I have access to lots of rechargeable AA Panasonic’s which are similar to eneloops. Is there a bright multi AA light that can be recharged with batteries installed? 2-8 cells and very bright with decent throw is what I’m after. I don’t know of any off hand but I’m not up to date.
It is not likely to find any with cells in series that are equipped with on board charging. Maybe parallel cells but I blieve in general lights with parallel cells are rare themselves, even without charging being built in.
Charging in series, forget it. But you wanna put 4- or 8 cells to good use, get a Cave Man EA8.
The UI takes a little getting used to, but it’s a nifty thrower and lets you burn down 4 or 8 cells at a time.
NiMH are by far the most complicated of the rechargeable cells to charge properly, and also one of the least tolerant of overcharge. No chance I’d trust a flashlight to do it, even if the option was available.
I had some spare time so I looked on flashlights.parametrek.com, not a lot listed that do in-light AA charging.
Pelican have some 4xAA Lights with chargers, but they’re $$$.
The very old Jetbeam SRA40 came with a power supply to charge the cells inside the light, but charge time was 10+ hours.
You could get some of those 3*AA to D cell adaptors (the AA’s are in parallel so still 1.5v). Then run them in a 3D maglite or something.
Assuming you’ve access to used cells, and own an analysing charger: run some test cycles and group the cells with similar characteristics, else one or two bad cells will result in poor performance.
Oh s* that’s actually really significant and I hadn’t even considered the possibility of a flashlight actually charging that slow. But ya, you would still need to take them out now and then.
So, if you charge NiMH very very very slowly, below 0.1C, like around 0.05C, and the battery was at least partially discharged before you started, then charging NiMH isnt really complicated at all, you just let them all sit there for 24 hours or w/e.
I hadn’t even considered that a flashlight with in-light charging like that was available because who TF wants to wait 24 hours to charge their battery? And that’s not 24 hours only when the battery is totally dead, that’s 24 hours from 50 or 60% capacity too if you want 100. I say 24 hours and not 20 for 0.05C because NiMH charging efficiency drops alot as it gets closer to 100 capacity, I don’t actually know what the number is for 0.05C but I do know that 0.1C charging takes 16 hours. But at 0.1C you have to start with a fully discharged battery, because even at 0.1C if the battery was only partially discharged it will overcharge if you leave it in for 16 hours. At 0.05C its not supposed to…but with LSD cells I wouldn’t leave them in there for days or anything. With 0.1C you’re just charging by a timer of what you think the capacity is. If you have an old cell, even fully discharging them and using this 16 hour charge method can overcharge them because you have no idea how much capacity they’ve lost over the years and they mightve hit 100% hours ago you’d have no way of knowing. You can take them out and analyze them like you said, but even then it wouldn’t change how the flashlight charges them.
I always fast charge them all at the same time in the same group they’re used in, either groups of 3 or 2 or however many will be going into the flashlight, and then try and keep those groupings together.
But even that’s not a perfect system because even minor differences will be amplified over enough cycles, if you only ever did in-light charging you’d eventually end up with very unbalanced cells. So every now and then youd still have to take them out. What I do if I see them going out of whack is discharge them down to the exact same low voltage at the same time at the same rate, hold them there for awhile, fast charge them back up most of the way and then do like a 0.05C charge for several more hours and that usually balances them out fairly well, I think. They’re never gonna be perfect, they just can’t be wildy off.
And then you have people like my grandma who will find I swear like the first carbon zinc AA battery ever made while cleaning the basement one day and just throw it in her blood pressure monitor together with whatever was on sale at RadioShack in 1997 and an energizer max lithium she bought by mistake because she thought it was cat food and she hasn’t exploded once afaik
Hey Jeffgoldblum, welcome to the forum!
I see that you first said that NiMH are the "most difficult to charge properly", and "also one of the least tolerant of overcharge",
and then you are recommanding to charge batteries for 16 hours at 0.1C... That's like 60% overcharge ;)
I would also recommend against charging at 0.05C (for 24 hours), because that is way too low. And unless you unplug the charger after 24 hours, you are likely to continue charging them for many more hours, because most chargers don't notice the voltage drop. Even at 200mA charger might have difficulty.
I know that not all NiMH batteries are the same, but I've learned that deep discharging is worse than overcharging.
I think the figure of 0.05C for 12h is a typical “dumb charger” charging “algorithm”, so it’s not looking for voltage drop (or anything else).
It would not be first time I’ve been wrong about chargers 
Oh, to go back on topic, the rechargeable peli lights (I looked up the Peli Recoil 2460R) have more reasonable charge time of 4 hours. I do wonder what charge circuitry they use… I’m assuming manufacturers can design/make proper 4S dV/dt charge controllers, I’ve never seen them separately like the li-ion TP4056-based boards.
Oh you think so do you? So you think that NiMH charging is close to 100% efficient then. Ok, ok, ok… And you don’t recommend charging at 0.1C for 16 hours? Cuz that would overcharge them 60%? Ok. Ya, totally.
Hey, unrelated, do me a favor. Go grab an eneloop or w/e NiMH AA/AAA you have handy and read what it says under “standard charge” it’s just on the box or on the battery itself.
See where it says “Standard Charge: (0.1C) for 16 hours”? That means it takes 16 hours to fully charge them at 0.1C. Because NiMH charging isn’t 100% efficient. And that’s how long it takes. XD
I’m not pulling numbers out of my @ss here lol. They write it on the battery.
I was just pointing out the contradictions ;)
If you want to talk more about Eneloops, we can discuss that here: https://budgetlightforum.com/t/-/6287
NiMH standard charging rate is 0.1C current for 14 hours.
Many dumb chargers with timer work in that way in the past and charge batteries in pairs.
Quality batteries have last many cycles in that inefficient primitive chargers.
Almost all the Panasonic Eneloop dumb chargers bundled with their AAs have 13 hour timers.