How do I know if I'm consuming more than I'm getting?

[Tariq0101]

I have 2 200w pv panels on the roof connected to my 12v flooded lead acid battery bank in a department over the kitchen through a pwm controller, I have a small screen that shows the voltage of the battery bank and I've installed it in a visible place (so I don't have to go up to each time)

I've adjusted the controller to give 14.6 volts because it's summer.
The voltages I'm getting are:
14.6v (no load)
14.4-12.2 (on load, depends on tge time of day, it indicates 12.2v on 4PM but it's mostly 14.4 during the rest of the day)
During the night it's 12.5v to 12.2v but the load is much lower than what I run during the day.
So my question is, on what voltage does the load starts depleting the charge of the battery, I know it's in the 12.x range but which is exactly?

Another question, how long does a flooded lead acid last if it never goes below 12.2v?

 

[BlueFox]

Current meter on the battery pack.

If it shows current going into the pack, or nearly 0 current flow = you have enough power from solar for your loads.

If it shows current coming out of the pack = you're pulling more than the solar can provide on its own.

>Another question, how long does a flooded lead acid last if it never goes below 12.2v?

That depends on the load, to measure lead acid capacity by voltage it needs to have no load or charger on it for several hours.

Another reason a current meter with coulomb counting is good to have, as it will tell you how many amp-hours you've taken out of the battery.

 

[snoobler]

I have 2 200w pv panels on the roof connected to my 12v flooded lead acid battery bank in a department over the kitchen through a pwm controller, I have a small screen that shows the voltage of the battery bank and I've installed it in a visible place (so I don't have to go up to each time)

I've adjusted the controller to give 14.6 volts because it's summer.
The voltages I'm getting are:
14.6v (no load)
14.4-12.2 (on load, depends on tge time of day, it indicates 12.2v on 4PM but it's mostly 14.4 during the rest of the day)
During the night it's 12.5v to 12.2v but the load is much lower than what I run during the day.
So my question is, on what voltage does the load starts depleting the charge of the battery, I know it's in the 12.x range but which is exactly?

There's no one answer. The moment you add a load without corresponding charging, then you're depleting the battery.

A typical FLA battery at REST is 12.05-12.10V @ 50% SoC. If you take them that low WITH LOAD attached, then you're HIGHER than 50%, which improves life.

Another question, how long does a flooded lead acid last if it never goes below 12.2v?

A very high quality deep cycle FLA (Rolls, Trojan, etc.) should last 2000+ cycles. It is critical that these batteries be monitored, properly maintained and equalized when needed.

Given that you are seeing 14.4+ most of the day, you are getting to at least 80% SoC.

Ideally, you should install an actual battery monitor that counts current and reports a true % SoC based on Ah used and rated.

Off-grid Solar Battery Monitors

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

 

[Tariq0101]

Current meter on the battery pack.

If it shows current going into the pack, or nearly 0 current flow = you have enough power from solar for your loads.

If it shows current coming out of the pack = you're pulling more than the solar can provide on its own.

>Another question, how long does a flooded lead acid last if it never goes below 12.2v?

That depends on the load, to measure lead acid capacity by voltage it needs to have no load or charger on it for several hours.

Another reason a current meter with coulomb counting is good to have, as it will tell you how many amp-hours you've taken out of the battery.

I'll look for one of those it seems pretty handy

 

[Tariq0101]

There's no one answer. The moment you add a load without corresponding charging, then you're depleting the battery.

A typical FLA battery at REST is 12.05-12.10V @ 50% SoC. If you take them that low WITH LOAD attached, then you're HIGHER than 50%, which improves life.



A very high quality deep cycle FLA (Rolls, Trojan, etc.) should last 2000+ cycles. It is critical that these batteries be monitored, properly maintained and equalized when needed.

Given that you are seeing 14.4+ most of the day, you are getting to at least 80% SoC.

Ideally, you should install an actual battery monitor that counts current and reports a true % SoC based on Ah used and rated.

Off-grid Solar Battery Monitors

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

I'll probably just get a current monitor because I mostly care about not using more than the PV current during the day.
My loads in the nights are just a wifi router and some LEDs.
But just to clarify, can I get 14.4v (charging voltage) while drawing more than the charging current? Shouldn't it fall to the rest voltage or depletion voltage?

 

[snoobler]

I'll probably just get a current monitor because I mostly care about not using more than the PV current during the day.
My loads in the nights are just a wifi router and some LEDs.
But just to clarify, can I get 14.4v (charging voltage) while drawing more than the charging current? Shouldn't it fall to the rest voltage or depletion voltage?

A fully charged FLA battery will settle to 12.7-12.9V at rest.

 

[12VoltInstalls]

Not one of your questions, but...

I ran (just barely sometimes) on 200W for a year or more. In my experience and based on your general indications ‘I’ would add one one preferably two more panels and - if you can - one more battery.

That headroom will be a comfort AND let you do more. Plus, keeping the batteries at a higher voltage on average will make them last much longer.

Another thing: it may only be 15 or 25% on paper, but going mppt with my Cc was an incredible difference. My pwm was fine, but making a pot of coffee for example recovers nearly immediately whereas in full sun, depending, it used to be an hour or two with the PWM. What happens with the math, the theory, VS what happens IRL in practical is sometimes very different. The early voltage the mppt makes is a big deal compared to waiting the full sun for best performance of the pwm.

Good ol’ Walmartha “Maxx” group 27 deep cycles are inexpensive. If you suck them down regularly you will see decreased performance or insufficient performance in a year or so. Treat them nice and discharge deeply (I try to do 12.4/12.5 as the lowest resting voltage) and I’ve had them last 5, 6 years with good performance. I had a couple with 2008 and 2011 mfg dates still working ok in 2018. Into 2019 they stopped maintaining voltage above 11.2-11.4 overnight. So I replaced