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Post by luke213 on Dec 22, 2014 13:42:03 GMT -5
So I'm wondering if you guys have had much experience fixing bad Ni-Cads and by that I mean basically overvolting them to restore some of their capacity. Since my gear has been sitting for years, I'd rather not have to buy 10ish batteries(I've still got a fair sized collection of AEG's and GBB's). There is this technique that I've seen talked about for several years it seems to have gotten it's start with Ni-Cad's from cordless drills which are notorious for going bad and being expensive to replace. Basically small hairs lacking the technical term grow within the cells shorting them out. By applying a large amperage source to the pack/cells it basically overheats and burns those small hairs within the cell removing the short. You do it in short bursts and in the past I saw guys doing it with say three 12v car batteries in series giving 36 volts and a whole lot of amperage. Though now there are videos of guys using Mig welders and all sorts of other options.
I did a test the other night on a Ni-Cad stick 8.4v 600mah battery for my MP5k. Before fully charged I'd get around 50 BB's fired before it would slow down and stop turning over the mechbox. This is a stock TM gun, oldy but goody and very easy to turn over so it should get a good life span even on these small capacity batteries. So I took a 12v battery charger I've got here with a 50amp start mode, hooked some wires to the connector then applied current to the battery positive to positive, negative to negative. There are guys that say to hook them backwards though that seems like a bad idea knowing a little about the Ni-Cad's. Anyways I pulsed it by hooking it up for maybe a quarter second, then pulling it for a half second then repeating for around 5-6 seconds. Afterwards I let it sit to cool(according to instructions online this is important), then 15 minutes or so later I hooked it up to my old school smart charger and charged it at around 4 amps.
Once it was done charging I tossed it into the gun and loaded up some high caps. And I'm running low on ammo so I didn't do a huge test but I got through 600 rounds before I decided to stop wasting ammo. I don't remember for sure how long that battery lasted new, but I suspect it was around 1000 or so rounds, and at 600 it wasn't slowing any as I can tell. So I'd say I recovered 50-60% maybe more of the capacity in the pack and it went from not usable to usable. I haven't had time to do any of the other packs yet, but I'm planning on doing more in depth testing with it along with trying possibly the mig welder to get a higher voltage/amperage try on some of the cells that are really bad in a few packs that were bad years back.
So I'm curious to hear if you guys have heard of this, tried this or anything around the airsoft community. I haven't I just knew about it from drill batteries. But if someone else has already done more testing I'd love to hear the results since so far it's very interesting, and in my case might save me a bit of money since I have a bunch of bad batteries around here now from sitting. Granted some of mine were dropping off 8ish years ago towards the end of my playing.
ALSO I'LL THROW THIS IN CAPS, HOOKING BATTERIES TO A HIGHER AMP SOURCE COULD BE DANGEROUS. BE CAREFUL IF YOU TRY THIS YOURSELF AND AS ALWAYS IT'S AT YOUR OWN RISK. IF YOU DON'T UNDERSTAND BATTERIES AND VOLTAGE I WOULDN'T RECOMMEND IT AT ALL. THE BATTERY COULD BLOW UP, ALL SORTS OF BAD THINGS IF YOUR NOT COMFORTABLE WITH IT, DON'T DO IT.
Luke
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Post by Ogre on Dec 22, 2014 16:58:35 GMT -5
Hey, I have been following your posts, its nice to see that someone who has been out for so long get back in. Who knows, maybe Hado will crawl out of the woodworks next. Anyways, welcome back
That being said, I would look into a few LiPo batteries. Hardly anyone uses Ni-Cad anymore so it might be hard to find anyone with that information. 3 or 4 lipo batteries will be plenty to keep all of you're replicas running and then some. 7.4v lipo's are common an cheap and will out preform almost all 9.6v batteries and are small enough to fit almost anywhere.
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Post by luke213 on Dec 22, 2014 17:17:11 GMT -5
I've been doing some research into LiPo's a bit too but I figured if I can revive some of these old batteries I can get them back;) The main reason I have as many guns as I do is for other players. Up here in the UP there hasn't ever been much of an airsoft scene. Which is why I used to travel downstate to games etc, but up here I pretty much organized our own smaller games most weekends however most guys didn't have guns and gear especially starting out. So I'd field 7-8 of my own guns to get more people out to the games. If I was just handling my own personal guns 2 would get me back in action since typically I run my M4 and maybe a GBB or this time of year with the colder weather a MP5k.
Right now I've got 2 CA M15A4's, ICS MP5A4, TM MP5k, TM AK47s, TM P90, TM VSR10 G-spec, TM G36k, and probably at least one or two guns that I'm forgetting or haven't found yet;) Well and that's not counting GBB's and whatnot but it's a fair number of guns to feed with juice at this point. I figure I might be able to bring back a couple of the loaner gun batteries enough to where they are functional for a few hicaps and I'll likely go through my CA M4 and get it running on a lipo since as you said that's the direction things are heading.
