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Re: [solectria_ev] Thermal Management System

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  • d. Bouton Baldridge
    Oh I forgot to mention, I had been told by a Sinopoly (formly TS) dealer that TS and SkyEnergy (Calb) originally were the two primary cell makers, and Sky
    Message 1 of 29 , Dec 4, 2012
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      Oh I forgot to mention, I had been told by a Sinopoly (formly TS) dealer that TS and SkyEnergy (Calb) originally were the two primary cell makers, and Sky (Calb) made the cells for their military so they were quite rugged could provide serious current, but that they had a shorter life than the TS. I have not used any Calbs, but I can attest to the TSs since I have at least 5 times brought the same group of cells back to life from 0v. Not on purpose mind you. My guess is that Calb has probably improved their product to give longer life with their new line, it is obvious that they have not been stingy with capacity sometimes 15% higher than rating. which would seem good except if your batch of cells are not matched, just keep it between the knees! good luck.
      Bouty


      ________________________________
      From: "theoldcars@..." <theoldcars@...>
      To: solectria_ev@yahoogroups.com
      Sent: Monday, December 3, 2012 9:47 PM
      Subject: Re: [solectria_ev] Thermal Management System

       
      Just a word of warning

      The CALB cells are not rated as many sellers on the Internet are showing 3C
      and 4C on their web sites. The SE series was rated by CALB at 1C and many
      have put them under loads of 3C or 4C. There is no data that I am aware of
      that shows cycle life under these higher C rates but it will be less.

      The new CA series which are also called the gray cells are rated at 2C by
      CALB.

      If your going to put a higher C rate on a CALB cell I would recommend it be
      the CA series.

      CALB for the most part has stopped selling the SE series except for a few
      sizes. The demand for the SE series has almost totally gone away with the
      release of the CA series.

      Jack from EVTV gives out some off some really off the wall advise and
      information. While some of what he does is good he also chimes in with baseless
      comments or beliefs that have no merit.

      On the 40Ah cells your going to see far more voltage sag under load. Cycle
      life would be less but as you point out its going to be a savings
      regardless over lead. I would highly recommend the CA 60Ah cells. The 60Ah cells
      hold their voltage very well. I know of one person who parallel two 40Ah of
      SE40 and their voltage sags more then a pack of 60Ah CA cells in series.

      Don Blazer


      In a message dated 12/3/2012 8:34:09 A.M. Pacific Standard Time,
      mailto:ev64bug%40yahoo.com writes:

      I have one question for Bouty:
      How many miles do you have on your pack?

      One question for the group:
      Does anyone have the dimension for the inside of the front battery box?

      I'm really interesting in Bouty's configuration. After 7 years and 22,000
      miles my poor old Pb pack is on it's last legs. I'm able to get 22 to
      24Ahrs out of the pack which is enough for a round trip to work and a very short
      side trip. Since the pack is fairly weak it takes 1.5 to 1.6Ahr per mile.
      I'm trying to hold out until summer for my switch to lithium when the
      weather is a little better and I have my battery monitor tested out. I'm
      interested in putting 49 40Ahr CALB "grey" cells (CA40BFI) for a couple of
      reasons:

      1. If my measurements are correct the complete pack should fit in the
      front battery box in a 7x7 array. By moving the charger up front all the 156V
      wiring will be under the hood with a very short run between the pack and
      the controller.

      2. The pack cost
      is comparable to if not cheaper than the Deka equivalent. 40Ahr CALBs are
      around $55 each. 49 x $55 = $2,695 before tax and shipping. 13 Deka
      batteries would have to be $207 just to be comparable ($2,695 / 13 = $207 approx.)

      3. My car will be shedding 661lb. The CALB cells at 3.3lb each x 49 = 161
      lb vs the 822lb (63.2lb x 13) of the current pack. I'm probably going to
      have to find the original springs for the Geo, otherwise the car will feel
      like it is permanently going down a hill.

      4. The "blue" CALBs (SE40AHA) already have fantastic C ratings and the
      "grey" cells have better cold weather performance. The max current of the
      force at around 240A dc should be no problem for the 40Ahr cells, they should
      be able to handle C6. There is some interesting test data on the cells:
      _http://blog.evtv.me/2012/06/battery-jump-shift/_
      (http://blog.evtv.me/2012/06/battery-jump-shift/)

      I know the general consensus is that 60 Ahr or 100 Ahr is preferable, but
      I've been logging all my driving for the past 7 years, most days I use
      between 16Ahrs and 20Ahrs and only a few times did I even come close to 35Ahrs.

