More Solar and Battery Power.

Last year I got a couple of 24V/100Ah LiFePO4 batteries and the plan was to use them as power supply for 24 - 28V power amplifiers, and as extra capacity for my two older 12V/100Ah batteries.

The 12V system has been used with 3x 100W solar panels, and has supplied a few radios with power in the period from mid February until beginning of November last year. In the dark months I needed to help charging from the mains power, but now the same radios can be supplied with solar power again. It's likely that I will add more panels and an extra charge controller or two to the 12V system.

The total capacity of the 12V system is about 2.5kWh, and I have used it with my power hungry IC-9700 and a bit of other radios. It's possible that I will add a bigger 12V battery later, for a capacity of about 6kWh.

Enter the 24V system. The plan is to add the capacity, so I will have a total of about 7 (or 9) kWh at the radios, using a simple DC/DC charger from 24V to 14V, with constant voltage/current setting and some switching control.

Some more solar panels need be added to th 24V system. I have some already, but I need to get them mounted.

I have found some reasonably priced 450W panels, and I will likely add a few of those to the system.

I have a small and a larger power station(s) that will likely be added to the system. Also, I have some LiFePO4 cells, so I can make a 12V, 24V and possibly a 48V system for the workshop upstairs.

A tiny system for lights and audio in the bedroom is also under construction. Yes, there are many smaller and a few larger projects to build here, along with the radio experiments.

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.

Solar Has Gone Into Winter Mode.

 The sun has been hidden (mostly) for quite a while. The battery I used is almost empty.

This is a good test of the system. The energy generated by the panels is simply too low for the load.

All the radio equipment is now running on mains power until the battery is (at least) 50% charged. That may take a while, as the days are short at 55 deg. North. More panels are definitely needed.

I will also have to make a test of RF noise generated from MPPT controllers. Those are definitely more noisy than the lower cost and lower efficiency PWM controllers. If I can reduce the noise to a sufficiently low level I will probably switch to MPPT. The expected increase of power is between 20 and 30%.

For now the battery receives a very low charge, simply because it has been cloudy for more than a week.

The existing panels used for charging are 2x 130W. 

I would expect to go solar again in mis February.

Yes, the station needs to be more energy efficient, and the battery/panel system needs to be improved. Still mush to do. Much of the indoor work should be done in the winter time: Monitor receiving system with lower energy consumption, and the bigger battery.

Building a big Battery for 12V in the Shack and the Lab.

After buying 28 LiFePO4 100Ah cells I started building batteries.

In the shack:

The intention is getting a battery build for powering the majority of my radio station, especially the monitor equipment, using mainly solar power for charging.

This has two aspects:

1.

Reducing the power needed for radios that should be on at all times, and the ones that are powered a lot of the times. This means that the older radios drawing 1-2A during stand-by are out of the question for 24/7 use.

Fortunately I do have some radios that can be used with low power consumption, more about this later.

The other radios with higher power consumption can then be switched on whenever I want to operate.

More about this in other posts.

2. 

Improving the power supply situation, so most of the monitoring can be run on solar power only.

This will be in stages. Right now I have 2 solar panels with a peak power of about 130W, feeding a charge controller. The batteries consists of 2x 12V - 100Ah LiFePO4 batteries, with a total of 200Ah available when the batteries are fully charged. This is just not quite enough for my use, so some of the cells will be used to create a 12V - 400Ah battery for the 12V supply in the radio shack. At the moment I have prepared 8 cells, running a "12V balancing" process right now. The test battery looks like this:

Yes, this needs to be protected against short circuits, but this is the preliminary setup.

What I need is finishing another 8 cells and make some more bus bars (connection between the batteries), getting the other 8 cells completely ready. Getting them balanced and fully charged, then connected together in a 12V configuration with 4 cells, then the second set of 4 cells connected as the second battery.

All this is done upstairs in my lab, and then I will have to use a cupboard for the 12V system with the 2x 12V batteries in parallel, plus heavy switches and fuses for the charging and power supply. 

