Author Topic: New Rechargeable AA batteries  (Read 2898 times)

Re: New Rechargeable AA batteries
« Reply #25 on: June 25, 2020, 02:40:19 pm »
Does anyone have any experience of these?

https://www.amazon.co.uk/dp/B0821ZNWKW/ref=emc_b_5_i

Flippin' expensive but if they work, should knock spots off the standard rechargeables.

It's quite an outlay as they are intended or use in a night-time infra-red camera (Browning something or other) which requires 8 of them - 12 volts. I've seen reports which suggest that rechargeables are pretty much a waste of time because they only put out 9.6 volts and the camera won't respond if the voltage goes below 9v.

You could do worse than give the guy at Battery Logic a call. It's a one man outfit - so you are unlikely to get through to the 'wrong' person.
He absolutely loves to talk about batteries and, IME, is very knowledgeable.

I recently replaced my entire fleet of rechargebles - most of which dated back to 2006.
That's an overall spend of ~£75.00
His advice on what I should buy was very useful, and he wasn't in the least bit sniffy that most of my old batteries, weren't purchased from him. (I bought a couple of BL 700 chargers from him)

fuaran

  • rothair gasta
Re: New Rechargeable AA batteries
« Reply #26 on: June 25, 2020, 02:41:25 pm »
It's quite an outlay as they are intended or use in a night-time infra-red camera (Browning something or other) which requires 8 of them - 12 volts. I've seen reports which suggest that rechargeables are pretty much a waste of time because they only put out 9.6 volts and the camera won't respond if the voltage goes below 9v.
I use Eneloop white in my Browning camera, works fine. Probably lasts a month or so.

Wowbagger

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Re: New Rechargeable AA batteries
« Reply #27 on: June 25, 2020, 03:47:21 pm »
It does, but I don't know how waterproof it is likely to be.
Eating's a serious business. Don't bollocks around wagging your tail.

Wowbagger

  • Dez's butler
    • Musings of a Gentleman Cyclist
Re: New Rechargeable AA batteries
« Reply #28 on: June 25, 2020, 04:40:05 pm »
Does anyone have any experience of these?

https://www.amazon.co.uk/dp/B0821ZNWKW/ref=emc_b_5_i

Flippin' expensive but if they work, should knock spots off the standard rechargeables.

It's quite an outlay as they are intended or use in a night-time infra-red camera (Browning something or other) which requires 8 of them - 12 volts. I've seen reports which suggest that rechargeables are pretty much a waste of time because they only put out 9.6 volts and the camera won't respond if the voltage goes below 9v.

You could do worse than give the guy at Battery Logic a call. It's a one man outfit - so you are unlikely to get through to the 'wrong' person.
He absolutely loves to talk about batteries and, IME, is very knowledgeable.

I recently replaced my entire fleet of rechargebles - most of which dated back to 2006.
That's an overall spend of ~£75.00
His advice on what I should buy was very useful, and he wasn't in the least bit sniffy that most of my old batteries, weren't purchased from him. (I bought a couple of BL 700 chargers from him)
He wasn't answering his phone, but on the strength of the above, I've ordered quite a few batteries and a new Technoline charger. I've had one of these for ages, but I think it's faulty, as it seems to be sending batteries way over their supposed maximum capacity.
Eating's a serious business. Don't bollocks around wagging your tail.

Re: New Rechargeable AA batteries
« Reply #29 on: June 25, 2020, 04:58:55 pm »
There's lots of fake eneloops out there.  For eneloop pro be sure to weight the pack before you open it.  A pack of 4 genuine eneloops should weight around 125g (30g per battery plus packaging).

Re: New Rechargeable AA batteries
« Reply #30 on: June 25, 2020, 10:32:10 pm »
Does anyone have any experience of these?

https://www.amazon.co.uk/dp/B0821ZNWKW/ref=emc_b_5_i

Flippin' expensive but if they work, should knock spots off the standard rechargeables.

It's quite an outlay as they are intended or use in a night-time infra-red camera (Browning something or other) which requires 8 of them - 12 volts. I've seen reports which suggest that rechargeables are pretty much a waste of time because they only put out 9.6 volts and the camera won't respond if the voltage goes below 9v.
I've got some that are similar, but lower capacity.

They aren't regular AA rechargeables - they are lithium cells with a regulator in the end to bring the voltage down from 3.7 to 1.5 V.
You should charge them via the built in USB port.

The battery will give the full 1.5 V right up until the regulator decides the cell has run flat, at which point it will just turn off.
My Garmin went from 4 bars (out of 4) to shut down in about 300 metres, and it could have been quicker if I'd been actually watching at the critical moment.

What could be a problem is one of the 8 turning off before the other 7.
In general, rechargeable cells don't like having current forced through ("reverse charging"), and are damaged as a result. Whether this is an actual problem in this case will depend on whether the regulator shut off is sufficiently robust.


On the subject of Eneloops, my black ones have done quite a bit better than the white ones.
After about 4 years, the black are running at 2420 mAh according to my MH-C9000 charger; the white are at about 1650.

