Headtorch: which rechargeable batteries?

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I'm after some rechargeable AAs for a new headtorch. They should have a big capacity and hold their charge well in cold conditions. I know nothing about batteries, chemistry, science and that. Any general advice? Not so much specific brands as types to look at (ni-mh, mah.. it's all just random letters and numbers to me)
 Fraser 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:
I use 7dayshop's NiMH batteries - their 2900mAh version, which have always served me well.

https://www.7dayshop.com/products/7dayshop-aa-hr06-2900-high-performance-ni...

Edit: I've not used them in properly cold conditions I'm afraid so can't comment on their usefulness in that respect.
Post edited at 12:17
In reply to Fraser:

Thanks, they definitely have the key benefit of being affordable!
 StuDoig 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

I use high capacity eneloops which have been great. Hold their charge really well over time and in cold conditions (they are what lives in my head torch year round and have done some long stints in the cold / dark!).

https://www.amazon.co.uk/Panasonic-2500mAh-Eneloop-BK-3HCDE-4BE/dp/B00JWC40...

Not the cheapest, but I've been happier with them than with cheaper rechargeables.

You get them at various capacities, last lot a bought a few years ago were 2500mAh.

Cheers!

Stu
 ScraggyGoat 01 Nov 2016
In reply to Fraser:
I've used these (or their forebears) for several years, so no issues on quality or longevity. Can't comment on real cold performance as my headtorch has a remote battery pack.

The only other thing you could think about would be to buy a separate battery charger for the car. Then if you realise after you have set off on your journey, that the batteries need topping up you can do so enroute.
Post edited at 13:10
 ScraggyGoat 01 Nov 2016
In reply to StuDoig:

'long stints'.......being kept in the dark again mate!
 maxsmith 01 Nov 2016
In reply to ScraggyGoat:

Im also using 7dayshop, but would probably buy something more expensive for alps etc
 The Lemming 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

I use hybrid batteries, including eneloop which hold their charge longer than normal NiMH batteries. They can hold a charge for almost a year. You would be lucky for HiMh batteries to keep their charge for a month.
 StuDoig 01 Nov 2016
In reply to ScraggyGoat:

Apparently once I stop misbehaving, I can come out of the cupboard.....

Stu
 r0b 01 Nov 2016
In reply to The Lemming:

Also I find that NiMh rechargeables need to be used relatively frequently to maintain their capacity; if I leave a set in the cupboard for a year or so then charge them up they show as fully charged but actually run out of juice in a few minutes! They then need to be charged and discharged a few times to regain their capacity.

Apart from that I find the 7dayshop high capacity NiMh batteries pretty good. I get 30+ hours of use with a Garmin Etrex GPS and 10 hours with an Alpkit Arc headtorch from two AAs.
In reply to Dan Bailey - UKHillwalking.com:

Thanks all; think i may splash out on those eneloop things
MarkM 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

On a related note, I've just bought an intelligent charger (https://www.amazon.co.uk/Technoline-Intelligent-Professional-Standard-batte... with the aim of prolonging/reviving the life of rechargeable batteries. It has a proper refresh function (repeat discharge and charge cycles til the batteries are at their optimum) and a test function which displays exactly what capacity each battery has when fully charged.

Only just started using it but seems very good and hopefully will pay for itself by eliminating the need to buy new sets of rechargeable batteries every other year...

Cheers
Mark
In reply to MarkM:

sounds interesting...
Removed User 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

I use the highest capacity AA rechargable batteries that I can buy, usually from Amazon, typically 2800mAh or 2900mAh and use them in a Petzl Myo headtorch, they hold their charge well and are easy to change. My only dislike is that the Myo is difficult to switch on/off with winter gloves. When away, I can recharge them using a portapow solar recharger.
 EddInaBox 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

If you happen to wander past an IKEA then their batteries have always served me well, but I haven't tried any of the current batch, mine are the old 2000mAh ones that got a decent write-up here: http://www.candlepowerforums.com/vb/showthread.php?387711-Ikea-Ladda-(AA)-A... .

The current ones are 2450mAh
http://www.ikea.com/gb/en/products/lighting/batteries-chargers/ladda-rechar...

Don't necessarily be fooled into thinking that a higher mAh rating (milliamp hour - basically capacity) means a better battery. Straight out of the charger a new battery should give its full advertised capacity, but some batteries lose their charge faster than others whilst just sitting around doing nothing, so if you come to use your batteries several days or even weeks after charging, then a large capacity cell that loses its charge quite quickly could last less time than a lower capacity cell that keeps its charge better. Hybrid cells (low self-discharge cells) are still NiMh cells (nickel–metal hydride) the chemistry is fundamentally the same, it's more a marketing name than anything else. The lower self discharge is achieved by better quality electrodes and by having a better separator between the positive and negative electrodes inside the battery, partly by using a higher quality separator and partly by making the separator thicker, which is why they have a lower capacity than the highest capacity regular NiMH cells, there's less room inside for the electrodes.

