This is a placeholder topic for “Lithium Ion Battery, 18650 Cell (3.7V 3400mAh, positive cap)” comments.
The 18650 you all know and love with an in-built protection module and a high discharge rate, perfect for robotics.
Read moreDoes the PCM have short circuit or overcurrent protection?
Hi Core
I note this cell has built in protection. I note also that you have given 2 different dimensions in your product description.
Which one is correct.
Due to the protection I suspect 69mm to be the correct length.
In the past I have had extreme difficulty fitting these cells into the commonly available holders. These holders seem to be built for a cell of 65mm which is fair enough as that is the length suggested by “18650”. I did manage to fit a couple of these cells into holders but damaged them a bit in the process and these holders are now only suitable for these protected cells which are up to 70mm long.
I did bring this up some time ago and was at that time assured by Core they only stock cells that will fit the stocked holders. ie; Cells that are 65mm long.
Looks like times have changed.
Cheers Bob
Being a bit academic here but these “cells” only become a “battery” when there is more than one of them. Like the common AA or AAA which is a “cell”. The 9V block types are “batteries” as they are made up of 6 X 1.5V “cells”.
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Hi Bob,
You would be correct in assuming that these cells are the longer variety with a length of 69mm. The product page should be updated to reflect this shortly.
The contacts on most 18650 holders should provide enough play to fit 18650 cells of this length. When testing some of our options, I found the designs that used tabs on either end of the battery to have the best fit, while the versions that use a spring to hold the battery in place are much tighter. I was still able to fit the longer 18650 into the spring design, but removing it required a lot of force by hand and is very close to requiring additional tools to pry it out.
Hope this helps!
Hi Samuel
“Should” and actually “Do” are two entirely different scenarios. Although these days it seems to be the norm to generalise a fair bit much to the frustration of the end user. This might be considered OK for the hobby market but is still a damn nuisance when things can’t be portrayed correctly.
It is all very well to copy directly from the manufacturers or suppliers splurge but most of the time in this area this leaves a bit to be desired also.
Of course they would as these have no nipple and would be that precious couple of mm shorter.
That is exactly what I am getting at. You should not have to do this. There is a real risk of mechanical damage to the cell with unknown results. Possibly explosion as seems to be the result with these units.
Cheers Bob
What is wrong with calling it 18690 so the end user would know it is longer before purchase.
Hi Bob,
This sent me on a fun dive into the naming conventions of different batteries. Very cool that 18650 is a direct reference to the size (18mm x 65mm).
I like the idea of calling it a 18690, but I’m hesitant to reword the product page as this term (while a brilliantly effective way to communicate the actual size) isn’t a recognised term for this kind of battery and will likely lead to unwanted confusion.
As an end user, what sort of descriptor would easily communicate to you that this product is longer than a basic 18650 cell?
Something like “18650 cell + PCM unit” or “18650 (Long)” may work? Your input would be appreciated if you have any good ideas for a way to communicate this difference while still retaining the information (and searchability) of a basic 18650.
Hi Samuel
Yes, I think it all comes back to the battery. I have noted on occasion other sizes like AA and AAA use the same sizing convention. A few years ago I purchased 2 AA protected cells and am yet to find a holder that I can fit them in. Way too long. The only use I found was in a flashlight or torch which required 2 AAs. I can use one of these and a dummy AA but the base with the spring is pretty tight.
You are not alone, I purchased some time ago a protected 18650 and a holder rom the same shop. I was not aware of this problem until I got home and tried to fit it. The shop person succeeded in fitting this cell but in doing so he flattened the “spring” contacts to the extent they no longer “spring” making this holder pretty useless for anything else.
I don’t have any suggestion for this problem. The holder makers and vendors sell these as “18650 battery holders” which they are IF the battery is indeed 65mm long. I reckon it is up to the battery (cell) makers to MAKE the battery true 18650. If they want to include a little protection device make the actual cell that little bit smallerWhat they have done is just add it to the top and make the overall length greater.
What mere mortals can do about it?? Not much I don’t think. About all the vendors such as Core can be expected to do is alert prospective purchasers to the problem. Then if enough people DID NOT purchase due to this problem the makers might sit up and do something about it. When it starts to interfere with sales figures they will quickly have a rethink.
I will put my Rose coloured glasses away now as I don’t like the chances of any of the above happening soon. The general populace will just have to put up with non protected cells or struggle on.
Cheers Bob
