BFL13,
I'd look carefully at SiO2 batteries instead of AGM. They share many of the attributes of LI, except they can be used at -40. Here is information the company (which is in BC) sent me.
"The maximum 5 second surge rate is 900A for the 100Ah SiO2 batteries.
This is higher and longer than what you can get with regular deep-cycle batteries.
For depth of discharge you can still get more charge/discharge cycles @ 80% depth of discharge (1500 cycles) VS 500-1100 cycles @ 50% DoD for regular and premium deep-cycle batteries.
At 50% DoD, SiO2 is rated for 2,800 cycles.
One of the other main benefits of these batteries, is their electrolyte does not freeze, and they can be used in -40C/F weather without damage.
Lithium cannot be charged below 0C, and flooded lead-acid can freeze and get internal ice-damage if discharged below -18C."
Matthew Longman, CTO
Azimuth Solar Products Inc.
1048 Richter Street
Kelowna, BC Canada V1Y 2K5
Cell:250-878-0409
Office:236-420-4228
Toll Free:1-888-252-2452
mlongman@azimuthsolar.ca
www.azimuthsolar.ca
http://www.azimuthsolar.ca/product-category/batteries/ull/http://azimuthsolar.ca/getting-silicon-dioxide-sio2-batteries-charging-instructions/Here is the pricing info:
http://www.azimuthsolar.ca/product/12v-100ah-sio2-battery/The 100 amp-hour 12 volt sells for 599.00 CDN! They offer a further discount if you buy more than three jars.
They do offer an 8D jar.
