Are Enersys Powersafe DDm batteries suitable for an off grid battery bank?

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JSarqui
JSarqui Registered Users Posts: 1
in Off Grid Solar & Battery Systems #1
Two used 48 volt, 510 Ah Enersys Powersafe DDm racks are available to me salvaged from a Verizon Cell Site. The individual battery type is: DDm85-13, @ 4v and 510 Ah capacity

Here is the specification sheet: http://www.enersysreservepower.com/documents/US-DDm-PS-004_0112.pdf

I noticed in the specs that the discharge rate in Ah seems fairly dramatic and there is absolutely no data on expected cycles versus discharge depth. These are AGM batteries but are they designed primarily for UPS and should not be considered for an off grid battery bank? These batteries were in service for about 4 years, how should I do diagnostics to check their viability?

Thanks in advance
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
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    Re: Are Enersys Powersafe DDm batteries suitable for an off grid battery bank?

    If you contact DDM they will probably say 'they were designed for FLOAT service" and not solar (ie daily cycleing). I just got some C&D telecom batteries. It puzzles me that they seem to disregard the fact that in telecom applications, the batteries are there for emergency use to keep the tel co in business. So, the batts have to discharge at some time but the makers do not recognize this just that they are constantly on FLOAT charge. I am planning to charge them to the Absolyte specs I used for my old AGMs with fine tuning...

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
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    Re: Are Enersys Powersafe DDm batteries suitable for an off grid battery bank?
    how should I do diagnostics to check their viability?

    That is the whole problem with any used battery. You are always buying a pig-in-a-poke. With sealed units you can't even check SG and level. Salvaged batteries are worth no more than salvage price, in my opinion.

    If you want to experiment with them and they're cheap enough, go ahead and get them. If you need to depend on the power, don't.
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  • 65DegN
    65DegN Solar Expert Posts: 109 ✭✭
    #4
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    Re: Are Enersys Powersafe DDm batteries suitable for an off grid battery bank?

    Being lead-calcium design they are likely designed for float service and a max discharge of ~20% DoD.
    To test for capacity, completely charge the bank then apply a resistive load of known current draw like a heater or incandescent light bulbs and time the discharge to 1.75 Vpc.
    Multiply, discharge time X current = AH capacity.
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  • topper
    topper Solar Expert Posts: 113 ✭✭
    #5
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    Re: Are Enersys Powersafe DDm batteries suitable for an off grid battery bank?

    Like Coot said, if you're depending on dependability of your batteries, spend the $4-8000 on a new set. If you're starting out, playing around and learning on the fly like myself, cheap is best. Used batteries are like a box o chocolates. You never know till you take a bite.
    Worst case, take them back to the salvage yard, and get 50-75% of your investment back.
    Read all you can, Think it through and one step at a time it'll all come together.
    Best of luck
    Ken
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