I should then have a solid 12V power supply system in the shack, with a capacity of close to 200Ah.

As I expect to have some power amplifier using 24-28V, and some laptop power supply, plus a 24V soldering iron I expect to add a 24V battery in the shack for this purpose. This could be a 50Ah battery, as it will be in use infrequently, or a set of 8 cells with BMS (100Ah).

If I want to use the radios with high power, (>500W) output I expect to use the mains for powering those, as the batteries and a corresponding inverter is not practical for this purpose.

In the Lab (upstairs):

The two 12V batteries in use at the shack right now will then be free to use in the lan upstairs, creating a 12V - 200Ah. As I expect the lab to be less in use than the shack, I think this will work nicely.

In the lab I have a few pieces of test equipment running on 220-230VAC, and I suspect that using a (pure sine wave) inverter is quite capable of providing power for those, as they will be used infrequently.

I do want to have 24V available in the lab. This could be done in 2 ways:

Either creating a true 24V system for the lab, or adding a 12V battery system in series with the existing 12V system.

Winter is coming:

For both systems, but especially for the shack system I suspect that there will be a energy deficit in the deep of winter, especially Dec/Jan, and probably also Nov/Feb.

If that happens, and the battery voltage drops below a certain value, I intend to get some power into the system from the mains power system, preferably in "low tariff" periods.

Solar panels:

This expansion means that I will have to mount more solar panels outside.

I have some, alrerady, now I need to make some solid supports for them. There will be some experimentation with amall panel arrays first, then I will go larger.

I am afraid I have been bitten by the solar power bug ;)

Es on 10m, 6m and 4m.

 The sporadic E season seemed to start a bit slow this year.

OK, I was away for a week around 3. June, so I have probably missed several openings.

Now I am back, and the activity has got going again.

In my 5W challenge I have worked a few dozen QSOs on 10 and 6m. The QSOs worked in the challenge just passed 200, so I am fully on track. On 4m I worked a single station with 25W, and could probably have done more with more activity.

The solar activity has been a bit lower after the quite strong activity we have had in April and May. The SFI just dropped below 100 for a few days, but now it is coming up again. There was one spotless day (the first this year, I think). The geomagnetic field has been rather quiet, as there have been no significant flares or coronal holes to send any substantial solar wind in the direction of Earth.

The solar power for the shack is still insufficient for the use of all the radios I want to make use of in this time when propagation monitoring is quite interesting for the high HF bands and the VHF bands. More battery capacity as well as solar panels need to be connected, and some low power monitor receiving equipment is also needed.

There are now 8  LiFePO4 cells ready to build a battery for the lab I have upstairs. All have been charged and balanced with the small solar power system for the lab, and I still have 20 cells to prepare for more energy storage.

What I need for making a good, solid battery (12V - 200Ah) will be some bus bars (heavy duty copper connections between the cells) Right now I will test the system with a somewhat lower load, and therefore I *can* use some heavy duty wire for the connections, but I will have to locate or make some of the bus bars if I want to use the battery efficiently for powering the main part of the lab. 

When ready the lab solar power system should be able to deliver/store 12V - 200Ah and shared with the 12V system, an added 12V -> 24V for use with soldering iron and computer. I also have a 100W inverter, so it should be possible to power the spectrum analyzer and the TRX test set, plus other 230V test equipment for limited periods. This system should also be used for the charging/balancing of the remaining LiFePO4 cells.

Also, I noticed a substantial amount of switching noise from my primitive switch mode charger for the single cells, so I will have to limit the charging/balancing of the remaining cell to the night time, then get some EMI filtering connected as soon as possible.

New LiFePO4 Cells For Use With Solar Power. Test And Charging.

I picked up 28 unused, but older LiFePO4 cells, and started setting up a test system for them.

I also picked up some BMSs (Battery Management System), 2 for 12V 50/100A, and one for 24V 50/100A systems. I may need to get one or two more.

