Paging Homebrew (and other DIY lighting nuts): DIY Battery Pack question- Mtbr.com
Results 1 to 19 of 19
  1. #1
    mtbr member
    Reputation: glenzx's Avatar
    Join Date
    Dec 2003
    Posts
    4,868

    Paging Homebrew (and other DIY lighting nuts): DIY Battery Pack question

    All mighty Homebrew (and Metroid and others): I managed to screw up my factory NiMH Light & Motion battery in the last few months, by letting it discharge and not charging it back up for weeks... doh! It would run for only 40-50 minutes where I used to get 3.5 - 4 hours out of it with my ARC HID set-up. I figured I now had an excuse to re-build the L&M pack with some new, 4000mAhr 4/3 cells.

    I got 'em cheap from Battery Station and carefully disassembled the old pack, drawing a schematic of how the wiring was done and the arrangement of the 9 cells and noted that there are THREE wires at the connector; 1 black, 1 white, and one red. The red wire is connected to the white wire via some little tiny diode looking thing, and runs right to the connector. The black & white wires do there positive/negative thing as usual.

    Besides the little diode/doo-hicky/flux-capacitor, there was another gizmo wired in line between the 4th and 5th cells - a small, black plastic flat rectangular 'thing', and I made sure to remove all these pieces carefully and solder everything together EXACTLY as it had been.

    The big test was plugging the battery into the charger (L&M's sweet turbo charger) and COOL! The "charging" light comes on and all seems good. Later on, after charging & conditioning, I remove the pack, plug it into my light head and fire it up. About 2/3rd's of the way through the 10-15 second "warm up" the light startys the rapid-blinking at the power button that indicates a low charge, and I shut it off immediately. I top off/recharge the pack again - same deal.

    I'm a little perplexed, and have no idea what may be the problem... I'll pull out the voltage meter and see what voltages are appearing across the connectors and post any of that data...

    Any thoughts, besides buying another *gulp* $100 battery pack?
    Last edited by glenzx; 09-02-2005 at 07:58 AM.
    "It's better to regret something you HAVE done, than something you haven't..." -

  2. #2
    rider
    Reputation:
    Join Date
    Jan 2005
    Posts
    2,355

    Condition the battery pack.

    Find a local company that rebuilds battery packs. Most "batteries for everything" shops do this. From what I hear all battery packs, new or overhauled, are put on a high-tech conditioning charger before being delivered to the end user. The service should cost around $5.

    A tip on a used nicad or NIMH pack that is no longer responding well to charging: Put it in a freezer storage bag and then put it in the freezer for about 24 hrs. Then pull it out and let it thaw, in the sealed bag for another 24 hours. The bag is to keep a bunch of condensation from forming durring the thawing process. Repeat this 4-6 times. If you want to go the extra mile, have a conditioning charge put on it as described above. Either way, the pack should perform much better than before. Sometimes the results can (especially in this case) be night and day.

    29erchico
    Last edited by 29erchico; 09-01-2005 at 11:22 PM.

  3. #3
    zon
    zon is offline
    Scofflaw Mountain Biker
    Reputation: zon's Avatar
    Join Date
    Nov 2004
    Posts
    2,720
    There a seller on eBay that has very good prices on NiMH battery packs. I picked of one for a little over 50$ and it works like a champ. Here is the link to a battery pack currently up for auction. Battery Pack
    ΜΟΛΩΝ-ΛΑΒΕ


    .

  4. #4
    user-created
    Reputation: singletrack's Avatar
    Join Date
    Feb 2004
    Posts
    3,174

    Unrelated

    I lost my Niterider batt.. it fell out a rust hole in the trunk of one of my Subarus! Doh.

  5. #5
    mtbr member
    Reputation: itsdoable's Avatar
    Join Date
    Jan 2004
    Posts
    1,902
    Re- cheap cells - you often get what you pay for. Smart circuits require all cells to be close to tolerance in voltage and discharge characteristics, voltage depression on one bad cell will signal the "smart" circuit to shut down. Also, as you have no idea at what state of discharge each cell was, and weither they were from the same production batch so variations between the cells plays havoc on some smart circuits.

