US Battery Charging Specs

AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
Hola Amigos,

We've been installing U.S. Battery L-16HCs for a number of our clients. We followed their charging recommendations which are here:

http://www.usbattery.com/usb_faqs.html

Using their specs, the recommended charging voltage works out to 61.992 volts in a 48 volt system. This seems awfully high compared to other battery charging recommendations, and I've grown increasingly worried we're frying these batteries at this level. We have a couple of installs that are using a lot of water after a few years.

We're using Outback MX-60 charge controllers with default charge/absorb settings, only changing the bulk charge and float voltages. Typical installation is 8 L16s with between 1,350 to 1,800 watts in panels. Temperatures during the summer can reach 95 for a couple of months.

Comments

  • mike95490mike95490 Solar Expert Posts: 8,497 ✭✭✭✭✭
    Re: US Battery Charging Specs
    AlanRT wrote: »
    We have a couple of installs that are using a lot of water after a few years.

    Odd, because if you were cooking the batteries, they would be using water the first month.

    I wonder if the owners are ignoring them till they get a problem (low water).
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: US Battery Charging Specs

    Hi Alan,

    You never did let us know what happened with that generator install. I, for one, would love to hear how it turned out.
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: US Battery Charging Specs

    I'll answer in that thread (if I can find it)
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: US Battery Charging Specs

    Anyone have any more input about these charging specs for US Battery?
  • rplarryrplarry Solar Expert Posts: 203 ✭✭✭✭✭
    Re: US Battery Charging Specs

    I agree 61.9v seems awfully high compared to Trojans 59.2v, but how are you going to argue with the manufacturer? FLAs are very forgiving, as long as there is liquid covering the plates they can handle almost anything you can give them. Maybe US Battery has a sulfation problem and they are trying to keep that at bay by using a higher voltage. ?Quien sabe?
    Larry
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: US Battery Charging Specs

    I put the question to US Battery this morning.

    I'll post the response once I get it.

    Saludos
  • mike95490mike95490 Solar Expert Posts: 8,497 ✭✭✭✭✭
    Re: US Battery Charging Specs

    61V sounds like the EQ cycle voltage, not the daily absorb / float voltage.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Re: US Battery Charging Specs

    I know, but that's what they're saying in their FAQs.
  • BB.BB. Super Moderators, Administrators Posts: 29,812 admin
    Re: US Battery Charging Specs

    Probably an issue between "fast charge" capabilities vs floating (longer term/non-use/storage).

    Too much "equalization" creates oxygen around the positive plates and will cause corrosion/failure in the positive plates (other pictures here of VRLA batteries with positive terminals / battery tops being pushed up because of corrosion).

    If the >60 volts charging has an appropriate termination setup (typically charging current falling by something like 90%) and then dropping back to float voltage--then all should be OK.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: US Battery Charging Specs

    Alan,

    I'm generally a stickler for mfr instructions, but I've never been comfortable with US Battery's instructions.

    Instead, and as Bill has suggested above, I like the "High Voltage / Short Time" strategy for winter battery charging (relatively "short" days), and "Low Voltage / Long Time" strategy for summer charging.

    You may find this old Rolls / Surrette Bulletin #614 to be useful.

    HTH, and good luck!
    Jim / crewzer
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: US Battery Charging Specs

    That high a bulk setting is especially strange with their recommend C/10 rate for stage one which is pretty conservative. At that relatively low phase 1 rate the battery is going to be pretty fully charged when it get to bulk voltage.

    I would not subject batteries to that bulk level on every recharge. A lead acid battery is a lead acid battery. Theirs are not especially different.

    A friend of mine has US battery golf cart size and they all died from plate oxidation in about two and half years. (high cell resistance)
  • AlanRTAlanRT Solar Expert Posts: 57 ✭✭✭✭
    Interesting Reply From US Battery...

    From:
    [FONT=&quot]K. Fred Wehmeyer[/FONT]
    [FONT=&quot]Vice President - Product & Process Engineering[/FONT]
    [FONT=&quot]U. S. Battery Manufacturing Company[/FONT]
    [FONT=&quot]1895 Tobacco Road[/FONT]
    [FONT=&quot]Augusta, GA 30906[/FONT]
    [FONT=&quot]Ph: 706-790-0218
    [/FONT]
    [FONT=&quot]The 2.583 volts per cell ([/FONT][FONT=&quot]61.992 volts in a 48 volt system) should only be used with time limited charge profiles and charge voltage that is temperature compensated.[/FONT] [FONT=&quot] [/FONT]
    [FONT=&quot]Note: The equalization mode in the MX-60 is not temperature compensated. Without temperature compensation, equalization charge voltage should be limited to <2.50 vpc (<60.0 volts for a 48 volt system).[/FONT]
    [FONT=&quot] [/FONT]
    [FONT=&quot]Following are recommended charge settings for single stage, 2-stage, & 3-stage charging systems. Even though the Outback MX-60 claims to be a 3-stage charge controller, it is actually a 2-stage [/FONT]
    [FONT=&quot](bulk and absorption without a finish charge stage). Float and equalization stages are not considered as charge stages since they are charge maintenance stages.[/FONT]
    Three-Stage-Charger.jpg
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