Dynamo AA battery charger - do they exist?

[tommydog]

I am looking for a solution to charge AA batteries from a dynamo. There are plenty of solutions for USB batteries / charging phones on the go etc, but I can't find a dedicated product just for AA batteries. I only require the ability to charge AA batteries. One option is a voltage regulator and then fed into a charger, but is there anything in one neat waterproof package?

[Tigerbiten]

....... but is there anything in one neat waterproof package?

I don't think there's much call for waterproof AA battery chargers, so probably not .....

I went for the charger and voltage regulator in a waterproof box route myself.
But I found you do need some way of keeping the batteries in the charger when you go over big bumps.

[gaz]

Philips Saferide 40 Lux lamp come with an external 4AA battery pack intended to be charged by USB mains charger.

Whilst my electrical knowledge is limited, I'd assume it can be charged from a dynamo via the usual e-werk type device. I have one kicking about somewhere but it may be faulty. The accompanying light "fried" itself a couple of years back and I don't know if the underlying fault was in the lamp or the battery compartment.

[Samuel D]

Might be better to charge one of those large USB li-ion batteries that don’t seem to care about current fluctuations, and from that run a USB-powered AA smart charger, e.g. the Sanyo NC-MDU01, at night to charge your AA cells.

[Sweep]

Looks interesting though have no idea how good is.

Suspect that it is not kind to the AA batteries but could still be useful.
https://www.ebay.co.uk/itm/USB-Battery- ... 0005.m1851
Anyone got any experience of it?

Edit
Or £1.80 from ikea
http://www.ikea.com/gb/en/products/ligh ... -40303632/

A page which also shows their white ladda batteries which some have actually reckoned are eneloops.
Am tempted to try this thing. Could be useful for providing batteries for my garmin rejuiced from my anker power bank.
Though only £1.80 that device apparently claims to have some sort of protective circuitry.

[mercalia]

Looks interesting though have no idea how good is.

Suspect that it is not kind to the AA batteries but could still be useful.
https://www.ebay.co.uk/itm/USB-Battery- ... 0005.m1851
Anyone got any experience of it?

Edit
Or £1.80 from ikea
http://www.ikea.com/gb/en/products/ligh ... -40303632/

A page which also shows their white ladda batteries which some have actually reckoned are eneloops.
Am tempted to try this thing. Could be useful for providing batteries for my garmin rejuiced from my anker power bank.
Though only £1.80 that device apparently claims to have some sort of protective circuitry.

the ikea looks worth a punt at that price - charge up the Lidl battery front lamp AA batteries from a power bank?

a slight difference in price between ikea and ebay?

[MarcusT]

I googled 'USB battery charger' and dozens of products came up. Same for Amazon

[Sweep]

I googled 'USB battery charger' and dozens of products came up. Same for Amazon

Can you recommend any? Knowleddge of any in use?
Suppose my main question is how long it might take to charge a pair of 2000 or 2500 AAs and whether the chargers, often it seems so cheap, might damage the batteries.
The anker 21,000 powerbank supposedly has some sort of "smart" charging system.
Might this help?
Suppose I could just use a separate set of "trashable" batteries with the device.

[mjr]

I've seen claims that a good USB converter outputs about 2.5Watts from a typical 3W hub dynamo input but I've yet to confirm that myself.

Assume an efficient charger gets at most about 2W into the battery from that and you probably won't be far wrong AFAIK.

Avoid the popular Uniross 2AA/AAA silver rectangle with one LED light and a flip down contact for changing battery size, and its clones. It is very inefficient but I forget exactly how bad.

There's a single battery MWU111 which is efficient but dumb so you have to do your own battery monitoring. The best intelligents I've used have been Soshine chargers which tolerate wide input ranges but does spend a bit on lighting up a display, although as an intelligent charger mine only puts 1½W into a single NiMH battery anyway. It'll put up to 4.2W into Li ion though - more than you can get off a dynamo.