    With cheap/unknown/surplus cells, I will cycle (charge & discharge) each cell independantly a few time to get them close to the same state before building the battery pack. For a smart circuit, I'd recomend building the pack with new quality cells for best results. I've not heard of the freeze-thaw method of rejuvinating cells, you learn something every day!.

    The "diode/doo-hicky/flux-capacitor" is a thermistor that senses the temperature of the pack - L&M uses temperature compenation to charge the battery. The "black plastic flat rectangular 'thing'" is an auto-fuse, it opens if the pack gets shorted, and resets automatically after a short time.

    Good luck!

  6. #6
    user-created
    Reputation: singletrack's Avatar
    Join Date
    Feb 2004
    Posts
    3,174
    Quote Originally Posted by itsdoable
    With cheap/unknown/surplus cells, I will cycle (charge & discharge) each cell independantly a few time to get them close to the same state before building the battery pack.
    I used to be way into racing R/C cars. We'd buy high-end cells that were computer matched for dsicharge rates and peak voltage to build our packs.

    The better Hobby Shops had a machine that you'd load 10-12 cells into, and it would charge/discharge the lot and label them according to their results. So you could match similar cells, or find the pick of the litter.

    When I build my replacement pack that's where I'm gonna look. Although gas is so prevelant now...

  7. #7
    Rolling
    Reputation: lidarman's Avatar
    Join Date
    Jan 2004
    Posts
    11,117
    Glen,

    I believe the strap is a short circuit polymer switch, if you short the battery, it acts like a temporary fuse to prevent a fire.

    The diode like device is probably a Thermistor. It's used to do temperature cut-off termination on the charge cycle. The charger monitors the thermistor and when the temp ramps up quickly, the battery is charged.

    What is odd here is the failure I see is the battery doesn't register the temperature and doesn't stop charging. Perhaps in your case, there is a defect in the thermistor making the charger think the batteries are charged when they aren't.

    Like you said, you should measure the voltage on the batteries. Also, if you can, measure it when you do the turn-on of the light so you can see the load effect.

    Also make sure that thermistor is in contact with the batter housing. Was it glued there before?

  8. #8
    mtbr member
    Reputation: glenzx's Avatar
    Join Date
    Dec 2003
    Posts
    4,868
    Quote Originally Posted by itsdoable
    Re- cheap cells - you often get what you pay for. Smart circuits require all cells to be close to tolerance in voltage and discharge characteristics, voltage depression on one bad cell will signal the "smart" circuit to shut down. Also, as you have no idea at what state of discharge each cell was, and weither they were from the same production batch so variations between the cells plays havoc on some smart circuits.

    With cheap/unknown/surplus cells, I will cycle (charge & discharge) each cell independantly a few time to get them close to the same state before building the battery pack. For a smart circuit, I'd recomend building the pack with new quality cells for best results. I've not heard of the freeze-thaw method of rejuvinating cells, you learn something every day!.

    The "diode/doo-hicky/flux-capacitor" is a thermistor that senses the temperature of the pack - L&M uses temperature compenation to charge the battery. The "black plastic flat rectangular 'thing'" is an auto-fuse, it opens if the pack gets shorted, and resets automatically after a short time.

    Good luck!
    LOL, OK, cheap may not have been a nice way to say it - cheap RELATIVE to the cost of the new L&M factory pack; but they were on sale, the Sanyo 4/3 4000mAh cells and cost $36 for 9 of them. The nicer ones would have been about $54 for 9 - still a good deal, but since this was my first stab at a home made pack I thought it best to experiment with less expensive cells.

    What I hadn't known about was the pre-conditioning or testing of the cells FIRST - doh. Seems like a smart & prudent way to not waste the 1 hr. it took to reassemble the pack and all... darnit. SOunds like I ought to disassemble the pack & cells, and check them all for consistency. The idea that 1 or more cells is either bad, or started in such a different state as to make the pack "wiggy" explains why it's not functioning properly.

    What's the best way to charge these cells - get a funky charger at an electronics shop that may accept this size cell? And what may be the best indicator that one (or more) cells isn't "good?

