[NTLK] Recell Emate Batteries

["Piotrowski Paweł (Newton)"]

Hi Frank,

Thank you so much for sharing this knowledge!

I don’t see this ‘project’ as something professional. More as kind of experiment.


> On 12 Mar 2018, at 20:14, NewtonTalk <newtontalk at pda-soft.de> wrote:
> 
>> This holder have almost perfect dimensions. So, we only need 4x NiMH
>> batteries to put inside, mount thermistor somewhere between NiMH
> batteries,
>> and solder ?positive? and ?negative? cables to pins on original white
> connector.
>> Piece of cake.
> 
> Please allow me to disagree with all due respect...

Of course! You have much bigger experience with Newtons than me!

> If this was a piece of cake, I'd have offered this as an alternative to
> battery rebuilds years ago. The reason why I've never offered this yet is
> the unfortunate fact that I've never found a holder that'll fit into the
> eMate's battery compartment and can still handle a current of 1.2 Amps for
> longer than a couple of seconds.

I didn’t knew that must be 1.2A there… I just get those holders. I’m going to try do an experiment and put 1.5A (5V) current on and monitoring temperature.

> A couple of years ago I thought I had found such a holder. But I was unable
> to get a datasheet for it. I exchanged several E-Mails with the
> manufacturer, and they said that "it would probably work". But they
> couldn't, or wouldn't, send me a legally binding datasheet. But they kindly
> sent me two samples. It took about four minutes until the first of the two
> started to smell and smoke. In your case, it might not be so obvious. It
> might take longer and depend on the ambient temperature. But I'd rather not
> leave an eMate alone while it is charging unless what I describe above is
> ruled out.
> 
> If you do find a holder that has a specified current of 1.2 Amps or more,
> and if you have the datasheet and a written confirmation from the
> manufacturer, it'd be cool if you let us know. Not that that'd be enough,
> though. After all, the battery contacts must also withstand 1.2 Amps forever
> without getting overly warm. Battery contacts have a tendency to deteriorate
> over time. Which will increase the contact resistance, resulting in higher
> contact temperature and even more deterioration. That's why Apple
> spot-welded their packs. Not spot-welding them would have been much cheaper.

I bought just cheap holders from China. I don’t think is it possible to find any datasheet for them :)

> 
> That  being said, let me shed some light on your pack's two components.
> You'll need the thermistor (that's the component with the two white wires),
> otherwise the eMate will not charge the pack. You don't necessarily need the
> thingie with the yellow sticker. The pack will also work if you replace it
> with a piece of wire. Just as you'll most likely reach your destination in
> one piece although you weren't using your seat belt. Unless, of course,
> something happens during your trip that makes you wish you had used it after
> all. It's about the same situation with this component. Do you normally
> buckle up?

About thermistor: I have had plan to use it in battery holder, because I don’t want to risk any fire at my house :)

Do you know maybe the value of this thermistor? And is it NTC or PTC?

> This component reduces the current if you accidentally short the pack's
> contacts out. For many, many years I had thought that this couldn't possibly
> happen, given the way a 2x00 pack is built. And then
> She-who-must-not-be-contradicted threw a pile of tools I had left on my
> living room table right on a freshly rebuilt 2x00 pack on my workbench
> because we were expecting guests and she rightfully thought that a dinner
> among well-used screwdrivers, glue cartridges and pliers might not be such a
> good idea. I noticed that about ten minutes later when I put the tools where
> they belong and was surprised that the pack was so warm. Hadn't Apple put
> that little component in, I might no longer have a house.

Nice story :)

> Cheers
> 
> Frank

Cheers,
Pawel