# 18650 battery charging issue **URL:** \ **Category:** Uncategorized\ **Created:** [12 October 2023 21:52 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253 "2023-10-12T21:52:03Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Robert251117](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@Robert251117](https://forum.core-electronics.com.au/u/Robert251117)\ **Post date:** [12 October 2023 21:52 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/1 "2023-10-12T21:52:03Z")
I recently built a series of LED fairy lights for my grandaughter. They are controlled by an arduino MEGA clone- i installed two 18650 batteries in series to power the board and LEDs- after a couple of weeks the unit did not run, so I put the batteries in the DIYfull charger, but neither seems to be charging. They are reading .2 and .7 volts respectively. Any suggestions? ---
**Author:** ![Jeff105671](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/jeff105671/32/3729_2.png) [@Jeff105671](https://forum.core-electronics.com.au/u/Jeff105671)\ **Post date:** [12 October 2023 22:13 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/2 "2023-10-12T22:13:00Z")
If the circuit you used to power the lights did not include battery protection, then it is likely that the batteries have become over-discharged. They might be recoverable. See here for some information, or search using the terms from that page. [Restoring/Recharging Over-discharged LiPo (Lithium Polymer) Batteries! : 6 Steps - Instructables](https://www.instructables.com/Restoring-over-discharged-LiPo-Lithium-Polymer-bat/) Some batteries advertised as ‘18650’ include charge/discharge protection, but most do not, so it is important to determine whether or not the batteries you are using require an external protection circuit. Batteries used for mobile phones, on the other hand, often include protection as part of the battery construction. ---
**Author:** ![Robert251117](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@Robert251117](https://forum.core-electronics.com.au/u/Robert251117)\ **Post date:** [12 October 2023 22:53 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/3 "2023-10-12T22:53:33Z")
Thanks Jeff- very much appreciated. ---
**Author:** ![Robert251117](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@Robert251117](https://forum.core-electronics.com.au/u/Robert251117)\ **Post date:** [12 October 2023 23:04 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/4 "2023-10-12T23:04:31Z")
Also - do you have a suggestion for a low voltage protection/alert module I could add to the two batteries running in serial? ---
**Author:** ![Robert93820](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@Robert93820](https://forum.core-electronics.com.au/u/Robert93820)\ **Post date:** [12 October 2023 23:07 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/5 "2023-10-12T23:07:29Z")
Hi Robert, Jeff If the cells are reading > [@Robert251117](#): > > reading .2 and .7 volts respectively. I think I would change > [@Jeff105671](#): > > then it is likely that to " it is pretty certain". It is unclear how much current the set up requires. Are you sure the battery capacity is sufficient for a reasonable operating time. Cheers Bob ---
**Author:** ![Jeff105671](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/jeff105671/32/3729_2.png) [@Jeff105671](https://forum.core-electronics.com.au/u/Jeff105671)\ **Post date:** [12 October 2023 23:21 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/6 "2023-10-12T23:21:58Z")
If your lights will operate from 5V this is a solution that provides convenient mounting for the batteries, easy charging, and protection for both charge and discharge. > **[2-Way 18650 Battery Holder](https://core-electronics.com.au/2-way-18650-battery-holder-1.html)** > > This easy-to-use 16850 battery holder with dual-slot offers micro and type-C charging inputs, five 5V/2A output ports, five 3.3V/1A output ports and one... At the component level, this is a typical device: > **[3 Cell 18650 BMS Module](https://core-electronics.com.au/3-cell-18650-bms-module.html)** > > Make your own 18650 Battery banks with this 3-Cell BMS module Core doesn’t seem to have a 2 cell BMS listed, but they are available. [2s 8a Li-ion 7.4v 8.4v 18650 Bms For Li-ion Lipo Battery](https://vi.aliexpress.com/item/1005005219398439.html) However Core does stock 2-cell battery cases which you could use with a 2-cell BMS. > **[2 x 18650 Battery Holder with DC2.1 Power Jack](https://core-electronics.com.au/2-x-18650-battery-holder-with-dc2-1-power-jack.html)** > > The 18650 lithium battery is a commonly used lithium battery in electronic products. It is often used in batteries of laptop computers and power banks. 18650, which... ---
**Author:** ![Robert93820](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@Robert93820](https://forum.core-electronics.com.au/u/Robert93820)\ **Post date:** [12 October 2023 23:38 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/7 "2023-10-12T23:38:06Z")
Hi Jeff, Robert Be aware that cells with a nipple on the positive end may not fit holders with this type of metal bit on the ends. I can guarantee that they will not fit into that 3 cell holder with power jack fitted as I have one. Core advised on an earlier query that they only sell cells that fit into these holders. That is flat topped cells which are 65mm long. Most of the nipple types are 69 or 70mm in length. Cells with built in protection are mostly in the 69mm category as they have to accommodate the protection circuitry in the top. Cheers Bob ---
**Author:** ![Robert251117](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@Robert251117](https://forum.core-electronics.com.au/u/Robert251117)\ **Post date:** [13 October 2023 01:00 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/8 "2023-10-13T01:00:37Z")
Thanks both- it seems that I’ll need to buy more 18650s- however if I continue with 2x 18650 batteries outputting 7.4v is it possible to get a simple voltage shutdown device to connect between the battery holder and the microprocessor? ---
**Author:** ![Robert93820](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@Robert93820](https://forum.core-electronics.com.au/u/Robert93820)\ **Post date:** [13 October 2023 01:18 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/9 "2023-10-13T01:18:06Z")
Hi Robert > [@Robert251117](#): > > is it possible to get a simple voltage shutdown device to connect between the battery holder and the microprocessor? See Jeff’s link above regarding 2 cell BMS. Cheers Bob ---
**Author:** ![Blayden](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/blayden/32/7535_2.png) [@Blayden](https://forum.core-electronics.com.au/u/Blayden)\ **Post date:** [13 October 2023 01:25 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/10 "2023-10-13T01:25:16Z")
Hey Robert, Regretfully we don’t currently carry a 2 cell BMS. Though Jeff’s link should be exactly what you are after. The other options for it are using a [lipo power booster/charger module](https://core-electronics.com.au/mp2636-power-booster-charger-module.html). Though that device is more useful for a single 3.7V Lipo. Cheers, Blayden ---
**Author:** ![Kimmo](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/kimmo/32/9037_2.png) [@Kimmo](https://forum.core-electronics.com.au/u/Kimmo)\ **Post date:** [14 October 2023 04:37 UTC](https://forum.core-electronics.com.au/t/18650-battery-charging-issue/18253/11 "2023-10-14T04:37:32Z")
On a related note, I tried to revive a dead laptop battery this week… It’s a 4s, with rectangular cells; I went to the trouble of removing the circuitry before juicing up the cells from dead flat to about 11V (nominal voltage 14.4V), before the epic hassle of re-soldering the board back on… Nada. Then I was like stuff it, and just soldered a couple of wires onto the pads, and gave it a bit more charge, still nothing doing. Had another go, got the pack up to like 14.2V, put it back in the laptop again, and the tray icon showed it was charging for a few seconds, but then nothing, and it still showed 0%. Not worth the hassle at all, considering a new battery can be had for as little as $45, but I gave it a go because it’s a pretty old model, and I figured a ‘new’ battery could well be far past its shelf life… Time to find out about that, I guess.