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Charging gel cells. — Parallax Forums

Charging gel cells.

GrampsGramps Posts: 117
edited 2010-07-23 16:40 in General Discussion
After swelling two gel cells to twice their normal size,
we now charge them safely by connecting to a UPS.
Anyone have a nice fast charge circuit with automatic top off?





Gramps

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'What is your life?"
"It is even a vapor that appears for a
little time and then vanishes away."
Saint James 61 A.D.

Comments

  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-07-21 13:53
    Is this for a Real Gel Cell or a AGM . as Gells dont take fast chages well.


    www.batterystuff.com/tutorial_battery_gel_agm.html

    you mentioned UPSs .most UPSs use AGMs as Gells also dont do well at high discharge rates .,EG 12V @100A for the UPS inverter ..
    for a AGM a 2 step can be made .........

    I have In the past used a LM 317 as a shunt Currnet reg and a 317 as a voltage reg on a 7.5 AH AGM batt for my old portable shack . ( RACES GO bag)
    I never had a dead batt or a over charge ...

    Let me draw it up for you ..

    the PDF is all about gel and AGM info with charge info too..
    Peter KG6LSE

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    LOL

    Post Edited (Peter KG6LSE) : 7/21/2010 2:17:34 PM GMT
  • ercoerco Posts: 20,260
    edited 2010-07-21 15:50
    ·I use·a dedicated SLA charger wallwart, I get them for ~$15 here in LA.·$25 online: http://www.rpelectronics.com/fc-612c-lead-acid-gel-charger-6-12v.html


    Nice idea, using a UPS as a charger. You could find a freebie UPS that someone chucks BECAUSE the batteries went bad. Now THAT's recycling at its finest!



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    ·"If you build it, they will come."

    Post Edited (erco) : 7/21/2010 3:57:11 PM GMT
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2010-07-21 16:28
    Hi Gramps,

    The easiest circuit is purchase of a PB137 from Mouser. ST Semiconductor, "POSITIVE VOLTAGE REGULATOR FOR BATTERY CHARGER", linear regulator 13.7 V at up to 1.5A. It is a safe float charger, not a fast charger.

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    Tracy Allen
    www.emesystems.com
  • LeonLeon Posts: 7,620
    edited 2010-07-21 21:05
    I use my bench PS.

    Gel cells at 2x their normal size must have looked quite scary!

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    Amateur radio callsign: G1HSM
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2010-07-21 22:18
    Great thread! Timely. I need to charge one of these bad boys. AGM

    Thanks for asking this question.

    OBC

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  • ercoerco Posts: 20,260
    edited 2010-07-21 23:22
    That's an oddball 8-volt battery. Good luck finding a charger for that!

    I'm with Leon, I want to see pics of the "swelled gel cell". Say that 10x fast.

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    ·"If you build it, they will come."
  • GrampsGramps Posts: 117
    edited 2010-07-22 01:25
    LOL
    We had to leave the pregnant gel cells in Mongolia.
    Didn't think of a photo, but it's easy to create one of your own, just hook up a battery charger to one and set the amps to about 10............
    Should have one in an hour or so.
    wink.gif


    P.S. yes, the UPS IS a junked one that had a bad battery............

    Gramps

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    'What is your life?"
    "It is even a vapor that appears for a
    little time and then vanishes away."
    Saint James 61 A.D.

    Post Edited (Gramps) : 7/22/2010 1:30:32 AM GMT
  • rahinajosephrahinajoseph Posts: 2
    edited 2010-07-22 09:06
    Hi..
    Gel cell batteries are commonly used in amateur radio emergency communications. Being maintenance-free and spill-proof, they are ideal for portable operation. Properly cared for, a gel cell battery can provide many years of reliable service. Failure to use a charging method specifically suited to a gel cell battery's internal chemistry will dramatically shorten its useful life.

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  • GrampsGramps Posts: 117
    edited 2010-07-22 12:31
    It sure will!






    .

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    'What is your life?"
    "It is even a vapor that appears for a
    little time and then vanishes away."
    Saint James 61 A.D.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-23 16:25
    I have a charger for 8-volt gel cells and rated up to 30amps. But of course, I bought it here in Taiwan along with the 8 volt 9ah gel cells. They are really wonderful for projects with 5 volt regulators that require a big backup battery, create very little waste.

    The only thing more scary than a pregnant gel cell, is a pregnant lithium battery (ready for a fireball?).

    It isn't so hard to make a charger that will trickle charge them. But fast charges will out gas. It just wasn't mean to be charged that way. The whole concept is to eliminate nasty acid burns and holes in your clothing by sealing the battery. If you want something to fast charge, get a 12v motorcycle battery that has vents and an overflow tube.

    It would seem a 9V 1amp voltage regulator (7809) would do a nice job on an 8 volt battery. 13.7/6 cells = 2.2833 volts/cell. An 8 volt would have 4 cells, so 2.2833 x 4 = 9.13 VDC. And of course, you can adapt another voltage regulator to be a current limiter as well if you really need it.

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    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan

    Post Edited (Loopy Byteloose) : 7/23/2010 4:30:24 PM GMT
  • LeonLeon Posts: 7,620
    edited 2010-07-23 16:35
    When I worked for Racal Comms some idiot put a NiCd radio manpack battery onto a standard bench power supply in the lab. There was a loud explosion some time later. Luckily, it was lunchtime and the lab was empty. No-one owned up to it, of course.

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    Leon Heller
    Amateur radio callsign: G1HSM
  • GrampsGramps Posts: 117
    edited 2010-07-23 16:37
    A 9 volt wall-wart should work for OBC's 8 volt battery........

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    'What is your life?"
    "It is even a vapor that appears for a
    little time and then vanishes away."
    Saint James 61 A.D.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-23 16:40
    Doesn't get much simpler. Why did I buy that charger?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
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