18650 Li ion batteries question

RE: 18650 Li ion batteries question

beacon_dave — Thu, 11 Nov 2021 17:04:13 GMT

"... 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

RE: 18650 Li ion batteries question

robogary — Wed, 10 Nov 2021 00:14:57 GMT

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

RE: 18650 Li ion batteries question

three-phase — Tue, 09 Nov 2021 22:14:03 GMT

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.

RE: 18650 Li ion batteries question

genebren — Tue, 09 Nov 2021 21:25:20 GMT

Hi Ralph,

I have run into a lot of high capacity battery that were pure junk (very similar experience to what [mention:f80b53cee57c44bc9d7c577d07d7c791:e9ed411860ed4f2ba0265705b8793d05] 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 [mention:ef601b47037147bfb9b0b4a3ab63026a:e9ed411860ed4f2ba0265705b8793d05] 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

RE: 18650 Li ion batteries question

ralphjy — Tue, 09 Nov 2021 20:55:13 GMT

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.

RE: 18650 Li ion batteries question

jw0752 — Tue, 09 Nov 2021 17:54:53 GMT

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

RE: 18650 Li ion batteries question

rsjawale24 — Tue, 09 Nov 2021 16:44:45 GMT

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.