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Battery talk — Parallax Forums

Battery talk

smithdavidpsmithdavidp Posts: 146
edited 2012-04-27 13:21 in General Discussion
I just recharged my new Tenergy battery packs with my new Li-ion Boe - Bot Power Pack Charger (7.5 Vdc, 1 amp adapter). I got a cell fault indicator on one of the cells. I reset it three times and continued to get the fault so I replaced the offending cell with anoter one (I bought 4) and all went well. Does this mean that the offending cell is defective or is it a quirkie kind of deal with those cells?

Comments

  • bsnutbsnut Posts: 521
    edited 2012-04-26 03:35
    Does this mean that the offending cell is defective or is it a quirkie kind of deal with those cells?
    I think that battery could be defective.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-26 10:46
    I'm not so sure it's defective.

    The Power Pack Charger was designed using normal (unprotected) Li Ion batteries. The protected Tenergy cells sometimes don't get along with the charger.

    There are two ways I'd try getting the battery to work. One (preferable) would be to discharge it to a lower charge state.

    The other way (I'm not so sure about) would be to charge it a bit by some other means. If you could give the battery about 500mA at 4.4V for about ten minutes, it might move the battery out of the zone that causes the fault.

    I used the charging technique with a LiPo pack that wouldn't charge with a different charger until I had recharged the low cell first with a bench supply. I don't think I've tried it with a Li Ion battery.

    Just so you know. Batteries (Tenergy) I initially had trouble charging, started behaving better after a couple of discharge and charge cycles.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-04-26 11:07
    Be sure to keep the receipt. Tenergy is usually pretty good about replacing defective cells. Assuming these were the kind with the PCB embedded in them, the board can simply be defective from the get-go, or it may have been damaged in handling, packaging, or initial use.

    -- Gordon
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-26 11:14
    GordonMcComb wrote: »
    Be sure to keep the receipt. Tenergy is usually pretty good about replacing defective cells. Assuming these were the kind with the PCB embedded in them, the board can simply be defective from the get-go, or it may have been damaged in handling, packaging, or initial use.

    -- Gordon

    Gordon,

    Do you have any suggestions on how to test them? I purchased six of the Tenergy cells from Parallax and several of them didn't seem to like the Parallax charger. I'm pretty sure they all work now but I haven't been keeping track of which ones have been used and which haven't.

    Any idea how to tell a reluctant cell from a bad one?
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-04-26 12:16
    Duane Degn wrote: »
    Any idea how to tell a reluctant cell from a bad one?

    Sorry, no. All of the ones I've gotten (not that many, maybe a half dozen) have all worked. The cells from Parallax are the ones with PCBs in them, no?

    MattG is the LiPo expert, and by no coinkidink, the expert on the charger as well. He'd be the best to ask.

    -- Gordon
  • smithdavidpsmithdavidp Posts: 146
    edited 2012-04-26 12:24
    All the other batteries worked just fine. I know this because the problem cell was put in a rotation with the other three batteries just in case it was one of those batteries that acts like a kid " I don't like him". Also was put in the other side and the fault followed it to the new side. These are the new batteries with the electronics package built in and were purchased from Parallax. I have multiple chargers (I'm a R/C Helicopter junkie) for radios and servos. But the are for the Li-po type batteries and also have a safety feature built in to keep you from blowing the battery pack up. Some of those packs are fairly large too. lol
    In any case I turned in a tech ticket with Parallax and I am waiting to see what I need to do.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-26 13:01
    GordonMcComb wrote: »
    The cells from Parallax are the ones with PCBs in them, no?

    Yes, these are the ones from Parallax with the PCBs. Matt mentioned he hadn't used the PCB batteries when he designed the charger. I know I'm not the only one who had some trouble with the PCB batteries working with the charger. I'm not sure if this was ever resolved.

    It doesn't matter much to me now. I don't think I've had a problem with any of the cell misbehaving lately.
    smithdavidp wrote: »
    I have multiple chargers (I'm a R/C Helicopter junkie) for radios and servos. But the are for the Li-po type batteries and also have a safety feature built in to keep you from blowing the battery pack up.

    I bet one of your LiPo chargers would charge the Li Ion battery. The chemistries are pretty close. Some of those LiPo chargers have a Li Ion option (I think mine does, I'm also a R/C heli fan).

    You wouldn't need to charge the battery all the way with your LiPo charger, just enough to get it out of its present state (I'm not sure about this).
    Or try discharging the cell a bit. Many LiPo chargers also have a discharge feature.

