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Thread: Lithium Ion battery for the E/X-Mag?

  1. #1

    Lithium Ion battery for the E/X-Mag?

    There's no doubt that battery technology has advanced from the time the E-Mag was initially introduced and I was wondering if there has been anybody that has looked into developing a Lithium Ion battery pack for the E-Mag.

    You probably need to develop a new charger as well, but I think the increased shot count per charge and weight savings VS the stock NiMH might make this an appealing upgrade for E/X-Mag owners.

    Thoughts AO?
    Steve Shuey , Team Crimson Reign

  2. #2
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    There is probably a battery pack ready made for the RC Airplane and heli market that would be readily adaptable to the emag.

    Plenty of charger options too. Would just take some research to find one that fits and at the right voltage. I believe the lithium cells come in at 3.7 Volts nominal. So you could expect to get packs in multiples of that voltage.

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    The lithium polymer cells are commonly used by the electric rc airplane and helis. These are popular because they lack the heavy protective casing around the cells. Since the E-Mag has a metal battery "case" anyway I see no reason that these batteries couldn't be used safely for this application.

    If you go messing around with lithium batteries make sure you take some time to learn about their quirks and how to safely use them.

    For instance, they like to catch fire if seriously abused. Also if they are over discharged there is a risk that they can catch fire when recharged. Or if they are charged with the wrong type of charger.

  4. #4
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    Someone get me some specs. I just happen to work for a conpany that makes lith car batteries. Ill talk to the engineer

    To leave feedback: Click seller/buyers name, Click feedback score, Click leave feedback

  5. #5
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    its hard to get the size right. 4 cell lipo is your go too.
    3 cell would work i think at 11.1 v.
    4 cell is 14.8 v
    but with lip you need a cutoff installed so you dont balloon your packs and have it melt your gun when it goes bye bye.

    ive been looking into getting packs that will fit but its really hard to get the size down.

    the the MaH would be small. but that wont be an issue since the lipos would run you for days.

    could get ahold or Orion, Maxxamps, Venom, etc, but they are big guys in the industry and an order would have to be for a 1000+ i think, if they could make 100+ for good price i may be able to buy em and resell to you guys.

    issues:-
    -size
    -price
    -cutoff for to save the battery.
    -and hookup to the marker.
    ** question for the techs who know:
    *_* can you opperate the emag off of 11.1 v? if so i will run testing.
    My sydarm weighs less than yours!!!

  6. #6
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    Here is a copy of a battery pack explanation I did a while back.

    A 4 cell pack would have a 14.8V nominal rating. 14.8V would cause a reduction in power by about 22%. That should still trip the sear, but it would cut into any buffer needed to maintain operational consistency in all instances. That means you better keep the mechanism clean. It would probably be better to add an extra cell.

    Don't go exactly by the rating on the cells or packs. In reality, Lipo cells have a fully charged voltage value of 4.25V so most charger limit it to 4.2V. The minimum safe voltage is 3V so most use a cutoff of 3.3V. That gives a four cell pack a voltage range of 13.2V to 16.8V. The discharge line from 16.8V to 13.2V is fairly linear and results in the 14.8V nominal rating. The calculations show a 15V average but in reality its not perfectly linear so the real average is 14.8V.

    NiMh cells have a fully charged voltage value of about 1.4V but it drops to 1.3V very quickly so the 1.3V value is used for the upper value when determining average operating outputs. The minimum voltage is 1.0V, but the drop from 1.1V to 1.0V occurs very quickly so the 1.1V value is used for the lower voltage. The resulting average is 1.2V which is the industry value used for packaging. A 14 cell pack rated at 16.8v actually ranges from 18.2V to 15.4V.

    Checking the voltage values of the lowest value for each pack type, it shows a reduction in power by 27% for the LiPo compared to the NiMh pack. This is worst than the 22% calculated using nominal values. As the pack gets discharged, you might end up with firing issues using a 14.8V LiPo pack.

    Therefore, I would recommend the 5 cell LiPo. The overall voltage will be a bit higher using the 5 cell LiPo pack. This will cause higher current draw which will heat the solenoid more. Its a 20% increase in power consumption when the battery is fully charged. I don't think the dwell of the solenoid will allow it to catastrophically overheat. If it proves to be a problem, put a 5Watt 0.5ohm resistor in series with the battery pack. That will bring the pack down to the same operating parameters as a NiMh pack.

    LiPo packs and lithium chargers in general are easily configured to be safely charged these days. An off the shelf RC charger has the ability to properly balance a lithium based battery pack and the packs have charge/discharge regulators built in so that you can't charge or discharge them past their danger point.
    Except for the Automag in front, its usually the man behind the equipment that counts.

  7. #7
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    Quote Originally Posted by knownothingmags View Post
    *_* can you opperate the emag off of 11.1 v? if so i will run testing.
    If a 3 cell is all that could be fit into the Emag battery pack a voltage "boost" circuit could be added provided there is a little room left over.

