Excessive Battery Floating?

mryimmersmryimmers Solar Expert Posts: 114 ✭✭✭
Hi, 
I have been running my small cabin system for 2 years now and am wondering if batteries can spend "too much" time floating. My work schedule has me gone for 2 weeks and home for 2 weeks, when I am at work system is not used. When I am home system sees light use, mostly during the day, and usually only 1 or sometimes 2 nights. Most of the time an overnight cycle brings bank down to about 90% full. Only a couple times has bank been down close to 80% full. Would it be better to shut system right down for the 2 weeks that I am gone if batteries are fully charged? Should I shut down charging and let the bank be drawn down a little deeper from time to time?  System is working fine, I just  think I am not working these batteries very hard and wonder if it would be better if I didn't let them float so much. Thanks.
510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.

Comments

  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    edited December 2015 #2
    .
    We have similar batteries. In our case they sit in float most of the winter. They are now 76 months old and doing fine.  If you EQ every so often and make certain the electrolyte levels are high enough yours should last a long time too. Float is much better than sitting undercharged or partially discharged. 
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • mryimmersmryimmers Solar Expert Posts: 114 ✭✭✭
    Trojan 105RE  6v X 4 as in my sig
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,288 ✭✭✭✭✭
    When new, it is good to cycle them when breaking them in.  Not a bad plan to do that now and then down to 50%.  Floating is not a problem as long as the float is not high enough to need excess watering. 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 30,758 admin
    What temperature and what float voltage?

    Also, what does your solar charge controller do? Some may start with bulk/absorb every morning (at least for a few minutes, some may go longer, depending on programming).

    As long as your controller goes to float (or quickly to float) as the sun comes up--Should be fine.

    If flooded cell batteries, how much water are you using? Probably aim for needing to fill every ~2 months (on average). If you fill every month or more often--Voltage/charging is too high. if you don't fill every 6+ months, probably you can raise the voltage a bit.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mryimmersmryimmers Solar Expert Posts: 114 ✭✭✭
    edited December 2015 #6
    If I recall correctly my float is at 27.2V and is Temp compensated. Located in Canada, very wide range of temperature.  CC cycles quickly to float in morning if bank is full. Bank is using very little water, I have only topped them up a couple of times in 2 years. 
    510 watt pv, TS-MPPT 60, Exeltech XP1100, XP600 & XP250 @ 24V, 4x Trojan 105RE, Trimetric 2030, Yamaha EF2400i gen.
Sign In or Register to comment.