10440 to replace AAA

New member here. Hopefully this has not been discussed before. I did briefly look.
I currently have a nightlight that has motion sensor & dusk/dawn option as well. It uses 4 AAA batteries that run for a decent time, but I just hate paying the money for the batteries.
I have some 10440s as well as an assortment of buck/boost drivers from other projects. My question is being that the light does not activate until it is dark & motion sensed; will this damage the driver as they are supposed to be attached to the device they are running. I know they will be attached to the circuitry but the light itself is not putting a load. Will the circuitry be enough to not kill the drivers.

Would it not be simpler to just get some decent, Low Self Discharge, NiMH cells and a decent charger…?

Please enjoy your time here, Hootowl!

If you want rechargeables to replace AAA, forget about 10440,

and buy:

this Eneloop 4 pack with charger

I’ve got a bunch of AAA, AA, A, and C motion activated lights. Some are better than others.
For 4xAAA you definitely do NOT want a 10440 with boost. There is simply no capacity there. You will not be happy with the result.
Get decent AAA as suggested by @jon_slider.

I also have some proprietary lithium motion activated lights. Look like little flat fluorescent lights. Cute, work pretty well, BUT, the battery is a small lipo, like a very large stick of gum. In a year half the capacity is gone. Needs charging every 3 days. I modded one of them to use an external 4x18650 in parallel and it now runs more than a few days, but it’s not so cute anymore.

Functionally the light is just a number of LED’s and a diffuse cover + battery + motion sensor. I made a similar franken-light that runs off a 2’ strip of 12v LED, external motion sensor, and 2x3s/2200mAh lipos in parallel. Works great, completely ugly. I like it.

To answer all.
I was planning on using 2 10440 in series (7.4v) and placing the buck in the space of the other 2. I’ve already measured & was going to make a fake cell to house it in.
The problem with rechargable NiMH is that they are only 1.2V. I was concerned that the light would not function because the NiMh,s would only be 4.8V total as it requires 6V (4 AAA).
But to the initial question just out of curiosity, would the buck driver be ok & not be damaged.

If the light was designed for 4xAAA, the it’s highly likely it’ll work just fine on NiMh. ALL of mine do. The ‘big deal’ about 1.2v is mostly just lack of information about how NiMh works vs alkaleaks.
FWIW, the best you’ll probably be able to do with 10440 2s is maybe 320mAh……maybe
With decent AAA you’ll get 700mAh+, no problem.
With losses from the driver you’ll be charging that thing every week, depending on your use.

But, if the experiment is important to you, have at it.

That’s not correct, the 1,2V is nominal voltage, NiMH’s load to 1,5V just as normal AAA’s do. It’s confusing but the non-rechargeable AAA are given their max or new voltage while rechargeable cell’s are given nominal voltage, just like the Li-ion’s that we call 3,7V while they load up to 4,2V, these 2 10440’s would thus be 8,4V just of the charger.

All batteries lose voltage during use, the non-rechargeable batteries also go from 1,5V down to about 0,9V when we call them empty so NiMH is a completely comparable alternative.

I agree. Very clear explanation, I hope Hootowl hears you

sounds dangerous

dont take my word, listen to this guy:

BATTERY WARNING: The QUARK QK16L MKIII will accept 2xCR123 or 2xRCR123 batteries. However, we STRONGLY ADVISE AGAINST THEIR USE. Catastrophic failure can occur when one of the two cells is not functioning correctly, causing thermal runaway in the other cell. There is a significant risk of fire and/or explosion when using two cells.

Eneloops are safer than a pair of LiIon

two 10440 in series is a dangerous idea,

based on mistaken assumptions about Eneloop not working…

they actually do work, and Eneloop are much safer than LiIon

protect your family from dangerous ideas that have unintended consequences, buy Eneloops and sleep safely

1 eneloop = 1.2V * 900mAh = 1.08 Wh.
4AAA ENELOOPS= 4.32Wh.

1 10440 = 3.7 * 350mAh = 1.3Wh.
2 10440 = 2.6Wh.

I think. So yes, technically, a single 10440 Vs a single AAA eneloop has more energy. But in the configuration you’re looking at, the 4*AAA has greater energy.

The 10440,s I have are rated at 350mah. I’ve used them in Mini Mags with a buck driver & they work well. I guess my main objective is just a simple solution to the “constant drainage” to my wallet vs battery. Sounds like the NiMh are a better solution as I really don’t want to add yet another project to my list. I use them (NiMH) in my remotes but that is another animal. I wasn’t sure what the effect would be for a light. Probably over-thinking it.
Thank you for the input.

