A Bit of Solar and Battery Activity, Restarted.

 Days are getting longer and that means more sunlight to convert into electric activities.

So, after the winter doldrums I restarted battery activities. Weather is too cold for outdoor activities, so indoor it is.

I restarted getting the Gel batteries up and running.

I have a set of 18-20Ah batteries that have been brought up nicely to about 14V with a total of 150mA current draw at 14.2V. Those should provide about 20Ah/240Wh of energy storage, and work nicely with a total panel peak power of about 100W, easily being charged, even on a non-sunny day at this time of the year In the winter season that will be a bit more tricky. For those I have been using a small switch mor´de power supply.

The next battery connected to the solar power system i the lab. The battery of the lab power system has a capacity of about 60Ah max. effectively and running with 2x 100W panels. I am using a current limit of about 500mA, and this should easily run the recharge of the 8Ah (or so) battery, without  heating the battery up too much.

I have one more battery with about 6-8Ah, that one seems to have a decent voltage, so it will have to wait.

The smallest of the batteries (4Ah) is currently running off a linear power supply with about 200mA current limit.

The smaller (4 - 10Ah) batteries are intended to run from small solar panels and charge controllers for smaller projects, such as monitor systems and maybe a small outdoor mounted (in the summer half of the year) small thest transmitter, used for e.g. range tests on the microwave bands, maybe even a very low powered QRSS or WSPR transmitter. Maybe also for some portable  operation, until I get some small LiFePO4 batteries up and running.

Then there are the LiFePO4 batteries:

For the shack solar power system I have been using 2x 12V, 100Ah batteries in parallel, and a charge controller for 20A (MPPT), connected to 2x 130W solar panels. This system could only power the IC705 during the deep of winter, especially Dec/Jan, so it needs improvements.

From the 100Ah LiFePO4 cells I have built a 12V/200AH system, and the intention is adding this to the shack power battery, giving me a total of 400Ah capacity. When full, the charge of this should last several days even with extremely low charging current. For the deep winter months this is still insufficient when longer periods of very low solar powermay only provide maybe 2Ah of charge. So the solar panel system needs to be considerably improved.

The current panel system is simply insufficient, so here is the general idea:

- Mounting a set of panels with 200W on the South facing side of the wall. This should provide maximum power in the deep of winter when the sun is down to a maximum of 12-13 deg above the horizon. This system should use its own charge controller.

- Getting two sets of 300W (total) panels mounted at an angle suitable for summer conditions. Even when there is very limited (or long duration cloudy weather) sunlight this should provide some additional charge, 

However, even with this system I expect to need the use of mains power at the lowest point, to keep the battery charge at a decent level. This can be done when the electricity price is really low.

Some of the LiFePO4 cells can be made into a better battery (effectively 100Ah for the upstairs lab solar power system, so I can retire (or re-purpose) the old Gel batteries.

The LiFePO4 battery, 12V - 50Ah could be added to the lab power system, or be used when going out in the field with the car. As that is an EV, the 12V battery has very limited capacity, so a "real" battery is needed for portable/mobile operation. There is no reason to use the much heavier Pb (Gel) batteries in the field, especially if they need to be carried around - up to a hilltop.

Finally, I still have 16 LiFePO4 cells left.

I am thinking of making myself a 24V - 200Ah (5kWh) battery which can be used with a 230V (pure) sine inverter, and a sufficiently large solar panel/charge controller system. This could likely be used in the summer season (when I drive more than in the winter) to charge the EV, especially when the sun is shining, a´with the battery as a buffer.  This is further into the future, the first priority is getting the shack system improved, and there is a lot of radio/antenna building in the planning this year. In any case, this can be a neat experiment, and if it is not useful for EV charging it can be used for the house, like the entertainment system.