well, the volt belongs to the SI, and centi is a SI prefix, so centivolt (cV) is perfectly valid. just like centimeter (cm).
it’s less commonly said probably because centi itself is a bit less common as it’s not a power of three. in engineering practices, powers of three seem to be favored. hence you hear a lot of nano, micro, milli, (unity), kilo, mega, giga. you express as those and shift the decimal place accordingly. not as much of the ones like centi, deci, or whatever else.
if you didn’t study the prefixes in school, memorize them all. they’re fun.
I have a few “hobby chargers”. They all will charge several chemistries, including NiMH, NiCD, Lead Acid, LifePO, etc.
They also can measure capacity and can give IR (sort of) readings. Just about any charger you get that is decent these days will have functionality that you don’t need to just to get the few things you do need. The nature of marketing and cramming every possible thing into a single unit.
I got the hobby chargers to be able to charge up to 6 LIIon cells at a time. Kept upgrading to be able to do more at a time… (one will do 10S) ,
But I had to build a fixture and wire up the balance charging plug properly. You will also need a good bench supply to power the charger. Which will cost you darn near as much as the MC3000 for a good one with enough power.
Thing is, I seldom use them. Only very occasionally for things like 3 or 4 cell NiMH packs. Or gently charging 6 volt lead acid lantern batteries.
I use the SkyRC darn near everyday. Much easier to do one to four cells quickly without messing with my fixture and messing with balance wires. BTW You WILL need to use balance charging for multiple cells. Otherwise you WILL overcharge and maybe damage your cells.
Yes, hobby chargers are great for some things. Essential even for charging LiION (which already come with the balance charging harness) or NiMH packs. But for single cells, you are wasting your money.
Ya I guess…it’s not just like centimeter though. Centimeter is an SI base unit. Volts is not an SI base unit, it’s a derived SI unit, like metres per second. It’s not It’s own thing, so that’s not a great analogy. A better one would be saying it’s like Newton metres. We don’t say centi-newton metres.
But we do use SI prefixes it as if it were a base unit. Just cuz it’s easy. So it’s valid I guess. But nobody uses centivolts in practice. Check it out, type out “centivolt” right here on this forum and it gets a squiggly red underline. It thinks you made a typo lol. It’s not even a word in the English language lol. For real. Try and find it in a dictionary. Millivolts is in there. Centimeters is in there. Centivolts is not. It’s not a word in the English language according to Webster’s. But it is technically valid. So why does nobody use it?
I’ve got some theories. So joule is the SI base unit of energy and a coulomb is the SI base unit of electric charge and 1J/C=V. That’d be a confusing equation if you were using centi. 1cJ/cC=cV? Too many c’s lol. This is my “two many c’s” theory lol.
See(pun intended), “c” is standardized in SI to represent centi, that’s not the case in electrical engineering notation, c is not universally standard. It represents too many things. Coulomb, capacitance, current, charge, conductance, constant etc based on context. Too many c’s. And too many cVolts even! Capacitance-voltage, control-voltage, constant voltage.
Too many sources of confusion. Got too many c’s as is. Plus not many reasons to use it. It’d be such a niche application in such a narrow range. Who would you use it? Why? It makes more sense to just jump from volts to mVs.
Oh! Never mind, I didn’t see the “packs” part. I would use that feature now and then. I do take apart and rebuild a lot of tool battery packs.
Another thing I was thinking of is just building a charger with prebuilt tp4056 boards but theyre all knockoffs. Do they even make the tp4056 anymore or are they just all knockoffs?
I can find some other uses or the bench power supply too I I’m sure. Electroplate everything on my car with zinc maybe lol
Tool packs already have a battery management system (BMS) built in. So the balance charging function of a hobby charger is not required. In fact, I THINK that the BMS in the pack and charger interact, so I am not sure that the hobby charger would work at all. The packs I am talking about are for things like drones or RC planes and cars. Or of course ones that you might build yourself.
as someone who has done a pretty solid amount of university engineering studies (and is rather pedantic), i disagree with almost everything in your post. almost can’t tell if you’re trolling me.
actually, the meter (not centimeter) is the SI base unit for length. base unit is a rather specific thing, and if you don’t think prefix is contained therein, consider that the base unit for mass is the kilogram (and not the gram!).
moreover, the type of unit (base vs derived) has absolutely no bearing on the applicability of prefixes. the real reason cV is not as common is explained in my previous post – powers of multiples of 3 are highly favored in engineering disciplines (including electrical engineering). did you miss what i said?
cV it is still used though. i very appropriately used it because it is the single word for 0.01V (the voltage resolution MC3000 presents in its UI). i have also seen it in writing and heard people say it before
also, a dictionary is not an authority on the SI and cannot be used to validate a unit. dictionaries will not contain every permutation of a word, especially for technical or very domain specific subjects. the authority on the SI is General Conference on Weights and Measures (CGPM).
actually, 1 cJ / 1 cC = 1 V, not 1 cV.
also, it’s def not too many cs. worked problems in math and science can be super long (many pages) and can include a lot of tedious dimensional analysis. that’s par for the course.
the centi (c) prefix is indeed standardized by the SI, though perhaps not as universally as i’d like considering we don’t fully use the metric system in the US.
there is zero confusion, however. SI units and prefixes are case-sensitive. c is the prefix symbol for centi, and C is the unit symbol for coulomb.
though you are right that the symbol for the concept (not unit!) of capacitance is commonly C, care is generally taken by good authors to avoid such ambiguity in writing. for example, a conceptual formula will generally consist of only conceptual symbols (e.g. using L for length).
your theory does not explain why decivolt (dV) and decavolt (daV) are also uncommon. the real reason is the one i have given.