    There is always another way to skin the cat... it just depends on how much work one wants to do.

    I just did a google search for lipo cells and came up with a few promising links but don't have the time to investigate in depth right now.

    Could someone post the internal dimensions of the Emag battery?

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    They have the 22v cell's I've done some searching and will post up links when I get home tonight.
    I have noticed that the inside if the battery packs could be milled to accept slightly larger cell's or a whole new pack and battery combo


    Where's Luke at?

  9. #9
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    You could build a voltage booster but they generally don't handle high currents. Starting with a lower voltage would require a higher current to maintain the wattage plus a bit more to allow for losses in the conversion. If you are going to add circuitry, consider using a solenoid with a rating closer to that of the lithium pack you want to use.

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    Quote Originally Posted by athomas View Post
    You could build a voltage booster but they generally don't handle high currents. Starting with a lower voltage would require a higher current to maintain the wattage plus a bit more to allow for losses in the conversion. If you are going to add circuitry, consider using a solenoid with a rating closer to that of the lithium pack you want to use.
    That's a very good point. Not to say that a suitable boost circuit couldn't be built... but by the time you build one that can supply enough current at the required voltage the bulk of it may large enough that you haven't gained anything.

    So far my experience with voltage boosting power supply circuitry has been limited to excercises that are just for curiosity sake. In all of my real world designs I have had the luxury of plenty of voltage overhead and I'm always stepping it down.

    I just wanted to throw some ideas out there to maybe get some wheels turning in someone's head.

    Your idea to swap the solenoid out for a lower voltage unit is promising. You would need to take a look at the driver circutry on the board and make sure that it is able to supply the additional current that would come along with a lower voltage coil. I don't have an Emag, otherwise I'd start pulling up some datasheets and checking this out myself just out of curiosity.

    I'm just shooting from the hip here but if necessary, I suppose one could build a solenoid driver circuit that would do the job, provided there is room inside the grip for another small add on board.

  11. #11
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    How about going green?

    Goal-Zero-solar-charger-backpack.png

  12. #12
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    Quote Originally Posted by oldironmudder View Post
    Isn't that what us with mechanical guns are doing.

  13. #13
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    Quote Originally Posted by blackdeath1k View Post
    Isn't that what us with mechanical guns are doing.
    Thats green before it was being green. So...... pick a color then. Ive seen dirt range from red, blue, green to orange.

  14. #14
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    Quote Originally Posted by rukh013 View Post
    They have the 22v cell's I've done some searching and will post up links when I get home tonight.
    I have noticed that the inside if the battery packs could be milled to accept slightly larger cell's or a whole new pack and battery combo


    Where's Luke at?
    Battery
    charger shield
    low voltage alarm

  15. #15
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    Quote Originally Posted by Levi View Post
    I'm just shooting from the hip here but if necessary, I suppose one could build a solenoid driver circuit that would do the job, provided there is room inside the grip for another small add on board.
    The driver on the board is more than capable of handling more current, so a lower voltage solenoid at the same wattage is just a drop in part without any additional circuitry.

    And a LiPo battery pack is a plug-in pack that has its own built in circuitry for charge protection. A new battery case with LiPo would be the easiest thing to make and it would be smaller and lighter than the regular emag battery and pack.

  16. #16
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    Quote Originally Posted by athomas View Post
    The driver on the board is more than capable of handling more current, so a lower voltage solenoid at the same wattage is just a drop in part without any additional circuitry.
    Considering that its AGD, I figured it was significantly overbuilt. But I try to never assume without verifying.

    I think you're on to something here.

    Hmm... this thread make me wish I had an emag or xmag to tinker with... too many more mags and the wife might start asking questions.

  17. #17
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    Quote Originally Posted by Levi View Post
    Considering that its AGD, I figured it was significantly overbuilt. But I try to never assume without verifying.

    I think you're on to something here.

    Hmm... this thread make me wish I had an emag or xmag to tinker with... too many more mags and the wife might start asking questions.
    Ha, sounds like my wife

    If the 22v battery pack fit in the emag pack, wouldn't we just need to change the connections to the board?

  18. #18
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    The 22V packs are slightly different dimensions than the emag pack. Other than that, any pack can be made to fit the existing emag pack connections.

  19. #19
    Would going with something like a 22v lipo pack make the thing lighter, and could there be something made with it to make it a drop-in replacement for current Emag batteries and work with current packs (meaning, all you would need besides the new battery is a charger, and all those custom milled battery packs wouldn't be going obsolete?)

  20. #20
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    The LiPo pack battery rating to get the same rating as the Emag is the 5 cell pack which would be a 18.5V rating. The 6 cell pack gives a 22.2V rating which would be quite a bit higher than the emag battery. You would need to change the solenoid to use this pack.

