I plan to recharge my AC180 from a 12V sealed lead acid AGM battery. My understanding is that the battery’s voltage should be kept above 10V or so.
Will the charging stop when the voltage drops too low or do I need to monitor it?
Thanks!
The AC180 DC input range is 12-60V, so it should stop charging when the battery drops below 12V. I believe this is to prevent a battery in a car from dropping too low to start the vehicle.
When using just a 12V battery out of a car, especially a lead acid, I’m not sure how much you’ll actually get in the way of charging, and I’m sure as it gets closer to 12, the rate of charge will drop.
A LFP should do better since it’s voltage is higher.
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Agree with @rgb The first point is that an AGM should not be cycled lower than 50% depth of discharge (DOD).
A fully charged and new AGM will rest at approx 12.8VDC, however as the AC180 can draw around 85W from a 12V charge = up to 8A, that kind of load will lower the voltage to around 12.5V. An AGM at 70% DOD will have a resting voltage of approx 12.3V, which means under load it could drop to 12.0V. This is the threshold of charge voltage, which means you will perhaps get about 1/3 of the AGMs usable power before charging stops or slows down.
33Ah at an average of 12.4VDC = approx 410Wh of charge. Then you need to recharge the AGM by other means. More…
Conversely, If you use a LiFePo4 100Ah battery it’s voltage will remain over 13V for most of its discharge cycle. For longevity, most sources recommend keeping Li DOD to 80%. i.e. 20% left.
Therefore 13V x 80Ah = 1,040Wh or almost doubling the AC180 capacity.
FYI, the 1152Wh of the AC180 divided by 13V = approx 88Ah, which is still possible from a 100Ah deep cycle Li battery. (Less recharging efficiency losses)
Thanks for the great info, guys. That’s a battery I already have (I’ve been using that with an inverter to run things during power outages and recharging it with a trickle charger). Sounds like it won’t add much to the AC180 (which I’ve just ordered), but I’ll try it out.