TENAVOLTS AA Lithium 1.5V rechargeable cells

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Pete7874
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TENAVOLTS AA Lithium 1.5V rechargeable cells

I picked these up on a whim, more out of curiosity than any particular need. This was a set of 4 cells and a charger, although I believe you can buy the cells separately as well.

These are basically 13430 3.7V 750mAh Li-Ion cells with a buck regulator that maintains constant 1.5V output throughout the entire discharge cycle, wrapped in AA shell. Such output is good for applications that have trouble with 1.2V output from a typical NiMH cell, but it’s also bad because there is no way to tell how depleted the cell is. It could be full or it could be empty or anywhere in between, and it’ll still show 1.5V when you check it with a DMM. Also, these cells are not designed to handle high current applications (about 1.5A max, I believe).

HKJ tested similar cells (different brand) recently.

Given this unique setup, it’s obviously not possible to charge them in your normal NiMH/Li-Ion battery charger. You have to use the supplied charger. It takes just under 2 hours to fully charge them. Each cell has a glow ring at the bottom that lights up during charging and turns off when charging is complete.



This is what the cell looks like disassembled (images from a youtube review of user vuaeco):


Running a discharge test on my Opus C2400 @ 500 mA discharge rate gives the following results. One of the cells shows slightly higher output voltage, but it appears to be just a bug in my charger – that particular slot always shows higher voltage for some reason. According to my DMM, that slot 1 was actually at 1.53V.

Voltage during discharge test:

Capacity (final):


Anyway, do any of you use such cells? If so, in what applications/devices?


Edited by: Pete7874 on 09/12/2019 - 15:03
lotrbfme
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This is great for my Blink XT cameras. They run on lithium AA at 1.5v and I cant run them on my rechargeables 1.2v eneloops. So I always have to spend $10 to change the batteries.

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Will these safely recharge on a Li ion/NiMH charger?  Does the charger identify  them as Li ion or NiMH?

 

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Pete7874
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MyRants wrote:

Will these safely recharge on a Li ion/NiMH charger?  Does the charger identify  them as Li ion or NiMH?


 

I mentioned that above:
Pete7874 wrote:
Given this unique setup, it’s obviously not possible to charge them in your normal NiMH/Li-Ion battery charger. You have to use the supplied charger.
MyRants
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Well, so you did.  I missed it.  My apologies.

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MyRants wrote:

Well, so you did.  I missed it.  My apologies.


No worries. It’s actually another drawback of these cells. If you misplace the charger, you have to get a new one.
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The Blackube ones HKJ tested use a USB charger which is actually kinda nice.

On the off chance the two batteries share internals otherwise, I wonder if the proprietary charger is also 5V based?

Seeking the light.

Pete7874
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pc_light wrote:
The Blacklube ones HKJ tested use a USB charger which is actually kinda nice.

On the off chance the two batteries share internals otherwise, I wonder if the proprietary charger is also 5V based?


The output on the terminals of the supplied charger appears to be 5.25V without the cell present.

Actually, it’s basically passthrough voltage from whatever USB power source you’re giving it. Looks like it’s feeding 5V to the buck regulator, which then charges the internal Li-Ion cell.

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So each cell has a buck converter?

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Pete7874 wrote:
pc_light wrote:
The Blackube ones HKJ tested use a USB charger which is actually kinda nice.

On the off chance the two batteries share internals otherwise, I wonder if the proprietary charger is also 5V based?


The output on the terminals of the supplied charger appears to be 5.25V without the cell present.

Actually, it’s basically passthrough voltage from whatever USB power source you’re giving it. Looks like it’s feeding 5V to the buck regulator, which then charges the internal Li-Ion cell.

Good to know, should you find yourself in a pinch without the proprietary charger.

Seeking the light.

Pete7874
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RobertB wrote:
So each cell has a buck converter?
Yes.
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I just ordered a set of these (4 with charger), on Amazon. $34.99 with a 30% clip coupon, and a coupon code (3678BX1X) I found on Slickdeals , brought the total down to $11.90. Thought they might be a descent companion to my Sorfirn SF11.

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Pete7874
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Dusty wrote:
I just ordered a set of these (4 with charger), on Amazon. $34.99 with a 30% clip coupon, and a coupon code (3678BX1X) I found on Slickdeals , brought the total down to $11.90.
Yup, that’s what I paid for mine. I thought this deal was dead. Glad it’s still on. I might pick up another set.

