AA/AAA rechargeable. Why no Lithium ion 1.5v ?

Forums › Gadgets, robotics, home automation, electronics (including wearables) › AA/AAA rechargeable. Why no Lithium ion 1.5v ?

seoras

55 posts

Master Geek

# 237945 26-Jun-2018 12:01

One person supports this post

I'm just about to buy (on Ali Express) some more Li ion AAA's having bought some AA's a few years ago.

From what I've researched it seems that the only Li ion AAA sized batteries are the ones that come with the RC toys and have a output voltage of about 4v.

The AA's (1.5v, 2800mWh) I bought a couple of years ago have been exceptional. I was wary of them to start with because of their high price and not being available in NZ but they've proven to be so good I'm now wondering why the hell you can't buy them here and avoid the long wait for overseas delivery?

The only problem I've encountered with them has been one toy which wouldn't work with them. I suspect it was expecting <1.5v but it got exactly 1.5v from each.

Someone gave my son a really cheap RC car which ran on AA's and when I put these in it went like stink and lasted ages before needing a re-charge.

Anyone else bought these and had trouble with them? I'm wondering why they've never become mass market since the NiHM seem so dated and awful in comparison?

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2167 posts

Uber Geek

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# 2044031 26-Jun-2018 12:26

How are you charging Li Ion AAA's?

seoras

55 posts

Master Geek

# 2044036 26-Jun-2018 12:36

It came with a USB charger which also double as a nice little LED torch too.

The charger takes 4 batteries at a time (AA or AAA).

I didn't want this post to come across as a product advertisement. I'm really just looking for pit falls here. You know "if something sounds too good to be true...".

Something doesn't make sense. Why would such a good product not be openly available here in NZ?

So I'm wondering if there's any known issues. e.g. exploding batteries, fire hazard etc.

These are the ones I've got with charger (slightly newer model with 3000mWh):

https://www.aliexpress.com/store/product/4pcs-KENTLI-1-5v-3000mWh-Li-polymer-li-ion-lithium-rechargeable-AA-battery-batteries-4-slots/2901122_32817792809.html

BuffyNZ

Will not stab you
237 posts

Master Geek

Subscriber

# 2044038 26-Jun-2018 12:39

Watching this thread with interest. I have been tempted along these lines myself but have never bit the bullet. Or the battery.

Recursion: See recursion.
--
“It is important not to let the perfect become the enemy of the good, even when you can agree on what perfect is. Doubly so when you can't. As unpleasant as it is to be trapped by past mistakes, you can't make any progress by being afraid of your own shadow during design.”

--Greg Hudson, Subversion developer

muppet

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# 2044059 26-Jun-2018 12:48

One person supports this post

seoras:

Something doesn't make sense. Why would such a good product not be openly available here in NZ?

So I'm wondering if there's any known issues. e.g. exploding batteries, fire hazard etc.

I would suggest because it's not actually that good of a product.

If you really must, must have 1.5v then I guess they're OK. But the fact they each have to circuitry in them to regulate the voltage, their tendency to suddenly shutdown at load and the fact they are Lithium based (more risk of explosion etc vs a regular NiMH battery) and the fact they have less capacity than a NiMH battery would suggest while they sound fancy, they're not really that great.

And good you're not charging them in a standard AA charger!!!

seoras

55 posts

Master Geek

# 2044078 26-Jun-2018 13:16

muppet:

seoras:

Something doesn't make sense. Why would such a good product not be openly available here in NZ?

So I'm wondering if there's any known issues. e.g. exploding batteries, fire hazard etc.

I would suggest because it's not actually that good of a product.

If you really must, must have 1.5v then I guess they're OK. But the fact they each have to circuitry in them to regulate the voltage, their tendency to suddenly shutdown at load and the fact they are Lithium based (more risk of explosion etc vs a regular NiMH battery) and the fact they have less capacity than a NiMH battery would suggest while they sound fancy, they're not really that great.

And good you're not charging them in a standard AA charger!!!

Interesting article. I bought mine to use in my Apple magic trackpad (the original one which needed 2xAA). At first I'd been using NiHM rechargeables which were as you'd expect. It struck me that this trackpad should have come with built in Li-ion, which it did when Apple released V2, so went looking for some Li-ion AA's.

They lasted about twice as long as standard NiHM batteries did in the track pad. So I'm immediately suspicious of the article's declaration that they don't last as long.