Re: New Rechargeable AA batteries
« Reply #31 on: June 26, 2020, 10:41:48 pm »
What could be a problem is one of the 8 turning off before the other 7.
In general, rechargeable cells don't like having current forced through ("reverse charging"), and are damaged as a result. Whether this is an actual problem in this case will depend on whether the regulator shut off is sufficiently robust.
I think that it is highly unlikely that it will be a problem.

These aren't just cells, they are a cells followed by voltage regulators. A Li-Ion cell shouldn't be taken below about 3 V, and its voltage will be dropping fast by then. It is still much bigger than 1.5 V even when flat, so it needs a cut-off to stop it going down to 1.5, even if used on it's own, and cut-offs are simple and well known and work well.

If one cell in a group goes flat, the other cells cause current to still be taken by the load so the cell voltage carries on going down. The same happens with power supplies in series. However, for power supplies the fix is quite simple. A suitable diode in parallel with the output will carry the current and prevent the voltage going more than about 0.4 - 0.7 V negative, which will normally prevent damage to a power supply. In fact, the most common way of getting a lower voltage from a higher voltage (a buck regulator if anyone wants to look it up) will normally contain a diode for its normal function, so its fairly well impossible to damage it in the over-discharge direction.

I would expect an almost instantaneous drop from 1.5 V to -0.5 V. If you have 8 cells, that's 12 V, so it will drop to 10 V when the first battery is flat. Most electronic loads will just turn off when that happens, but those that don't won't cause any damage as the diodes protect the cell electronics.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Kim

  • Timelord
Re: New Rechargeable AA batteries
« Reply #32 on: June 26, 2020, 11:15:06 pm »
Someone will start molishing those with regulators that mimic the discharge curve of alkaline or NiMH chemistry next...
Careful, Kim. Your sarcasm's showing...

fuaran

  • rothair gasta
Re: New Rechargeable AA batteries
« Reply #33 on: June 27, 2020, 02:50:13 am »
Those lithium ion AA are an interesting idea. There are some cheaper versions on AliExpress etc.
Some with USB charging built in, some need a separate charger. Maybe better capacity on the type without USB.

I'm wondering how well they really work. What is the actual capacity?
And how do they compare for self discharge? Or working at low temperatures, when NiMH can struggle?

Re: New Rechargeable AA batteries
« Reply #34 on: June 27, 2020, 10:38:19 pm »
You do want to check the voltage and charging specs.

Some are just lithium ion, can be charged in any lithium ion charger with suitable charging bays, but are 3.7 volts and stand a good chance of killing your standard AA device if you just swap them in for alkaline or NiMh AAs. These would normally be sold as 14500 cells (14 mm dia x 50 mm long, which is the size of an AA), but there's no relying on marketing people.

The ones that are regulated down to 1.5V would normally need to be charged via their USB port, or via a dedicated charger

frankly frankie

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Re: New Rechargeable AA batteries
« Reply #35 on: June 28, 2020, 11:49:36 am »
I've seen reports which suggest that rechargeables are pretty much a waste of time because they only put out 9.6 volts and the camera won't respond if the voltage goes below 9v.

They'd be absolutely fine provided you didn't have a dud cell in your 8 - but unfortunately the chances of having a dud cell in 8 are very high.
The 1.2V per cell that is typical of NiMHs is maintained on a level plateau right up to the point (within a few minutes) where they run flat.  So on that basis they are suitable for your application.
When I tested the black Eneloop Pros they had an impressive 4 good cells out of 4 for both the 4-packs I tested - and I've never encountered that before in any other 4-pack of cells - there is always 1 cell in any 4-pack that is markedly weaker than the rest.  The trick is to identify it, mark it and if necessary discard it.  For your 8-cell application you would need to buy 3 similar 4-packs at the outset.
It's not dark yet but it's getting there.

Re: New Rechargeable AA batteries
« Reply #36 on: June 28, 2020, 11:51:48 am »
IME the charger is more important than the batteries.  Charge at 300mA, using a charger than monitors each battery individually, and they will maintain capacity and last for years.  Charge at more than 500mA or use a charger that does 4 at a time with the same current, and they won't last very long at all.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Re: New Rechargeable AA batteries
« Reply #37 on: August 02, 2020, 09:28:30 am »
Someone will start molishing those with regulators that mimic the discharge curve of alkaline or NiMH chemistry next...
Big Clive has done a teardown on one, where it was not so much a discharge curve as a discharge step.
https://www.youtube.com/watch?v=rncOmGKe4Bc

I've just realised that making the output voltage droop when the Lithium-Ion battery is low will lead to some automatic cell balancing, which is a slight bonus. However the charging of these is in parallel and separate end-of-charge limiting for each cell, so balancing during discharge isn't so much use.
Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

fruitcake

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Re: New Rechargeable AA batteries
« Reply #38 on: August 02, 2020, 10:06:38 am »
IME the charger is more important than the batteries.  Charge at 300mA, using a charger than monitors each battery individually, and they will maintain capacity and last for years.  Charge at more than 500mA or use a charger that does 4 at a time with the same current, and they won't last very long at all.
I agree that the charger is the thing to sort out first. I used what I thought was an intelligent charger for years and after an upgrade I found it was half charging. Trickle charging is key (at least for the final part of the charging process).