Li ion batteries are probably a better way to capture power because 3.7V is closer to the USB 5v than the NiMH 1.4v but it's probably not worth charging a pack then charging AAs from it.

What's the current thinking?

[Tigerbiten]

My thinking is it all depends on how much excess power you have.
I run a 20 watt solar panel through an e-werks and use the output to charge batteries.
On sunny days when it makes sense to maximize the power saved, so it's power bank and pass through to the battery charger. Both get fully charged.
On dull days when I struggle to get any output, it's only the battery charger first then the power bank.
Battery charger is for the Garmin's AA and the power bank is mainly for the Kindle and the AA's if the weathers very bad.

A hub dynamo should be similar on tour.
Long days on the flat, you should be able to charge both, either one after the other or both a the same time.
Shorter days in the hills, you may be lucky to charge one.

As for which model ??
Very cheap may a false economy due low efficiency and doesn't switch off when batteries are charged.
Other than that, no idea .......

[Sweep]

Don't tease us tiger

Yes I am wary of something that seems so cheap.

So which AA battery charger do you plug into your powerbank?

[Tigerbiten]

So which AA battery charger do you plug into your powerbank?

I've used 3.

First was a 2x2 (4 batteries but must charge a pair) battery egg shaped one from Maplins. I liked it as it switched off after the charged device was full so no wasted charged. It was supposed to stand on a flat base so without it, it's shape made it awkward to use and it died after ~4 years use ....

Second is a 2x1 dumb one like the Aldi one above. It's small size makes it very convenient to use on tour as I rarely need to charge more than 2 batteries at any one time. But being dumb, if you left it charging batteries from a power bank overnight, it would keep charging them no matter what and waste a lot of charge. It's slowly dieing after ~3 years use, if a battery not in exactly right it won't charge it.

Third is a smart 2x2 PortaPow one. Larger size makes it not so convenient but being smart makes it better. Only used it for a year.

Ideal would be a smart 2x1 battery charger. Small size with each battery being independently charged. Which comes in very handy if you need to charge the odd battery for a 3 cell torch or charging each battery singly with a very low wattage input. Must start looking for one if I go on another long tour.

Luck .......

[andrew_s]

By way of an alternative, I did come across these AA batteries that charge directly from USB.
https://www.amazon.co.uk/SOEKAVIA-Batte ... b+chargers
The capacity is a bit lower, but they would save carrying a charger.
A splitter cable and/or multiple ports on the power bank would doubtless be handy.

I've got an 18650 for my head torch that similarly charges using a micro-USB plug in the side, which is doing well so far.

I'd have though that a smart AA charger working directly from a dynohub wouldn't go well, long term, in that I would imagine that the fluctuating dynohub output would make it very difficult for the charger to spot the negative delta-V end of charge indication. Lithium batteries are a bit simpler in that the battery voltage is more closely related to the state of charge, so working via a power bank would probably be better, in spite of the inefficiency of charging a battery to charge a battery.

[mjr]

I'm hoping that any USB converter output has some smoothing. I should go plug a charger doctor into mine but it's too cold in the shed these d days.

[tommydog]

I googled 'USB battery charger' and dozens of products came up. Same for Amazon

I don't want a USB battery charger. All I want is a AA battery charger with a built in voltage regulator that I can hook up directly to a dynamo, in a sealed unit. I can't understand why all the cycling gear seems to be targeted at USB. It's about the worst connection to have on a bicycle in terms of waterproofing. There are much better connections which are truly waterproof. AA batteries provide so much flexibility, particularly for GPS on long tours.

This is probably the best pack out there - but again it's USB. It's beyond me why they can't make something like this with a weather proof connector, without me having to look for separate enclosures and mess about with DIY solutions:

Goal Zero Guide 10 Plus USB Power Pack - Silver
https://www.amazon.co.uk/Goal-Zero-Guid ... +Recharger