      ________________________________
      From: d. Bouton Baldridge <mailto:_cfrkeepr%40yahoo.com_
      (mailto:mailto:cfrkeepr%40yahoo.com) >
      To: "mailto:_solectria_ev%40yahoogroups.com_ (mailto:mailto:solectria_ev%40yahoogroups.com) "
      <mailto:_solectria_ev%40yahoogroups.com_ (mailto:mailto:solectria_ev%40yahoogroups.com) >
      Sent: Sunday, December 2, 2012 7:26 AM
      Subject: Re: [solectria_ev] Thermal Management System

      Hi Wade,
      In my opinion, the balance thing has been greatly over blown and your re
      adings are perefectly acceptable especially after using so much capacity
      having only +/-.1 v or so from the mean is fantastic. The big thing is avoiding
      going beyond the knees and your system seems to be working just fine doing
      that. As for the Ahmeter issue, It has been my experience that voltage is
      not a reliable means for determining capacity. In my case I have found the
      reaching the limiting voltage was caused by the pack warming up; for me it
      was the sun. Now that the ambient temperature is lower in the winter season
      my charge resets closer to zero, but in summer it stops on the plus side
      by .1 ah each cycle when the outside temp is above 80 degrees. My guess for
      you is that when you charge for a few hours, the pack temp increases higher
      than when you were driving and the voltage is slightly higher as a result
      this stops the charger earlier than
      the previous Ahour
      reading. I am not sure if this is happening as a function of breaking in
      or aging. But it was not an issue with lead since it woul be overcharged
      routinely and had the automatic reset. I am a few months shy of 4 years and
      this slight precession is only an annoyance it has not seemed to impact the
      utility of my pack. Since I have a pretty long warm season I would just
      occasionaly reset the Ah meter to zero just so I wouldn't have to remember
      every time. Now that my cells are getting twice as old as any Pb pack would
      last, I am getting into new territory for longevity and at some point I might
      find some of these answers, but for now I am saying congratulation on your
      project FWIW,
      Bouty

      ________________________________
      From: Wade Perry <mailto:_perrypeas%40gmail.com_ (mailto:mailto:perrypeas%40gmail.com) >
      To: mailto:_solectria_ev%40yahoogroups.com_ (mailto:mailto:solectria_ev%40yahoogroups.com)
      Sent: Sunday, December 2, 2012 1:47 AM
      Subject: [solectria_ev] Thermal Management System

      Greetings all- I've driven over 1,000 miles on lithium now.

      I drove a fair bit today, it was mostly empty when I was coming back home
      from the last errand so I thought I'd take the long way home and discharge
      a bit more than I usually do. Until today the maximum I'd taken out is
      probably around 45 Ahr. I had set my limit around 50 to be safe.
      So after I got home I drove the block a few times with the heater on. Went
      well past 50. I measured pack voltage and some individual cells while I
      did this and felt fairly safe as I was getting down towards the bottom.
      Finally drove it around one last time in econ with no heater and it was
      around 57.5 when I was done. Then I ran the heater by itself to get it to
      59. Took the voltage on each cell.
      Made a new column to my battery balancing spreadsheet, it's here-
      _https://docs.google.com/spreadsheet/pub?key=0An5nm8itUMMcdHhQV3RsSUdfbzRTQk
      FlNmtaSy05MHc&output=html_
      (https://docs.google.com/spreadsheet/pub?key=0An5nm8itUMMcdHhQV3RsSUdfbzRTQkFlNmtaSy05MHc&output=html)

      The cells were springing back as I was measuring them. When I was done I
      went back and measured CK, where I'd started measuring the pack. it was
      .04 volts higher than I'd written down the first time. By the time I was
      finishing measuring, all the cells were coming in around 3.04 or 3.05. So
      they're reasonably well balanced.

      One cell stands out. JA. It measured 2.93 when its adjacent cells were
      measuring an entire ~0.10 volt higher. I haven't figured it out yet.
      Other than it happens to be the one that I noticed arrived from the
      factory at 4.23% below 50% SOC. You can see that on the sheet. It stood
      out at the time because all the other cells came in at 1 or 2% over 50.
      This was the only one that was below, and by a fair amount.

      Anyway then I ran the heater some more, watching JA in particular. It
      would have been cool to have a graph of all the cells at once. But they
      were falling off quite quickly. Some dipped down to 2.75 or so. JA dipped
      all the way down to 2.50. But I discharged down to a full 60.00 Ahr on my
      counter! Finished with a pack voltage of around 160. (which was
      undoubtedly springing up also. I didn't wait around to check but plugged
      in the charger so I can drive again tomorrow)

      This is great, because I had feared I was losing capacity permanently by
      charging below freezing. I'd hoped this wasn't the case, but was concerned
      because on especially cold days there'd be +1.00 or +2.00 Ahr still left on
      the counter when the charger shut off. Warmer days I'd be back to -0.14 or
      something like that. I'd been worried that I was gradually damaging the
      cells.

      Apparently I'm not. Or at least not to the extent I'd feared. This is
      with a battery box that's not even put together yet- the 60 Ahr cells are
      taller than the gels I took out, so when I finally do get things put
      together properly, I'll need to shim the cover over the battery box. Right
      now it rests on top of the cells, so there's probably a 1" space all
      around, letting cold air in. I did put in a 60watt incandescent light bulb
      back there to keep things warmer (and bright and cheery) in the battery
      box, whenever the car's plugged in.

      So. What I'd really like to do is hook up the Solectria heating mats to AC
      power, so I can be more setup for winter. I myself took it apart back in
      August, but obviously didn't pay much attention to what I was doing. I've
      searched this list repeatedly but can't find anything that talks about
      where the AC power hooks up to the heaters / sensors... Can anyone point
      me to a resource about this?

      Thanks for the help!

      Wade Perry
      1998 Force
      56 CALB CA 60 Ahr

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