People think about NiMH cell chargers probably as much as they think about batteries, unless it’s time to replace the cells in whatever device they’re installed in. This doesn’t make a teardown of one of these marvels any less interesting, especially when you can get an 8-bay charger with eight included NiMH cells for a cool $25 brand new. The charger even has USB ports on it, so it’s got to be good. Cue a full teardown by [Brian Dipert] over at EDN to see what lurks inside.
Of note is that [Brian] got the older version of EBL’s charger, which requires that two cells of the same type are installed side-by-side instead of featuring per-bay charging. This is a common feature of cheaper chargers, and perhaps unsurprisingly the charger was struggling with NiMH cells that other chargers would happily charge.
Opening up the unit required hunting for plastic clips, revealing the rather sparse internals. Unsurprisingly, there wasn’t a lot to look at, with the two USB ports apparently wired directly into the AC-to-DC section. There’s a CRE6536 AC-DC power management IC, the full-bridge rectifier and an unmarked 16-pin IC that presumably contains all of the charger logic. On the positive side, the mains-powered charger didn’t catch on fire (yet), but for anyone interested in leaving battery chargers unattended for extended periods of time, perhaps look at a more reputable brand.
What are more reputable brands?
Xtar ones have always done me well.
EBL. Really, their chargers are fine. I have a few and they’re very reliable.
Just look for ones with independent cell channels (the ones that charge in pairs say something like “charges 2 or 4 cells at a time”). Even EBL makes some, but you can also look at Panasonic (aka Eneloop) and Tenergy.
I have a 4 cell charger with USB power from Ansmann which can charge dead cells which many “smart” chargers don’t. I bought it specially because the other 3 chargers i had did not do this. I suppose what all do is they have read the voltage on the battery when it is connected and if it is too low they just don’t charge it. This is a common situation when multiple batteries are left in a device after one battery is discharge all the way to 0 or even a bit reversed.
It delivers.
I have been using a Tenergy for 3 years and I like it, pretty cheap at $22 for 8 cells. It has kept the batteries going for these last 8 years so it seems to be gentle on them. It charges the cells individually and has an LCD bar graph for each cell.
The charger I had before boiled the batteries like a hot dog, shrinking their wrappings and making their life-span very short
Typo, I marked the batteries December 2022, and they are still going strong, in cordless mics used 2 hrs 4x a week.
I have the 16 cell version of the Tenergy — pretty good for my needs.
Hobby RC chargers are pretty powerful. I’ve never had a bad charger out of the many I’ve purchased over the years. Multiple battery chemistry options from lead/acid to hi voltage lipos standard on even the cheapest.
Posting over 50 pictures with a 19.mm round metal object does not make it more interesting. I would have been more interesting if at least a part of the schematic was reverse engineered, but I am only interested in battery chargers that have monitoring for individual cells. Apparently this one was advertised with separate led’s for each cell (assume separate charge control for each cell) and the product sent clearly is not similar. That would have been enough to just send it back.
A bunch of years ago I bought a Liitokala Lii-PD4 It was not an expensive charger, but it seems well built. But as it turns out, I do not use it enough to really know how good it is. The few cells I have get charged less than once per year, and it surely gets that job done, but I can’t do a real review.
Had the same thought. The most interesting IC had no markings.
I was thinking about the possibility of an open source battery charger, the main issue being a decently low cost and low component way to do programmable constant current. You can just have a switch mode DC-DC in CC mode with different resistors switched in by FETs, but it would be nice to have something I2C. And also a programmable discharge system on the same basis.
EBL is garbage. Suspect from day one. A few years on and dozens of cycles later, 90% of my EBL batteries went in the bin. Not sure if it was the charger or the batteries, but the IKEA cells seem to be holding up just fine.
EBL used to be near the top of the heap, but they’ve fallen miserably in terms of quality in the last decade. IKEAs are good when you can get them cheap (I can’t). My Harbor Freights continue to do well, strangely enough. Todd over at Project Farm has a video on all of these batteries.