Author Topic: Re-chargable batteries.  (Read 1161 times)

Offline KrissGC

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Re-chargable batteries.
« on: October 04, 2018, 08:59:44 pm »
Hi All.

What rechargeable batteries do people recommend for petzl duo and why?

Online PeteHall

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Re: Re-chargable batteries.
« Reply #1 on: October 04, 2018, 09:19:41 pm »
Energizer NI-MH 2500mAh

Relatively cheap, readily available, decent capacity.

Charging two sets now as it happens...
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Online PaulW

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Re: Re-chargable batteries.
« Reply #2 on: October 04, 2018, 10:37:42 pm »
https://www.7dayshop.com/products/7dayshop-aa-hr06-2900-series-high-performance-nimh-rechargeable-batteries-with-free-storage-case-4-pack-wh2-7dayaa29004case

I sought techy guru footlegs advice and was pointed in the direction of these

We run 30 duos for scout trips and these will easily last a weekend of normal caving

Online alastairgott

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Re: Re-chargable batteries.
« Reply #3 on: October 04, 2018, 10:51:11 pm »

Eneloops all the way. There's a thread where people talk about chargers, but none of them suggest there are any better batteries. I use the 1900 but have used a higher mah before.
"if eneloop 2500 are the..." is the topic
https://ukcaving.com/board/index.php?topic=16158.0

I just plumbed for a higher number of charges before the battery decreases it's capacity. The 1900's suggest their capacity stays up with more charges, whether it matters at all I don't know, but worth a shot.

I've also upgraded my charger, which I think will make the difference. Each battery will be charged separately rather than like the simple wall chargers which charge two on the front and two on the back.

I reasoned this change would help keep capacity up, as pairing a good battery with a low capacity battery could lead to less capacity all round.

Duos use all four batteries together, but at some point one battery will be lower than the rest, if you marry this up with a good battery on charging, then the bad battery will not charge completely. therefore reducing the length of time your light can be ran for. If now you pair up the bad battery with another good battery, then it will still not charge completely.
 Whether any of this is true and a bad battery can bring down the whole set, I don't know but I'm experiementing, so we'll see how it goes.

Online Ian Ball

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Re: Re-chargable batteries.
« Reply #4 on: October 05, 2018, 12:50:55 am »
Eneloop Pro or Fujitsu Black are my recommendation.  Use a charger which is well respected such as a Tehcnoline BL700, avoid a Chinese copy such as the Youshika.

You could also consider the Petzl duo battery pack?  It is a decent battery pack if pricey.

Online Pete K

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Re: Re-chargable batteries.
« Reply #5 on: October 05, 2018, 07:46:33 am »
https://www.7dayshop.com/products/7dayshop-aa-hr06-2900-series-high-performance-nimh-rechargeable-batteries-with-free-storage-case-4-pack-wh2-7dayaa29004case

I sought techy guru footlegs advice and was pointed in the direction of these

We run 30 duos for scout trips and these will easily last a weekend of normal caving

I second this. I've got about 25 lamps for work running on these and they are excellent value for money.
I'd go for the expensive Eneloops if I was going to leave them in a bag for a while as they don't discharge as quickly as some rechargeables. Self discharge of batteries is fairly common, the Eneloops do it much slower. My bottom of bag spares are Eneloops for that reason.

Offline KrissGC

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Re: Re-chargable batteries.
« Reply #6 on: October 05, 2018, 02:18:35 pm »
Thanks for all the responses. I think I'll buy a selection as I can't decide! :bow:

Online Ian Ball

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Re: Re-chargable batteries.
« Reply #7 on: October 05, 2018, 02:46:32 pm »
I don't wish to appear knowledgeable beyond my station, but the chemistry NiMH in a cylindrical cell suffers a self discharge of upwards of 5% on the first day and very much worse at high temperature.  It continues to drop at a lesser amount, usually a NiMH will hold charge for a month.

The Sanyo Eneloop technology (bought by Panasonic) which is now copied/rebadged everywhere (Duraloops hoho) else is Low Self Discharge, better insulator material etc in the cell, so it has almost a zero percent self discharge which is why cells can be sold as pre-charged and why they can theoretically hold charge for 10 years.

The 7day shop cells, and Ansmann photo and all the cells that claim well over 2000mAh in capacity will lose 5% of that in the first day, so charge them overnight and go caving the next day and that is fine, they will also loose top end capacity with every charge, so a refresh cycle charger is a good idea.  the 7day shop cells dont say how many times they can be recharged and maintain a 2700mAh, I would expect they will struggle to stay at that capacity after more than a handful of charges.

My advice is buy 2 sets of batteries and carry them both. 

