1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Best Battery Charger / Conditioner ?? Help wife is gonna kill me

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SEaton, Dec 1, 2013.

  1. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Ok so my wife is going to kill me.

    No not because the car is in pieces in the garage
    Not because I have a battery torn to pieces across the garage
    Not because it will be that way for 3 weeks (shhhhh she has not figured that out yet )

    No, because I think things to death !!!
    I read study ponder, and think things till they have been thought over and over and over. Sorry ADHD kicking in, SQUIRREL !!!

    I am looking and there are sooo many chargers / options out there to choose from. What should I look for in a charger / what is the best value / functionality in a charger?

    I have looked at the Supermate DC6, lots people seem to like these, and IMAX B6 etc. I also wonder if I just buy this charger, or do I need to buy / build accessories to go with them.

    I have also considered the RB992-Super-Brain-Palm-Charger/dp/B00363WPBA

    I did not post a link, I wasnt sure if it is allowed and didn't wanna tick anyone off.

    Thunder 1220 Professional Multifunction Lipo/Lilo/LiFe NiCd/MH Balance Charger looked the most interesting to me. The reason I say that, is a bunch of the RC chargers appear to have very very low loads, so the discharge of something like 0.7 would take, well forever to cycle a battery. Versus some of these such as the 1220 can discharge at up to 5 Amps, that would significantly lower the amount of time required for conditioning.

    The Thunder AC6 looked interesting where it could be hooked up usb to a computer, not a must have, but would be cool to have

    It seems to me that ideal features would be .....
    A good discharge rate
    a good charge rate
    the number of modules it can balance at a time (4)
    A/C would be nice, D/C is doable if need be
    A computer output for graphing stats and such would sure be nice, but not a must.

    Thoughts ?
    Thanks folks


     
  2. greasemonkey007

    greasemonkey007 Active Member

    Joined:
    Sep 20, 2013
    287
    106
    0
    Location:
    South Central Arkansas
    Vehicle:
    2006 Prius
    Model:
    N/A
    I bought 3 of the hitec x4 chargers. Actually it was one x4, one x4 eighty, and one x4AC plus. You're right about the discharge time. These will discharge up to 1A but I used the .7A rate because I didn't want to experiment. I have since talked to someone who discharges at 5 or 6 amps but I'm not sure what kind of charger they used. I am ready to install my batt pack now. If everything works correctly I plan on selling the 2 DC powered chargers and keeping the AC/DC powered one. Other than the time involved I was pretty well pleased with the chargers. I did have issues with some of the batteries. I had to run several cycles on a few of them but I believe it was the battery and not the charger. I think I spent $125, $150, and $225 respectively. I also bought the USB adapter for the computer but never opened them. Just didn't take time to download the software from Hitec. I think the're pretty good for the money.
     
    SEaton likes this.
  3. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    SEaton, it is better to overthink than underthink ... especially in this context!

    I was thinking through the same purchase decision a couple of weeks ago. You are asking the same questions was. I ended up buying 4 of the Supermate DC6 due to the low cost and their popularity here on Priuschart ... I figured it would be easier to get questions answered.

    Having read through some postings here and on the RC forums, it appears many of the single chargers (e.g. iMax B6, Supermate DC6, Thunder whatever) are nearly identical. Even the Hitec seems to have a similar user interface and is seemingly 4 of these single units integrated into one unit. I was initially a bit leery of the quad chargers due to fears they may not dissipate the discharge heat for 4 batteries as well as 4 separate units in similarly sized packages, e.g. the DC6 or iMax. Having said that, 1 of my DC6 died (during discharge) and mushatsu has also had a failed DC6. I have not read of any Hitec quads dying.

    As you note, the time limitation on these is due to the relatively low discharge capacity. The DC6 (and many others) can dissipate up to 5W. For our voltage (i.e. number of cells), this works out to a 0.7A discharge rate. I don't know about the Hitec (as greasemonkey uses) but the firmware in my DC6 will not allow a higher discharge current for this setup. (For battery packs with lower voltages, it will go up to 1A.) Discharging 6.5A at 0.7A takes a bit over 9 hrs. I have been playing with the idea of modifying a DC6 charger to discharge faster (using external load/heat sinks) but that's a whole other topic.

    These RC chargers can typically charge at a max of 50W or 5A. This is not much of a limitation in our context. 5A represents a charging rate of 0.77C and I wouldn't want to go much over 1C (6.5A). A 5A rate works out to 1.5 hr charging but it will take a bit more due to the overhead of the delta V readings ... maybe 2hrs max.