Solar Power Charging: 

The charging system for those batteries are configured like this:

I am using my solar system in my lab, described in the previous post, i.e. 2x 100W solar panels, charge controller and 3x 30Ah / 12V batteries. This may be expanded a bit with more batteries in parallel. providing a nominal capacity of about 180Ah. Because the batteries are GEL type, I count on a total usable capacity of about 90-100Ah.

The single cell charger consists of a DC/DC buck (step down) converter capable of delivering a maximum peak current of 20A, with CV (Constant Voltage) and CC (Constant Current) settings available on the PCB. To be sure of avoiding overheating I have set those like this:

CV: 3.60V (the upper limit of charge voltage for LiFePO4 cells)

CC: 10A (Just to keep it cool)

The circuit does have a fuse in the battery lead, a 15A one. A bit of redundancy is good. The system should not make a show of spontaneous combustion ;) .

This system is now running, and the first cell is being charged. Things seem to run smoothly right now - no overheating.

More Efficient Energy Use:

The intention is to get all 28 cells tested for capacity, then match them for the best possible batteries.

For this I could just use a resistive load and waste all the energy. Here is the idea to avoid some of this waste:

When I have 4 cells fully charged I will get them balanced for voltage. This happens with 4 low-value resistors, one in series with each battery (plus connection). When connected all in parallel the 4 battery-resistor sets will slowly balance the voltage of the cells. This is the simplest way to do this, and may not keep the batteries in balance long term, but that can come later, when all cells have been fully tested.

The first 4 cells can then be connected with a BMS to form a second 12V power supply, provisionally. With this and a second charging circuit, and considering the losses in the system, this system should be capable of charging 3 cells from (near) 0 to full charge. The 4th cell can be charged from the solar system, providing a new 4-cell battery for test charging the next cells. I could also be connected as a provisional (second) solar power system.

This is a long process, but it will test the cells for reaching the full charge voltage.

Checking Capacity Of Single Cells:

The intention is expanding the 12V system for the radio station, and also create an expanded battery capacity in the lab upstairs.

I expect the 12V battery at the station to be about 300Ah (12 cells), and the lab system to be 200Ah (8 cells).

The first system should likely be the one for the lab. So a full test will have to be made of enough matched cells (8 pcs) to make the 12V - 200Ah battery with all cells the closest possible with respect to capacity.

For this a discharge system has to be made. This could be a simple resistive load with a digital meter. The meters I have seen, however, need 6.5V, so they cannot be used for testing a single cell. Hmmm!

Can I program an Arduino (or the like) and make a simple circuit for testing capacity? Of course...

The simplest solution will be making a simple constant current load (or a simple resistive load) and measure the time before the output voltage reaches the lower limit of 3V, then read out the time and switch off the load. Not too difficult with an Arduino, even with my limited programming skills.

I do not need to measure the absolute capacity, just to match the cells, so the resistive load should be sufficient. The absolute capacity can then be measured when the cells are connected as a 12V battery.

It will take a while, as I am not constantly home to monitor the process.

Also, making this with simple means, things do take time, although they battery/cell testing is not too time consuming, as other things can be done while the tests are running.

I suspect some building of supports for solar panels, and some simple receiver circuits and/or microwave stuff, is in my future, along with the battery testing - and doing some QSOs with the radios.

No time to be bored...

Update: After some hours of charging the first cell still charges with about 8A, and the voltage rises very slowly.

Solar Power Expansion.

I moved the older GEL battery system batteries upstairs into the lab:

The 4x 30Ah battery is now connected in parallel (again) and placed on the shelf next to the lab desk. 

I set up 2x 100W solar panels in series with a (max) 6A cable to the indoors. (maybe more). This is a preliminary setup, so the system can be tested (well, it has worked before, so why not again?) . A certain voltage loss is expected, but less so as the panels are in series, and the current in the cable is therefore reduced. Preliminary cable laid, and a charge regulator added, the lab 12V 60Ah system is now running and charging.

Further needed:

- improved (and shorter) cable from panels to the indoor charger/battery system

When I get more batteries I will probably move the 2x 12V/100Ah LiFePO4 batteries upstairs to use as the base 12V system. The existing lead-acid batteries can then be used together providing 24V/about 100Ah along with providing 200Ah -> about 100Ah at 12V. More solar panels will be needed for this extension, of course, as I want the charge to be the best possible.

