Forum Discussion

BFL13's avatar
BFL13
Explorer II
Apr 27, 2018

Bank These Batteries? UPDATE

Updated 28 April

(Changed topic so starting new thread)

Now I need an opinion/facts if I can bank this big one with my two smaller AGMs even though they have different "cycle use" charging specs (lower 14s vs higher 14s) They do have the same Floating specs.

If I did, then I would be running inverter loads on the 450AH bank too. Now I use the two 100s for inverter and the 250 separately for the rest of the 12v stuff.

A. Just bank them and discharge and recharge them all at once
B. Bank them only for discharge and recharge separately
C. Leave them separate the way they are now (means usually getting the big one down to 50% while there is still lots left in the inverter's bank)

This big AGM seems to have been built at or next door by the same factory as my two 100AH AGMs. They even have exactly the same carrying handles. Their spec sheets/graphs are written to the same format.

Here are the two spec links again--

EDIT--had the the wrong link for the big one, sorry! Mine is the ESG with 14.1 to 14.4 for cycle use, but the other link has the same other specs. (it would be too easy if these two 6GFMs were in fact the same battery and had the 14.8--)

http://www.esg100.com/index.php/product/index/g/e/id/35.html

http://www.wegosolar.com/products.php?product=SKR%252d125AGM-Stark-AGM-12V-Solar-Battery-Sealed-125A

http://cn.yahengpower.com/data/upload/file/201612/8b4d4c59da39f4428b9ff79f380ab271.pdf

BTW, bestconverters is selling that "Stark" one (mine are actually 121 100AH but wegosolar has now gone to the 125 version--same specs) as a "UPG" brand. (They seems to all come from that same factory in Canton :) )

http://www.bestconverter.com/UB121000-100-AH-Deep-Cycle-_p_293.html#.WuJQYlKWxLM
  • BFL13's avatar
    BFL13
    Explorer II
    Apr 27, 2018
    Got them at hit the wall fully charged separately and on their Floats. I am always on a Float charge at home. Right now I float them separately but to the same voltage--13.8 with a temp adjustment if really hot or cold.

    So next step would be to bank them and discharge to about 50%. My bank wiring would be the two 100s as a 200 in parallel with the 250 for 450 and put load/charge across between the 200 and 250 via Trimetric shunt for negs.

    Discharge at 22.5a (20 hr rate) for about 10 hours and stop when AH are down 225. Disconnect all three and let them sit for 24 hours and check the three voltages.

    What would it mean if they are not the same? How different is too different?

    I can bank them today, do the 10 hr tomorrow, and the wait day Sunday, get the voltages Sunday evening.
  • time2roll's avatar
    time2roll
    Nomad
    Apr 27, 2018
    Seems they will be fine while in use or on a float charge.
    Disconnect if storing with no float.

    (opinion only)
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Apr 27, 2018
    You'd have to shut your system down for 24-hours to do the following.

    1. Guaranteed hit-the-wall recharge everything.

    2. Discharge to around 50% SOC

    3. Disconnect between battery types

    4. Measure voltage potential each battery after 24 hours disconneced
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Apr 27, 2018
    "means usually getting the big one down to 50% while there is still lots left in the inverter's bank"

    Certainly a 50% discharge is talked about mucho on this forum but its just a convienent number. Trojan for instance says on their Signature Flooded Line including T105, T125 and T145 that if you discharge to 50% you can expect 1,250 cycles but if you only discharge to 60% you can expect 1,500 cycles....almost an extra year of camping. I'd keep them separate, protect the most expensive battery first and switch when you get to a 60% SOC.

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