    In prior work, I have had access to the professional chargers that can discharge much faster. The cost is so much higher that you could buy 4 DC6 or one Hitec for less. While the professional charger would go faster, you would be needing to move it from one module to the next more often. For most DIYers, it is more convenient to buy multiple chargers, set them up on several modules, and come back every 1.5 to 2 days to switch to a different set of modules. (Also, you will probably get more help here if you are using the consumer-grade RC chargers.)

    As for other eqmt, I fabricated a few cables but that is not entirely necessary. (The chargers comes with cables that have alligator clips. I prefer more stable connections ... if you consider yourself ADHD and have some electrical background, I expect you will feel the same.) If you buy chargers that require a 12V input, you will need some type of power supply. Do a power budget to ensure whatever you choose can supply adequate power. (PC power supplies and 12V car batteries seem to be most popular here. I am using a car battery that has a 'maintainer' charger on it.)

    /Marc
     
    Jason-is-my-name likes this.
  4. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Marc and GreaseMonkey

    Thanks so much for the help guys, you are the best

    Great information. Yeah I am so new here, so sure I am missing things here. So the modules are 7.2V 6500mah or 6.5 AH. From what I know of Nimh, 1C is the magic number. In theory a person could discharge a cell at 1C or less safely (so 5 -6.5A seems reasonable). I have always been told that to condition such a battery you don't want to exceed 1/10C when charging, so I would think we would want to charge at a rate around 650mah or less. This seems to me like I would be charging at 650mah and would be significantly slower than what i have read some people are charging at, and would take well forever.

    Then a person wants to discharge down to .9V per cell (6*.9) so 5.4 V on the low side ? I noticed on here people going down to 6v. I know if you push it too far it can make them reverse, not good. I read that was to allow it to break up any large crystals forming on the cells.

    I guess that ultimately the IMAX B6 etc, are basically charging up the batteries at a very very slow programmed rate, and then discharging at a known rate. They don't really do much magic, other than I am assuming they tell you a projected mah capacity, and maybe internal resistance of the battery.

    So we know that to condition each of our packs, we will run them through the charge / discharge cycles 3 times each or so to condition them. So would it not make sense that a person doesn't need to use the B6 except to charge them slowly and to know the conditions of the cells ? Could not a person use a dead load (e=I*R) and discharge them with something as simple as a simple light circuit with a bulb and resistor ? If calculated to be say a 3 amp load, I imagine a person could take the totally charged cells down to 5.4 or 6 volts in a very reasonable amount of time. Then after a resting period, a person could use the B6 to charge them back up at a controlled rate to repeat. and then use the B6 or Hitec for the last discharge cycle to see what your numbers look like ?

    My thought being that only using the Hitec or B6's as the chargers at 2 hrs per charge, frees them up. and of course use them on the final discharge cycles to get the stats. But it would seem that in the middle a person could use a simple load to shorten the discharge cycles significantly.

    Like I said, I am sure i am missing something
     
  5. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    Yes, those are the correct battery capacities. The batteries can safely be discharged at a much higher rate. With the monitoring software on a running Prius, people report on the order of 50A continuous and up to 100A as a peak. So, you can discharge at much more than 1C. As for conditioning the battery, higher currents are used (optimally pulsed) in other technologies to break up crystals. That is not such a problem for NiMH but for many of us it might be ingrained to charge quickly for this reason. In any case, charging efficiency is better for NiMH at higher charge rates. For example, 90% efficiency is typical at 1C in the mid-part of the SOC whereas 70% is typical at (1/10)C. That wasted energy is heating the battery so I don't think you are doing it any favors by charging it so slowly. I have not heard of using (1/10)C as a threshold except for trickle charging without a good cutoff mechanism, e.g. delta V.

    0.9V is considered typical for a discharged NiCd cell. 1.0V is considered discharged for most NiMH cells. Many chargers default to these values and battery specs often use these values, e.g. http://www.gpina.com/pdf/6GP7PVS_DS.pdf

    Correct though I would not say they give a projected capacity. However much is discharged on the last cycle is the capacity of the battery at that time. My chargers (Supermate DC6) do not measure internal resistance. This is usually done with an ammeter, voltmeter and a load. (If you use a bulb, note that it has a variable resistance meaning you must derive the battery resistance from current, open-circuit voltage, and loaded voltage.)