The 12V - when finished - should be powering things like the GPS/10MHz reference generator for the spectrum analyzer, frequency counter and the transceiver test set.

The 24V part should be powering the small 24V temperature controlled soldering iron, and also a small laptop. 

When the bigger battery gets installed I can try using a (pure sine wave) inverter to power some of the 220V instruments, like the transceiver test set, spectrum analyzer and a few more.

While this system should work well in the summer time It may need some additional assistance from the mains grid in winter time. I should build some relay switching for this before the winter comes, because, of course - Winter Is Coming  (but not for several months) ;) 

For now I do have enough panels for improving the existing system with the batteries at hand, but I need to build much better supports for the panels. I also expect to start getting some larger panels, a few at a time.

Right now it is about extending the solar power system, and getting the antenna system maintained, and some indoor activity with getting some microwave (and other) stuff up and running.

There are interesting times ahead at OZ9QV. I hope it is not in the Chinese sense ;)

Shack Solar Power Update.

 During the past week I have worked a bit on my solar power system. 

A local friend had some panels he could not get much use from. They work fine, so I decided to get some of them and put them to work. The panels are:

2x 130W peak, 17V

4x 100W peak, 17V

Just before going to my friend I purchased and picked up 2x 12V/100Ah LiFePO4 batteries, as they are considerably more efficient than the (gel) lead-acid batteries I already have. For the shack I want to use them in a parallel connection configuration, so I now have 200Ah at 12V.

First step: Setting up some of the new panels.

I started setting up the 2x 130W panels, connected in series, and connected them to the old batteries via a charge controller. This controller is capable of delivering 20A charge current, and capable of accepting up to 55V (open circuit voltage, OCV) input from the solar panels. The OCV from the panels is under 40V, so there is a good margin. The panel setup is just an intermediate step. They are resting on the ground, leaning to the out-house South wall. I will need to build a lasting support, but right now it is a matter of getting the system up and running.

When coming home from the trip I realized that I missed a bit of hardware, so I went and got 2 100A switches, some 16 mm2 cable and some eyelet connectors for the battery. Next problem: The connectors were impossible to crimp with my current tools, so now I am waiting for a hydraulic crimp tool for the connectors.

The initial indoor set-up is them made with some 2x 4 mm2 speaker wire as the connections, so there is still a good deal of improvement to do, but apart from the improvements needed, the system is essentially ready to use, and the two radios originally connected to the old system have been re-connected.

The first test shows that in the good sunlight, even in the mid to late afternoon, the batteries charged from 89% up to 100%, even with the small load of the IC-705. Right now the 10m FT8 has been added, and the remaining sunlight is insufficient to provide much charge (well, sunset is about now (2000 MEST) in Copenhagen). The real test will be adding load, and see how this works long term. 

Here is the experimental setup of the panel:

Given that we are in the summer half of the year I expect the system to be running nicely with lots of surplus energy, even with just the 2x 130W panels. In the deep of winter time it is a different matter. I expect to have to use some supplemental power from the mains, in order to keep the batteries sufficiently charged.

For now I need to make myself a power budget to see what I can connect to the system. This will also involve testing the power consumption of modules, like the Raspberry Pi(s) I intend to use for FT8/WSPR decoding and QRSS grabber(s)

Now it is time to connect some more load - yes, more radios running on pure solar power here. I think that the first should be either:

1) running the QO-100 down converter (satellite LNB), possibly the 739MHz IF receiver - and the Chinese up-converter mounted indoors. Then I need to test the stand-by power drain of the old IC-821 transceiver. ... or

2) running some more stand-by monitoring equipment, such as more receivers and/or raspberry Pi(s) for QRSS/WSPR or FT8 monitoring, first on 10m, then on other bands, such as 6m, 4m or 2m.

A preliminary second solar power system can be used for powering the 2.4GHz power amplifier(booster) at the feed point of the TX uplink dish. For energy saving reasons I should make the voltage for the booster remote switchable from the shack.

