Eneloop batteries

[Funkstar]

Does anyone have a recommended source for Sanyo's Eneloop batteries and chargers?

I think we need to build up a stock of batteries at home to power the kids toys, remotes and other gadgets around the house. Been reading up on the Eneloops and the fact they come ready charged, and will hold onto about 75% of their charge even after 3 years is pretty amazing.

What I don't want however is stung for some fake batteries or European chargers. the ones I looked at on Amazon seem to get a fair number of negative reviews for the chargers having two prong Euro connections instead of a standard British plug.

[kalniel]

They are great batteries. I got the batteries from Amazon (direct, not a third party), and a cheap charger from Play, which was a UK plug one.

If you buy from Amazon.co.uk they have to supply the correct plug type I think.

[MadduckUK]

7dayshop.com have a 4 pack and a charger for 7.79, 5.35 for just the batteries. worth watching hotukdeals if there isnt a rush as ASDA seem to periodically sell a 4 pack for £2

[TheAnimus]

at the end of the day a charger is just a current source that switches off, you don't need a special one.

Thou the faster ones will probably heat up and wear out the batteries faster, so if you have the time just go for a slower overnight charger that can take 12 at a time or whatever, and keep a set always charged!

[MadduckUK]

at the end of the day a charger is just a current source that switches off, you don't need a special one.

Thou the faster ones will probably heat up and wear out the batteries faster

Yeah, well put

[peterb]

at the end of the day a charger is just a current source that switches off, you don't need a special one.

Thou the faster ones will probably heat up and wear out the batteries faster, so if you have the time just go for a slower overnight charger that can take 12 at a time or whatever, and keep a set always charged!

Well no, the more expensive battery chargers monitor the output voltage as the battery charges to determine the state of charge, and modifies the rate of charge accordingly. Some also monitor ambient and battery temperature to ensure that a fast charge doesn't damage the battery during the charging process.

THe type of battery chemistry also requires different chargers - some require a constant current source, others a constant voltage. Again, more expensive charges determine the appropriate charging requirement, and some will discharge the battery first to start from a known state, and/provide a conditioning facility. Batteries that are treated properly last longer and perform better.

But to answer the OP, I'd buy from a reputable UK company (avoid E bay!!!)

http://www.batterylogic.co.uk/default.asp seems OK (not used them myself, but IIRC others in the HEXUS community have)

The other reason I mention them is that they also sell the BL-700 intelligent battery charger, which has a reputation for being one of the better and more versatile chargers on the market.

[TooNice]

I got my Eneloop and Infinium (Panasonic equivalent, but with 5% more charge and occasionally cheaper which is the bigger reason I got them) from 7daysshop/Amazon. Originally I considered getting a fancy battery charger for the reasons peterb mentioned. I kept putting off the purchase until I couldn't be bothered anymore, but over 3 years later those batteries are still alright. That is, whatever damage I might've caused the batteries from not using a fancy charger, and occasionally forgetting to take them out of the charger for days isn't noticeable enough for me to get a fresh sets.

[TheAnimus]

Well no, the more expensive battery chargers monitor the output voltage as the battery charges to determine the state of charge, and modifies the rate of charge accordingly. Some also monitor ambient and battery temperature to ensure that a fast charge doesn't damage the battery during the charging process.

Really?

I would say with current battery (ie no cap) technology, its always best to slowly trickle charge them.

That means a current source, a current source watching the voltage drop? I always used to charge mine just on a lab style power voltage/current source set to current accordingly....

[Rave]

I've been happy with my set of GP ReCyKo AAs, though I'm not really a demanding user. You don't need a special charger, any decent NiMH charger will be fine.

[kalniel]

Really?

I would say with current battery (ie no cap) technology, its always best to slowly trickle charge them.

That means a current source, a current source watching the voltage drop? I always used to charge mine just on a lab style power voltage/current source set to current accordingly....

Trickle charging has been the charge of choice for the last couple of generations of technology - even ni-cads prefer it. I don't think it can be beat even for modern low-discharge types, you just modify the charge time. My charger (net cost £1) is exactly that - a trickle charger and you just keep it on for the length of time that's required - there's a chart from which you can extrapolate values even for newer, higher capacity batteries than the charger was designed for - it's more future proof than some mid-range chargers for that reason.