    Regarding the discharge, yes. I have been thinking similarly of going 'off-script' relative to what is typically done on this forum. The primary advantages to using the chargers to discharge the battery are (1) it is automatic so you don't need to worry about over-discharging; and (2) you have the capacity recorded. If you do decide to do your discharges manually, I would recommend that you not discharge all the way as you need a consistent discharged level before you start a charge cycle. (The charging only puts a set amount of energy in the battery relative to its current SOC.) You might manually discharge to something in the 6.25 to 6.5 V range. Then, have the charger take over so it discharges to exactly 6.0V.

    I agree with your reasoning but let's run some numbers to make sure I fully understand. For the standard method, the first discharge will be from a SOC in the 50% range so it takes on the order of 4 hrs. Then, you have 2 full discharges (~9 hrs each) and 3 full charges (~2 hrs each). Total 28 hrs. With your suggestions and an effective 3A load, these values would be (approximately) 1 hr initial discharge, 2 hrs second discharge, 9 hrs third/final discharge, and 2 hrs for each of the 3 charges. Total 18 hrs. You would be saving 10 hrs/module (at a cost of more babysitting). Correct?
     
    SEaton likes this.
  6. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A

    Right, you are right in line. My cells are mostly all at 8.2 (too high) for some reason. Guessing due to the bad cell it over charged the cells ? so if I did it the old way even my first discharge would take like 9 hours. And using 3A is probably being very conservative, I don't see why a person could not do more. So yeah the old way I would be looking at 9 * 3 or 27 hrs of discharge, + 3 * 2 or charge or 33 hrs per module. 38 modules at 33 hrs =1254 hrs.

    The other way say I discharge at 3A (maybe I should do 5). I would be looking at 4 hrs for 2 full discharges, + 9 hrs using the B6 + 6hrs for charges so 19hrs per module. 19 * 38 = 722 hrs.

    The kicker on this would be the chargers could always be running. For each charge, I could have another cell completely through a discharge and ready and waiting for a charger.

    The dischargers should be pretty cheap to build, and i could make several of them. If I got fancy even I was thinking something like this EEVblog #102 – DIY Constant Current Dummy Load for Power Supply and Battery Testing | EEVblog - The Electronics Engineering Video Blog

    I haven't priced the components, but not much to that. No reason a person couldn't use an inverter to drain them down either. Hook em up in series and drain them down to 6.25 *2 = 12 volts, then use the charger to finish the cycle.

    its not perfection, and yeah lots of babysitting, but if i can cut from 1254 hrs to 722 ( I would argue less as I can charge and discharge at the same time).
     
  7. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Yeah I see no reason why a person couldn't discharge at 6A, that would significantly improve things.

    So yeah the old way I would be looking at 9 * 3 or 27 hrs of discharge, + 3 * 2 or charge or 33 hrs per module. 38 modules at 33 hrs =1254 hrs.

    Say I discharge at 6A. I would be looking at 2 hrs for 2 full discharges, + 9 hrs using the B6 + 6hrs for charges so 17hrs per module. 19 * 38 = 646 hrs.

    I would think that I can always have modules down to 6.25 just waiting on the chargers to be free for the 2 hr charge (maybe 2.2 with the slight .25 discharge).
     
  8. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    Good point regarding doing these things in parallel ... you almost cut the time in half.

    If you do decide to do this piecemeal, note that you might not want to charge all the way on your last iteration. You might save another ~hour per module. (You wouldn't get the cell-balancing benefit of that last full charge.) There have been other posts where people have put a fully-charged pack in their car only to get an 'overvoltage' error since the Prius is expecting to keep the pack between 40 and 80% SOC. Britprius recommended that I discharge my pack some (manually) after the final balancing (i.e. when all the modules are tied together) to avoid this problem.

    I just noticed (after seeing your mention of 38 modules) that you have a Gen1 so I understand you have even more reason to try to speed the process. I think it is good to see the arithmetic as a sort of mental CRC but note that you will probably need to run more than the 3 cycles on several modules. It is hard to gauge how many until you have taken a measured discharge. I plan to go beyond 3 cycles on about 1/3 of my modules. (My pack is in pretty good shape with no dead cells. My goal is to get them all back to at least 6.0 Ahr.)

    If you do build a discharger using power resistors or similar, be sure to post the design, pics, and your results.
     
  9. greasemonkey007

    greasemonkey007 Active Member

    Joined:
    Sep 20, 2013
    287
    106
    0
    Location:
    South Central Arkansas
    Vehicle:
    2006 Prius
    Model:
    N/A
    This is communications with a seller on ebay where I was looking to buy some gen3 mods to put in my batt pack. Oldest ones are at the the bottom.

