Bottoms Up Bottom Balancing Again

Well, I needed to once again do a bottom balance on my cells. Not because of any issues while they were in the vehicle but because I mucked and messed with them and knocked them out of balance from each other since I last had them in my car. I had 24 100ah Hi-Power cells to balance. I did 26 of them. The main issue here is setting up a little balancing station for your own build and if you decide to bottom balance this would be a very simple setup. The main issue of course is how do you drain the cell with reasonable speed and not burn anything down. My first attempt was pretty crude but it worked and took out power at nearly 100 amps but was not automated. It required me to sit for long periods babysitting my cells while they drained. In the process I had decided I had enough time to run in and grab a quick cup of coffee (pour, cream and sugar) then come back out. Ooops. I was pulling power out so hard the cell had drained to near zero while I had stepped in for a quick cup of Joe. Bummer. Not going to do that again. This video was 2 years ago.

So now we move on to a bit better setup with a very simple meter. This is where the JLD404 and JLD5740 shine. Setup the JLD404 to count Ah out and the JLD5740 to monitor your volts and to stop and start your setup when you reach your required voltage. The relays in these babies are just perfect. You do need your 75mv shunt. I am using a 1000 amp shunt in my setup. Once connected and tested that all the systems work in harmony I begin my discharge testing. Ok lets back step a bit here. First you really need a load to connect to your battery. I use my spare motors. This time I only used my old Military Starter Generator. I could have connected up another couple motors but I did not want to drain them at too high a current draw. So only one motor was used and it provided about 33 amp draw. It was pretty consistent so I used that. My volt meter was set to shut the contactor off at 2.5 volts then when the voltage bounced to 2.8 or above the contactor was once again turned on so the motor would create another draw and then when the batter hit 2.5 volts again it would shut off. This would and could go until you no longer get the cell to bounce back over 2.8 volts. In effect bringing the cell to a balance at 2.799 volts. I actually did not allow this to go to long as I needed to bring down 26 cells. But if I left and forgot the setup I would be safe knowing that my cells would never get below 2.5 volts and never over 2.8 volts until I shut it off. I plowed through 26 cells. The result was that most bounced back up to 2.9 to 3.2 volts even after emptying them to 2.5 volts under 33 amp draw. If done at a higher amp draw the bounce would have been higher. So in order to take out most of the rest I setup another setup using my PowerLab 8. I have it set up to drain the cells at a constant 10 amps until the voltage comes down to  2.8 volts again. 2.8 volts being my balance point. The lab is set with a CC/CV algorithm and to cut off when the amperage draw reaches C/10 or about .5 amps or some where in that range. I figured it would give the amperage time to settle well so the cells should not go past 2.8 volts. Well most of them actually rose to about 2.85 volts and a couple reached into the very low 2.9 volts. I did not however have time to read all the voltages in the morning after the final trimming because the new owners of the cells arrived at 6:30 am to pick up the cells. But my quick check on a couple revealed 2.8 was the range but higher than 2.800. Most were at least 2.85... volts that I actually tested.

Here is the list of cells from the bulk charge, Ah out, Resting voltage, Trim Ah out, and time to do the final trim. The reason you see a few blanks is because I forgot to log a few cells so those are blank. I also decided later to add two extra cells from 24 to 26. So this is what you get. Voltages are lousy to use for trying to figure out SOC. Now the cells are in balance for the new owners. However the owner will most likely undo all my hard work because they are in the top balance camp. But they have my reason and they are thinking about it. They did not really give much thought and just followed the monkeys. I am totally in the bottom balance camp. Bar none. 

Links:

JLD
http://www.lightobject.com/Search.aspx?k=JLD404
http://www.lightobject.com/Search.aspx?k=jld5740

911SE
http://eporsche911.blogspot.com
http://www.diyelectriccar.com/garage/cars/357
http://www.diyelectriccar.com/forums/showthread.php/electric-porsche-66464.html

Metro
http://www.diyelectriccar.com/forums/showthread.php/metro-80287.html

57 Deluxe 23 Window Double Door Bus
http://www.diyelectriccar.com/forums/showthread.php/1958-vw-bus-panel-1st-ev-80329.html

