600 AH 2 volt cells - Charging specs, availability used slightly over scrap price

H2SO4_guy
H2SO4_guy Solar Expert Posts: 213 ✭✭✭
in Off Grid Solar & Battery Systems #1
I put in a tech support request to C & D technologies in reference to their 600 AH 2 volt cell batteries. (RHD-600) I explained that the only voltage shown was 2.25 – 2.27 volts per cell to float them. He stated that it is not recommended to use in an off-grid application, however, the initial EQ and charge is to be 2.35 volts per cell at 20% of capacity at the 8 hour rate. Normally when they are discharged they are just floated to full capacity at the 2.25 – 2.27 volts per cell. He also stated that they were normally used in the Telecom field as backup batteries. I have 12 of the cells I acquired for $635, and hope to get more to make at least 1 string at 48 volts and hopefully 2 strings. The battery place will trade them back in if they can’t match them up to get different stationary batteries.

I will report back on additional availability and how they work out.
12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: 600 AH 2 volt cells - Charging specs, availability used slightly over scrap price
    H2SO4_guy wrote: »
    He stated that it is not recommended to use in an off-grid application, however, the initial EQ and charge is to be 2.35 volts per cell at 20% of capacity at the 8 hour rate. Normally when they are discharged they are just floated to full capacity at the 2.25 – 2.27 volts per cell. He also stated that they were normally used in the Telecom field as backup batteries.

    There is a large difference in plate design and the composition of the lead alloy used between batteries designed for multiple discharge/charge cycles (necessary for PV off grid) and batteries designed for just a few discharge cycles occasionally during a long life on float charge.

    Even if they are in "like new" condition, it may not be worth what you paid for them for off-grid use.

    This is just very general advice. Based on the manufacturer and model number of the batteries, some others on this forum can discourage you more exactly. :-)

    Or you just may get lucky.

    PS: The specifications for the battery are available here.

    It looks like they are AGM batteries, which makes it difficult for you to determine their condition without doing a long term load test. (You cannot measure the electrolyte SG.)
    The cycle life actually seems tolerable if you are willing to settle for a shorter life consistent with the lower price you are paying.
    Cycle Life – 1200 Cycles to 80% D.O.D. at 77F (25C)

    The number of cycles at 20% DOD might get you four or more years of useful service.

    They strongly recommend a temperature-compensated charger, which you would want for any batteries in PV use.
    SMA SB 3000, old BP panels.
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