Quote:
Thought they might be a descent companion to my Sorfirn SF11.
How much current does the SF11 pull?
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I’ve never used such batteries but after reading your review and HKJ’s on the Blackube some thoughts on the pluses of such a battery could be -
1. No alkaleaking!
2. Fast recharging
3. Lower self/shelf-discharge than LSD NiMH (?)
4. Better low temperature performance than NiMH, or alkaleak
5. Flat 1.5V versus falling from 1.7V for primary lithium

And some minuses might include –
1. Relatively expensive initial cost
2. 5V charging, requiring proprietary charger; unless one has the USB version/brand of baattery
3. Loss of efficiency when used in 1.5V boost light, after having been bucked from higher lithium voltage

One application I’d like to try might be 2S in a direct-drive driverless LED arrangement. For example, if the 2S 3v is as flat as the single 1.5v cells one could use this to mod an incan 2-AA by simply dropping in a 3V LED on a suitable heatsink pad for a flat output single mode light.

Seeking the light.

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I just bought a set using the coupon and code.

How will these compare to running an eneloop in a single AA flashlight?

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brad wrote:
I just bought a set using the coupon and code.

How will these compare to running an eneloop in a single AA flashlight?


Which specific flashlight?

These Tenavolts cannot deliver as much current as Eneloops can.

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If you look at the 2 Blackube reviews HKJ did the top USB charge [Gray] seems to have a bit more capacity and better amp support than that [Black]. The Tenavolt capacity is more in line with the [Gray], but the amp support more like the [Black].
People seem to have an issue with “yet another charger”. Jeez, our shelves and drawers are crawling with chargers, batteries, holders, and lights. I say, give it a rest. The charger is so small you can use it for a 4xcell holder if you want.

I do find some applications that don’t need a LOT of amp support, but do benefit from 1.5v actually do run better. I have 12 of these, and every one is in use somewhere. I like ‘em. The product seems to be made well and the batteries have been consistent in all my tests.

For about $3/cell on specials (frequent), they are a reasonable buy and work pretty well. For the long haul……we are all beta testers I think.

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Pete7874
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flydiver wrote:
People seem to have an issue with “yet another charger”. Jeez, our shelves and drawers are crawling with chargers, batteries, holders, and lights. I say, give it a rest. The charger is so small you can use it for a 4xcell holder if you want.
To me the issue is primarily about compatibility/convenience. If you lose/misplace the included charger, you will not be able to recharge these cells in any other charger, unless you feed them 5V directly. Alas, if you order several sets of these Tenavolts, you will have multiple backups. Smile
flydiver
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Occasionally the ‘special’ allows the use of the discount code to get only the batteries for another couple $$ off. Haven’t seen that the last 2 cycles though.
For full price these are ridiculous. When they get down to Eneloop pricing they become attractive if you have the right use for them.

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HKJ did a review on them, and the charger: http://budgetlightforum.com/node/69034

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pc_light wrote:
3. Lower self/shelf-discharge than LSD NiMH (?)

I don’t think any rechargeable lithium cell can get anywhere near the current Eneloop spec (70% capacity retention after 10 years).

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Pete7874 wrote:
To me the issue is primarily about compatibility/convenience. If you lose/misplace the included charger, you will not be able to recharge these cells in any other charger, unless you feed them 5V directly.

A plain ol’ AA holder with flying leads and bare usb socket is all anyone’d need to be able to charge these on the fly. 2 soldered connections is all it takes.

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flydiver
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nibble wrote:
pc_light wrote:
3. Lower self/shelf-discharge than LSD NiMH (?)

I don’t think any rechargeable lithium cell can get anywhere near the current Eneloop spec (70% capacity retention after 10 years).

I have a LOT of Eneloops. I just flat don’t believe that spec. Maybe a brand new, specially selected cell, placed in a 40* cool dry place….might…..maybe….pull that off. No battery in real use will get close to that.

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Wellp, I popped one into my E03, and brightness is comparable to a new alkaleak.

Of course, it’s way brighter with a 14500, but all those levels are quite bright. M is comparable to H (ie, little discernable difference in brightness), and L is still hella bright, way too bright to use late at night.

At least with lower voltage, modes are quite evenly spaced, and L is suitable for moonlight-duty with diffusion film.

 

Hjeh, now that I got mum set up with an LED desk-lamp (another vipon special) instead of having to use flashlights to read, etc., I might be able to completely do away with those detestable little leaky things.