Some antenna work will also be necessary, for the lower frequencies. I want to be able to work on as many bands as possible from 160m (630m?, 2200m?) to 13cm, and later 10GHz, maybe 3.4 and 5.7GHz, but I expect the latter two bands to be just experimental as part of my band-QSO-challenge.

Interesting time ahead for OZ9QV

Solar Power Update.

 Today I made the latest update to the solar power system for the shack.

The system now consists of a battery capacity total of 120Ah nominal, 4 pcs. 12V / 30Ah batteries.

Additionally, the 50W panel has been replaced with a 100W panel. The intention is adding another 100W panel, so the battery *can* be charged with a peak current of just under 20A. In the summer part of the year this should be sufficient to run some of the monitoring receiver systems 24/7. For the winter season a back up system using mains power in the low light solar periods should probably be added.

A higher current rated solar charge controller is also added. The previous one could only handle 10A charge current, the new one handles 20A, corresponding to 2x 100W solar panels. The system should operate within safe parameters. I do have the second 100W panel, so it is a matter of making a good mounting system.

At the moment this system powers my IC-705 fully, and more should be possible:

1) If the voltage drop from inside to the outdoor QO100 PA at the dish is not too high, the second use would be adding this with a switch in the shack. This is necessary as there is a current draw of somewhere about 100mA from the PA, as it is just using a WiFi ("8W") booster that has a DC/DC converter and is also active in "receive mode". It uses a very fast "HF-VOX" transmit-receive switch, so it is usable with SSB signals. The current power supply for this is using an extra DC/DC converter. This way the PA can be mounted in a smaller box closer to the feed antenna.

2) I located an adapter for cigarette lighter connector, so now it is possible to connect the hand-held 10m transceiver to use as a 24/7 monitor receiver for the FT8 frequency on 10m.

3) A small CW-only transceiver with <= 50W on the 80-40-30-20m can be used for mostly monitoring on one of those bands

4) I have crystals for 7074kHz (40m FT8) and 14074kHz (20m FT8) that could be used in simple receivers for monitoring those bands. Other options for building simple receivers for other bands are available.

5) Some "transistor radios" with SSB function can be used on other frequencies not covered by crystals available to me, and for some broadcast frequencies. This requires some extra voltage regulators as their voltage requirements vary from 2 - 4.5 - 6V, maybe others.

Long term I intend to make a separate solar power supply system for the QO-100 system, and a system for lighting, and maybe later some electrical tools.

In the past week I also found some, not too expensive, solar panels. 1 100W panel and 5 50W panels.

I should now have solar panels for peak power of up to a total of 600W. I intend to find more and looked a bit around. I could find some panels similar to the new ones I got this week in Germany, but as far as I can see, a "local" (I can drive there and pick up) has some 280W panels for 24V systems.

When I get those I will definitely need some high capacity batteries for storage. I have been looking into this, and the best solution - long term - looks like using LiFePO4 type batteries. Longer life time/more cycles possible than with lead-acid (gel) batteries so all-in-all a lower cost system. This does require better charge controllers, but I think it is worth it.

I am aware that it will not be possible to go completely off grid where I live, but I can, at least,  reduce the cost of energy in the longer term. A combination of mains and solar power will be the way to go here.

First Radio Running on Solar Power. And First QSO.

I have now set up my small 50W solar panel with a charge controller and lead-acid batteries with a combined capacity of - officially - 60 Ah, using two "30Ah 12V" gel batteries. A more realistic estimate, for avoiding draining the battery below a safe level, would probably be about 30-40Ah from a fully charged battery. 

In the summer months I would expect this set-up to power for all activities with my IC-705, so that radio has now been connected to the solar small power system. 

Now I will have to check how the voltage/capacity holds up.

I expect to have the 705 running for about 16 hours per day. The current drain at stand-by is about 300mA, so about 4.8 Ah is expected to be spent, with the transmit periods I would not expect the consumption to exceed 6Ah per day, except if I would be running a full contest, or the like. This should leave sufficient capacity for adding a few (very) low powered receivers for 24/7 monitoring.

