Build Hybrid Battery Maintenance Gear For Under $100

Discussion in 'Gen 2 Prius Main Forum' started by PriusCamper, Mar 25, 2021.

  1. mpalomba3

    mpalomba3 New Member

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    Hey everyone, hoping someone can provide me with a little more info, mostly regarding actually using the DIY charger. I bought all the supplies and will be building the charger once everything arrives, but I am worried about overcharging.

    Since the DIY charger (using the HLG-80H-C350A) is a higher voltage than the Prolong charger, is overcharging a concern? How long should the battery be left on the charger to complete a full balance (first step according to Prolong's instructions)?

    Also, regarding powering the hybrid battery fan (using the RS-75-12 MEAN WELL), should the voltage knob be turned down to avoid burning out the fan? There seems to be some conflicting info on whether 12V is too much power.

    Any info would be appreciated. Building the charger should be no problem, but I haven't found a drop of info on actually using it and I would prefer not to accidentally destroy my hybrid battery, lol. Thanks!
     
  2. mpalomba3

    mpalomba3 New Member

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    Did a bit more research. Hopefully someone can tell me if I'm correct. The additional voltage should not be a problem and I should charge the pack until it holds a steady voltage for about 5 minutes (should stop charging around 235-240V according to Prolongs website for balancing). Then I should use the light bulb discharger, switching to lower wattage bulbs at the appropriate voltage. (200W bulbs until 196V, 75W until 140, 25W below 140V). As for discharge cycles, it should be 134V 1st discharge, 101V 2nd discharge, 84V 3rd discharge.

    This all seems pretty straightforward, so if that is correct, I've answered most of my own questions.

    The only question I still have is regarding the RS-75-12 MEAN WELL and what voltage I should run it at in order to not mess up the battery fan.
     
  3. alftoy

    alftoy Active Member

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  4. Ancel Bhagwandeen

    Ancel Bhagwandeen Junior Member

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    Hi guys. I just completed my simulations on a new safer grid charger. Why? Because an automotive service student near me lost an eye ) by having a Prius C battery explode (see the batt image) on him by using a commercial Grid charger with fan cooling (can't state the brand here....you guys know it well) . It happened because the fan cooling was inadequate, maybe the PWM fan controller failed or was intermittent. Anyway, because of this crap on the marketplace harming ppl I designed one as per these features:

    1. Integrated thermal (battery temperature sensed) throttling of charge currents. No more fan cooling is required at all. A significant removal of dangerous failure risk as I mentioned above.
    2. Electronic self resetting fusing (800ma) as well as 2A fast blow fusing.
    3. IGBT linear current control. Typically about 0.36A avg.
    4. NTC thermal sensor attached permanently to battery post ring connector: Calibrated to 45°C => progressive linear current throttling down to 50mA current flow at 45°C. This permits continuous blade voltage balancing but no longer overheats the battery, the current being < 0.1C of the blade's actual AH. Means a blade has to be under 0.5Ah capacity before it can heat with this approach.
    5. Mechanical relay used to create a latched 290VDC peak output via a safety push button separate from the main on/off power switch. Thus no Hi V on the output until u press this, normally open , push button to latch the output relay. Audible beep when hi voltage goes live. This ensures no accidental electrical hazard upon power up.
    6. Built in 12V aux. lead acid battery charger, up to 30A charge current ready. Safe float V limit of 13.8V, so suitable for sealed deep cycle/AGM etc.
    7. Displays Grid voltage, grid current, grid Wattage and accumulated KWh charged to guide you to assess the battery's capacity.

    Now this grid charger can service HV batteries up to 34 blades. Including the small 20 blade unit batteries. It will tolerate charging discharged batteries as low as 30V, or lower.

    Parts on order, expect the build to be done in a few weeks and then live testing at established/accredited Hybrid Service centres for final quality control; and validation.

    I will develop a discharger and then a Bluetooth ready brain to control both Charge/discharge for full battery cycle service. Perhaps by end of year for all 3. The discharge & charge will show the KWh rating of the battery and also the Charge/discharge efficiency of your battery!...so no more guess work on the battery, its condition or expected life.
     

    Attached Files:

  5. alftoy

    alftoy Active Member

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    Looking forward to the final product.
     
  6. PriusCamper

    PriusCamper Senior Member

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    This is great stuff... Can you share links to where some of these parts can be purchased. Also any links to get further details of the person who was injured? Possibly details of the position they were in when the tops blew off?
     
  7. Solman636

    Solman636 Junior Member

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    fach, can you tell me where I can get exact voltmeter you have. My meter doesn't give good format on HV. Thanks!
     
  8. alftoy

    alftoy Active Member

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    4 digit 10amp 500volt DC AliExpress
     
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  9. Prius92

    Prius92 Member

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    It is my understanding that NiMH cells/modules are designed to be charged with constant current and NOT constant voltage. That is why using a car battery charger or computer desktop power supply to charge NiMH isn't generally recommended.