Article Quote " Overall, this cell is… interesting. Just don’t expect a miracle in a steel can. "

Actually they are a miracle in a steel can. Which is why I'm puzzled at their lack of popularity and his overly negative review.

The only negative point from the article that I can verify is that if you have a battery life indicator on your device it's going to say 100% right up until it dies.

That's just how good they are. I'm again puzzled as to why this is seen as a negative. A solid 1.5v all the way to the end is a good thing isn't it? :-/

Then there's the weight of them. That's the first thing you notice when you pop them out of the package into your hand, just how light they are compared to other AA/AAA's. My sons RC car benefited as much from the weight reduction as it did from the solid 1.5v. I've been testing them in everything I can since I got them and I'd honestly use them before any other battery.

Let me go through the articles "cons" list.

Low capacity – provides a mere 1200 mAh (1800 mWh) @ 2 amps, and up to 1700 mAh (2550 mWh) @ 250 mA (even alkaline batteries can do better than this)

Nope. 3000mWh. (Mine are 2800) and have outlasted anything else I've seen, used & replaced.

Abrupt shutdown when the battery is overloaded, overheated, or over-discharged

Not experienced this. Abrupt shutdown when needing re-charged. They give you no warning. That's the only "negative", if you think of it as such.

Runs hot at high loads (and therefore is fairly inefficient)

Never. Always run cool for me. Even in the car getting hammered by my kid.

1.5 MHz converter and unshielded inductor can cause excessive EMI (electromagnetic interference) in sensitive devices

Could be, I've not noticed any interference. That might explain not getting an NZ import licence or consumer approval.

Expensive! Costs approximately $10/cell

Well, yes, your initial outlay is high. I took a gamble which paid off. I've had them for 4 years now and they work as well as the day I got them. So $2.50 a year isn't too bad. This is what really bothers me about the NiHM. They 'aint cheap and they are crap. Lower voltage than the disposable AA/AAAs with memory issues and not a great life time.

Requires proprietary charger

Yes which they (Kentli) chip for free.

Putting Kentli to one side and looking at this from a technology point of view - why isn't Li ion tech making any head way into the AAA/AA battery market place?

Is there a good reason why we are still stuck with disposables and NiHM for this battery format when every other battery format has gone Li ion?

muppet

2167 posts

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# 2044089 26-Jun-2018 13:31

seoras:

Putting Kentli to one side and looking at this from a technology point of view - why isn't Li ion tech making any head way into the AAA/AA battery market place?

Is there a good reason why we are still stuck with disposables and NiHM for this battery format when every other battery format has gone Li ion?

You've measured your battery to have 2800mAh, or you're reading what's on the label? Because the ones he tested (see his previous post) are the same 2800 ones you say you have. There's lots of 5000mAh branded 18650's on the market, but they sure don't actually have that capacity.

I hardly consider his post highly negative, he states "Overall, I’m on the fence when it comes to this battery."

He shows his testing setup, how he tested them and I see no obvious reason for him to be lying. I'm sorry the article doesn't agree with how you perceive these batteries.

But the simple fact these things don't exist mass market should make it clear why LiIon tech isn't making its way into the AAA/AA market:

You need a converter circuit in each battery (additional failure point), which is at best 80% efficient to get the voltage from 3.7 to 1.5v. 20% of your LiIon is lost to heat.
There is no reliable way for current devices to know if it's 100% charged or about to go flat.
Requires a proprietary charging station.

Things that need LiIon use LiIon. Trying to shoehorn LiIon into AA/AAA doesn't currently work very well and isn't as efficient, it's that simple.

seoras

55 posts

Master Geek

# 2044098 26-Jun-2018 13:39

muppet:

seoras:

Putting Kentli to one side and looking at this from a technology point of view - why isn't Li ion tech making any head way into the AAA/AA battery market place?

Is there a good reason why we are still stuck with disposables and NiHM for this battery format when every other battery format has gone Li ion?

I'm sorry the article doesn't agree with how you perceive these batteries

Things that need LiIon use LiIon. Trying to shoehorn LiIon into AA/AAA doesn't currently work very well and isn't as efficient, it's that simple.

I'm reporting as a consumer who's used them for some years that they are excellent. I'm sorry that my experience with them doesn't concur with your online research throwing up an article that dismisses them off hand. In this day an age it's worth taking anything you read with a pinch of salt - yes even what I say.

It's simple. They are batteries and this is 2018. We've fixed bigger problems than this. It stinks a little of the incandescent bulb problem. A dated tech that's become complacent because it makes money.