    I knew it was too easy ;-)

    And thanks everyone for the advice! The collective mind(s) here is awesome.
    Last edited by glenzx; 09-02-2005 at 08:11 AM.
    "It's better to regret something you HAVE done, than something you haven't..." -

  9. #9
    mtbr member
    Reputation: glenzx's Avatar
    Join Date
    Dec 2003
    Posts
    4,868
    Quote Originally Posted by lidarman
    Glen,

    I believe the strap is a short circuit polymer switch, if you short the battery, it acts like a temporary fuse to prevent a fire.

    The diode like device is probably a Thermistor. It's used to do temperature cut-off termination on the charge cycle. The charger monitors the thermistor and when the temp ramps up quickly, the battery is charged.

    What is odd here is the failure I see is the battery doesn't register the temperature and doesn't stop charging. Perhaps in your case, there is a defect in the thermistor making the charger think the batteries are charged when they aren't.

    Like you said, you should measure the voltage on the batteries. Also, if you can, measure it when you do the turn-on of the light so you can see the load effect.

    Also make sure that thermistor is in contact with the batter housing. Was it glued there before?
    Rich! Sounds like you smart folks are on the same page - that the two mystery components (to me) are a thermistor and a CB. Cool. Make a lot of sense now.

    The thermistor wasn't glued to the cells, but was nestled between them snugly. I reassembled evertything as precisely as I could and let it be at that. I think I found a couple of bad cells in the 9 I got, and took them out of the pack, inserted the best ones charge & condition wise from the old pack (temporary - I know this is probably bad, but I want to check out everything...) and am recharging the whole she-bang as I type this.

    The 1st pass at the pack I made, the output voltage was only 9.2 - 9.3 volts. Bad, as 9 X 1.4 (the reading voltage-wise I get with my beat up old voltmeter) = 12.6V, the voltage the pack is supposed to put out (that's the same reading I got on the freshly conditioned other, good 4+ hour burntime pack I have). This 2nd pass, combining the good/old cells with the new/good cells gave me 12.6V, so I plugged the charger into 'em and am letting it go now. I taped the thrmistor snugly to one of the cells, as the whole pack is strung out in pieces on the dining room rable at the moment, but will check how warm all the cells feel when the pack completes charging.

    I'm very curious to see if the defect may have been the thermistor as you noted. When I get a healthy pack built and charged up, we'll see what kind of run time I get and see. Is one of these thermistiors a regular sort of Radio Shack type part? Looks like it's got specific color stripes on it that if I recall from my old model RR days have significance in terms of voltages/amperages/resistance and so on...
    "It's better to regret something you HAVE done, than something you haven't..." -

  10. #10
    Currently in Exile
    Reputation: Frozenspokes's Avatar
    Join Date
    May 2004
    Posts
    2,303

    As mentioned earlier

    Try to find a good hobby shop that has the charger that will condition each cell individually. Or see if the place that you purchased the batteries from could do it and maybe even build it up properly for you.

    If you insist on doing it yourself, I highly recommend getting a high end peak charger at your local hobby shop. This will set you back a pretty good chunk of change, but they do wonders with wiggy battery packs. A good one can rejuvinate a pack that seems pretty fried. I have had NiCad packs that had developed a pretty bad memory braught back to life by my Tekin 110. All old stuff, but I am really cheap, and I have a LARGE collection of NiCads.

    From what I have read about Nimh batteries they don't have the memory issues that NiCads have, but what you described is exactly what happens to a NiCad after it develops a memory.

    Maybe a primer on the proper care and feeding of our Nimh is in order for all of us cycling folks.
    "There are those who would say there's something pathological about the need to ride, and they're probably on to something. I'd wager though that most of the society-approved compulsions leave deeper scars in the psyche than a need to go and ride a bicycle on a mountain." Cam McRea

  11. #11
    mtbr member
    Reputation: glenzx's Avatar
    Join Date
    Dec 2003
    Posts
    4,868
    One other unrelated question: Anyone know if the plug/socket assemblies L&M use are to be found anywhere? I looked high and low last year and never found anything close..... if my 1st battery pack proves worthy here, I may "snip" all the factory connectors and replace them with a more standard type plug/socket, though the L&M ones are nice & waterproof... and it'd be better to keep everything standard for when I'm racing 24 hour events and demo/borrow some of their batteries/heads from the 'booth'.
    "It's better to regret something you HAVE done, than something you haven't..." -

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jan 2005
    Posts
    7
    Rich,

    Thank you for sharing your knowledge on this topic. I also am attempting to build my own battery pack and am curious if the Thermistor is necessary (apart from safety reasons). I am using a third party "rapid" charger which perhaps will not monitor the thermistor?

