/ Rechargable AA's for a headtorch - any battery geeks?

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Ben Sharp - on 14 Aug 2012
I'm looking for some info on the best types of rechargeable batteries to use with an RXP headtorch. I have very little knowledge of what to look for in the batteries or the chargers so any info would be much appreciated. I know there are a few people here with an unhealthy knowledge of batteries so hopefully someone can enlighten me.

My knowledge pretty much finishes with "the more mAh the better", which is probably far from the whole story. For example I'm guessing that some ebay 2900mAh batteries from china are going to be rubbish compared to a higher quality set of 2600mAh.

I was wondering if I should just pick up a set of AA 2500mAh NiMH from the supermarket or if I'd notice much difference with a higher capacity set. There's a charger and set of 4 Ansmann 2850mAh for 17 here (http://tinyurl.com/cqtdun4) which seems like good value.

Any other insights into rechargeable batteries would be welcome: Are there any disadvantages to getting a set with higher mAh? Are there any other things to look for? Can you pretty much charge any rechargeable battery with any charger or are there chargers to avoid/features to look out for? Is Ni-MH the only option with rechargable AA's or are there better alternatives?

Thanks

Ben
mkean - on 14 Aug 2012
In reply to Ben Sharp:
A lot of rechargable AA batteries put out 1.2v instead of the 1.5v put out by 'normal' cells. I don't know if your head torch will like that.
Ben Sharp - on 14 Aug 2012
In reply to mkean: Hi, cheers for your reply. Apparently, unlike a lot of Petzl's sport range, the RXP is designed to be used with rechargeable batteries so presumably the voltage difference isn't a problem.

Ben
tjin - on 14 Aug 2012
In reply to mkean:

As for voltage. When the battery is under load, Alkaline batteries drop in voltage while NiMH don't. NiMH has a more consistent output in voltage and have a higher possible discharge rate.

English: Using NiMH the battery a directly driven powered light will not dim as much during use and is able to power more powerful lights.

As for NiMH:
More Mah = more stored power, but it loses it's power during storage more rapidly. 2500 - 2700 Mah is only useful when you expect to drain the batteries in 2 weeks.

If you plan to use the batteries for a longer period of time, go for 'Low self-discharge' NiMH, like Sanyo Eneloops or GP Recycko's. They are only 2000 - 2100 Mah, but the batteries barely drain power when not in use.
Mountain Llama - on 14 Aug 2012
In reply to Ben Sharp: Hi Ben

Which tip AA rechargeables uniross 2400 premium hybrio, energizer accu, go recyko, maplin create hi capacity, ansmann digital.

Use uniross hybio in my rxp.

HTH Dave
Ben Sharp - on 14 Aug 2012
In reply to tjin: Cheers, interesting to know that the higher mAh batteries lose their stored charge faster. I had looked at precharged rechargeables that hold their power longer but for most times I'd use them I'd be draining them quite quickly and then coming home so would be able to recharge easily.

I guess the ideal option would be to have the choice of using both, the higher capacity ones for short term discharge and the longer life ones for going away. Would both types of battery charge in the same charger?

Ben
Brownie on 14 Aug 2012
In reply to Ben Sharp:
What tjin and mountain Lion say
Get hybrios or eneloops they keep their charge in storage much better so are ready when you need them, also they are now available in 2300/2400 mAh versions. I just got some uniross 2400 series hybrio and they are good.
tjin - on 14 Aug 2012
In reply to Ben Sharp:

A NiMH charger should be able to charge any NiMH that dit in to the slot. I do recommend a charger with independed bays. This allows each battery to be fully charged.

Charging in pairs mean one is always under charged and the other over charged.
ChrisJD on 14 Aug 2012
In reply to Ben Sharp:

+1 for Sanyo Eneloop
Ben Sharp - on 14 Aug 2012
In reply to tjin: How do you define independent bays? Do you mean any charger where the batteries don't touch each other on the connectors and instead have separate slots?

Ben
tjin - on 14 Aug 2012
In reply to Ben Sharp:

With independent bays, i mean each slot is tested, chargers and meassured seperatly. This allows each battery to be charger fully. For example chargers such as Maha powerex MH-C9000.

