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m.k

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    DeWalt DCG 405

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    Austria

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  1. May i ask what this test is all about? You test if the battery can supply the current of a tool idling? What does that tell you? Only thing you do is risking shorting your battery out and bricking it with what? copper plates? I mean, you can test the battery against the cell manufacturers datasheet - capacity and high current runs with a electronic load. Or you can measure internal resistance with an impedance meter. Even then - what are you going to do, you have data. But what counts is if the battery works for what you do WITH the particular tool under LOAD. You have probably discarded batteries with 85% State of Health in your life before, and still use some with 60%. The current under idle test is superfluous, you can pull the trigger and hear if the motor slows down. If it doesn't your battery current is constant. Have fun..
  2. Eh, you should be aware that tools and batteries are capable of a lot more than the 10A current range of your Multimeter. You could damage it. I used a clamp meter when measuring battery current. If you want to know if your battery is still good, just try out the tool. If you can screw in a screw with your known good pack, the other one should be able as well.
  3. In this special case it could kinda be an indicator Normally, it really isn't - even a worn pack will show similar voltage directly after charging, because normally a Li-Ion battery is charged with a CC-CV charging characteristic. So first the current is limited and when the voltage comes up, as the battery fills the voltage is held constant, to slowly fill up the last few %. Makita doesn't do that, they skip the CV phase. I don't really know why exactly maybe the self balancing effekt (which they used at their early LiMn2O4 batterys, the non star ones) works best that way, or they said "we at the site ain't have time for topping the battery up". Yes that looses some capacity, on the other hand it is good for lifetime. If you take that into account with your old/new battery therory - the charger always cuts off at 4,1V per cell in CC mode. A worn battery will have higher internal resistance and therefore more voltage drop when charging - and will have a lower "idle voltage" when finished. But there are a lot of factors to take in account when doing this, mostly battery chemistry and temperature. A worn 5Ah will have a lower voltage after charging than a new 5Ah (if they have the same cells). But to compare a 3Ah and a 5Ah can be misleading, the 3Ah will probably have worse internal resistance right out of the box so...
  4. The main problem with this would be letting people cope with unprotected Li-Ion cells. Just look at all these e-cig guys that put unprotected 18650 in the same pocket with their keys. Further annoying would be the no doubt higher price. You would have to have all time cell voltage monitoring because you could put non-matched cells in there, the contacting would be non trivial etc. But i have to say the concept is interesting
  5. m.k

    Knock Off Batteries

    Exactly. Each cell is 2750-2850mAh (if that is the correct datasheet for the actual cell and the rating is correct). So the whole pack is rated at 5,5-5,7Ah depending on which rating you want to go with (nominal or minimal). With cells in series the voltage adds up, with cells in parallel the capacity and current handling capability adds. Your pack has 5 cells in series and 2 parallel. 3,6V*5cells=18V and 2,85Ah*2cells=5,7Ah. (If you want to know the energy stored you multiply those and get 102,6Wh). There is no discharge current specified but the internal impedance of the cell. The internal impedance decides how much energy is wasted as heat in your cell and therefore dictates how much power you can draw and how hot the cell gets. 35mOhm is not really powertool cell territory. Typical maximum values are: Samsung SDI 25R (2,5Ah): 18mOhm; LG Chem HB6 (1,5Ah): 20mOhm; LG Chem HG2 (3Ah): 17mOhm. So i would expect poor performance with high drain tools and thermal issues. But I didn't try them and therefore can't say if they are up to the work you do. And yeah, for 40 bucks even getting something that sort of has 6Ah is more surprising than disappointing to me
  6. m.k