    The LiPo packs are typically lighter than equivalent mAh packs made from NiMh cells. The dimensions are slightly different though. A 5 cell pack, which is closest to the emag pack rating so that you wouldn't have to change soleoids, is an odd size. You either have a really long skinny pack, or a really fat short pack, or a 3 + 2 pack. I would use a stacked (3 on top, 2 on bottom) 600mAh series pack. It will fit into the existing emag battery pack with room to spare and will be less weight.

  21. #21
    Is there a battery pack like that on the market right now, or are we in "custom" territory? I'm putting a lot of search terms through Google but coming up empty when it comes to a pack like you're describing...

  22. #22
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    Quote Originally Posted by Justus View Post
    Is there a battery pack like that on the market right now, or are we in "custom" territory? I'm putting a lot of search terms through Google but coming up empty when it comes to a pack like you're describing...
    Yes and no.

    The individual cells are available that will allow you to put together the configuration you want. The packs are available through anyone who builds custom packs. The 600mA cells are approximately 70mm long x 20mm wide x 7mm thick. You can make your own arrangement using a serial connection of the batteries. You can even add a balance connector so that you can keep the pack together and balance charge them properly without having to charge the cells individually.

    I think the smaller ones are often referred to as nano cells.

  23. #23
    I really don't know anything about making custom battery packs. But if a pack could be made that is significantly lighter than the standard NiMH pack, I'd be very interested. Anyone interested in taking the bull by the horns and seeing if this can actually happen?

  24. #24
    I've got 2 dead packs now, so I'm hurting as well.

    I think its clear we are in custom territory on this one, however there are many options for groups that build custom battery packs.

    The questions become:

    1. Do we want NiMH? Or do we want LiPO?
    2. What are the "No Kidding" Operating limits of the xmag circuitry? What is the ideal battery output?
    3. Do we want a drop in replacement for all battery housings? Or do we want a new battery housing as well?
    4. If you go LiPO how are you going to charge it? (I was thinking a hole in the bottom for a charging plug?)

    Food for thought..

  25. #25
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    Quote Originally Posted by mostpeople View Post
    1. Do we want NiMH? Or do we want LiPO?
    LiPo has more capacity for the size, so it will always be the smaller, lighter option.

    Quote Originally Posted by mostpeople View Post
    2. What are the "No Kidding" Operating limits of the xmag circuitry? What is the ideal battery output?
    The circuit board itself is quite robust, although I can't look up the specific limits because my emag is packed away for a change of address. The solenoid is designed to operate at a specific voltage in order to draw the correct amount of current to develop the required power needed to consistently work properly.

    Quote Originally Posted by mostpeople View Post
    3. Do we want a drop in replacement for all battery housings? Or do we want a new battery housing as well?
    This is a possibility for both types of packs.

    Quote Originally Posted by mostpeople View Post
    4. If you go LiPO how are you going to charge it? (I was thinking a hole in the bottom for a charging plug?)
    You could put the charging plug between the two top contacts, in the bottom of the pack (it would be easy to change the bottom piece), or on the lower back of the pack inside the groove (where it would be protected, but would require some machining).

  26. #26
    My opinion and reasons:

    LiPo pack for lightweight. A NiMH pack is what we have already, right?

    Needs to be able to drop-in to current battery housings. If not, then people with finished custom (anodizing, milling, or both) or original restored Emags and Xmags won't be customers. A secondary option of a new battery housing isn't a problem, but backwards compatibility is a must.

    It would be better if the battery pack could be taken out to be charged, that way a person could have two of them, keeping one as a backup. Then if they forget to charge it and it dies, they don't have to sacrifice their battery housing to charge the battery. Instead, they can take it out to charge it and pop the fresh battery back in and keep going.

  27. #27
    I am on the same page with you Justus, backwards compatabity is a must.

    Ideally though, we could charge a new battery with it still in the pack, making it easy to use.

    Let me do some research on this one. What I don't have and need to know is the board and solenoid specifications.

  28. #28
    Quote Originally Posted by mostpeople View Post
    What I don't have and need to know is the board and solenoid specifications.
    How are those acquired? I can take off my grips and read any of the numbers you want, if that will work. Maybe even provide a high-res photo?

  29. #29
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    This place can build custom packs. My emag pack has 14 AAA batteries. It would cost $42 to get a duplicate pack made. The only difference would be 14000 mAH instead of 650. Should just last longer

    http://www.cheapbatterypacks.com/cus...ks.aspx?mid=20
    DAVYBOY

  30. #30
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    Quote Originally Posted by absocountry2 View Post
    This place can build custom packs. My emag pack has 14 AAA batteries. It would cost $42 to get a duplicate pack made. The only difference would be 14000 mAH instead of 650. Should just last longer

    http://www.cheapbatterypacks.com/cus...ks.aspx?mid=20
    The pack using 1000mAh batteries would be a 1000mAh pack at 16.8V because the cells are in series. If the cells were in parallel, then you would have 14000mAh, but the pack voltage would only be 1.2V instead of 16.8V.

    Those batteries are expensive. I typically pay about $1.00 per cell or lower when I buy 1000mHA AAA cells, but that doesn't include building the pack.

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