Lots to do

Been bottom balancing a batch of cells today. Set up is simple yet automated. Not a science project either. But rather a simple tool to do the work needed. A motor, 12 volt battery, shunt, contactor, JLD404 AH meter, JLD5704 volt meter, and one switch. Oh! and a pile of cells to drain. Connected together they work perfectly and in harmony to do the unforgiving task of draining the cells and logging the amp hours taken out and the starting voltages. My setup for the meter is 2.5 volts for the low and 2.8 volts for the high. When running it will take out electrons until it reaches 2.5 volts, at which point the contactor is shut off by the volt meter relay. Then when the voltage reaches 2.8 it will again turn on and the cycle starts over. Usually at this point the cycling is rather quick but some cells don't just bounce back up so fast. Others bounce crazy fast while others just hit the bottom and lie there flat as a pancake and slowly rise. Each has a mind of its own. Current draw has a play in all this as well but I just want to drain the cells. So a simple setup that can safely run on its own is a good thing. It allowed me to do other tasks around for my other project, the 914 Porsche. Brake Calipers are now on and the car once again on its wheels. I am now working on the pedal assemble to replace all the plastic bushings to oil bronze bushing. Should now last another 100 years. I need to take the pedal assemble to the local shop to see if they will remove the drift pin from the assembly so I can finish cleaning the thing. Should blast it and paint it too while its all apart. Might just do that. Then I can bleed the brakes and be done with this whole mess.

The Roadster is now on its feet after a long year on stands. Dirty and dusty and covered in spider webs its time to give it a bath. Then it will be time to bottom balance the CALB SE cells that will be going into that project.

Nearly have the funds for the AC-75 for the Porsche. That is good. I can get some Toyo LRR tires for the Porsche that are perfect original size.

Video will be coming for the bottom balancing setup I did.

I also still have a very nice 9" GE DC Series motor for sale that is designed for the VW. Its a motor and adaptor in one. And I have the Synkromotive controller for it as well for $1800. Its an excellent way to get into the EV thing on a budget but have an excellent controller and motor for your ride without breaking the bank. So if your in need I have it. Local pick up only please.

I am in northern California.

Pete :)

Porsche 914 Rear Calipers

I have been working on the Porsche 914 rear disc brakes. PMB Performance provided the kit to rebuild my calibers and the kit is nearly complete. You do however need some hard parts from your old calipers to finish the job. The kit includes a ready to rebuild caliper as well. For under $200 bucks shipped it is far better than spending nearly $400 per side buying a completed caliper that is not going to be any better than what you will get from this kit and your old calipers. I have a video coming of the rebuild and a quick picture of the second caliper after the parts were cleaned and laid out for final rebuilding. I have both completed but not yet installed. Video will come later. Brakes are important and wanted to show the process. Don't be afraid of brakes but you do need to know what your doing. This is the price you pay for converting or hot rodding old cars. Most of the time brakes will need to be at minimum rebuilt. At worst they need to be totally replaced. Don't' skimp on brakes, you need them.

Pete :)


PMB Performance is an excellent place for early Porsche brakes. pmbperformance.com

Electric Bus

This is a 1958 VW 23 Window Deluxe that started life as a Panel Bus. It was converted to a 23 Window Deluxe and has the Semaphore style turn signals. It sports the small narrow rear hatch. Has early pressed bumpers. A nice touch and not so easy to find part. The bus has a belly pan and the cargo floor was opened up to allow the mounting of the cells under the floor but yet not sticking below the frame rails of the bus and the belly pan safely protects them from road debris like little rocks and such. Keeps out the water too. When the cargo floor was cut it was make to be replaced over the cells to protect them and to allow full use of the cargo area. A very nice touch and one in which I am going to do to my bus as well. I did suggest that this should be done and it is a perfect place to stash the cells. If you need even more space you can load the old fuel tank shelf with cells and even put in a wall to hide them when looking at the motor in the motor bay. Lots of room in a Bus for cells without taking up any cargo or passenger space. And you can do it with out hacking the crap out of the vehicle.

You can follow the build here at this forum site and take a look at the advances he did with this bus and its conversion to electric. The Bus sports an AC-50 and I believe the 650 amp controller. Looks to be plenty of power for such a vehicle.

See the first drive with the bus below and enjoy.




First Electric VW microbus test drive from jehu Garcia on Vimeo.

AC-75

The count down has begun for the purchase of a new AC-75 and the Curtis 144 volt controller. I have sold a few items and have a few more things to let out into the community for those wanting a good deal for their first projects. I still have two motors and a controller. I'd like to let one of the motors and controller go as a package deal for someone wanting a good deal for a VW conversion. Strong solid motor and for all practical purposes a brand new Synkromotive controller.

I am now only a tiny bit away from getting my new AC-75 and controller for my Porsche 914. I am hoping that the new owners of the motor and batteries are happy with their purchase and that they get some good use out of the batteries. My brakes are done on my Roadster and now I need to build the pack case and install the batteries and controller and seats. I am going to have the front clip replaced as it was kinked a bit in its life. Should be an easy repair. I am glad to be working on the project once again.