Battery temperature and charging advice

Comments

• mcgivor Posts: 2,219Solar Expert ✭✭✭✭✭

  November 2017 #2

  The temperatures stated are not radically high or low, the actual battery temperature will take time to change, a remote temperature sensor insulated from ambient temperature, under styrofoam for example, would take care of charging voltages, with the controller, most auxillary chargers won't have this ability, but better than nothing to get something in before your solar takes over to finnish the job. It would seem you have done some research regarding array size etcetera, so won't comment further.

  1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
  
  

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• littleharbor2 Posts: 1,036Solar Expert ✭✭✭✭

  November 2017 edited November 2017 #3

  Cold tempratures tend to slow down battery aging and self discharge. As long as your battery is in a relatively high state of charge cold temps will not hurt it.
   Here's a good read on the subject,   http://batteryuniversity.com/index.php/learn/article/charging_at_high_and_low_temperatures
  

  2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

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• Estragon Posts: 2,850Registered Users ✭✭✭✭✭

  November 2017 #4

  Personally, I would reconsider the choice of charger. If my arithmetic is right, charging voltage should be increased by ~ .75 volts at your low temp. Although the chemical reactions in the battery happen more slowly at lower temps, they still happen. Without temp compensated voltage, there's some risk of sulfation from long term chronic undercharging.
  
  This wouldn't normally be a problem, as off-grid we tend to typically use the generator just to bulk charge up to ~ 80-85 SOC, and finish with solar doing a temp compensated absorb. If your solar can finish charging, and the controller has a remote temp sensor to properly finish absorb, it isn't an issue. If you're relying pretty much entirely on the generator though, it could be.

  Off-grid.  
  Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
  Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter

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• jimbuck Posts: 42Registered Users ✭✭

  November 2017 #5

  Thank you for your replies.
  
  I have looked into the charger and it is the only one here (uk) that is customisable e.g. 14.8v absorb and can be run from a poor power source (generator) I cannot afford the Honda inverter genset yet but allready have a standard 2k generator. There is also a remote temp sensor. It mentions temp compensation but doesn't give specific values.
  Thank you for the link to more information, I will read that tonight.
  
  I feel confident that the batteries will not be affected at the temperature ranges stated so I will go ahead and order them, I just need to build a bigger box and vent it to the outside. I think the temp sensor mounts to a terminal but I may be wrong. I will try and line the box with some insulation too.
  
  Many thanks, Jim

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• Estragon Posts: 2,850Registered Users ✭✭✭✭✭

  November 2017 #6

  If it has temp compensation, you should be fine. My banks live in an unheated crawlspace. Ambient temps can go below -40°C, crawlspace can get to -15ish.

  Off-grid.  
  Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
  Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter

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• jimbuck Posts: 42Registered Users ✭✭

  November 2017 #7

  Thanks Estragon
  
  Jim

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