    Dear greasemonkey347,


    2nd gen is better for your case, and is cheaper.
    I'm doing same, but using 6A charge, 6A discharge, which shows low capacity if discharged with 0.7A
    But some of the cells does not increase the capacity after cycling.


    - hybrid.parts
    Click "respond" to reply through Messages, or go to your email to reply
    [​IMG]
    [​IMG]



    From: greasemonkey347
    To: hybrid.parts
    Subject: Re: Other: greasemonkey347 sent a message about TOYOTA PRIUS HYBRID BATTERY CELL MODULE 2010-2012 fit 2001-2003 2004 2005 2006 #251350144738
    Sent Date: Nov-11-13 03:44:23 PST


    Dear hybrid.parts,

    I used a Hitec x4 charger to discharge at .7A and charge at 5A for 3 cycles. I set the capacity shut-off at 7250mAh and the safety timer shut off at 660 min. The display on the charger records the charge and discharge capacities. The ones that were in the 4500 to 5500 range I ran for a couple more cycles and got them up to around 6000mAh discharge. Someone told me I would be better off getting gen2 batteries to keep them closer in age and capacities and the gen3 battery might be just a little bit bigger in physical size. My car is an 06 with about 140k miles. I've got 5 or 6 that I'm going to cycle again and try to get up to the 6000 mark so they'll all be pretty close to equal in capacity. Any suggestions are always welcome. This is my 1st hybrid to work on.
    Thanks,
    Charley

    - greasemonkey347


    From: hybrid.parts
    To: greasemonkey347
    Subject: Re: Other: greasemonkey347 sent a message about TOYOTA PRIUS HYBRID BATTERY CELL MODULE 2010-2012 fit 2001-2003 2004 2005 2006 #251350144738
    Sent Date: Nov-10-13 19:56:16 PST

    Dear greasemonkey347,


    Charging/discharging is not a balancing. They are tested with 3 times charging/discharging and this help the capacity to be increased.
    How did you measure the 5500-6200 capacity - what charge / discharge current. That's is pretty new batteries only.
    Capacity depends of the charging / discharging current. We have all kind - from 4.5 to 6.5Ah.
    A car at 80k miles 2007 has usually 4.8-5Ah
    Thanks
    Nick


    - hybrid.parts


    From: greasemonkey347
    To: hybrid.parts
    Subject: Other: greasemonkey347 sent a message about TOYOTA PRIUS HYBRID BATTERY CELL MODULE 2010-2012 fit 2001-2003 2004 2005 2006 #251350144738
    Sent Date: Nov-09-13 19:23:15 PST

    Dear hybrid.parts,

    Have these batteries been balanced (discharge/charge 3 cycles) and tested checking the capacities and resistance? I saw that on the gen 2 listing. I've just did my battery pack and I need 1 mod but want to buy two. My capacities are in the 5500-6200 mAh range. I plan to work on the lower ones to get them all around 6000 or so.

    - greasemonkey347




    [​IMG]
    TOYOTA PRIUS HYBRID BATTERY CELL MODULE 2010-2012 fit 2001-2003 2004 2005 2006
    Item Id: 251350144738
    End time: Nov-30-13 07:01:20 PST
    Seller:
    hybrid.parts (273[​IMG])
    99.1% Positive Feedback
    Member since Jun-02-08 in United States
    Location: NV, United States

    Listing Status: This message was sent while the listing was active.
    Here are more items from this seller

    4 RUNNER RAV4 REAR AUTO DIMMING DIM CHROMATIC MIRROR COMPASS OEM 2001... Toyota Prius HV HYBRID VEHICLE CONTROL UNIT ECU COMPUTER 2001 2002 2003 01 - 03 TOYOTA PRIUS 1.5L I4 EFI 4D PASSENGER RIGHT SIDE TAIL LIGHT F... LEXUS HEATED SEATS CONTROL, HEADLIGHT WASHER BUTTON PANEL MODULE Rx40... 04 05 06 07 08 09 TOYOTA PRIUS HYBRID POWER STEERING CONTROL MODULE 8...
    [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
    0 Bids $75.00
    Shipping: Free
    [​IMG] $69.00
    Shipping: +$19.95
    0 Bids $65.00
    Shipping: Free
    0 Bids $65.00
    Shipping: Free
    0 Bids $29.00
    Shipping: +$6.95

    Visit seller's Store [​IMG]




    [​IMG] Marketplace Safety Tip [​IMG]