Also have a scan of a review site for more info, my favourite is this Danish guy.

https://lygte-info.dk/


Online PaulW

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Re: Re-chargable batteries.
« Reply #8 on: October 05, 2018, 04:39:57 pm »
i was of the understanding that refresh cycle chargers were good for NiCad batteries and that NiMh batteries were fine with just a simple charge

I charge Nimh couple of days before and they last the weekend fine, I also bulk buy duracells, something like 20 quid for 40 of them that get carried as spares

Online Ian Ball

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Re: Re-chargable batteries.
« Reply #9 on: October 05, 2018, 06:05:35 pm »
I think voltage depression is possibly reversed by a discharge and recharge cycle in Nimhs. Though I thinkmthere are more ways to reduce capcity than that.

with a duo you have 4 cells, if you have a capacity monitor charger you should be able to spot one knackered cell in the 4 and avoid overdrive/reverse polarity problems.

PaulW, what is the capacity of the cells you use and the output of the lamp you are using and how long do you use your lamp for over a weekend?
« Last Edit: October 05, 2018, 06:28:46 pm by Ian Ball »

Online PeteHall

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Re: Re-chargable batteries.
« Reply #10 on: February 15, 2019, 01:22:29 pm »
After the 2nd light failure in as many weeks, due to knackered old rechargeables, I decided it was time for some new and remembered the virtually unanimous praise for eneloop's on this thread.

I have since done a little more reading and have come to the conclusion that the 'Amazon Basics, Heavy Duty' are virtually identical in performance and considerably cheaper.

Even Google reckons they are 2nd only to the eneloop in terms of performance.

I decided to trust the stats and bought 16 of the Amazon batteries, which arrived in the post yesterday and I will be putting them through their paces at the weekend.

Does anyone else use them, and if not, why not?
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Online Ian Ball

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Re: Re-chargable batteries.
« Reply #11 on: February 15, 2019, 03:28:43 pm »
Because they are Amazon.  I like the look of the Ikea Ladda


Offline Topimo

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Re: Re-chargable batteries.
« Reply #12 on: February 15, 2019, 06:43:49 pm »
I use both the Ikeas and Amazons in flash guns and my backup light (which I also use for running and general use) and for anything round the house.

I'm yet to experience an outage!

Offline Fulk

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Re: Re-chargable batteries.
« Reply #13 on: February 15, 2019, 07:33:32 pm »
Quote
Because they are Amazon.

Agreed

Online PeteHall

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Re: Re-chargable batteries.
« Reply #14 on: February 15, 2019, 09:52:25 pm »
Quote
Because they are Amazon.

Agreed

Exactly why I nearly didn't buy them. Not sure why Amazon creates such a sense of disgust, moral or otherwise, but it does...

But at the end of the day, if they are decent, they are decent, whatever name is on the side, so I thought f**k it and bought them anyway  :)
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Offline pmccarron97

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Re: Re-chargable batteries.
« Reply #15 on: February 16, 2019, 12:14:23 am »
Because they are Amazon.  I like the look of the Ikea Ladda

Ikea Ladda batteries are my go to cells these days. However, whenever you are choosing them, make sure they are the 2450mAh cells, and they are the "Made in Japan" variety.
From what i've gathered online this basically means they are Eneloop cells - from some rough testing, i was able to get just slightly above the rated mAh rating, which is very much unheard of for most AA NiMH cells.

Plus at only £5.50/4 cells, its honestly a pretty great deal.

General rule of thumb I go by at the moment, if its rated at more than 2500/2600mAh, then they'll discharge faster when not used and you'll tend to not get the rated capacity.
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Online PeteHall

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Re: Re-chargable batteries.
« Reply #16 on: February 16, 2019, 07:30:02 pm »
i was able to get just slightly above the rated mAh rating, which is very much unheard of for most AA NiMH cells.

I'm no expert, but as I understand it, the mAh varies depending on the current you are drawing. I think you usually get more mAh at a lower current, which is why in reality in a high powered caving lamp, you'll never get close to the rated capacity.
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Online Ian Ball

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Re: Re-chargable batteries.
« Reply #17 on: February 16, 2019, 11:27:20 pm »
NiMH AAs are often able to give a higher mAh capacity than their rating.  Manufacturer cycle claims are boosted by claiming a near max capacity so as the cells age and lose capacity, they still hold their claimed rating.
This is because customers apparently rate charge cycles more than top end capacity.

Wilhelm Peukert detailed the effect of current on capacity of lead acid cells back in the 1800s.  The effect is also there on NiMH NiCad, Alkaline, but I think it is so little in LiIon that it can be disregarded.

There are many discharge cycle graphs on the net for the cells you are considering buying, it is worth seeing what the current draw of your lamp is and seeing how that effects your cell choice.



Offline ZombieCake

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Re: Re-chargable batteries.
« Reply #18 on: February 19, 2019, 10:08:57 am »
This video just appeared testing various batteries: