I have one 200 W panel, one 100 amp solar charge controller and 2 non-maintenance lead acid deep cycle batteries connected parallel (Interstate 24M-EFB/77AH 140 RC/700MCA). What is the lowest and highest voltage I should allow during its cycle? Is it 12.2-12.8? The voltage is currently reading 14v (which I worried is too high, but have read that it might be leftover surface charge and not to worry about it). Also would anyone recommend separating the batteries and getting a switch to allow one battery to charge separately while the other one is in use? And lastly, if I separate the batteries, I understand that I would need to get an additional solar charge controller. Anyone have prior experience with this?
Is there an automatic switch for the off-grid system to go between 2 battery deep cycle lead acid banks?
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chrisski
Solar Boondocker
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Can you give a link to the battery?
Trying to find a spec sheet for charging voltages. A coupe of different types of maintenance free batteries which require slightly different charge voltages.
I think this is it, but not sure:
www.interstatebatteries.com
If it is, EFB, enhanced flooded battery, leads me to believe its a FLA anot maintenance free.
If this is the same battery, I see no reason two seperate them.
Trying to find a spec sheet for charging voltages. A coupe of different types of maintenance free batteries which require slightly different charge voltages.
I think this is it, but not sure:
24M Enhanced Flooded Marine Battery | Interstate Batteries
Need a marine battery engineered to outlast the rest? Discover the power of the 24M enhanced flooded battery from Interstate Batteries.
www.interstatebatteries.com
If this is the same battery, I see no reason two seperate them.
mikefitz
Solar Wizard
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During the charge cycle set the charger for an absorbtion voltage of 14.6 volts and a float of 13.7 volts. After a charge is completed, the resting battery, with no load or charge, should read around 12.9 volts. I suspect your reading of 14 volts is with the charger connected.
Charge the batteries In parallel, attempting to cycle separately usually causes issues.
The discharge limit is difficult to assess using voltage, since the terminal volts depend on current delivered to the load. Assuming no charge is taking place, 12.2 to 12.0 volts would be a useful limit.
Expect 200 to 300 cycles from your batteries.
I think your 100 amp controller is a PWM type, changing to a true MPPT type would alow more power from your 200 watt panel and have far better settings for the charge voltages.
Mike
DIYrich
Solar Wizard
50% SOC for Lead Acid is about 12.25v (SLA) to 12.10v (FLA). I wouldn't go any lower than that.
scrubjaysnest
Solar Enthusiast
All the charts I've seen say don't go below 12.2 vdc. This is an old article that still has value. http://marxrv.com/12volt/12volt.htm
The only real way to tell soc of flooded batteries is measure specific gravity which for agm and gel cannot be done.
Edit. For my agm batteries I try to stay above 12.4 or 80%.
Thank you for taking the time to respond!! Your comment really has helped. I think I need one more thing , and that's a fuse in between the two batteries?
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pollenface
Solar Addict
Nothing to gain by separating them unless you need redundancy.
I use automotive voltage sensing relays to allow system batteries to discharge below 12.8v while vehicle batteries remain isolated. When system voltage rises above 13.3v the relays reconnect.
I use automotive voltage sensing relays to allow system batteries to discharge below 12.8v while vehicle batteries remain isolated. When system voltage rises above 13.3v the relays reconnect.
Thank you! I appreciate you taking the time to respond.
Thank you
pollenface
Solar Addict
I'd do the same for anyone.
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