I've actually had some experience with these modern lithium cells with another hobby of mine e-cigarette's as guys who knew me back in the day could attest I was a constant smoker, 1-2 packs a day for years. At games I constantly had a smoke hanging from my mouth pretty much the whole game. But getting into that last year I did allot of research into these newer lithium cells and their capacity for that application. Early this morning I was digging into building my own pack using 18650 Sized cells with 30-40amp limits which would put me around 8.4v fully charged though they will drop down quickly to the 7.4v range and I'm assuming that's what they are using in these new cells for airsoft as well.
Something I am curious about amp limits are used in ecig stuff, and discussion of batteries I'm seeing 20c ratings and I was reading that basically you need to calculate how much amperage it's drawing to get that value(don't recall the equation off the top of my head). That said the ratings these were pulling were in the 60amp range, which I gotta say sounds a touch insane. In ecigs higher amp batteries are a bit of an obsession for some people building crazy things, not me mind you I'm into simple and functional. But I do know that the average amp limit on 18650's is between 30-40 amps and that's constant not pulse. What concerns me is has anyone actually done much testing on these cells that they are actually safe to their rated limits? Reason I ask is there are a fair number of China batteries out there in all markets that people really don't know the rating's of the cells in the pack or for that matter what cells are even used under the shrink wrap. Just sparked my curiosity since I would expect if we were seeing that high of amp batteries in common usage I'd had heard about it on the ecig front, I'm wondering if they are making up specs or if they are actually handling those loads.
Just curious;) I was reading about it off and on but haven't had allot of time to dig into what cells they are using and what form factor, if they are up to spec then I'll likely go that route since with li-po batteries I'd rather have more overhead then less. That said if I can't figure out what they are using I'll probably build my own packs since then at least I know for sure what the amp limits are on the equipment. But then I also need to test how much draw I'm pulling down with my m4 to make sure it's safe as well.
Either way thanks for the welcome, maybe we'll see some more old timers come back into the fold, I've gotta admit I've got the bug again. I doubt I'll be making trips downstate anytime soon with all my responsibilities these days. But I do expect I'll be organizing some small games up here with some locals to keep a little group running like I used to. Who knows maybe we'll see some old names pop back in;) But the only one here coming back is me and my brother(pending he can handle it;) he's expressed interest and I took some time to run through his m4 and get it all in shape again. Though he wasn't really on the forums much at all back in the day either he just played all the games and did a couple downstate games.
Take care!
Luke
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Post by Ogre on Dec 22, 2014 18:28:21 GMT -5
There is a group in Houghton from Michigan Tech that play a lot. Breathe is one member from the area, I would talk to him and see what can be organized.
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T6e9a
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Post by T6e9a on Dec 22, 2014 20:03:22 GMT -5
Not sure how to calculate amp draw, but how to calculate amp supply in batteries, at least Lipos, is:
Amperage=(C-rating)x(capacity in Ah) Ah=(mah)x1000
So like an 11.1 20c 2200mah 20x2.2=44
Example battery supplies around 44 amps.
Things in the system that increases amp draw are things such as lower ratio gears, stronger springs, improper shimming, week motors, etc
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Post by luke213 on Dec 22, 2014 20:41:11 GMT -5
I get that but what I'm getting at is are the cells actually rated for 44 amps or are they just claiming that. From what I've read most AEGs are around 20 or less so likely it's not a huge issue. But in other applications you see companies claiming 30 amps but they are wrapping 10amp cells etc.
And with lipo batteries drawing too much current can cause them to vent like a dead short.
Measuring amp draw you need to put a meter basically in the circuit between the battery and the rest of the system and measure the draw. That said most multimeters won't handle that level of draw without failing so I haven't looked too far into how to test that yet.
Luke
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Post by T6e9a on Dec 22, 2014 21:13:59 GMT -5
Stock guns usually draw around 20 or so amps. But once you start tuning and upgrading, they start to draw more.
From my research, it doesn't matter what the amp supply is, the motor will only draw however much it needs.
Past that, I'm not too deeply versed in LiPos/battery tech.
