David Bowling's Continuous Charging Device

[tinman]

Crikey mate, those few hundred bucks you spent could have brought you a few cartons.

Lol-i dont drink.Was $345 in total,but i was buying a small inverter anyway for camping,and batteries always come in handy.
I will actually need a few batteries that size in the future,as i will be building an electric cart with one of those smart drive motors soon enough.


Brad

[pomodoro]

Good to know you have use for them. I thought for a moment you spent all that money to prove it doesn't work! 

[tinman]

Good to know you have use for them. I thought for a moment you spent all that money to prove it doesn't work!

Well i was not going to purchase the items just yet,but this seemed like a good reason to buy the equipment now lol.

Lets see where it go's before we make any claim's,although i think most of us know what the outcome will be,as i have been down this road before,many years ago.
But David has an extra in there,by way of the boost converter--hopefully David will post the best model he has,in the way of the boost converter.


Brad

[tinman]

Thought i would throw this into the mix while i was at it.
This is the setup where you have the two 12 volt batteries in series(24 volt battery),from the positive of the 24 volt battery,through the positive of a dead 12 volt battery,through a DC motor,then to the negative of the 24 volt battery. The motor will not rotate to start with,and as the dead battery begins to take charge,the internal resistance drops,and more current flows through the circuit. This allows the motor to start turning--this is normal.
But this time,i decided to use an AGM battery(absorbent glass mat),and to my surprise ,we had sharp current spikes shooting through the circuit. I am not sure what is happening inside this AGM battery,but i have not seen this happen with flooded lead acid batteries.

Enjoy

https://www.youtube.com/watch?v=T7N6SxsLVRA


Brad

[Dbowling]

Brad,
Your schematic is the one I started with 8 years ago. You are not going to be able to keep the inverter running because as the voltage on the two primaries drops and the voltage on battery 3 rises, the voltage potential decreases and the inverter shuts off. Also, you are going to damage battery three because you are hitting it with voltage that is too low for a proper charge. I talked about this, and about the fact that I have a pile of DEAD batteries from running the setup this way over the last 8 years.


Since I came back on this forum to talk about my experiments after a LONG absence I have made SIX posts. In FOUR of the six I speak of the NEED for a DC to DC converter to maintain the charge level at a voltage higher than what is in battery three in order to properly charge it and to properly run the inverter.
     post # 384
post #394
post #392
show it in a video in post 392
post # 397



But it isn't in the schematic you posted. Nor do I see it in the video. So please don't assume you are testing the system I am working with when you are running your tests, because you are not. And I use FIVE batteries, not three. Charging or discharging batteries causes ions to move in a specific direction. To reverse the flow of those ions, as in moving batteries from a position where they are charging to a position where they are discharging uses up energy to reverse the ion flow. So I let batteries REST before switching their positions.


I will show a single battery moving through this rotation to explain it.  It begins as battery one of the two batteries in series. Battery one and two are discharging so a battery can move from position one to position two with no problem. Then it needs to move into a rest position. Then it moves into the battery three position where it charges. Then it moves into a rest position. Then it is ready to begin the cycle all over.


With only three batteries, you have no way of keeping the system going. You will charge battery three as you run the inverter for a little while, but once battery three is charged,  you are done. I'm not sure how, with such a short term LIMITED test you will have the data necessary to determine whether I am correct or incorrect in my claims. Bt at least you are testing. That's more than most folks do, and I sincerely appreciate that.


I should also mention that if you do not measure the continuity between the two negatives on your inverter (there shouldn't BE any, but some inverters show continuity there) you will damage the batteries) You SHOULD be using a pure sign wave inverter.


As to the wonky behavior of your AGM battery. My first experience, which I related here years ago, was with three 12 volt AGM batteries. One battery would take a charge, but would not hold it, so I put it in the third position, much as you did with your wonky battery.  When I connected the system up, the voltage across battery 3 was over 24 volts, and the motor would not run. When the voltage across battery three dropped down to 18 volts, the motor would begin to run, and the voltage across battery three would continue to go down. Now with EVERY OTHER SETUP I HAVE RUN SINCE, the voltage will go down to around 14 volts and stabilize, but with this FIRST setup, the voltage would go ALL the way down to around 8 volts, and the motor would shut off. The voltage across battery 3 would immediately jump back to over 24 volt, and the cycle would repeat over and over and over. I decided that if I could keep battery three from charging, it would prevent the system from shutting down, so I hooked an inverter to battery 3 and ran loads off the inverter. I ran loads 24 hours a day for over four weeks, and the system never ran down. Then I took it on a plane to California (to show it to a patent attorney) and it never worked again. Since that day I have been searching for a way to replicate that system, so do not discount the value of a wonky battery. It may be a treasure.