[peterb]

Really?

I would say with current battery (ie no cap) technology, its always best to slowly trickle charge them.

That means a current source, a current source watching the voltage drop? I always used to charge mine just on a lab style power voltage/current source set to current accordingly....

Yes really.

For example, a lead acid battery should e charged from a constant voltage source at 1.4v/cell. The charge current will be high to start with, then drop as the battery charges. (OK, not relevant to the OP, but an example)

Most (but not all) Li batteries (and NiCd batteries) need a constant current source. If they are put on a constant vaoltage source, they will draw excessive current and overheat - very quickly! A lab type PSU that you mentioned can be both a constant current and constant voltage source depending on the load connected to it. (and how it is set up.)

The trickle charge rate (ie, the current at which a battery may be left permanently connected without damage) epends on te battery capacity and chemistry and construction, but is typically less than C/10 where C is the battery capacity.

Some sources state that NiMh and some Li batteries should NOT be trickle charged at all. (A good read aout secondary batteries in general!)

To quote from the full article:

Charging Rates

Batteries can be charged at different rates depending on the requirement. Typical rates are shown below:

Slow Charge = Overnight or 14-16 hours charging at 0.1C rate
Quick Charge = 3 to 6 Hours charging at 0.3C rate
Fast Charge = Less than 1 hour charging at 1.0C rate



Slow charging

Slow charging can be carried out in relatively simple chargers and should not result in the battery overheating. When charging is complete batteries should be removed from the charger.

Nicads are generally the most robust type with respect to overcharging and can be left on trickle charge for very long periods since their recombination process tends to keep the voltage down to a safe level. The constant recombination keeps internal cell pressure high, so the seals gradually leak. It also keeps the cell temperature above ambient, and higher temperatures shorten life. So life is still better if you take it off the charger.
Lead acid batteries are slightly less robust but can tolerate a short duration trickle charge. Flooded batteries tend to use up their water, and SLAs tend to die early from grid corrosion. Lead-acids should either be left sitting, or float-charged (held at a constant voltage well below the gassing point).
NiMH cells on the other hand will be damaged by prolonged trickle charge.
Lithium ion cells however can not tolerate overcharging or overvoltage and the charge should be terminated immediately when the upper voltage limit is reached.

An 'intelligent' charger will monitor some or all of the parameters to ensure optimum performance and terminate the charging process at the appropriate point. Whether or not the cost premium offsets the increased reliability of the battery is of curse a matter for the user in each circumstance. but if I was using a battery in an expensive piece of equipment, I don't think I'd want to risk damaging it frm a battery that fails because I skimped a few pounds on the charger.

[Barakka]

I've been happy with my set of GP ReCyKo AAs, though I'm not really a demanding user. You don't need a special charger, any decent NiMH charger will be fine.

I also use the ReCyko ones, got a set of 4 with a 2 hour charger from CPC, I also have a larger one for doing C size and has a conditioning charge.

ReCyko like Eneloop are LD-NiMH technology which retain 85% of their charge for 12 months, although their full capacity is approx 20% less than standard NiMH cells* (but still more than alkaline)

The main thing to get a decent charger is to look for one that is described as an "intelligent" charger, and specifically that has temperature sensing and independent charging channels - ie each battery is charged and monitored separately. It's not unusual when charging a set for all four to finish at very different times, especially once you get past 100 re-charges.



*Standard NiMH cells hold the most charge but self-discharge 5-10% in the first 24 hours then 0.5-1% per day after that.

[TheAnimus]

Most (but not all) Li batteries (and NiCd batteries) need a constant current source. If they are put on a constant vaoltage source, they will draw excessive current and overheat - very quickly! A lab type PSU that you mentioned can be both a constant current and constant voltage source depending on the load connected to it. (and how it is set up.)

Interesting, I thought that the chemistry was pretty much all the same! I wouldn't have thought any AA charger you bought now adays would be anything but a current source. And that most would simply trickle at 250ma or so, which would work for most batteries. Good link!