Bernard in Ireland
New Member
- Joined
- Sep 6, 2022
- Messages
- 6
Hi all,
I'm Looking for some advice on charging regimes for Lead acid batteries.
I feel I’m going around in circles, possibly overthinking the problem. I’ve a strong background in electronics, but am new to Lead acid charging.
If someone could sanity check what I’m saying here, and maybe point me in some direction?
The product:
I have full control over Hardware (electronic design) and software.
The application isn’t particularly price sensitive… ie there is scope to double the battery capacity or PV panel capacity or whatever else helps make for a durable design.
The current consumption of the electronics is less than 20mA
The current consumption of the motors is 2 minutes @ 5A (worst case)
All in all, these two added together is small in the scale of the battery capacity (less than 3.5% of the battery capacity)
So, If the PV panel could ‘keep up’ on dull/rainy day, the battery would never discharge by more than 3.5%.
I’m trying to understand a ‘decent’ charging regime to use in a low (but not zero) drain situation like this.
Sanity check 1:
I guess My question is , in a situation like this, would a simple CV charger, with a well-chosen charge voltage, perhaps with a bit of temperature compensation perform quite well?
ie give ‘sensible battery’ life. 4-5 years would be nice.
Sanity check 2:
My understanding of a CV charger is simply one gives more current to the battery as the voltage drops below the set point (like a fixed voltage and a series resistor would)
Eg
2.3V 0 ma
2.2V 200ma
2.1V 400ma
2.0V 600ma
(in each case above currents obviously further limited by the solar power available at any particular time)
Any pointers would be much appreciated.
Bernard
I'm Looking for some advice on charging regimes for Lead acid batteries.
I feel I’m going around in circles, possibly overthinking the problem. I’ve a strong background in electronics, but am new to Lead acid charging.
If someone could sanity check what I’m saying here, and maybe point me in some direction?
The product:
- 20W solar panel
- 20Ah Lead acid battery 12V.
- A Motor that get switched on for aprox. 2 minutes per day (taking aprox 5A)
- Custom designed Timer PCB charging circuit on it.
I have full control over Hardware (electronic design) and software.
The application isn’t particularly price sensitive… ie there is scope to double the battery capacity or PV panel capacity or whatever else helps make for a durable design.
The current consumption of the electronics is less than 20mA
The current consumption of the motors is 2 minutes @ 5A (worst case)
All in all, these two added together is small in the scale of the battery capacity (less than 3.5% of the battery capacity)
So, If the PV panel could ‘keep up’ on dull/rainy day, the battery would never discharge by more than 3.5%.
I’m trying to understand a ‘decent’ charging regime to use in a low (but not zero) drain situation like this.
Sanity check 1:
- Constant current charging to get the bulk charge done, is probably not appropriate for this level of discharge. .
- Topping charge (2.30 to 2.45 per cell) sounds good to me, but I’m told it’s not good to leave a battery at this voltage for an extended period. Sounds easy to achieve with a CV charger.
- Float charge ballpark 2.27V also sounds sensible and is easy to achieve with a CV charger
I guess My question is , in a situation like this, would a simple CV charger, with a well-chosen charge voltage, perhaps with a bit of temperature compensation perform quite well?
ie give ‘sensible battery’ life. 4-5 years would be nice.
Sanity check 2:
My understanding of a CV charger is simply one gives more current to the battery as the voltage drops below the set point (like a fixed voltage and a series resistor would)
Eg
2.3V 0 ma
2.2V 200ma
2.1V 400ma
2.0V 600ma
(in each case above currents obviously further limited by the solar power available at any particular time)
Any pointers would be much appreciated.
Bernard