  13. #13
    Do It Yourself
    Reputation: Homebrew's Avatar
    Join Date
    Jan 2004
    Posts
    5,720
    Quote Originally Posted by glenzx
    One other unrelated question: Anyone know if the plug/socket assemblies L&M use are to be found anywhere? I looked high and low last year and never found anything close..... if my 1st battery pack proves worthy here, I may "snip" all the factory connectors and replace them with a more standard type plug/socket, though the L&M ones are nice & waterproof... and it'd be better to keep everything standard for when I'm racing 24 hour events and demo/borrow some of their batteries/heads from the 'booth'.
    L&M is using a proprietary connector just for this reason. They really don't want you DIY'ing with their system. The best way to do the initial charge is with a dumb charger just to get some charge on it and then put it on the turbo charger. Or put it on the Turbo then take it off for a minute and put it on again to make sure it's full. Then it still won't get full charge until you've fully charged and fully discharged it a couple times. When I had a L&M Dual Logic, I was able to cycle mine with the aligator clip leads on my Maha charger. I agree with the others, the third cable is for the thermistor and the square thingy wired between the cells is the resettable fuse. Check the pics in the battery building FAQ...

    http://forums.mtbr.com/showthread.php?t=52685
    Long Live Long Rides

  14. #14
    mtbr member
    Reputation: glenzx's Avatar
    Join Date
    Dec 2003
    Posts
    4,868
    Quote Originally Posted by Homebrew
    L&M is using a proprietary connector just for this reason. They really don't want you DIY'ing with their system. The best way to do the initial charge is with a dumb charger just to get some charge on it and then put it on the turbo charger. Or put it on the Turbo then take it off for a minute and put it on again to make sure it's full. Then it still won't get full charge until you've fully charged and fully discharged it a couple times. When I had a L&M Dual Logic, I was able to cycle mine with the aligator clip leads on my Maha charger. I agree with the others, the third cable is for the thermistor and the square thingy wired between the cells is the resettable fuse. Check the pics in the battery building FAQ...

    http://forums.mtbr.com/showthread.php?t=52685
    Cool!

    Thanks again - your battery/lighting threads and posts are awesome!
    "It's better to regret something you HAVE done, than something you haven't..." -

  15. #15
    R.I.P. DogFriend
    Reputation: jeffj's Avatar
    Join Date
    Jan 2004
    Posts
    6,887
    Couldn't you just put an additional pigtail on the battery pack that would hook up to a third party charger using something like a Dean's plug.

    Better chargers have more settings such as those that allow you to determine the charge rate (amps/hr) and adjust the voltage drop (that tells you when the pack has 'peaked') to suit battery type (nicd or nimh) and intended usage.

    The "conditioning" is not rocket science. It's basically peak charging them and then discharging them to about .9v per cell for garden variety 1.2v cells (usually three for three complete cycles).

    This charger looks like it could fit the bill nicely (even 'conditions' your batteries):

    http://www.globalhobby.com/public/gallery/350364.asp

    Being it's 110vac or 12vdc, you might be able to use it on the way to the trailhead if you hook it up safely (whole 'nother subject). There are some dc chargers that don't like being hooked up to a running automobile (too much input voltage with the alternator giving it around 14.6v), but some like it just fine. Done it many times with the right gear.