    • Keep your money safe - never pay for items with cash or instant money transfer services, such as Western Union or MoneyGram. In the past some sellers have exploited these payment methods in order to defraud buyers, so eBay has banned them from the site.
    • Received a Second Chance Offer email? Double check that it's genuine: Second Chance Offer emails come directly from eBay and are shown in your My Messages.
    • Trade safely. Beware of anyone who contacts you about buying or selling outside of eBay. When you trade outside of eBay, you're not able to leave feedback or take advantage of protection programs and case resolution tools available on eBay. Report an inappropriate email.
    • eBay helps guard your privacy and online safety when you use our messaging tools. If you and the member you're contacting haven't bought or sold from each other recently, our tools may make both of your email addresses anonymous.

    [​IMG]
    Email reference id: [#a02-15v095ypvg#]_[#40118dcf8d874fe5b6e99209fe0b2472#]
    Please don't remove this number. eBay customer support may ask you for this number, if you should need assistance.

    Learn More to protect yourself from spoof (fake) emails.

    Another eBay member sent this email to your email address through the eBay platform. eBay takes no liability for the sending of this email or its content.

    Visit our Privacy Policy and User Agreement if you have any questions.

    You can report this message as unsolicited (spam/spoof) email.

    Copyright © 2013 eBay Inc. All Rights Reserved. Designated trademarks and brands are the property of their respective owners. eBay and the eBay logo are trademarks of eBay Inc. eBay Inc. is located at 2145 Hamilton Avenue, San Jose, CA 95125.

    [​IMG]



    Next messagePrevious message
    |
    View full message



    Start of LayerEnd of Layer
     
  10. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Thanks for the info. I will have to take some time to absorb what all he had to say. On the one hand he says discharging / charging is not balancing. It helps to increase capacity.

    So the cycles are conditioning the modules to get the most out of them I guess.

    On the Gen 3 hand, I stumbled across a bunch of those today. For $450 I can pick up a gen 3 HV out of a wrecked vehicle that looks to be good, and $150 more gets me a pack that is dented a bit, not sure how many cells in there are good, I am running up there tomorrow to look at it. If I could get enough cells out of those 2 packs I could use those and then cell my cells I guess.

    So by conditioning charging / discharging the cells 3 times. That allows a person to what ? determine the capacities of the cells which helps a person get a better idea of what modules might be a good match for a replacement ?
     
  11. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    I am thinking that by balancing people are just referring to making sure the voltages are the same across all the modules. The last step really before going back together for the final run. The 3 cycles are what ? conditioning ?
     
  12. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    "Charging/discharging is not a balancing. They are tested with 3 times charging/discharging and this help the capacity to be increased."

    Thanks for the info greasemonkey. As SEaton, I question this statement. Perhaps the ebay seller is using different nomenclature and considers "balancing" to be only the process of equalizing the voltages across multiple modules. SEaton, I do not think people in general (or on this board) would say that calling the charge/discharge cycling "balancing" is incorrect.

    The charge/discharge cycles do a couple of things. On the charge side, we are actually 'overcharging' the module. In normal operation in the Prius, the battery pack stays in a middle-point in its SOC capability. Gradually, stonger cells will take on more of the charge while weak cells (e.g. those that have lost electrolyte due to heating) will lose capacity. Overall, the SOC remains at the midpoint but at the cell-level some are charged to near capacity while some are taking on much less charge.

    As a specific example, suppose a module (6 cells) has 1 weak cell that cannot hold any capacity and that we were able to charge a single module. If the other 5 cells (healthy) are charged to 90%, then the module can still attain a 75% charge which appears healthy enough at the module level. The bad cell is never forced to take any charge. As the healthy cells take on more charge, they take on more heat (due to lower charging efficiency as we near 100% capacity) meaning they will gradually weaken. (This is a contrived example for explanation purposes.)

    By charging the module to its full capacity (which may be a bit beyond its specified value), we force all the cells, including the weak ones, to take on charge and restore their capacity. The repeated charging balances the cells against each other within the module. Note that the devices we are using are termed "Charger/Balancers."

    An even better way to balance modules (battery packs) is to charge each cell individually (either directly or indirectly). That is effectively what these charger/balancer devices do when using the "balancer" boards with lithium batteries. (RC lithium batteries typically provide access ports to each cell so they can be balanced.) Ideally, we would have such access ports to each cell in our modules so we could do the same.

    A high discharge rate can break up crystals but these are more of a problem with Cadmium. I would term that 'conditioning.'

