Is there a battery charger under $75 that is accurate at testing a batteries mAh?
I have the Liitokala Lii500 and itâs good enough at measuring cell capacity. The internal resistance readout is quite unreliable though, because of the spring mechanism, but cell capacity is quite accurate.
I have liitokala lii-m4s & m4 and I didnât know that they could do that. I feel really stupid right now.
Xtar vc4sl, vapcell S4+, that liitokala, the opusâŚprobably others.
You could really use almost any charger to check capacity even if theres no display, if you can choose charge current. Drain the battery to the voltage in the datasheet, put it in the charger on a low current so the CV stage is so short itâs not significant, mark the time, and see how long it takes to finish charging. If you used 500mah and it took 4 hours, there ya go.
If it displays mah, even better. Donât have to do math.
I just got the xtar vc4sl yesterday. And Iâm doing a âgradingâ test on 3 of my unmarked 18650 batteries.
I should have asked a different question. Of the 3 chargers that I have (liitokala lii-m4s, m4 and xtar vc4sl) which one would you use to test the mAh?
For some reason I didnât realize what the test function was for on my liitokala chargers. I thought it was just testing good or bad. I didnât even pay attention to the information.
Donât think itâs just the spring loading mechanism. I have 2 Li-500 and had one more. ALL of them gave me EXACTLY the same IR. Unless they fixed it, something is not right.
For any of the spring loaded capacity chargers with IR capability the reading is âerraticâ, but itâs better than no reading at all.
No idea which charger would be more accurate. ALL of them are measuring a semi-moving target using a somewhat calibrated ârulerâ. You WILL get different readings from all of them. You will get somewhat different readings from the SAME battery and charger. Not necessarily a lot, but itâs more reference, aging, and quality checking than precise measurement.
i wish xtar would take the VC8 Plus and chop it in half. i like the straight forward numerical display w/o the speedometer read out but in a smaller size.
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But to measure capacity it has to be done on discharge. My experience has been that on any meter that measures input charge, it is always significantly higher than the real capacity measured on discharge. There is just lots of inefficiencies in charging cells.
That is why chargers that measure capacity do a charge/discharge/charge cycle and measure capacity on the discharge part of the cycle.
You can get an estimate using a charge cycle, but it will always be higher than what the cell can do.
True, manufacturers almost always set capacity based on discharge.
Iâd argue though that this isnât because of inefficiencies during charging, because the same inefficiencies are present during discharge; charge efficiency and discharge efficiency of lithium ion is virtually identical at room temp. Thatâs the other half of why you put in more than you get out, the combined efficiency losses that occur during both charging and discharging. Iâd argue that the reason itâs done this way is because it was easier to standardize, cheaper and safer to repeat, and gives a number thatâs more relevant to the end user.
But itâs all an estimate. Thereâs no such thing as true capacity. Itâs always dependent on other variables, and probably impossible to ever really determine with 100% accuracy. Even if there was a universally agreed upon true capacity standard you would still have a sort of Schrodingerâs Cat situation in that any type of sensor used to measure capacity and maintain a constant discharge rate adjusted for temperature would itself have an impact on capacity just through its operation and constantly varying resistances in the system, intended or unavoidable.
For our purposes, I donât think it really matters whether you measure capacity using a slow charge or a slow discharge. Both are rough estimations not representative of actual use.
I think you always need to put more energy into a cell for a given SOC than you can ever get out of it given controlled conditions.
Still looking for scholarly articles. But yes, I guess for a rough estimate it may not be a big deal. I just always measure capacity with discharge rate over time from a known level to a target cell voltage. Using the same analyzing charger over time, you may not get absolutes, but you certainly have a good basis for comparing cells⌠Even if in a relative way.
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I am learning a lot by reading everyoneâs responses but the only thing I really understood in your reply was Shrodingerâs cat. I get the super position analogy but only in the barest of context.
I can agree with you on this. If we could combine a little from xtar, opus and liitokala we would have the perfect charger.
SkyRC Mc3000. But, comparatively it is expensive.
I almost bought that charger, but then I discovered some of the cheaper ones like LiitoKala. Is there anything the SkyRC offers that makes it worth the price compared to some of the other chargers?
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I wanted that charger and I almost bought it. Until I woke up with a toothache and there went the purchase of the SkyRC up in smoke.
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For me yes. It has independent settings for darn near every parameter used in charging. Including termination current and voltage. It can be calibrated. The charging algorithm is spot on. Decent, fairly repeatable IR reading. Relevant info always displayed on single screen. Resting/charged voltage displayed real time for each cell on a single screen. Good NiMH charging. (even a setting for eneloops)Can be connected to a PC for real time monitoring and logging of the process. App to set it up and save multiple charging routines for about any chemistry, termination voltage etc. Lots of settings, but the app makes it easy to set them and save different ones by name for easy recall. Easily setup routine for âStorage Chargeâ . It is an advanced âHobby Chargerâ with bays for cylindrical cells.
Or as simple as, put in a setting for LiIon cells, leave it. Put cells in and hit start. Works every time.
About everything that people have asked for in the cheaper chargers⌠BTW they developed it with CPF folks and over time (a couple of years) incorporated about everything they asked for. Plus squashed about all of the bugs. There is a huge thread over there on the development. Also Search for Silvefox Mc3000 review.
Great documentation. User guides and settings. One here on BLF, where there is a spreadsheet where you put in what you want to do and it gives you all of the settings that you need.
A fully mature charger. Maybe an example of getting what you pay forâŚ
I have at least 6 different $30 to $50 chargers. The MC3000 is my daily driver. Honestly, none of the other chargers talked about in this thread can compare in most ways⌠except price. Do you need all of that⌠Up to you.
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Donât worry about it, I was replying to another commenter.
Ya if course, otherwise the battery would be pulling energy out of the air or something lol. Thatâs not what Iâm saying. My point was theres inefficiencies on both sides, during charge and discharge. And theyre more or less the same inefficiencies. Rising temperature, thermodynamic stability, mobility, all the side reactions, intercalcuation/deintercalculation efficiency, etc, all present during both charge and discharge.
Ya for sure. I do the same thing
Can anyone recommend a good starting place for learning to modify a flashlight?
I was looking through the âmountain Electronicsâ website yesterday and it seems to be a fairly easy process to upgrade a flashlight.
However I donât understand a lot of the technical jargon, for example, I know what a driver is for but I donât understand the individual components on the driver.
I can solder and I can follow basic instructions but I canât read a schematic. So if anyone can give me some starting advice I would greatly appreciate it.
True.
I recently treated the spring-loaded sliding terminal assys on my Opus with DeOxit D-100, and it appears to have stabilized my internal resistance readings noticeably. They are now more repeatable / consistent. It also seems that its lubricity properties have reduced âstictionâ in the slider assys., which can also contribute to more uniform / repeatable spring pressure.
The absolute accuracy of such measurements is still far from assured (design-dependent / limited), but for repeatability of relative measurements, it appears to have had a very positive effect.
In terms of absolute accuracy, I still consider it sub-optimal, but even given that, better consistency is nevertheless a positive thing.
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DeOxit D-100 - that got me curious. I looked it up and there are a bunch of DeOxit D-100 varieties. What exactly were you using, and why that one?