clockworkpi

Once again, battery

Thought lots of guys have received the devterm. Then of course different people are using different batteries. So I wanna know, as I am going to buy my batteries, which length fits the best?

After reading through a lot of threads, my impression is that both protected ( longer ) and flathead fits, just the protected one needs some wrestling to jump to its place.
I personally use flathead for now, and it was easy to install. Given those strange noises during charging , I am planning to eventually switch over to a pair of protected ones.

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I bought button-top protected cells, but it seemed to be a little bit large in both diameter and length.

I’ve contacted to the customer service and got a reply:

You don’t need protection circuits on batteries. The PMU will protect them.

I think they’ve designed the battery compartment with unprotected cell dimensions in mind, and protected cells tend to be larger (>=2-4mm longer in length, >= 0.5mm larger in diameter).

edit: However, it is definitely not recommended to use unproteced cells for yourself. Plaese see this comment:

Unfortunately, I only can buy protected cells since my country prohibits buying unprotected cells for normal customers…
I’ve ordered another smallest flat-top protected cells that I could find.

This is a really wrong advice. the “PMU” will not protect the cell against short circuit polarity inversion and some type of over discharge (and overcharge to some extend).

Short circuit is actually quite important if you do store the battery out of the DevTerm. If they never move it is somewhat ok, but there is a reason why virtually all LiPo that can be unplugged do have the protection circuit, even when they are in a device you can’t open easily)

As said multiple times, the “protection” you will find in the DevTerm is to protect the DevTerm itself, not the battery. The protection in the battery are to protect the battery and you. You really don’t want a Lithium battery to go nuclear.

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Thank you for pointing out that!
I’ll edit my comment to link your comment.

I got these that are protected and they fit.

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I have the Samsung 3000mAh 30Q batteries and they have a protected circuit, like the ones linked from @h6y3 , they have a shorter button so the overall length is still short enough for the devterm housing.

on the topic of protected or unprotected: if you only have two batteries, will always charge them in the device, and never plan on removing the batteries from the device then unprotected are fine. The protected circuit in the devterm will keep them safe while they are in the device.

However, I have 4 batteries. A wall charger that I use to charge them and hot swap them in. For my use case protected batteries are 100% needed. The batteries can short against each other when they are out of the device and the external charger may not be as sound in its electronics as the devterm.

just my thoughts…

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