When I have tested the '705 system for a few days, I shall see, if I can add more.

The batteries are meant as a large buffer for the solar panel. With the 50W panel I would expect the average capacity of approximately 16Ah per day, probably more in the longer and sunny days of summer, and less on days with heavy cloud cover, but hardly ever going down to zero per day. 

For the winter season I should probably add a bit of charging via the mains power supply. but it needs to be checked. For now I expect to be able to run my IC-705 solely on solar power for many months.

Further, other systems with small solar panels are in my thoughts, like some lighting for my workshop, with a small panel and some low cost, low power LED lights, mainly for finding my way around at night. This may not be so often, so a large-ish buffer battery with a small 20-30W panel should be sufficient for this.

Later, when I can afford it, I do intend to make a system with larger batteries, this time LiFePO4 type batteries. This will need larger solar panels. 

This may become a life long project. I suspect that I cannot become fully off-grid, but I would expect to be able to run some essenstials, like fridge/freezer and some light on solar. Heating is another matter. That may be beyond the limits of what I want to set up in the garden.

Small Update on the Solar and Batteries.

2 small updates in one:

1)

The 20Ah Battery (lead-acid, so more or less effectively 10-12Ah) has been prepared and connected to the solar charger with the 50W panel. The battery was full, so charging is intermittent.

With this I should be able to run the IC-703 on receive 24/7, as it draws less than 300mA. (x24 -> 7.2Ah/day) There should be sufficient juice from the panel to charge 10Ah on a daily basis, with a bit to spare on very cloudy days. I will have to set up a test.

If that works nicely, a DC/DC boost/buck converter "lab power supply" will be added, so I can do more electronic experiments at the operating place. I have a 24V DC operated soldering iron, so that should be possible to operate as well, with a DC /DC boost converter. For that I might need to set up a larger 24V system with he two 100W solar panels, the second charge controller and 2 larger batteries in series.

2)

On the advice of a friend who has I have increased the possible current draw for the "revived" 28Ah batteries, and increased the voltage to the max "allowed" 14.4V. This is to see if the current stabilizes at a lower level, indicating that the battery is fully charged. 

If that looks good, some charge/discharge tests need to be done to determine the energy storage capacity of the batteries. If that works with the two batteries that look like being close, they will be added in a second solar system, likely running as a 24V system.

3)

If all this works, I may use some 20-25W panels I have available with a charge controller to start reviving other batteries, so I can use (at least partly) solar power for the revival of old batteries, in place of using mains power all the time.

4) 

Yes, I can see already that I will have to do more with panels/controllers, and then start using LiFePo4 batteries for higher power. That will be a whole new adventure, so it will be a bit later.

Solar Panel Re-Location.

For a while I have had a 50W solar panel running with a sealed (gel) lead-acid battery indoors, running with a charge controller.

Last year I realized that the panel was part in the shade during the deep of winter,  and the battery had been discharged, just by supplying the controller. but at the time it was too late already, so nothing was done.

Looking outside today around noon I saw that the panel was only  about 2/3 illuminated, so I got to change it. 

The panel is now about 1m above ground level, and placed a bit further from the building shading it. Yes, the sun is very low above the horizon at this time of the year here, somewhere around 10-15 deg. at winter solstice, so it does not take much to put the panels in shade.

There will only be a few hours of charging, but it is dfinitely better than at the previous position.

This brings me to another project that should be worked on this winter (apart from the 10GHz equipment). I have been working on re-conditioning some gel-batteries, but they are not yet ready for deployment. I have now decided that as a start, I will get some new batteries, so I can increase the storage capacity,.

Apart from this, I do have a small store of a few 30W (small, flexible) panels, and some very small solar panels. Some of the smaller panels I should use with some LiIon cell chargers (yes they are with BMS) to supply some low power consumption stuff, like a HB100 TX or the like.

The aim is to have some simple low power equipment for monitoring purposes powered entirely by solar, and with the panels and batteries I already have that should be possible.