Good batteries can still end up being crappy when using a cheap/bad charger.
Ben Sharp - on 14 Aug 2012
In reply to ChrisJD: I've seen a few recommendations for the eneloops but they all seem to be in the 2000-2500mAh range. What's the advantage of the Eneloop XX 2500mAh over the Ansmann 2850mAh?

Given they're the same price and both from decent manufacturers, if the only difference is in self-discharge rate then presumably in a fast discharge application the higher capacity batteries would be more suitable.

Ben
Ben Sharp - on 14 Aug 2012
In reply to tjin: Cheers for the info,

Re. the Maha powerex MH-C9000, 50 is quite a price for a charger. Is there really much noticeable difference between that and you're run of the mill 20 chargers?
tjin - on 14 Aug 2012
In reply to Ben Sharp:

The MH-C9000 is one of the best. But most Maha chargers are good.

Other alternatives are: BC-700 charger (sold under various brand names)
Ben Sharp - on 14 Aug 2012
In reply to tjin: thanks for the info, certainly looks like a good charger but probably more than I need.
Brownie on 14 Aug 2012
In reply to Ben Sharp:
The higher capacity Ansmann are not of the LSD low self discharge type (the limit on these is about 2300/2400mAh with current technology) so they will lose power in storage much faster - ie when lying in your torch unused for a few weeks, the new LSD types will still have most of the charge power after several months - very useful when you go to get a torch out when the s,,, hits the fan and your not sure the last time you topped up the charge.
Ben Sharp - on 14 Aug 2012
In reply to Brownie:
> (In reply to Ben Sharp)
> The higher capacity Ansmann are not of the LSD low self discharge type (the limit on these is about 2300/2400mAh with current technology) so they will lose power in storage much faster - ie when lying in your torch unused for a few weeks...

Thanks for your reply, I might end up going with some lower capacity pre-charged in the end although I still like the idea of making the most of the battery life by getting the extra capacity ones. I don't think the self discharge will be a massive problem during the winter (it would be unusual for me to go 3 days without using a head torch let alone a few weeks) but I guess it would come in handy during the summer, not having to top them up as often. I'm not really sure how much an extra 450mAh would give you anyway.

Ben
iksander on 14 Aug 2012
In reply to tjin: Another vote for Eneloop
Guy Hurst - on 15 Aug 2012
In reply to Ben Sharp: The Maplin Hybrid and Uniross Hybrio AAs have both performed very well for me in terms of not losing charge and producing plenty of power when needed. However, their performance will soon drop away without a decent charger, so the money you've spent on good batteries will be wasted. One of the best reasonably priced chargers is the Techno Line BL700.
Oujmik - on 15 Aug 2012
In reply to Ben Sharp: The best decision I have made regarding batteries is to buy a digital multimeter! Now I check the voltage of my batteries before use as it's easy to get them mixed up or let them discharge. A fully charged NiMH should be at about 1.35 Volts. I've got quite a few Vapextech batteries, they seem okay but not noticeably better than Duracell.
cliff shasby - on 15 Aug 2012
In reply to tjin: was gonna say that,i use a maha and decent batts...
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Sean_J - on 15 Aug 2012
In reply to Ben Sharp: another +1 for Sanyo Eneloops, they are THE SHIT. I used several sets in the Himalayas for my headtorch and digital camera on a 5 week trip (with a homemade solar charger), and had no problems at all with them dying on me. Always had a spare, fuly charged set on me just in case, but only seemed to need to change them once or twice over the entire trip. They stay fuly charged for a long time, as already mentioned, but their other main advantage is that they work well in the cold as well. My digital camera was totally fine up to 7000m+.

Don't bother with crap batteries off ebay, it's full of cheap rubbish from China nowadays. Get some proper Eneloops from a decent supplier - there's a few online UK companies, I used 7dayshop.com

As for alternatives, NiMh is the only really practical option at the minute. I did look into lithium technology - non-rechargeable lithium cells are a good backup solution (lightweight too and good in the cold), but there's no AA-sized rechargeable lithium cells around yet.

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