What's a good battery level monitor?
What's a good monitor that I can install in my Casita to see the battery level throughout the day? Ideally a monitor that draws minimal power since we boondock frequently. When we're camping in an...
Forum Discussion
When I compare my "morning voltage" (close to resting) and its SOC with the AH count, that gives me a rough capacity. Since 12.1v is about 50% of whatever the capacity is, then if I am down 200AH, capacity is about 400AH.
I do a little math using the temperature vs capacity graph from my battery specs, and see if that is a reasonable number. There will be some more for battery age/usage.
My 460AH (as rated) might be 400AH on a cold morning, down 13% from rated.
If I did it the other way , using 460 as my capacity entry, and was down 200AH, the monitor would say I was at 57%. (the morning voltage would be 12.1v though-indicating 50%.)
By the time the monitor said 50%, it would actually be (230 down from 400) 42.5%.
On the recharge from actual 42.5%, I am unclear what the Ali would say. There is the business of whether battery temp is ambient or internal as it warms up from being recharged, and what temp to use with the temp vs capacity graph.
If the capacity is still lower, then the amps will taper to zero when it has its 200AH back (with heat loss allowance correct) before the AH counter gets its 230AH back. If capacity is closer to 460 again from internal heating, amps will run longer so the Ali comes out closer?
I do 50-90s with gen/charger so never get back up that high, and also get "progressive capacity loss" from repeated 50-90s. I can keep track of that doing my own math, but I don't see how a monitor could keep track of it all with a fixed capacity set for it.
In the summer with not so much temperature swinging (except in a desert) and closer to 77F, on solar getting to full most days, the monitor would not drift as much and also you have more chances to "zero" the AH counter too by getting to full so often.
I do find it confusing trying to imagine how different monitors would handle things.
I do a little math using the temperature vs capacity graph from my battery specs, and see if that is a reasonable number. There will be some more for battery age/usage.
My 460AH (as rated) might be 400AH on a cold morning, down 13% from rated.
If I did it the other way , using 460 as my capacity entry, and was down 200AH, the monitor would say I was at 57%. (the morning voltage would be 12.1v though-indicating 50%.)
By the time the monitor said 50%, it would actually be (230 down from 400) 42.5%.
On the recharge from actual 42.5%, I am unclear what the Ali would say. There is the business of whether battery temp is ambient or internal as it warms up from being recharged, and what temp to use with the temp vs capacity graph.
If the capacity is still lower, then the amps will taper to zero when it has its 200AH back (with heat loss allowance correct) before the AH counter gets its 230AH back. If capacity is closer to 460 again from internal heating, amps will run longer so the Ali comes out closer?
I do 50-90s with gen/charger so never get back up that high, and also get "progressive capacity loss" from repeated 50-90s. I can keep track of that doing my own math, but I don't see how a monitor could keep track of it all with a fixed capacity set for it.
In the summer with not so much temperature swinging (except in a desert) and closer to 77F, on solar getting to full most days, the monitor would not drift as much and also you have more chances to "zero" the AH counter too by getting to full so often.
I do find it confusing trying to imagine how different monitors would handle things.