    I am not sure if the grid charger that caused those modules to explode and the person to lose an eye was constant voltage or not, but if so, it highlights the dangers of constant voltage charging. CV charging causes thermal runaway.
     
  10. PriusCamper

    PriusCamper Senior Member

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    Yea, lots of bad info on youtube. That guy isn't really teaching a "master's class." NiMh are not balanced properly from the method he's using, which is similar to "balance from below" where you balance voltages between modules at the bottom of the charge level. That's a method used for Lithium. NiMh are balanced from above, meaning super low amp high voltage constant current so when some modules are fully charged they dissipate more charge as heat and because it's less than a 1/2 amp it doesn't damage the modules. His method in the video does this with much more amps via a 12v so he's wise to only do it very briefly. But once you run that pack in normal conditions it will come out of balance far more quickly that the proper balancing from above method

    I also looked at another one of his videos called: "Which is the best charger to use in a hybrid battery? Let's break the myth" where he says a Prius C pack is out of balance because of temperature distance instead of voltage difference. That pack didn't have anything wrong with it, yet he charged the customer to "fix" it, but then didn't actually do anything that changed it. However, his method for balancing that pack using a Prolong grid charger was correct. This thread teaches you how to build a higher quality grid charger than the one Prolong sells for 5 times the cost.
     
  11. Solman636

    Solman636 Junior Member

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    Just watched a video of Jose from Hybrid Solution Diagnostics who is mentioned a few comments back in thread with utube with him conditioning a Prius battery, but I also watched Jose charging an LFP battery from an Ioniq with a Prolong and he stated any charger would do so long as it was low current 350 mA and volts were in reasonable range above the rated voltage.

    My Gen 2 Prius could actually be a full EV 95% of the year if you gentlemen can answer a question for me and help an old man out. I have the Nexpower LFP upgrade I recently installed. All I need to do is charge at 350 mA for about 6 hours a day to move the car and driver 2 miles a day which is all I drive normally. Except for exercising the ICE occasionally to lube, it would be just along for the ride except for annual road trip. According to Jose, it is perfectly safe to charge LFP HV at this low current, and all that is needed is to have the charge voltage a bit higher than nominal. I have on my desk the LPC-100-350. Does anyone see any reason I can't use this in the same way I used the Maxx Volts to charge the old pack? I don't have the MaxxVolts anymore. I figure with the LFP charging at such a low current that it will likely not get hot, but I will use the fan initially connected to a 12v anyway. Can I just connect a couple of ring terminals to the HV as I did with Maxx Volts on some leads to a plug. Then connect the energized Mean Well and charge and monitor temp and voltage for an initial test? I understand how the diode on the + side would be helpful if power fails, but the Mean Well is not that expensive to risk a trial run til I get one. Not clear on the purpose of the capacitor on the Olrowdy diagram, but eventually my hope is to build it to his diagram and use it daily to top up the Nexpower. Sure, I know it would probably void the Nexpower warranty, but on the other hand I will have a Prius EV to use til I am 104 years old using my own solar power generation if I don't blow something up. If I can make this work then I can give the money saved to my needy children, and some younger high mile fellow could have the EV I would otherwise buy. Does this make sense? Possible? Thanks for any advice.
    upload_2022-8-5_18-22-9.png
     
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    I don't know if what you describe will work the way you want it to. I have read here in the forums that the HV battery ecu gets annoyed if the pack voltage is higher than what it wants. Throws codes, and does other (non efficient things) to use up power and get the voltage down.

    Also don't know what you would do to prevent the ICE from running. I recall there were very narrow limits to the "EV mode" button hack function.

    I think there were some weird hacks that the Gen2 PIP mods did to make it "work". You would have to research that.

    Posted via the PriusChat mobile app.
     
  13. PriusCamper

    PriusCamper Senior Member

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    While it is true that Hybrid Automotive's 350mA charger connected to your nexcell pack can safely charge it, the problem arises when the battery is fully charged. The difference is at full charge the NiMH readily sheds that 350mA as a discharge as heat. But when Lithium is fully charged it doesn't as easily shed that extra charge as heat and over time you could potentially damage your cells. And damage from overcharging is not going to be covered under Nexcell's warranty.

    That being said, you could use a battery management system to prevent this problem... Post 84 above also describes a system that would be required to ensure you don't overcharge. Also if you regularly plugged your pack into this system, you might increase the amount cycles / decrease longevity. Of course that's not really an issue w/ LiFePo4 as its chemistry is rated for far more cycles than other lithium.
     