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Post by luke213 on Dec 22, 2014 21:50:53 GMT -5
Well with batteries as a whole they will only draw max what the motor or whatever is hooked to them, but I'm not sure what the absolute max a motor can draw and that's one thing I'm wondering about. I can't also remember what fuse size most AEG's come with but keeping a fuse less than what the max amp the battery is capable of might be another good idea. Basically though let's say pulling numbers out of the air, that an AEG can draw 30 amps and not normal but the grease is hard in the gearbox and nothing is setup properly. And the battery is only rated for 25 or for that matter less than 30 amps, there is a very good chance that battery will vent and depending on how/where it's installed it might be an issue. Battery safety is a huge thing on Ecig forums right now because ecigs themselves are under so much scrutiny that no one wants to see someone have any sort of accident. That is probably why I'm so attune to the issues about lipo's is that I'm hearing about battery safety non-stop. Either way I took a look through lipo's on a few sites and I didn't see anything that really lit my fire. I'm looking for something could be small but doesn't have to be with a larger capacity than I'm seeing listed. Typically I play in a pretty heavy firing role, or at least a ways from the ability to charge so I like 2000 or so mah for my own guns. Seeing lots of options in the 1000mah fit anywhere lipo's but not allot larger. That is leading me down the path of researching a bit more into stacking a setup with 18650 batteries like I use in my Ecig, they are 3.7-4.2 each cell 2500mah, and rated to 35amp. I'm considering getting something like this to build them into: www.airsoftgi.com/product_info.php?products_id=15434Interior dimensions are tight though so I'm not sure but I'm 99% sure I'd have to remove some material. The cells are 18mm x 65mm and the interior is 16mm x 64mm so depending on how close their dimensions are it might work;) Either way I'm thinking that's the direction I'm heading for my gun, depending on what I find research wise on stacking the cells safely etc. I'll keep you guys posted though how it works out, since this might be a slightly different direction than other people have taken with Li-po batteries so far with airsoft, and it might give a pretty good boost in capacity for the size. Take care! Luke
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ctres
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Post by ctres on Dec 22, 2014 21:55:37 GMT -5
If you are looking for lipos skip the airsoft sites altogether and check out hobbypartz or hobbyking. Airsoft lipos are ridiculously overpriced. RC lipos are typically much cheaper than Nimh or NiCd.
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Post by luke213 on Dec 22, 2014 21:59:30 GMT -5
What sort of connectors are you guys running these days is everyone on deans? Or the old school style that I can never spell the name properly:)
Luke
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ctres
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Post by ctres on Dec 22, 2014 22:02:52 GMT -5
Deans is the way to go. There are other RC connectors out there such as 4mm bananas or xt60s but deans are more compact and do the job perfectly for airsoft applications. All my guns use deans exclusively, but a lot of people, especially people who are newer to the sport, use tamiyas since that is what guns still come with mostly.
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Post by T6e9a on Dec 22, 2014 22:08:00 GMT -5
If you are worried about low mah with restricted space, you could always get like 2 1000 mah 11.1 batteries and wire it in sequence or parallel. Forget which one does what, buying recommend a unit that you plug the batteries into. One will give you a 22.2 1000 mah battery, the other will give you a 2000 mah 11.1.
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ctres
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Post by ctres on Dec 22, 2014 22:15:57 GMT -5
Parallel will double the mah and therefore the amount of current the battery can provide. Parallel is when the positive lead of one battery is connected to the positive lead of the other and negative lead to negative lead. Series will double the voltage and mah will stay the same. This is done when you connect the negative of one battery to the positive of the other. Both of these have potential risks associated and should be done with caution when using lipos, but if done correctly are both fine.
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Post by luke213 on Dec 22, 2014 22:28:31 GMT -5
Yep and in my little bit of research in the last little bit it looks like wiring in series is slightly safer for lipo's since apparently the cells don't have to be matched as close. In parallel if one cell is not quite as strong it will draw from the other causing issues. In series according to my initial reading that shouldn't be an issue or less of one. Either way if I go the route I'm looking into I'll be charging and checking the cells individually since I've got the gear to do that already from my flashlight/ecig hobby. I did take a quick look and they are interesting but I'm still not seeing the amount of power in a small package that 18650's will give me. So I'm still leaning that direction, I don't mind digging into the research to see if it's the best option. But at this point it's looking that way to me, for building a small high mah, but still safe amp level pack I think it's going to be the way to go. And the cells should only cost shy of $20 and if for some reason they don't work out as planned they can be re-purposed;) Here is an example of what I'm talking about as well, this setup: www.hobbypartz.com/98p-25c-2400-2s1p-hardcase.htmlThat's Size: 139.06 *47.44 * 24mm now unless I'm forgetting something the pack I'm looking at building would be 65mm x 36mm x 18mm and maybe a little bigger depending on how I actually enclose it. But for the size of that pack, I could wire up two sets in parallel and come in at 5,000mah in capacity while still keeping safe amp limit wise. Granted that pack would cost around $40 plus fiddling to get everything working properly and building an enclosure with low resistance contacts etc. But it seems like the kind of Frankenstein project that might yield interesting results;) Luke
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