Loading ...
Sorry, an error occurred while loading the content.

Re: [RoboMower] Batteries

Expand Messages
  • Danny Miller
    And I d agree. Based on general feel of the response and little actual objective data, I think the EB20-12 seems more reliable at only slightly more cost.
    Message 1 of 40 , Jan 22, 2010
    • 0 Attachment
      And I'd agree. Based on general "feel" of the response and little
      actual objective data, I think the EB20-12 seems more reliable at only
      slightly more cost.

      I've also got a pretty strong theory that it's not the running down
      doing the killing, it's the charge cycle. There have been cell balance
      issues observed , and more of a concern, thermal runaway. Thermal
      runaway is a problem with fast chargers that lack a battery temp
      sensor. When the battery warms up, it needs a reduced charging voltage
      or it'll draw too much current at standard charging voltages, even when
      fully charged. That current isn't being stored as chemical energy in
      the charge, it just burns up as heat and heats up the battery which may
      cause the problem to "run away" and melt the battery-literally. One
      user here observed it, battery case was all warped.

      I suspect that we've frequently got lesser cases of this problem where
      it only delays the exit out of high-rate charge, and only cooks the
      battery a little, but resolves itself before a total runaway occurs.
      Unfortunately, I don't have an easy answer to this. I can design and
      build a temp-compensated balancing charger but it won't be cheap enough
      for you. I don't see any way to modify the existing chargers. It's
      possible to build shunts to prevent balance problems (which is different
      than thermal runaway), but the shunts may themselves interfere with the
      charging cycle and cause a major problem. Also there's a balancing
      shunt regulator design out there by "Lee Hart" that unfortunately really
      can't do what they're designed to do. There's a way to do shunt regs
      but that one isn't it.

      The one firm recommendation I CAN give is this: NEVER FAST CHARGE A WARM
      BATTERY. It's just asking for a runaway. Tempting, since most of us
      get 2 batts and take the warm one off the mower and throw it on the
      charger while running the second. That's a very bad idea. Takes hours
      for a batt to cool down.

      Danny

      Ben Sporl wrote:
      > I bought them from Batteryspec.com (San Jose, CA).
      >
      > If you need to buy them now, I'd suggest BB Battery EB20-12. I think they have better feedback overall.
      >
      > http://robomowerwiki.com/index.php/Battery_pack#BB_Battery_EB20-12
      >
      >
      >
      >
      > ________________________________
      > From: jeff <rainycityguy@...>
      > To: RoboMower@yahoogroups.com
      > Sent: Fri, January 22, 2010 12:26:47 PM
      > Subject: Re: [RoboMower] Batteries
      >
      >
      > what venor? where buy? And folks, this is why I am asking. Others have said this
      >
      > ____________ _________ _________ __
      > From: Ben Sporl <bsporl@yahoo. com>
      > To: RoboMower@yahoogrou ps.com
      > Sent: Fri, January 22, 2010 10:04:04 AM
      > Subject: Re: [RoboMower] Batteries
      >
      >
      > I purchased the Tempest TD22-12 late last summer but don't have a good measure of their performance. One of the batteries was bad forcing me to send it back for repairs. Since the vendor is in California I pay shipping both ways for warranty repair. This experience left a bad taste so I'd hesitate recommending them.
      >
      > ____________ _________ _________ __
      > From: jeff <rainycityguy@ yahoo.com>
      > To: RoboMower@yahoogrou ps.com
      > Sent: Fri, January 22, 2010 8:32:50 AM
      > Subject: [RoboMower] Batteries
      >
      > It's almost time to order while suppliers have stock. Does everyone still think the Tempest TD22-12 is the way to go? Thoughts or suggestions? Who is the best (price, quality,service) supplier online? I've been looking at batteryspec. com but what others has this group dealt with?
      >
      > Thanks all
      >
      > [Non-text portions of this message have been removed]
      >
      > [Non-text portions of this message have been removed]
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >
      >
      >
      >
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
    • Richard Gard
      I just bought four EB20-12 (i have 2 robos) from digikey. $291 total including $47 shipping from midwest to new england. 14lbs each = 56 lbs. Digikey shipped
      Message 40 of 40 , May 22, 2010
      • 0 Attachment
        I just bought four EB20-12 (i have 2 robos) from digikey. $291 total including $47 shipping from midwest to new england. 14lbs each = 56 lbs.

        Digikey shipped the same day i ordered and gave me a ups tracking.

        They have been in business a long time. I did a lot with them when they sponsored my high school robot team. Good people.

        ~richard

        -----Original Message-----
        From: Danny Miller <dannym@...>
        Sent: Saturday, May 22, 2010 7:36 PM
        To: RoboMower@yahoogroups.com
        Subject: Re: [RoboMower] Batteries


        That's not all THAT good of a deal. Digikey's got EB20-12 at $57 each,
        but there's not tax... the price is similar. But there's a significant
        shipping charge. They'll ship pretty much immediate if they're in stock.

        I do believe the EB20-12 is going to be a notably better battery than
        the Universal.

        Danny

        Ken H. wrote:
        > The last time I bought batteries at Battery Depot I paid about $50 each. I believe the name of the battery is "universal". The specs are the same as the original batteries. I guess the big advantage for me is that I don't have to wait for them and there is no shipping charges. I hope the price hasn't increased in the last two years. Probably no such luck.
        >
        > Ken
        >
        >
        >
        >
        > ________________________________
        > From: Danny Miller <dannym@...>
        > To: RoboMower@yahoogroups.com
        > Sent: Sat, May 22, 2010 5:48:04 PM
        > Subject: Re: [RoboMower] Batteries
        >
        >
        > What brand and model of battery have you "gone through every two years"?
        > What brand and model are the Sam's Club batts?
        >
        > My recommendation for ordering the EB20-12 pair from Digikey still
        > stands as the "best known option".
        > We haven't used them for enough seasons to estimate. And the usage is
        > so inconsistent from person to person that blindly co

        [The entire original message is not included]

        [Non-text portions of this message have been removed]
      Your message has been successfully submitted and would be delivered to recipients shortly.