Of course as batteries go through charge and discharge cycles, over time their overall capacity is reduced. People upgrading to new batteries after a few years may well extol the virtues of their new cells in comparison to the old ones, not remembering that the old ones were just as good when new.

Rechargeable batteries have a fairly flat voltage curve compared to regular disposable batteries, alkaline batteries have a nominal voltage of 1.5V but that drops steadily over time, NiMh batteries have a nominal voltage of 1.2V but it stays close to 1.2V for most of the discharge cycle and suddenly drops off as the cell gets close to being empty. If your head-torch has circuitry in it to maintain a constant voltage to the LED as the battery is used then you wouldn't see a difference in brightness. With cheaper head-torches that don't have that circuitry, fresh disposable batteries will start out brighter than rechargeables but get progressively dimmer over time. Rechargeables will provide a relatively constant light output and then suddenly dim very rapidly as they get close to exhaustion.

It isn't a good idea to completely discharge NiMH batteries, this is because they don't all become exhausted at the same time, once one cell becomes discharged the remaining cells push current through it, which causes loss of capacity, which in turn means that it goes flat sooner the next time and gets damaged some more. Very fast charging also reduces the capacity more than slow charging, so if you have the time (and your charger has more than one setting) it is better to charge your batteries at 200mA for fifteen hours than at 2000mA for one and a quarter.
 inboard 01 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:
We use eneloop for a lot of stuff and I've found it ok for head torches tho no experience of use in serious cold.

I also like black diamond revolt torch - comes with rechargeable batteries (BD branded, not sure who manufacturer is) and charging is by USB which is great for topping up in the car, and easy for holidays. I've skied (downhill touring) with the revolt and its plenty bright enough - also use it for my rural (part off-road) cycle commute. Revolt has been fine in serious cold and holds charge well if left unused in rucksack for ages.

Not sure whether eneloop are happy with 12v ab charger.
Post edited at 20:38
 Martin W 04 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

I use hybrid NiMH AAs and AAAs from Lidl - which, coincidentally, are coming back in to stock next Thursday. £2.99 for four. The AAs are 2300mAh - not as high a capacity as the 7dayshop ones, for example, but being hybrids they keep their charge much longer while they're in storage. In my experience, when you're grabbing a handful of batteries out of the drawer, lower-capacity ones which have 90% of their charge left are rather more useful than higher-capacity ones which are half discharged.
 wercat 04 Nov 2016
In reply to Martin W:

I bought some 2300 hybrids from a seller who imports in bulk from the makers in China. That's his main line of business and I see often him at electronics events to chat to and has done it for as long as I can remember. He recommended them as the best value. I asked about the so called high capacity ones he was selling.

He said the makers offered him identical batteries with alternative markings to indicate the seller's desired capacity whereas the 2300s seem to be "honest". I'm pretty pleased with him. I believe him, having suffered counterfeit electronic components originating from China. Good that we can increase our trade with them now!
 CurlyStevo 04 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

+1 eneloops are the best - I've used a hybrio batteries and they aren't a patch on eneloops.

I've used eneloops in all in one head torches (ie no seperate battery pack) down to -20 with no problems.
 wercat 04 Nov 2016
In reply to CurlyStevo:
I thought Eneloops were a kind of hybrid?


sorry just seen that there is some trade name or other like that ..
Post edited at 14:22
 CurlyStevo 04 Nov 2016
In reply to wercat:

hybrio is a trade name. They don't hold their charge as long and don't work as well in cold temps compared to eneloops.

I have a bunch of both of different ages and when I come to check if they need a top up they are always lower charge than the eneloops.
 CurlyStevo 04 Nov 2016
In reply to wercat:

eneloops are a NIMH battery with certain advancements in the design.
 wercat 04 Nov 2016
In reply to Dan Bailey - UKHillwalking.com:

thanks for the info - always useful to be armed with foreknowledge when buying
 Martin W 04 Nov 2016
In reply to CurlyStevo:

> eneloops are a NIMH battery with certain advancements in the design.

Eneloop is Sanyo's brand name for their low self-discharge NiMH rechargeables. The same basic technology is referred to by other manufacturers/vendors as "hybrid", "ready to use" or "pre-charged".

https://en.wikipedia.org/wiki/Nickel–metal_hydride_battery#Low_self-disch...

> hybrio is a trade name. They don't hold their charge as long and don't work as well in cold temps compared to eneloops.

Hybrio is indeed the brand name that Uniross use for their range of low self-discharge NiMH recharge batteries. I've not been particularly satisfied with the few Hybrio batteries that I've tried. The main problem was that their performance seemed to deteriorate quite rapidly after only a few recharges. Sounds like our experiences have been similar in that respect.

That said, I've not been blown away by the Eneloops I've tried, either. I no longer have any Hybrios or Eneloops in my 'stable' of rechargeable NiMHs.

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