  16. #16
    Preemptive Revenger
    Reputation: rapwithtom's Avatar
    Join Date
    Feb 2004
    Posts
    867
    Quote Originally Posted by glenzx
    One other unrelated question: Anyone know if the plug/socket assemblies L&M use are to be found anywhere? I looked high and low last year and never found anything close..... if my 1st battery pack proves worthy here, I may "snip" all the factory connectors and replace them with a more standard type plug/socket, though the L&M ones are nice & waterproof... and it'd be better to keep everything standard for when I'm racing 24 hour events and demo/borrow some of their batteries/heads from the 'booth'.
    I had the same issue with Jet Lite - they try to get you to buy more of their stuff by not allowing for interchangeability...in this case, they use a proprietary connector that they won't sell you, so you have to buy their outrageously priced batteries.

    My solution? Sell the Jet Lites shite on EBay. It's good stuff, but I don't want to patronize a company that seeks to make money by inconveniencing me. Screw that and screw them! (I was an evangelist, now I'm an anti-evangelist..)

    So I built my own (Trailtech & Battery space Li-Ion) using some connectors I got at www.mouser.com. If you care I can tell you the exact connectors I used, they pretty good and quite cheap.

    By the way, all this DIY stuff was not that difficult, but it took a lot of time to get up the learning curve on exactly the sorts of issues that you are asking about. In the end, I have two nice HID lights with some great batteries, and they were cheap. But I also have a lot of hours into it....I probably wouldn't do it again.
    Friends don't let friends give their money to NORBA.
    Get a bicycle. You will not regret it. If you live. - Mark Twain

  17. #17
    Do It Yourself
    Reputation: Homebrew's Avatar
    Join Date
    Jan 2004
    Posts
    5,720
    Quote Originally Posted by rapwithtom
    I had the same issue with Jet Lite - they try to get you to buy more of their stuff by not allowing for interchangeability...in this case, they use a proprietary connector that they won't sell you, so you have to buy their outrageously priced batteries.

    My solution? Sell the Jet Lites shite on EBay. It's good stuff, but I don't want to patronize a company that seeks to make money by inconveniencing me. Screw that and screw them! (I was an evangelist, now I'm an anti-evangelist..)
    I don't know about the latest stuff from Jet but I had a Jet Phantom 20W for years. It had standard 2.5x5.5 connectors on the battery. Check the battery building FAQ:

    http://forums.mtbr.com/showthread.php?t=52685

    The battery in the pics were for my Jet using standard parts from DigiKey and RadioShack. Funny, because it's actually the EXACT same as the connectors for the Trail Tech HID which I'm using now.
    Long Live Long Rides

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jul 2004
    Posts
    394
    Sorry if I'm jumping into your thread but this seems like a great one for my question (you guys really seem to know what your talking about). I will start by saying I know nothing about batteries or electronics. I have an old nite hawk and lost the battery and charger for it but have the wiring and the lights... I'm looking for a cheap/simple solution to get this thing rolling again. I think that the system is 12volts and was a 2.5ah battery so I'm assuming I need something similar to replace this? I've heard of people using RC batteries for homemade ones will that work fine? Would anything like this work, or does anyone have a better solution?
    http://www.batteryspace.com/index.as...OD&ProdID=1494
    http://www.batteryspace.com/index.as...ROD&ProdID=166
    http://www.batteryspace.com/index.as...ROD&ProdID=172
    https://www.batteryspace.com/index.a...OD&ProdID=2139

    thanks.

    also, I'd like to eventually use one light on the bar and one on the helmet so maybe I can get two small 12v 2-4ah packs?
    Last edited by usr666; 10-13-2005 at 08:00 PM.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Oct 2004
    Posts
    692

    Initial Charge

    Smart chargers look for voltage peaks. The voltage of a NiMH battery will actually roll off as it reaches full charge. The problem with a new, unevenly charged pack is that the smart charger will often shut off when the first cell peaks. This leaves the rest of the cells with a partial charge.

    To balance a pack, use a slow charger like a appropriate voltage wall wart. If you have a 4ah battery, use a 0.4a (C/10) charge current and just charge it for 24 hours. This will ensure that all the cells are fully charged. A descent NiMH can handle a C/10 charge current almost indefinitely. Once the pack is balanced the fast, smart charger should work fine.

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2020 VerticalScope Inc. All rights reserved.