I started this article in the hope of finding anyone else who'd bought and used them. Articles are good, but if they state things that are opposite to what I've experienced then I'm not going to take them seriously. Sorry mate...

muppet

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# 2044100 26-Jun-2018 13:40

So your 2800 rating, where did that come from?

I know confirmation bias is alive and well, I suffer from it badly too.

seoras

55 posts

Master Geek

# 2044102 26-Jun-2018 13:41

muppet:

So your 2800 rating, where did that come from?

Not interested....

muppet

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# 2044103 26-Jun-2018 13:42

seoras:

muppet:

So your 2800 rating, where did that come from?

Not interested....

Translation: The label :)

Ok no worries, I will go away now.

But for anyone else following along, there's another decent discussion about them here. As per the OP a few positive results and people who are pleased, but most agree they're very specialised.

Edit: And another biased, negative review here.

djtOtago

547 posts

Ultimate Geek

Subscriber

# 2044117 26-Jun-2018 14:08

seoras:

<snip>

Is there a good reason why we are still stuck with disposables and NiHM for this battery format when every other battery format has gone Li ion?

The nominal voltage of lithium-ion is 3.60V/cell. In real life, the voltage of a lithium cell is 4.2v charged to about 2.8v discharged.

So to get 1.5v there needs to be some form of voltage converting electronic circuitry added to the battery.

What we need are toys and things designed to run on 4.2v - 2.8v range of a standard lithium cell, like the 18650 lithium battery.

seoras

55 posts

Master Geek

# 2044120 26-Jun-2018 14:19

djtOtago:

seoras:

<snip>

Is there a good reason why we are still stuck with disposables and NiHM for this battery format when every other battery format has gone Li ion?

The nominal voltage of lithium-ion is 3.60V/cell. In real life, the voltage of a lithium cell is 4.2v charged to about 2.8v discharged.

So to get 1.5v there needs to be some form of voltage converting electronic circuitry added to the battery.

What we need are toys and things designed to run on 4.2v - 2.8v range of a standard lithium cell, like the 18650 lithium battery.

Yes I agree with that sentiment.

One of the things I'm wondering is if this is just an economic factor rather than a technological one.

Cheap toys will mostly be 1.5v battery powered. When you spend more than $50 on a RC toy it tends to come with a higher voltage Li ion battery.

The AA's I have do include the voltage converting circuitry, in 2018 you'd expect this to be easily doable. I'm confirming it has, to my mind anyway.

The problem with anything cheap that needs a battery is that to keep it's cost down it can't include decent batteries or it requires off the shelf ones (AA/AAA) which means 1.5v and multiples of.

My only disappointment is that Kentli hasn't done a decent 9v battery. Is there such a (good) Li-ion beast?

neb

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# 2044481 26-Jun-2018 23:36

seoras:
It came with a USB charger which also double as a nice little LED torch too.

The charger takes 4 batteries at a time (AA or AAA).

I didn't want this post to come across as a product advertisement. I'm really just looking for pit falls here. You know "if something sounds too good to be true...".

Something doesn't make sense. Why would such a good product not be openly available here in NZ?

Probably because they're not really that good for what you're paying. They use a buck converter to get the steady 1.5V, so you'll have a higher self-discharge rate than LSD NiMH's, and an even worse one if powering low-current-draw equipment over a period of time. The capacity is carefully given in mWh rather than mAh, a back-of-the-envelope calc with freely invented figures for conversion efficiency etc puts them at about the 1500mAh mark, vs. close to 2000mAh for equivalent NiMHs.

So it's hard to work up much enthusiasm for something that's probably not much better than, possibly worse than, a cheap NiHM AA.

andrewNZ

2138 posts

Uber Geek

# 2044545 27-Jun-2018 08:28

I think a major factor is safety.
Your average user will plug them into a normal charger, and they will probably explode.

Location: Dunedin

seoras

55 posts

Master Geek

# 2044558 27-Jun-2018 08:40

andrewNZ: I think a major factor is safety.
Your average user will plug them into a normal charger, and they will probably explode.

I thought of that but then I've got sitting here on my desk a Li-ion battery that came in a more expensive "Carrera" RC toy car (awaiting repairs) which came with it's own charger.

That battery is of a AA form factor but is 3.7v/600mAh and comes with it's own charger.

You could say that is a safety failure since it could be plugged into an NiMH charger but it's available, with plenty of others, in your local Toy World where I bought it.

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