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DIY High Voltage Battery Reconditioner - Grid Charger

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by tgtech, Jul 31, 2022.

  1. tgtech

    tgtech Member

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    My 2010's mpg dropped a bit, so I checked all the normal things ... tire pressure, brakes, bearings, etc. All were fine. I figured the traction battery might be losing some pep, so I researched battery reconditioning. My traction battery hasn't ever thrown a code, but since it is now 10+ years old with 150K+ miles on the car, I figured a recondition was in order. Since the commercial reconditioners are expensive (Prolong and others), I built one for about $150 in parts.

    After doing the research on the reconditioning process and building the unit, which is also called a grid charger, I ran a charge/discharge/charge cycle on my battery. My mpg increased by about 10%, so I think there was some positive benefit.

    I attached a PDF of my schematic, pictures, and a parts list if you have any interest in this. Of course, this is DIY and there are no warranties expressed or implied … and working with high voltage stuff requires care and proper PPE!
     

    Attached Files:

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  2. PriusCamper

    PriusCamper Senior Member

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    Nice work... Very clean and clear presentation compared to the chaos we have on the thread over at:
    ----> Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat

    Have you given thought to a resistor based discharge beyond the light bulbs? I still use the lightbulb method, mostly because sourcing an affordable solid state resistor is problematic. One guy on here used an electrical brake from an old elevator.
     
  3. tgtech

    tgtech Member

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    Thanks! I have thought a bit about using 1Kohm/100W resistors, but they are relatively expensive and would probably need heatsinking and/or fans to keep them cool. It would be neat if the discharge cycle energy could be used to do something useful .... hmmm.
     
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  4. PriusCamper

    PriusCamper Senior Member

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    Yea, ideally you'd want to rig up a system to discharge into your home powerwall, or even just for powering your hobby chargers for module work, but as always managing this gets expensive real quick and most people just need the light bulb trick.

    What's good about the light bulb method is the intensity of the light with a quick glance tells you your discharge status. What's bad about it is the resistance of the filament changes depending on its temperature so you aren't discharging with a stable resistance value.

    Over in another thread we're talking about this SKYRC discharger that allows you to get a discharge chart for each module on your computer. That's a game changer for me when it comes to getting more accurate discharge data: SkyRC BD250 Battery Discharger Analyzer I'll probably buy one of these in the next few months.
     
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  5. tgtech

    tgtech Member

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    My next step is to automate the charge/discharge cycle with an Arduino and some other inexpensive components. I'm waiting for a few parts. I'll post info when I get it working well. Goal is to be able to run this charger without automation (as I posted above), or plug in the Arduino box between the charger and the battery harness to have it run automagically.
     
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  6. Myndex

    Myndex Junior Member

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    Doh... Just found this thread after purchasing the Prolong setup.

    That you found an ideal power supply for $30 is rad...
     
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  7. Albert Barbuto

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    Impressive build and excellent pdf documentation. A big thank you for sharing this! :)
     
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  8. tgtech

    tgtech Member

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    Thanks, I am trying to "give back" to this excellent PRIUSchat community so I invested some time and energy to document it well enough so others could understand it and build it. Given the skyrocketing price of cars and general inflation, I'd like to keep the car on on the road as long as practical and keeping the hybrid battery in shape is a big part of that.

    I have the parts to begin automating the charger, but need to find the time to design/implement.
     
    #8 tgtech, Sep 9, 2022
    Last edited: Sep 9, 2022
  9. Dxta

    Dxta Senior Member

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    Nice work. Thanks for detailing this setup. Being studying every bit of the schematics on page 4 ever since I download the paper.
    Any updates yet on your automation plan?
    For my own setup, I'd be using a different brand of power supply, with the following specs:

    MOSO X6-150M43 LED driver
    Input: 100-240V, 50/60Hz, 2.0A Max.PF:0.95
    Output: 80-143V, 0.15-1.50A
    Max: 170V, Max power: 150W.

    I'm connecting these two power supplies serially, to obtain, ~300VDC @ 1.5A.

    https://www.mosoleddriver.com/linear-industrial-lighting-led-driver/57314486.html
     
    #9 Dxta, Sep 10, 2022
    Last edited: Sep 10, 2022
  10. tgtech

    tgtech Member

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    As long as the power supplies are internally isolated, you can run them serially to boost the voltage. I am not a full fledged battery expert, but the lower the charge rate (amperage) the "gentler" it is on your battery. The 350mA rate seems very safe and any cells that reach full charge dump the excess energy through heat while lower voltage cells keep charging, I would be guessing 1.5A would be fine, but would recommend you monitor the voltage of the pack carefully and disconnect at your target voltage and keep the battery fan running so the heat is dissipated.

    I will be working on the automation when I have some spare time. It will likely be an Arduino controlling a MOSFET to connect/disconnect the Prius battery from the load/charger when the battery voltage hits certain values.
     
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  11. Dxta

    Dxta Senior Member

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    Thank you for your reply. I have already gone far, with my prototype using the power supplies I have.
    1. I used a mobile phone charger, as the power source for the volt/amp meter
    2. Sourced 4 diodes 1N4007(must not be 4), from an old phone charger also, and a 3M ohm resistor
    5. A piece of flat plywood, with piece of connectors.
    6. I have tested the circuit, and works perfectly. Used a 240V bulb, as the "battery", just to see if it works.
    7. Continuing with the DC side later tomorrow, again.
    Thanks so very much.
    Your pdf was very helpful.
     