    Knock Off Batteries

    Source: http://li-b.cn/post/43527.html Seems to be more of an electric vehicle cell, sadly i couldn't find a discharge current rating. If you look at the internal impedance you can expect less power than from an powertool cell. You will probably find this 2 row pack performing like a original 1 row pack (with longer runtime). Nothing for angle grinders or circ saws but on an impact I'd expect it to run fine. Thanks a LOT for showing us the insides, very interesting indeed.
  7. As much information as possible. Sure just a very small of buyers would be interested, but enthusiasts and more tech heavy people sure appreciate it. I don't know about the US homepage but in europe DeWalt states at least some info on output power from battery tools. Like 360W output from the DCD795 or 800W from the DCG405, for this one even 1000W input power is stated. That is worth gold if you want to compare tools or choose batteries. Or one time i wanted to find out the dimensions and weight of a XR 6.0Ah battery. Couldn't find them on the homepage so i had to search reviews on forums and blogs to get the info. Why? Just state it...
  8. Oh, okay Sodium solid electrolyte batteries. Even further off but maybe we'll find a working solid electrolyte material that works
  9. I don't know which battery you are referring to, but I don't know any coming soon... I heard some excitement about Li-Ion batteries with solid electrolyte, which are expected to come to market in the mid 20s. I don't want to dampen your enthusiasm, and we certainly don't really know the exact specifications but I don't think powertool will be one of the early uses of any solid electrolyte batteries (lately marketed as "solid state"). Solids are not that good at conducting ions so fast charging and high power are not their principal strengths. The mayor advantage will be energy density and safety, so phones or electric cars will be the first examples that come to mind. With Li metal negative electrode material (which is enabled by the solid electrolyte) you of course don't have problems with lithium plating because It's what you do in this case and lithium plating is limiting the charging of today's Li-Ion batteries. But if the internal resistance of the electrolyte is kinda high you would just heat up your battery and don't charge it much. If you read specs about solid electrolyte cells in research they never mention power output or charge times when comparing them to "todays technology" and 5min charging claims don't have traceable sources behind them. I am excited for anything regarding batteries, don't get me wrong, just don't know when this technology is ready for powertool use
  10. It is indeed a bit sad that tool manufacturers don't offer real fast charging. With those Powertool cells you could go 3C or something if you would care a little about cooling. Especially if the battery was used before. If i got that right it uses the piece where the lock is to suck/blow air through the battery. Could be wrong, never seen the "fast"-charger (8 amps) in person. I would personally even think about active cooling with a peltier cooler or something. Then 16amp charging or something, limited to 3C or there about. That would be a real fast charger. Seems nobody really cares too much, and you can have more batteries as well as solution...
  11. Don't be mistaken, the Ah rating tells you the capacity, not the power. You can push a 4Ah Pack harder than a 18650 6Ah Pack, because it is empty before it can get too hot for instance. And the maximal peak power would be about the same. And I don't know too much of aftermarket batteries, but 40$ for a 6Ah Pack seem a little bit too good to be true. Without knowing i would suspect used 2,5Ah cells or something like that in there. AvE on youtube once had a aftermarked pack with used cells (premium cells, but yeah, can't expect the full lifespan is left). If you buy one please tear it apart and show some pictures, would be very interesting what hides in there.
  12. Maybe a TIG. Welding would be a great hobby i guess, i have a little ac stick welder buzzbox but fine and/or stainless is more interesting to me...
  13. New toy and I absolutely love it. Very powerful and compact, even comes with a slide switch (not too much of a fan of the trigger or paddle versions). In Europe the paddle style version is called DCG406 and in America it is DCG413, so you may know this unit under a different name. I made a little hands on video with an input power measurement:
  14. m.k

    DeWalt 5s3p XR Pack

    Hey guys, I'm in the middle of doing a conversion from an defective DeWalt 4Ah 5s2p Pack to a DeWalt 4,5Ah 5s3p. Even though this is a very niche thing to do (as you guys in the states have the 20700 6.0Ah Packs) you may be interested in how i made a very low cost solution for a high power battery, until 6.0Ah batteries arrive in europe. I documented the process on youtube pretty much as an experiment (gaining experience for a single tool review i want to do in the future). I can share the CAD for the 3rd battery cage and the case enhancement as soon as it is done. Feel free to ask stuff! I don't know if I am even allowed to share this here as there is some self promoting limitation. That said I don't really care for YT views or subscriptions, because I don't plan on doing much on YT (not really that good at it either :D). Then again mods will delete it anyways if it is against the rules.
  15. That is the safe version and in most of the cases it turns out to be right. But when you know what you're doing and follow the recommendations of the cell manufacturer you can possibly revive packs. I don't mean stupid and dangerous "hook it up to a NiCd charger" or "jump start it with another battery" youtube videos. More like read this https://www.nature.com/articles/srep30248 and understand whats going on in a serial string of batteries. Then measure cell voltages and decide if you want to proceed (when all cells are at 3,6V and one is at 0V then yeah, extract the good ones if you need them for anything else but your pack is toast). If all are like 1,5V-2,5V one should consider reviving the pack. There is no guarantee though that no cells have been negative charged in the previous discharge cycle! So look up the cell manufacturers datasheet and look for the recommended revival current. This current is that low, that a cell with a internal short wouldn't come up to voltage. You'll find something like: With low discharged cells (as you can read in the article above) you expect a damaged SEI layer in the cell. The life and performance is greatly dependent on the SEI layer of you battery. Therefore you should consider to make a low current charge (charger with current set or maybe a bench power supply and good supervision) and discharge (lamp or radio) cycle. This should help to properly form the SEI again which translates to the best possible recovery for your cells (if it works out). If the battery can't hold the charge, its defective, if it doesn't perform properly its defective and should never used again. But maybe you have just discharged the cell that little amount that the threshold of the charger isn't reached anymore. Oh and btw. It is not a bad idea to make such a low current cycle with a new out of the box battery as well. The SEI isn't 100% formed yet and low current means less stress for the battery until the SEI is fully there.
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