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All of my designs are open source in hopes of helping people with these issues and making life easier for people who are trying to do the right thing environmentally. I will be selling units at the end of the summer that are microcontroller controlled so they will be fully automated both at charging and discharging. I also plan on giving full multi-week E-classes on real-world off-grid systems which will include advanced electronics for building ultra efficient sine wave inverters (identacle to the Outback, Xantrex, Magnum, etc pure sine inverters), high frequency DC-DC converters (I.E. Flexmax 80 type of charge controllers), Tracking controllers, pulse recovery systems for “dead” off-grid batteries. Building heating systems such as concentrated solar heliostats and using Organic Rakine cycle (ORC) for driving turbines for power generation while heating and or cooling homes. Also there will be in depth information on water recycling through both aquaponics, solar steam distillation, and how to replace the base minerals and PH of water in such systems. If I have not built and used the technology here at our home, I won’t be going into it deeply in the classes. This is all hands on, practical, build it yourself type of information on fairly advanced and critical power systems used to keep a family totally self sufficient in all aspects of power, water and food.
Most of the above used to be tightly held trade secrets, but I have a feeling people may need this information and skills in the coming years to make it easier to deal with possible changes to our way of life.
In the meantime, the simplest way to build an electronic battery pulse recovery system is to use a 555 timer, or micro-controller. You need to set the PWM frequency at 30-60Hz and it will be driving a very low RDS-ON mosfet rated in the 75 Volt @ 100 ampere range (IRF 2805 is fine). The power supply can be anything in the 20-30VDC range, even a solar panel. The power is regulated by a high voltage regulator capable of 50VDC or so (which are now very common). You could also use an AC source at 120 VAC, then use a step down transformer to go from 120VAC to 30VAC, then rectify to DC and charge the cap directly from this source. The capacitor is sized at around 10,000 to 50,000Uf. Each pulsed to the gate of the mosfet releases an entire capacitor charge into the battery and thus “chips away” at hard sulfation layers on the battery plates, without heating or substantially boiling the electrolyte. The pulse width (duty cycle) only needs to be about 2 to 5 milliseconds in width as we are giving the battery a long rest period after each intense pulse from the capacitor discharge. This eliminates heating of the battery, and yet the voltage is low enough that is does not shed any lead from the plates. This really performs an equalization charge, but at a slower, and more controlled rate, and without damaging the battery in any way. The cables from the unit need to be in the 4 gauge or larger size in order to transfer maximum energy to the battery. High quality industrial battery cables can be used, or you can use fine stranded welding wire. There will be a small amount of inductive ringing in each pulse because of the cables, but not enough to worry about.
The more advanced units I am building test the batteries internal resistance by sending a single pulse out, and then counting how long it takes for each pulse to be absorbed. Since we can use RC time constant, we know exactly what the internal resistance is. We can then tailor our frequency and duty cycle to that specific battery, even as it changes while charging. We also superimpose higher frequencies on top of the base waveform which greatly increases the speed of the recovery of the battery. We then log the internal resistance and other parameters to an SDcard in the form of a text file so we have a log of how bad the battery was when we started and what happened as we progressed through the process. This allows one to make a spread sheet with charts to see how the process went. It also allows for immediate revealing of shorted cells (mechanically damaged cells).
Once a full cycle is done and the battery is topped out at 15.5VDC, 32VDC, etc (equalization voltage), we then intentionally discharge the battery at a 20 hour rate down to 5 percent or less charge capacity, then we repeat the process. This eliminates the hard sulfation layers that other electronic methods cannot touch. Each full charge/discharge cycle that is performed typically recovers about 40 to 80 percent of the capacity of the battery. The first cycle can take anywhere from 2 days to over a week depending on how thick the sulfation layers are. But once at least 2 to 5 full cycles have been performed, the battery is at factory or better rating.
Anyone with basic electronics knowledge can build this unit for you.
Sorry for the long winded response = )