It’s probably not used because engineers are practical and 10^3 notation is just more practical and they have no patience for scientists and all their frivolous non-10^3 prefixes lol
Oh I know, I meant like building/rebuilding packs. They gotta be at least kinda balanced first.
There’s a lot of variation between brands and battery lines as far as the BMS’s go. Some put most of it in the battery and not much in the tool or charger. Most are the other way around. They arent designed to do that much balancing and some chargers will just refuse a battery thats not mostly balanced. They all interact with each other somewhat. Except for some amazon brands.
I was just going back to the post about buying a hobby charger instead of a dedicated cylindrical cell charger. I have three (maybe 4) hobby chargers. I have used one of them, maybe, 4 times in the last year. I use my MC3000 just about daily…multiple times per day.
As this started as a topic dealing with the MC3000, my thought is that, for its intended purpose, it is far more valuable than a hobby charger. AND, for that purpose, it is far more flexible than a hobby charger.
In fact you can balance cells , just charge them. Each will charge according to its current condition. Then you can sort them by capacity, resting voltage, IR or whatever. A balancing charger will distribute the charge so that all cells finish . You have no clue what they are doing when it finishes.
yeah… the fact that no one has commented on my spreadsheet tells me that it’s either flawless or no one cares (more likely, lol).
MC3000 is not perfect, but after looking a little at hobby chargers, there is no way i would want one of those instead of this. besides, i only use single cell devices anyways.
as you can see here, i was looking for a charger a couple years ago:
no one replied, and i also never found something that looked good, so i finally broke down and bought a MC3000. i love it, but i’d love a cheaper charger that can do the above things to leave at my summer place.
I looked briefly at the spreadsheet. But not enough to fully appreciate it. Probably because it was more complex than a quick look would allow. I am not sure why you used a spreadsheet. I think that everything in there would go well in a standard “Word” document. That would make it easier to read and maybe less off putting for some. I am hoping to get back to it. But from what I did see, it looks like it is a good start. The information is solid.
Somehow I was thinking that you were going to document settings that you use for different chemistries and sizes of cells. For that, a column for each setting with values on a line for each battery type would work.
because it’s a calculator. you put in the cell capacity (and, optionally, other inputs), and it makes programs. it also serves as convenient documentation. the cells have useful notes that you can view by hovering.
for example, every program parameter cell has the explanation from the manual built into it. you mostly don’t have to refer to the manual anymore.
you can also read the cell formula to understand how the value was derived instead of just scratching your head.
WOW! That was not apparent on first look. Maybe I would have known better if I looked at more than the first page. I wonder if that was lost on others?? Not everyone is familiar with how spreadsheets work…
I will look closer. Me and spreadsheets never have gotten along that well. I downloaded it as an Xcel spreadsheet. We will see if the macros survived.
Naw it’s probably cuz it’s flawless. Well, the charger section of this forum is pretty dead for whatever reason. So is charger discussion in general. Ever since onboard charging became real common. Too bad. Is there anybody still reviewing chargers beyond just an unboxing video?
I looked at it. Looks fine to me. But I don’t have the charger so idk how this really works in practice. It doesn’t hot when you’re discharging at 0.5c? Must have a good cooling fan.
The most recent version has two fans.
Even the Original model that I use daily and that has a single fan, does not get “that” hot when cycling cells. At least the cells do not get above around 50C.
@SYZYGY, thanks for this! A real help when preparing programs for the MC3000!
One question: I noticed you set the D. REDUCE option to OFF by default for Refresh; I’ve been experimenting with my LG MJ1s and have measured some disappointing capacities (around 3100mAh – that was with “TARGET VOLT” set to only 4.1V, but IME the capacity provided by going from 4.1V to 4.2V wouldn’t make up for the remaining 400mAh – and all other parameters set as per its datasheet).
So now I’ve been experimenting with D. REDUCE set to 0.34A (which is half of the datasheet-recommended 0.68A discharge current), but I’m kinda worried that it could force the cells too much and perhaps harm them – what do you think?
Good question. I am a bit confused as to what the D.REDUCE actually does. Honestly I have never messed with it at all. Sounds like I may be missing something important here. So a good explanation, or some links to help me understand the setting would be greatly appreciated.
BTW, page 22 in the manual did not really enlighten me…
THX
EDIT:
I re-read the description several times. Maybe this is the important part?
“Setting this option will extend the discharging period beyond
the time for normal discharge cut-off, discharge even more electric charge, but never let the
battery fall below the cut-off voltage.”
So it is a way to take into consideration the recovery process to coax a bit more out of the cell?
So I see the concern @dmenezes mentions. I can also see why setting it to zero may not be good.