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  12. a.mcintosh

    a.mcintosh Junior Member

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    I am going for the gentler, lower current approach. I just received my Mouser order of 5 @ MeanWell APC-8-250, and an eBay order that has a battery pack chassis, so I can try my ideas with a few modules on the bench. The cooling solution is still pending. I am going to mount this on an oak board with rubber feet, and an all-hole metal cage for tourist protection. I vaguely hope for the steampunk look.
     
  13. Dxta

    Dxta Senior Member

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    I think
    The oak board idea is pretty cool. I did same thing too, to try out my ideas, of the gridcharger I saw here too. That helped me prototyped everything on a plywood board, before transferring my charger circuits into a stainless steel sheet metal I made out of a scrap printing machine I scavenged from a junkyard. I got all the printers harness wires, and connectors, and some parts elsewhere to assemble it.
    Would post my own grid charger once I'm done here too.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    It's kind of making me think of the old Southwest Technical Products look.

    [​IMG]
     
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  15. a.mcintosh

    a.mcintosh Junior Member

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    The first test was the temperature on the modules during charging. I placed 6 decommissioned cells between pressure plates, with 1 reverse connected and 1 out-of-circuit (attached photograph is different configuration). This kept the voltage within the limits of the constant current charger at all times. I re-patched the connections so that each cell went to maximum charge, and afterward went to a deep discharge. Being in Texas, the temperature in the garage was pretty warm at night, but the module temperatures stayed not far above ambient.

    This design pushes the energy from the discharging module into the other modules, does not have a load resistor, and results in each module being charged to saturation for a long period. I don't know if that is a problem. It does let the system run at constant current before the end condition, so that I can directly calculate amps (or coulombs) in and out. I can measure voltage on each module.

    This is, of course, a research phase. That is because I am a scientist, my car battery is expensive, and I am using an abundance of caution.

    The next task is to build a resistive load, so that the constant current supply, the module 6-pack, and the resistor are all in series, and the voltage supplied by the power supply is within limits all the time.. This will dump the discharge battery energy into a light bulb, and the elapsed time will directly correspond to the amps discharged. In this design the light bulb will have constant brightness. I think this will let me know the capacity of the rejuvenated modules, once I know how to interpret the voltage by amps data. I don't have a data logger at hand, so I will be taking voltage measurements from time to time. I will look for a negative spike in the 2nd derivative as the endpoint.

    Looking forward, I am building the connector to the traction battery. At present, I have a shopping cart at Mouser Electronics with 16 ga stranded wire (5' red, 6' black) and 20 ga stranded wire, 1', for a fuse-able link.

    Although I would like to use the same connector that tgtech used for his J1 & J4, because the community is better off if we can design interchangeability, I want to use a 2 pin connector and his choice is 3 pin. I welcome discussion on this. Maybe he will change his choice :)
     
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  16. Dxta

    Dxta Senior Member

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    Would your two pin connector be able to handle the current "draw" capacity your grid charger or AC circuit be pumping out?
    Do you have schematics or diagram of your set-up?
     
  17. a.mcintosh

    a.mcintosh Junior Member

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    IMG_20221017_121954676.jpg IMG_20221017_121954676.jpg IMG_20221017_121954676.jpg For whatever reason, the photo did not post earlier.

    To be clear, this is a 0.250 A charger. Although it is a "grid charger" it is not high amperage.
     
  18. MarkySparky

    MarkySparky Junior Member

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    The next task is to build a resistive load, so that the constant current supply, the module 6-pack, and the resistor are all in series, and the voltage supplied by the power supply is within limits all the time.. This will dump the discharge battery energy into a light bulb, and the elapsed time will directly correspond to the amps discharged. In this design the light bulb will have constant brightness. I think this will let me know the capacity of the rejuvenated modules, once I know how to interpret the voltage by amps data. I don't have a data logger at hand, so I will be taking voltage measurements from time to time. I will look for a negative spike in the 2nd derivative as the endpoint.

    :)[/QUOTE]
    a.mcintosh, Could you please explain how to apply your "2nd Derivative" math to this application? I'm sorry, I barely made it through high school math many years ago! Trying to catch up on my math skills, and it's very helpful to have real-world examples to work with! Thanks!
     
  19. CR94

    CR94 Senior Member

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    Just in case a.mcintosh isn't watching this thread, I'll guess he meant when you see a relatively sudden change (which would include a reduction) in the rate of change in voltage.
     
  20. JohnStef

    JohnStef Member

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    I recently found your post as I attempt to restore hybrid batteries on (4) of my gen 2's. You have an excellent build, thank you for posting!

    To draw the hybrid battery down in stages the wire wound variable resistor which uses center tap connectors looks promising to me. My plan is to get the 300w 500ohm unit with (3) center taps and clamp the tap at the correct value. They will also make a "custom".

    https://www.aliexpress.us/item/3256802277471615.html?spm=a2g0o.cart.0.0.782638daU1zsV2&mp=1&gatewayAdapt=glo2usa

    upload_2023-5-12_8-40-55.png
     
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