18650 Li ion batteries question

Hi! The battery capacity varies as per manufacturer. Even for the 18650 type, they are available in different capacity.

I recommend to buy from a vendor that gives a datasheet along with the battery.

Also, since this is a Li-ion battery, you'll need a specific charger for this. I think a generic Li-ion charger can work fine.

Hi Dubbie,

Unless you are paying for a quality brand name battery do not expect to get the mAh that is printed on the battery. I have tested many different East Asian Brands with ratings of 2500 mAh, 4400 mAh, and others and they seldom actually produce more than 900 to 1000 mAh of usable energy. For charging it is good to charge at 1/2 C or about 500 mA for these batteries until they get close to Full charge and then allow the current to taper off. I usually charge them on my bench supply with the voltage set to 4.2 volts and the current limited to 500 mA. If you are going to charge them while in series it is best to have some sort of battery charge control circuit to equalize the charge on each battery.

John

You also need to be aware that 18650 batteries can vary in physical dimensions - especially length.  Flat top batteries are about 65mm, button tops are a bit longer and protected types can be 2-4mm longer.  I had a battery holder on a robot that would only fit flat tops and I bought the wrong batteries .  So be careful that the batteries match the holders.  Luckily, I also have flashlights that have spring contacts that are a lot more forgiving - so I didn’t have to return the batteries.  The charger that I use can also handle the length variation.

Hi Ralph,

I have run into a lot of high capacity battery that were pure junk (very similar experience to what jw0752 mentions).

I have also found that there are some great battery suppliers out there.  I have had good luck with the Panasonic/Sanyo (840mAH 14500) and Vapecell (1000mAh 14500) cells.

Reading through some of Gough Lui reviews (like: https://goughlui.com/2020/10/06/review-keeppower-26650-3-7v-5500mah-protected-li-ion-battery-p2655c/ ), I have seen find some winners (Keeppower).

I would stick to some of the well tested brands of batteries, and always remember the saying, "If something sounds to good to be true, it probably is".

Gene

I would recommend taking a look at some model shops to get an idea of battery packs and chargers available. 7.2V packs tend to be NiMH cells, they are quite popular in model boots and cars and also in emergency light fittings. Lithium battery packs will tend to be specified as 7.4V. The link below will give you some ideas.

https://howesmodels.co.uk/product-category/batteries-chargers/li-po-batteries-and-chargers/

I use Samsung Li-Ion 18650 cells, which have always been reliable.

Kind regards.

https://somanytech.com/18650-battery-specifications-datasheet-18650-battery-specs/

MiniZeroCam This blog by maxpowerr uses a TP4056 based Li battery charger. It's a generic one and inexpensive.

This vendor (https://www.addicore.com/TP4056-Charger-and-Protection-Module-p/ad310.htm ) is selling one for about USD 1.2 along with the datasheet. 

Surprisingly, it's available for much lower price (INR 24 ~ USD 0.32) in some online Indian stores

"... I would like to replace this battery with Li-Ion batteries, specifically the 18650 type. I am thinking of using two 18650..."

This appears to be an of-the-shelf Li-Ion battery pack made from two 18650 cells:

https://www.overlander.co.uk/2200mah-7-4v-2s-li-ion-battery.html

Dave,

Thanks for this suggestion. I've had a look and it seems the sort of thing I am looking for, except that I still do not know what to use to charge them with. Is there some sort of standard charger (that I just do not seem to be able to find!)?

Dubbie

Gary,

This was very helpful. My knowledge is slowly increasing. I may soon be at a point where I can actually buy the batteries that I want. Or get them as Christmas presents anyway.

Dubbie