  14. Solman636

    Solman636 Junior Member

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    Gentlemen, Thank you for your comments and observations. Very helpful. For what it is worth the EV button has worked perfectly for my 2 mile roundtrips at 100% EV mode with no ICE startup since I installed the Nexpower. With approx. 1 minute of charging by putting car in D and pressing accelerator or just following a longer drive to charge the HV battery shows 77% SOC and all bars on the screen but one are green. I do not need to overcharge or attempt to charge 100%. The daily charge using a slow rate of charge that I would need to refill is within the capability of the Mean Well. Basically, the experiment with the EV button has already proven to work. All that is required is to add half a kwh a day for the short drive which accounts for 99% of my driving day. PriusCamper, you make a good point about the LFP chemistry being well suited for long life and many cycles. That was the only reason I bought it since the old OEM battery still worked fine. The LFP should also be very tolerant of deep cycling. If I proceed then your idea of providing a high end shutoff is a good idea. I was thinking of experimenting by using a timer to slowly approach the level needed for the 2 mile trip. IF using this conservative slow charge to just the threshold needed and not trying to achieve 100% SOC then the experiment will be a success. Seems like worst that could happen with fan running and with LFP chemistry is that after 6 hours the SOC would be 85%. I guess this all begs the question why bother? Well, it is annoying to have the ICE kick on with all the undesirable aspects and fumes for basically no reason, just to warm up the car essentially when a 1/2 kwh grid charge would do the job. Saves wear on engine, reduces pollution, increases mpg from 28 to infinite!

    My main concern is of course not shorting out the expensive new LFP battery fooling around. I have in the past installed the Maxx Volts and all was well. But I don't have on hand yet the diode to prevent current from going back to the Mean Well if power goes out. Am I wrong to assume that as long as the Mean Well is energized this won't happen? And what is the purpose of the capacitor on the Olrowdy shown in this pic? Is it to prevent arcing when making connection. I am confused by seeing it connected to both the pos and neg wires. How is that possible? I understand that in refrigerators etc a capacitor is in place to smooth the startup. Is the purpose along that line? But I never knew that the capacitor was connected to both L and N.?? No hurry on this project. I want to keep it simple and minimal, but if you understood my driving needs of only 2 miles a day then you would agree that essentially I am turning the Gen 2 into an EV for a lot less than buying a Chevy Bolt etc. And why waste so much lithium battery on an old man to go to Walmart or to the park for a walk daily?? Long range is not needed for everyone daily. But I have the ICE for the annual trip to visit family too so this solution has many advantages. I don't want my desire to be efficient go to the extreme though. Perhaps that is the case. But for some reason i can't help but proceed slowly to investigate this, and so far I am very pleased with the EV mode mod and the Nexpower battery. If I go no further and just do the daily battery charge with the ICE that is fine, but still a waste of gas and wear on the ICE too.

    Here is pic re: capacitor question. Any clarification appreciated. Thanks again for your input!
    upload_2022-8-6_7-16-46.png
     
  15. Solman636

    Solman636 Junior Member

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    So far with air temps from 70 to 100 F the EV mode button works every time and no ICE as long as I have enough bars showing. However, ask me again in winter. I live in Florida, but it could be the cold temperature will make this whole experiment moot. We'll see!
     
  16. Solman636

    Solman636 Junior Member

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    Ancel Bhagwandeen, You are a genius! The tragedy of the lost eye is certainly very sad and also alarming and an important cautionary tale for old hackers like myself who sometimes have too much tea and use themselves for a short circuit!! No doubt many of us look forward to seeing your new charger with some of the safety features and more background on what parts you actually use.
     
  17. alftoy

    alftoy Active Member

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    It's a resistor not a capacitor. Why not just get an electric bike to go to Walmart if you are so concerned about having the ICE kick in. Otherwise let the BMS deal with charging the LFP.

    You obviously have too much time on your hands.

    " The 100K resistor is used to speed up the discharge of the high voltage of the Mean Well supply when you switch to "Discharge" or power OFF. Without the resistor (commonly called a "bleeder resistor") the supply will take much longer to reduce the high voltage to safe levels if you need to tinker inside the case. I connected D1 and R1 right near the charging harness socket on the front panel."
     
  18. Solman636

    Solman636 Junior Member

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    Alftoy, that's a reasonable suggestion, and I did use the trusty ebike for 10 years and the Prius sat motionless for months. However a succession of neighbors with dogs for a penchant of jumping directly in front of the bike over and over and demanding heart stopping braking and maneuvers to avoid getting my neck broke finally taught me that the safety of the 4 wheel car is necessary on this street. For 1/2 kwh charge a day into the EV the cost to achieve this goal and longer life seems worth a bit of effort. Not only my life, but if such a simple solution exists why put wear on the ICE and inefficiently burn up fuel when a $100 charger can get me down the road without the fumes and waste?

    So those are both resistors? But what is the purpose of the one connected to both the pos and neg? Isn't that a short? Thanks for your input, and it makes a lot of sense. Could be I will just give up on the charging as you suggest, but since I have almost everything in place to make it work the idea won't go away?
     
  19. alftoy

    alftoy Active Member

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    D=Diode
    R=Resistor

    Good luck, electrocuting yourself will make this all moot.
     
  20. Solman636

    Solman636 Junior Member

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    Of course, I come to you here on this thread to try to explore the DIY charger idea safely. :) Isn't that what this thread is about? Can anyone clarify the purpose of the R1 100k connected between the pos and neg lines?
     
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