Looking for recommendations for the best, most compact single bay charger out there. Strong preference to USB input for power and must be reasonably durable. I do need it for NIMH as well as li-ion. Is there anything better than the olight magnet charger?
Klarus K1 is pretty compact. Can charge Ni-Mh, Ni-Cd, LiFeP04 and Li-ion. It has a 73 mm bay that fits 21700 cells. It gets good review by HKJ.
The iMax B6 is worth a look if you want an everything charger. It can charge 1 cell of whatever chemistry, or balance charge a whole pack through it balance ports.
LK101?
Do any of these single cell chargers have data display, possibly testing features?
In the long run it might be more practical to use a multi-battery-charger, and the size isn’t much bigger either, because you don’t look at the KLARUS CH4S
Opus BT-C100. It does everything.
The iMax always shows mAh transferred, whether charging or discharging. It can discharge at a rate up to 2.0 amp and charge at a rate up to 6.0 amp. In 0.1 amp steps.
The Liitokala 101 works well for me. There are a few others from different brands that look like pretty much the same thing. They don’t have a display or testing features.
This one from Fenix does have a display and measures capacity.
Best single bay charger: Opus BT-C100.
Power supply from 12V or USB.
Charge: 200 to 2000 mA. Li-Ion 4,2V, 4,35V, LiFePO 3,2V, NiMh, NiCd.
Discharge: 100 to 1000 mA.
USB output 2.1A - Power Bank.
Long bay for protected cell 21700 WUBEN!
That Fenix and the BT-C100 look real nice for this, but do they support nimh as well? I”ll have to take alook at some of reviews/tests out there and check them out!
Yes BT-C100 supports NiMh and NiCd charging.
I’m using magnet charger from Foursevens which similar to Olight’s.
It supports both Li-Ion and NiMH but no powerbank feature.
Is there a single-cell charger with a switch or other way to force default to LiFePO4 charging?
I want to give an elderly friend a light with a safe LiFePO4 cell and a single cell charger for that, with no risk of overcharging by accident.
I am just not trusting that the “hold the button down until you see the setting” approach is wise for this person’s use.
I’d just get one dedicated to LFP cells only. I was in the same situation, just swapped LFP for Li-ion.
If LFP means lithium iron phosphate LiFePO4, then yes, that’s exactly what I’m looking for, a dedicated charger.
But I have’t found one yet.
Hmmm, this may be one — description but no price: https://www.durnergy.com/lifepo4-li-ion-rechargeable-battery-charger-ifr18650-2slot.html
If there’s a way to recalibrate/alter any of the many single cell chargers to change the final voltage, I could do a little soldering or other modding.
I have too many single li-ion chargers accumulated over time.
Did you mean Lii-100? Best selling li-ion charger in the world…
For those of you interested in a dedicated LiFePO4 charger: any charger with termination current can be modified by setting a couple schottky diodes in series at the output, they can be easily set low side at the negative terminal cable which goes soldered to the rail tab. This should result in 2 × ≈0.3V of voltage drop. Should also work well with a single standard rectifier. No problem if the drop ends up being a little bit higher, LiFePO4 doesn't really needs 3.6V just 3.4V is enough. Remember to use diodes with enough current rating. Of course, charging efficiency will drop. 
For Buck91, who asked the original question —- yes, what Barkuti wrote. The Li-100 (and its 2-cell version) are nice, simple, reliable, excellent.
All you have to do is watch the blinkenlights to set it.
I was thinking of either buying a Klarus K1X or a Fenix Are-D1 and I ended up buying the K1X because it is smaller (slightly) and I don’t have to adjust the current. The charger seems to charge just fine. Ther is nothing obviously wrong about it. However, the USB output mode, which is rated just 1A, has a problem when I use 5A-low resistance cables, like Ugreen’s or Orico’s. The charger’s display will flash a few times before shutting down, although this doesn’t happen when I use normal cables. I suspect that the shut down might be caused by the pin contacts of the USB of the 5A cables as they have 6 pins, whereas other normal cables that I have have 4 pins. Just something for you to consider as I’m also trying to find the best one bay charger.
I’m not sure giving any newbie, elderly or not, a lithium-ion light is a good idea. Especially if that requires external charging. Most people will treat cells like they’re as safe as alkaline batteries. It’s just way too easy to short lithium-ion cells, and way more dangerous than shorting an alkaline.
There are 1xAA lights that will give you 500 lumens from an Eneloop. Most people would probably be amazed by that. Why give them the safety issues with lithium-ion lights, even if those LiFePO4 cells are slightly safer than the regular variant.
Plus, a NiMH light can use alkalines too, if they keep the brightness down to a moderate level.
If the person really wants a lithium-ion light, get one with built-in USB charging and low-voltage protection. Load a cell in it (a regular 4.2v cell is fine), and loctite the head and tail threads so it won’t come out.