because I >finally< have the generator automation dialed in and reliable (fingers crossed)<br>
<br>* Prompt recharge after discharge...because there's an OK sized solar array, many sunny days plus the genset backup<br><br>
* Electronic sulfate dissolver is installed on the battery string<br><br>* Average cycle depth of 50% discharge. I'm using this value to factor in the times when the cabin is occupied and therefore cycling harder on the battery<br>
<br>* Limited heat stress on the battery. The cells are in a crawl space in alpine terrain so they will range from cold to cool, never warm<br><br><br>**************************************************************<br><br>
Thanks in advance for your assistance. The <u>Wrench List</u> is the bomb!<br><br clear="all">Mick Abraham, Proprietor<br><a href="http://www.abrahamsolar.com">www.abrahamsolar.com</a><br><br>Voice: 970-731-4675<br>