JUMA SCC is a ham radio friendly low
quiescent current lead acid Solar Charge Controller. It has a common
negative ground rail (unlike many other controllres). It will charge a 12V
lead acid battery with a continuous solar panel current until the selected
target voltage is reached. When the target battery voltage is reached
the controller will shift to very slow PWM switching frequency, thus it can
not generate Radio Frequency Interference (RFI). See a video clip here of almost fully charged
battery.
Recommended continuous float charge voltage is 13.8V. You can select higher target voltage in active cycle use or when the battery is colder than 20ºC. Here are the recommended float charge target voltages versus battery temperature.
Note.
Leave the target voltage setting to the recommended float charge voltage
when you are not using the battery.
Solar panel should be intended for 12V system (typically 36 cells in a panel). The panel power can be from 10W up to 200W with an open panel voltage of max 30V (not for a panel with higher open voltage or panels in series). Use an analog current meter acconding to your panel power, it can be up to 20A. The 12V lead acid battery capacity can be accordingly from 10Ah to 400Ah or more depending on the load conditions.
The quiescent current of the controller is very low. It is not discharging your battery almost at all during dark times. The quiescent current of the controller is abt 500uA and quiescent current of the the LCD voltage meter is 1mA, totally only 1.5mA. Your battery will stay in perfect charge for very long time without solar power.
You may think why I am using an old fashion analog current meter for charge current indicator. The reason is that it is practically consuming zero power and the accuracy is absolutely sufficient.
The controller needs only one simple adjustment.
1. Turn the target voltage selector to 13.8V.
2. Feed precise 13.80V to the battery terminals. Do not yet connect a solar panel.
3. Adjust trimmer R13 until the voltage between TP1 and TP2 is zero (<5mV).
Note. If your battery is in a warm place (>25ºC) use 13.70V for the 13.8V float voltage adjustment.
Downloads
Schematics Rev A
Main board layout
Front panel layout
BOM The parts are cheap but the Lascar EMV 1200 LCD voltage meter is rather expensive but it is worth of that.
Important notes!
1. Always use a fuse near the battery. I am using a 10A blade fuse near the battery.
2. Connect your battery to the controller with short and thick cable. I am using 1 meter long 4mm2 cable.
3. The controller LOAD screw terminals is intended only for medium current, max 10A.
4. Connect your 100W transceiver directly to the battery with shortest possible cable 2x4mm2 with a 25A fuse.
5. The charger will not start charge if the battery voltage is below 7V. Charge an empty battery first with another way.
Update 2022-09-19 OH7SV
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Recommended continuous float charge voltage is 13.8V. You can select higher target voltage in active cycle use or when the battery is colder than 20ºC. Here are the recommended float charge target voltages versus battery temperature.
| 20ºC |
10ºC |
0ºC |
-10ºC |
| 13.8V |
14.0V |
14.2V |
14.4V |
Solar panel should be intended for 12V system (typically 36 cells in a panel). The panel power can be from 10W up to 200W with an open panel voltage of max 30V (not for a panel with higher open voltage or panels in series). Use an analog current meter acconding to your panel power, it can be up to 20A. The 12V lead acid battery capacity can be accordingly from 10Ah to 400Ah or more depending on the load conditions.
The quiescent current of the controller is very low. It is not discharging your battery almost at all during dark times. The quiescent current of the controller is abt 500uA and quiescent current of the the LCD voltage meter is 1mA, totally only 1.5mA. Your battery will stay in perfect charge for very long time without solar power.
You may think why I am using an old fashion analog current meter for charge current indicator. The reason is that it is practically consuming zero power and the accuracy is absolutely sufficient.
The controller needs only one simple adjustment.
1. Turn the target voltage selector to 13.8V.
2. Feed precise 13.80V to the battery terminals. Do not yet connect a solar panel.
3. Adjust trimmer R13 until the voltage between TP1 and TP2 is zero (<5mV).
Note. If your battery is in a warm place (>25ºC) use 13.70V for the 13.8V float voltage adjustment.
Downloads
Schematics Rev A
Main board layout
Front panel layout
BOM The parts are cheap but the Lascar EMV 1200 LCD voltage meter is rather expensive but it is worth of that.
Important notes!
1. Always use a fuse near the battery. I am using a 10A blade fuse near the battery.
2. Connect your battery to the controller with short and thick cable. I am using 1 meter long 4mm2 cable.
3. The controller LOAD screw terminals is intended only for medium current, max 10A.
4. Connect your 100W transceiver directly to the battery with shortest possible cable 2x4mm2 with a 25A fuse.
5. The charger will not start charge if the battery voltage is below 7V. Charge an empty battery first with another way.
PS. I have got few spare PCB
boards. I can sell a main board and a front panel with 15€ + shipping cost
abt 5€.
Edit.
The boards are now sold out but pse contact me if you
are interested www.qrz.com/db/oh7svUpdate 2022-09-19 OH7SV
Back to OH7SV projects