    In summary, I disagree with the ebay seller's comment that cycling the modules is not balancing them. I would ask some of the experienced board members to comment.
     
  13. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Thanks so much for the clarification, yes that was not jiving with my electrical knowledge. I used to be an electronics tech in the military, so I have a lot of background. So while I am comfortable with electronics / electricity, I know just enough to be dangerous :)

    Speaking of dangerous, I have figured out what I am going to do for my first discharger attempt. I have attached a picture of attempt number one, I will let you know what the results look like. Basically this device should be a constant current discharger, it will discharge at a constant current regardless of voltage. I will still need to use a meter on the cells to make sure I don't drain them too much, however if that works well, then I will add a simple device to cut off at a set voltage. Basically I am using voltage regulators, kind of in reverse. A voltage regulator basically controls the current side of the equation which is what helps it keep a constant voltage. I am reversing the process, and using the regulator to control current flow, ignoring the voltage side of the equation.

    Anyway, that's the theory of it :)

    I am driving up to pick up a huge power supply I got a steal on, and after that I will have my first cycle started on my battery today.
     
  14. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    Just to give you heart failure, I have included pictures of what the first run might look like. Note these are not from my setup, but the setup I based my design off of.
     

    Attached Files:

  15. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    That is more elegant (soldering job notwithstanding) than what I was considering. I was considering simple power resistors with, effectively, a 6V regulator tied in to prevent over-discharging. That would have the obvious problem that the current would gradually decrease during the discharge

    In your pic, are those regulators rated at 1A max each (total of 6A)? I see where the inputs pins are tied together and that the adj/gnd pins are tied to the output on each regulator. However, I cannot see where the gnd pins are tied together (as I am expecting). Maybe everything is grounded to the case?

    I have a handful of LM1086 adjustable regulators (1.5A each) that have been sitting around ... maybe I have a use for them now!
     
  16. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A

    Depending on which ones you use, the LM317T is 1.5A I believe each. I figured I would put a meter on it and add one at a time. The guy I was following claimed they were 2.5 each, but looking them up on the net they showed 1.5 or 1 depending on the package they were in. I won't probably play with them till thurs or so after I get this project well under way.

    Yeah they are all grounded through the heat sink. Yeah I think I would be a bit fancier on my connections :)

    No reason why a person couldn't use resisters, this was more of just a fun being creative thing.
     

    Attached Files:

    marcs_carhole likes this.
  17. marcs_carhole

    marcs_carhole Junior Member

    Joined:
    Nov 1, 2013
    44
    14
    0
    Location:
    Durham, NC, USA
    Vehicle:
    2004 Prius
    Model:
    II
    Thanks for the schematic ... pretty simple. You are correct that those devices are typically 1.5A max current in the TO220 package. Good luck and I look forward to seeing your results.

    Don't you hate that the discharge methods all just dump the energy into heat? Wouldn't it be nice if we could feed it back into charging some other battery? Besides not wasting the energy, the discharge would no longer be limited primarily by the heat dissipation.
     
  18. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A

    It's snowing like crazy and cold, so I don't mind heat at the moment ;)

    Ok, being the rocket scientist that I am, I just now started my first cycle on 4 modules. It ofcourse always makes sense to kick something like this off at 12:10 am.

    Charger name to withheld to protect the innocent :) once I have figured out what all I did wrong if anything I will add that. Right now I am super optimistic, if it works well, I will be super happy. Even though the specs said it would only discharge at an amp, it will actually discharge NiMh at 2A, NIIIIICE. So we will see how things work and how bad I messed up the settings. hopefully it will all work.
     
  19. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    First setttings

    Charge 5A (it can do higher)
    Discharge 2.0A 6.0V
    re-peak 3
    cycles 3

    capacity cutoff 7200
    safety time disabled
    rest time 15min
     
    autoz likes this.
  20. SEaton

    SEaton Junior Member

    Joined:
    Nov 28, 2013
    29
    3
    0
    Location:
    Eagle Mountain, Utah
    Vehicle:
    2002 Prius
    Model:
    N/A
    well, something is not right. The discharge part seems to be working right, but the charge was over charging. I kicked in a manual discharge cycle and will try again when I am back to 6V. The 7200 cutoff capacity (6500mah ?) might be the problem, I know that was too high, but I thought that is just the safety cutoff , it should be charging based off delta V I thought. I think there is another way I can tell it to charge and tell it the exact voltage I want it to get up to.

    any ideas ? just set it for the 7.2v and charge it up that way ?