18650 batteries are set up in this way in typical pack such as drill/tool batteries as well as laptop batteries. I have taken plenty apart to scrounge the good batteries & components when they, as a whole, no longer function.

dont be surprised if the unit works fine on 1 li-ion.
while it probably wont fit in the unit without some modding or at all 1 18650 laptop salvage cell holds double the capacity of those aaa’s.
led stuff runs 4s alkaleak to overcome sag at high current.
but even a used laptop salvage has very little sag in something like your motion light and most common flashlights.
i have a few motion lights modded to 1 18650 and a tp4056 board connected to a small solar panel.
1 has been in service 10 years like that.

^
Its guaranteed that Eneloops will hold a higher voltage when under load than Alkalines. The higher the load, the better NIMH will do. At low loads though, Alkaline will “perform better” (hold a higher voltage).
Just lookup and compare discharge curves…

I have a 10440 light myself, and they’re cool little batteries.

…or other AAA brand/models which can perform as well or even better, using this battery comparator from HKJ.

I chose Varta Ready2Use (advertised as 1000 mAh, I have measured around 950 mAh), slightly cheaper than Eneloop, and I am very pleased with them.

Other batteries not from the same factory as Eneloop/Fujitsu don’t have the same cycle life/longevity. But it is definitely possible to have higher initial mah than Eneloop pros. It’s all about your use case.
I will keep using mine till they won’t hold a charge, I don’t need the highest possible mah. I need a battery that will last for years and years to come and no other batteries come close to Eneloop/fujitsu

If you have no use for NiMh longevity that approach can be used. Initial battery quality, capacity, and then use pattern ALL affect the ultimate longevity of a battery. Higher capacity NiMh of the same size, tend to deteriorate faster than lower capacity. This is from an interview of 2 Eneloop technicians:

**What is the differences from a technical and design/construction of regular Eneloops and Eneloop Pros that allow the regular Eneloops to retain charge for longer and have more recharge cycles and the Pros to have a higher capacity?

More volume is more capacity. The Pro batteries have a thinner canisters so there is more active material and electrolyte . The reason why there is a difference in the cycle life is the difference between the amount of the positive and negative electrode. The bigger the difference the more cycles it can have. With Eneloop Lite being on the exact opposite of the Eneloop Pro.

The ‘regular’ Eneloop spec is 2000 cycles, the Eneloop Pro is 500.

In my ‘real life’ use of rechargeable batteries, going on 20 years now, I’ve found this to absolutely be true. AA NiMh that I have over 2500mAh, rapidly ‘go to hell’, (2800 NiMh go to hell fast) and aren’t worth much after only a few years. At……very low……discharge they may show capacities are aren’t too bad, but they stop being able to put out any kind of current, the IR goes WAY up, and the charging gets unreliable in ANY charger.

Then……as is being discussed here, there IS differences among chargers, especially with regard to accurate termination of NiMh, which is actually more difficult than Li-on.

I don’t toss a NiMh for simply losing some capacity. I have applications that can still use them. I DO recycle them when the capacity loss is excessive, and/or the IR gets too high and termination becomes dicey.

Also note that running 4s nimh increases the odds a call will reverse.
3s should work fine and when you hit 1v/cell you are very near vf of the leds.
So its self limiting and not as likely to reverse a cell.
Reversing a cell damages it.

I agree that although Capacity may sound as the Holy Graal, other points need be considered.

My (limited) experience is (AA format):

  • GP ReCyko+ 2050 mAh: still very usable, and moderate IR, after 14 years!
  • Maha Imedion 2100 mAh, 13-year old: rather high IR, but as flydiver said, still quite usable in low current devices
  • Maha Powerex 2700 mAh, same age: I had to trash two of them after only 5 years or so, because of major capacity loss and high IR. Two other units are still usable but have high IR. This may back up flydiver's statement on high capacity models.

In AAA size:

  • 14-year old GP ReCyko+ (820 mAh) still behave very well,
  • 12-year old Maha Imedio (800 mAh) are also still OK,
  • 9-year old Varta Ready2use (800 mAh) still good as well,
  • Duracell 1000 mAh and Maha Powerex 1000 mAh were trashed after a couple of years (and few cycles): again a confirmation of "higher capacity = lower lifetime"?

I bought more recently (less than two years) Varta Ready2use in their more recent version (1000 mAh), too early to evaluate them.

BTW, which IR values are considered good, fair, and bad, for NiMH batteries?

[quote=Rockenrooster] I need a battery that will last for years and years to come and no other batteries come close to Eneloop/fujitsu [/quote] Any source to back up this statement?

quick 10 sec google search:

Interesting Rockenrooster, but to conclude they are "better than others", "others" should be tested in the same 10-year old conditions. And how about IR?