To be sure, this location of the panel is temporary, and a more permanent location (more mechanically stable) is needed.

Oh, well. I am probably never running out of things to do or try. No time to be bored here. Was there ever?

Batteries for Portable and Fixed Use.

Today I brought my hand held VX-5 on my walk. Yes, I am trying to work myself up to a daily walk of at least 2km. I thought the battery was well charged, and all was fine just operating in stand-by. Having a local chat with the highest power level ... oops! Battery died. Maybe this is because the battery is fairly old. I am now going to check the state of the battery (Li-Ion type, 7.2V)

I may have to purchase a couple of spares, because it is a nice little radio. The standard battery is rated to 1100mAh.

For now, I am thinking of making a battery pack with 3 18650 Li-Ion cells and a cord/connector, just to be sure to have some spare capacity. This way I have can always have a fully charged battery, and I can change the cells when it goes too low. The cells are used, but tested cells with more than 2000mAh, so even with full power (5W) I should have enough juice for some local chatting. I **could** use lead acid batteries, but I don't want a hole in my pocket or rucksack after all those batteries are heavy as lead ;)

I have a good supply of Li-Ion cells and battery cassettes, so I expect to use those for several portable experiments, including going to local hills with the 10GHz WBFM experiments.

In China I found 2 solar chargers with a 3-cell (18650) battery casing, and including a BMS system, possibly fine for portable work.

At home I am slowly building some battery supply, charged mostly by solar panels, but in winter time it is probably necessary to add some juice from the mains power.

Initially this is intended for very low power equipment, such as a 28200 simple beacon receiver and some other simple monitor receivers that should run 24/7, and preferably also when mains supply fails, even if that does not happen often here.

For some of the computing the plan is to use some Raspberry Pi boards. The idea is using this for both WSPR/FT8 propagation monitoring and QRSS. 

As usual, ideas a-plenty, now it is about making time to do something with them.

Revival of Old Sealed Lead-Acid Batteries.

I now have some more solar panels, but not enough batteries to match them.

Enter an amateur radio friend of mine. He has a large solar array at his house, and he has a bunch of old dis-used 12V/48Ah batteries. Only trouble is that they have all but died.

He told me that it is possible to bring them back to life, probably not with full capacity, but also warned that it could take quite some time, sometimes a month or so, to bring them into a useful state.

The trick is to provide a voltage of 14.2 to 14.4V to the batteries, and if there is any current, even a few mA, it should be possible to revive the batteries. 

I got 4 batteries to try out.

Talking about this on the radio I may have found a second source of (used) batteries, we shall see how that goes.

For that purpose I got myself some modules from China:

- a 24V/14A switch mode power supply

- a few adjustable DC/DC buck converters with voltage as well as current limitation, both adjustable.

Now the DC/DC converters can be set to 5 - 23V, the current limit to 0 - 5A. That is the specification, but I intend to limit the current to considerably less for the revival process.

Having the modules connected, the process has now started.

After a week or so, the first (best initial voltage) battery does draw more than 1A current with 14.2V, but because a cell might be bad I have set the current limitation to 300mA. The voltage is now slowly - very slowly - increasing, and has reached 9.7V. Yes, there is still a long way to go, so we shall see how it goes, and how long it takes.

The second battery was connected a few days ago, and is now drawing about 100mA at 14.2V. It is slowly increasing, in the beginning the current draw was just about 5mA.

It may be a good idea to mount the two regulator modules in a box, at the moment they are just loosely attached to a shelf - or maybe make it wall mounted, with the 24V supply at the back of the shelf.

The two other batteries had an extremely low initial voltage, so I doubt that they can be revived. They may truly be dead, and if so they will go to scrap metal.

Apart from the radio activities there are some interesting times ahead.

The battery revival does not claim too much time, just some monitoring a few times a day, so other activities can slowly re-start. The electronics workbench/test-bench is still quite messy after starting the reference oscillator activities as well as the battery revival equipment. 

I see a lot of tidying and organizing  in my future ;)