USB-C AA/AAA battery chargers?

[iljitsch]

After earlier USB-C discussions, I'm wondering about chargers for rechargeable NiMH AA and AAA batteries. These batteries are still amazing work horses after many decades, having upgraded their mAh ratings and conquered their self-discharge issues more recently.

I currently have an Ikea charger that's pretty good, but that 230 V stuff (yes, that was a compromise between the mainland Europe 220 V and British/Irish 240 V but we didn't go back to 220 after brexit) is starting to annoy me fast.

So... any good AA/AAA chargers that take USB-C power?

Especially interesting would be ones that use PPS to deliver the exact right voltage.

The Wirecutter has a pretty nice recommendation but that one doesn't seem to be for sale in Europe.

 

[iljitsch]

Unless you're trying to liberate yourself from AC power plug adapter hell.

This. I currently have a UGREEN USB-C two-port charger behind my couch that I want to upgrade to one with more ports. That charger sits on top of an Eve Energy smart outlet that switches on when electricity is cheap. I want my battery charging to take advantage of that.

My current 230 V Ikea charger is mostly fine (it does emit high frequency noise especially when the batteries are fully charged) but "mostly fine" is not the same as "ideal" or even "pretty good" so hence my interest in something better.

 

[iljitsch]

What? You're talking about maybe 100 Wh a day if you charge multiple phones and a laptop on the cheapest hour, so at 10 cent/kWh difference, a whole cent of savings.

You're not wrong. I'm now at 22 kWh for about 16 months so that's around 50 Wh. But the price difference can be bigger than 10 cents. Right now we have only 8 hours of daylight and barely any sun, but a good amount of wind. This means the wholesale spot price for electricity is only 1 cent or so in the middle of the night, which is about 16 cents after ~ 2 cents extra costs, ~ 11 c fixed taxes and 21% VAT. But around dinner time demand is high and I pay 35 cents.

So yes, less than a cent a day.

I think I saved more money by running as much stuff as possible when the electricity prices were negative a few times last year.

Optimizing heavy users like dryers (3 kWh per load), dishwasher (0.7-1.5, depending on program) or even oven usage (when to bake a bread from scratch) is much more important.

My clothes dry for free. But yes, dishwasher and laundry make the big difference for me. Sunday afternoon is usually the best time to run these. Charging an electric car from your own outlet is the big one, though.

 

[iljitsch]

Ok, I ordered the LIMETA 8 Bay AA AAA Battery Charger, which can charge eight AA / AAA batteries at once, including strange types such as LiFePo4 ones. (I believe these are 3.2 V so that seems like a hazard, and at only around 600 mAh, how are these better than 3000 mAh 1.2 V NiMHs?? (I.e., just under 2 Wh vs 3.6 Wh...))

But the cool thing is that there is an app for monitoring everything over bluetooth. Apparently the app isn't that great, but as we all know, everything is better with bluetooth.

The IKEA charger does 4 x AA, which is not too bad, but can only handle 2 x AAA at the same time, which is not great. With this one, I could charge 8 AAAs at once, so that's pretty good. Especially as I have some stuff that takes 3 - 6 AAAs.

I also looked at lithium-something AA and AAA batteries with a USB-C port, but ultimately decided against those as the AAA ones have bad reviews and although a steady 1.5 V is good for some stuff I'm not sure it's worth the extra cost and hassle. I do like my 9 V batteries with micro-USB a lot, though.

 

[iljitsch]

Well, 1.2 V NiMs are well understood. Perhaps they don't do 3000 mAh as advertised. But still, good quality modern ones have 1900+ mAh capacities and quite low self discharge rates. Really the only downside is that you don't get 1.5 V when full so some stuff doesn't wort with them at all, or, more likely, say's they're dead after a very short time.

I got a couple of AA batteries that charge through micro USB but those were pretty bad...

Most of my stuff works on 1.2 V really well, but a couple of devices prefer 1.5 V.

An important consideration is whether a device reports depleted AA/AAA batteries or not. Having alkaline ones run down below minimum charge and then leak is not something you want. AFAIK NiMHs don't have this problem.

 

[iljitsch]

About NiMH self-discharge: I got the impression my regular NiMHs didn't do any worse than my Eneloops advertised as low self-discharge. So I did some testing and it looked like the charge fresh and after a month didn't materially differ. So is this a solved problem?

 

[iljitsch]

Which brand/model?. Low self discharge/Pre-charged/Ready to Use batteries are very common now, including the pre-charged AmazonBasics and the

Ah, that explains it:

IKEA Ladda

Does this mean some/many other brands are not equally low self-discharging?

 

[iljitsch]

Ok, the Limeta R8 Air arrived a little earlier, and there's a lot to like about it. The device itself is pretty basic with not the most ideal ergonomics in the world. For some reason, it bothers me that the batteries go in with the plus side pointing back/down. Each slot has a green LED that flashes during charging, also not something I like. And the batteries are packed so tight that it's not really possible to remove one sitting between two others.

However, the app is pretty nice:



So you get to see the details for each battery, and afterwards you know how many mAh the charger put in and how long that took. You can aso adjust some settings:



So if you select a battery chemistry you can then change the charge current between 0.1 and 1.0 A in 0.1 A steps. Leaving it on auto seems to mean 0.5 A.

So this means a choice.... 0.5 A means charging at about 6 mAh per minute, so that way charging a 2540 mAh Ladda should take around 7 hours... At 1 A one of those Laddas got a bit warmer than it'd like, though.

I think a good good setting might be 0.8 A, which the Eneloop AAA 750 mAh batteries are rated for when fast charging. And that's still a good bit faster for the AAs.

The app works over bluetooth and that seems to work well. Too bad though that the (presumably very rough) charging progress indicators don't update without going to the previous screen and then coming back to this one.

Not bad for 19 euros.

 

[iljitsch]

Mine are smart radiator servo valves so they power a decently powerful motor, plus 800 Mhz radio and sensors. Alkaline last longer than NiMH but not long enough for a whole heating season, depending on location of course.

I have these from Tado. Five of the six work really well on a couple of NiMHs. I recharged all of those before it got cold and they all show a completely full battery logo in the app. But the sixth one is probably an earlier version that Tado says you need to feed alkalines. And indeed the two eneloops have been dead for months or maybe even a year.

I tried to revive those with the new charger but first try it only charged them by 100 mAh in fifteen minutes and declared them full. But they wouldn't power a radio for half an hour even though full NiMHs get around 8 hours.

I then tried charging them again, and it charged one for 1:15 and the other 1:45. Is this normal for over-discharged NiMHs?

In general I find that this new charger doesn't charge my batteries to anywhere close to the rated capacity. So that either means they're not drained as much as I thought, or the capacity has deteriorated significantly. The former makes sense because my AAs are virtually always used two in serial, so over time, it's unlikely that they'll become depleted at the same time. The latter makes sense as these batteries aren't spring chickens.

As for the Laddas: the ones I have are 2450 mAh made in Japan. They must be at least five years old, probably a few years more. In my relatively limited testing I didn't see self-discharge after a month.

My main use of AA and AAA batteries is in smart home stuff, remotes and a radio. The nice thing about these NiMHs is that you can just go around the place and replace them all with freshly charged ones and AFAIK virtually no risk of leaking.

Non-rechargeables may be a better fit for many applications, but the downside is that you'll want to use them fully and thus need to replace them at inconvenient times. And you need to stay on top of that to avoid leakage.

If my camera flash doesn't flash quite as often with those LSD batteries I can live with that. I've never depleted a set of batteries using my Nikon flash. But then, I'm still a beginner when it comes to the subtleties of flash photography.