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Odd. Ran down a Tenavolt in my E03. Can’t recall running down a cell to nothing in a long time. My EBL 14500 that I had in it since I got it was used lots longer (and brighter in all modes) and after swapping it in still had/has some oomf in it. (Just checked, 3.45V, so could stand to be charged, but still…)

Anyone have observations that they run down fairly quickly?

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Lightbringer wrote:

Anyone have observations that they run down fairly quickly?

Since they run at full 1.5V, they will spend themselves faster than other cells that run at lower voltage.

How many amps does the E03 pull?

Also, when the Tenavolt cell has no more energy to give, it may show 0V on my DMM, from what I’ve seen.

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From Illumn (and others confirming same):

Ni-mh cell:
Low: 20mA, 10 lumens, 20hrs+
Medium: 135mA, 60 lumens, 4hrs+
High: 500mA, 200 lumens, 1hr+

14500 Li-ion:
Low: 300mA, 90 lumens, 2.5hrs
Medium: 1000mA, 320 lumens 45min
High: 1560mA, 430 lumens, 30min

So figure maybe a half-amp-ish even at 1.5V vs 1.2V. Below an amp on high, at any rate.

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I don’t mean this as an insult, but are you sure you had a fully charged cell? It’s impossible to tell except freshly charged, or empty and dead.
I have a dozen, all tested at 1.6Ah @ 0.5v, or slightly better. Good consistency.

I don’t get the specs. How does, say a 2000mAh NiMh pulling 500mA only run for 1hr+? Math doesn’t work out. Should be near 4 hours. That much inefficiency?
I’d expect the Tenavolt to go somewhat over 3 hours on high.

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flydiver wrote:
I don’t mean this as an insult, but are you sure you had a fully charged cell? It’s impossible to tell except freshly charged, or empty and dead.

As soon as I opened ‘em, I popped out the plastic thingy, loaded ‘em all up, powered up the charger, spun each cell around ‘til the bright part of the ring was on top, and let ‘em burn. After a half-hour or so, poop! poop! poop! poop!, all 4 lights eventually went out. Charged, I presume.

flydiver wrote:
I don’t get the specs. How does, say a 2000mAh NiMh pulling 500mA only run for 1hr+? Math doesn’t work out. Should be near 4 hours. That much inefficiency? I’d expect the Tenavolt to go somewhat over 3 hours on high.

NiMH is only 1.2V. It has to boost the voltage to the LED to 3.whatever. So if it boosts the voltage 3× to 3.6V, current would be 1.5A from the cell to supply 500mA to the LED, assuming 100% efficiency.

Granted, it’s the lousiest route as far as efficiency, going from 3.xV from the internal cell, down to regulated 1.5V, then back up to 3.xV to drive the LED. Still, I prefer the more evenly-spaced modes at 1.5V, even if not nearly as bright, vs all-bright directly from a 14500.

Besides, I gotta find something to use ‘em in. LOL

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flydiver
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Got a battery powered: nose trimmer, beard trimmer, 2xAA Sonicare travel toothbrush? Really perks up devices like that, small motors that are kind of laggy, especially as the batteries get old.
The only lights I put them in are small 2XAA or 4xAA motion lights I have all over the house. Some of them that I want to keep brighter and are harder to change out seem to do a bit better with these.

A minor point, but important to me, is that the battery grip in some of those lights is damn aggressive. I can shred the top edges of the cell prying it out, or break a fingernail (ouch!). Some cells I actually need a tool which can cause even more damage. The Tenavolt are a tad smaller diameter, much nicer and harder skin/wrap than any other battery I know (including Eneloops), and slipperier. They go in and out nicely. For a permanently mounted light near the ceiling I like that a lot.
The best cells I had for those particular lights were some REALLY old RayOVac 4.0 and Eneloops. They are getting tired and need replacing anyway. They have hundreds of cycles. Those old ROV have actually been amazing. Manufactured in 08/2011, I beat the snot out of them and most of them are still OK, not great, but still buzzing along. Good enough for stuff like that.

BTW, thanks for the efficiency explanation. Didn’t think about the multiple conversions going on. That would not help out at all.

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After finding out the hard way just once, I’d stick a thread or thin string under the cell to help yank it out later if wedged-in.

But yeah, things that directly take 1.5V are what these cells are best suited for.

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