    I hope you let us know what Parallax says about it.
  • smithdavidpsmithdavidp Posts: 146
    edited 2012-04-26 14:24
    Well.....this is the conversation so far and I have heard nothing since I last replied:

    P/N 28987. I bought them from Parallax along with the charger and adapter. Look on your Web site ;-)

    I’m pretty sure you can pull up the invoice by my E-Mail or maybe someone in sales could do it? I’ll go look and see if I can find the box that the stuff came in.
    From: Parallax Support [mailto:support@parallax.com]
    Sent: Thursday, April 26, 2012 3:25 PM
    To: smithdavidp@yahoo.com
    Subject: [SUPPORT #XSC-761-25008]: Defective Tenergy Cell




    Hello,

    We don't have any Tenergy batteries for sale. What part number are you referring to?




  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-04-26 16:22
    Really? That's odd! No problems smithdavidp :smile:
    Please PM me with your shipping address.

    I think we're in the process of getting cells from a different supplier, so that may be the issue- sorry you're getting bad data...

    edit: although, with that part number, the tenergy cells come up...odd - "Heads Shall Roll" in the mornin'!
    -MattG
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-04-26 16:37
    ...and Duane and Gordon are right, the Tenergy's have built-in PCB's. I have experienced a couple cells where the protection circuit (inside the cell) is way too over sensitive. The Lion Pack will work with both protected and un-protected cells. In fact, the un-protected cells, while in the charger pack are - in fact - protected, because the charger circuit continuously monitors the temperature and current input into the each of the cells (independently of each other).

    As you know, the charger pack also has a 2 amp fuse to prevent too great of a discharge rate. This is in addition to the internal discharge current limiting circuit internal to the cells. Therefore, given my druthers, I prefer the "un-protected" cells, but for liability sake, we went with "double-protection without representation"- or something like that. Feel free to use un-protected cells in the Packs.

    Duane's suggestion:
    There are two ways I'd try getting the battery to work. One (preferable) would be to discharge it to a lower charge state.
    is preferable than the "other method" :thumb:

    -MattG
  • W9GFOW9GFO Posts: 4,010
    edited 2012-04-26 16:52
    I have two of the LiPo chargers and really like them.

    I modified the cell holders to make changing out the cells easier. On one I cut off both the "wings", It makes removing cells very easy yet they seem to be very secure. On the other, I removed one "wing" from each holder. It is still fairly easy to remove the cells and there is no way it is coming out accidentally, short of throwing it against a wall.

    I salvaged six cells from a Dyson battery pack that no longer functioned in the vacuum. After running them through the charger they all are working fine. I think at least one cell must be bad, but so far I cannot determine which one. I also intend to salvage some cells from a couple laptop batteries.

    Note that if you do salvage cells to be careful to insulate the positive end, so that you cannot short it during handling or installing in the holders.

    I have already blown a 2 amp fuse. I have one mounted to a Stingray, when the motors stalled, a few seconds later the fuse blew. 2 amps seems to be on the conservative side, what is the real max current that is safe to draw?
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-04-26 18:18
    Hey W9- nice pic...where'd you take that :thumb:

    Some Cells that have PCB built-in protection have an internal fuse that blows if you draw too much (to protect the cell). Since this charger can work with both protected and un-protected cells, we erred on the side of caution by putting an external fuse on the Board. That way, the *cheap* fuse blows, but the protected cell's internal fuse does not. So feel free to put a larger rated fuse in there (especially if you're using un-protected cells) if you'd like - at your own risk. Remember though there's going to be an upper limit to the amount of current that can flow through the PCB traces. Lots of amps to be sure, just be careful...

    I've even used a penny for a fuse jumper - no strike that - I've never done that, nope not me :innocent:

    -MattG
  • smithdavidpsmithdavidp Posts: 146
    edited 2012-04-27 01:59
    When I was a kid and wanted a piece of gum I always knew where to get the money to buy it. My mother would complain that her dishwasher and garbage disposal wouldn't work when my Dad came home. The Gum was good though.

    If you feel the cell is safe then I will go ahead and use it. I'll just keep an eye on it when charging. But I am curious about one thing though. If the charger trips a Reset Fault, will it continue to charge the cell?
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-04-27 07:02
    If the charger trips a Reset Fault, will it continue to charge the cell?
    Nope. You'd need to power cycle the cells (remove them (it) from the holder) and re-insert it.
    -MattG
  • smithdavidpsmithdavidp Posts: 146
    edited 2012-04-27 11:31
    I hope you let us know what Parallax says about it.[/QUOTE]

    Just to let you know I have requested a new Cell from Matt. I will be shipping the defective cell either to him directly or Parallax in general. Waiting on my E-Mail reply from Matt.
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-04-27 12:35
    Hey smithdavidp -
    I haven't received a PM (Private Message) or an email from you yet. I just PM'd you, but if you prefer, you can email me directly: mattg@parallax.com
    I'd like to send you a new cell, but I need to know where it should go :tongue:
    -Matt
  • smithdavidpsmithdavidp Posts: 146
    edited 2012-04-27 13:21
    You are right. Just checked my E-Mail and it wasn't sent. I sent it again. By the way you can just call me Dave or Knott Head. smithdavidp makes me feel like I'm back in the Army. lol
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