2.4V rechargeable lithium coin cell?  (Canon camcorder) - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: February 11, 2023, 03:11:55 pm
content: I have a Canon Vixia HF R400 camcorder that mostly works, but the built-in CMOS battery isn't preserving the date/time and settings. I have another of that same model that has a dead LCD display, but the CMOS battery in that one still works. However, it measures 2.35V. I could switch the parts and end up with one fully functional camcorder, but am a bit suspicious of the 2.35V. I believe that's the fully-charged voltage, but will confirm that.Anyway, is there such a thing as a 2.4V lithium rechargeable coin cell? It's soldered in place, so I can't see what the part number is. It's about the size of a CR2032. I haven't found any Canon document that identifies what the battery is.If it's supposed to be 3V, or 3.7V, wouldn't it still charge to no-load full voltage even if its capacity has deteriorated over time? The AC adapter inputs 5.3V, and the main battery is nominally 3.6V. The instructions say to plug in the AC adapter to charge the CMOS battery. I know the main battery preserves the data, but I don't know if it also keeps the coin cell charged.

author: ConKbot
author_rank: Super Contributor
timestamp: February 11, 2023, 04:55:55 pm
content: Is it two NiCd/NiMH CR2016 cells stacked on each other and packaged up to install as one battery? Or definitely a single cell?

author: magic
author_rank: Super Contributor
timestamp: February 11, 2023, 05:09:52 pm
content: Canon Powershot cameras employed rechargeable cells based on some sort of Li chemistry, but I don't remember the details. They had no USB charging, so the cell was always recharged from the main battery.Can you just connect the charger and see what happens?

author: RoGeorge
author_rank: Super Contributor
timestamp: February 11, 2023, 05:10:23 pm
content: At that voltage might be a supercapacitor as well.Some cameras do have a supercapacitor instead of a battery, so to preserve camera's settings and run its datetime clock for a few hours to days at most, while the main battery is supposed to be out of the camera for a recharge.

author: mariush
author_rank: Super Contributor
timestamp: February 11, 2023, 06:39:14 pm
content: Try desoldering the battery, there may be something engraved on the other side, like a code for the battery (ex CR2032)At least that should narrow out things, if there isn't anything you could still measure it to get thickness and diameter.They make rechargeable lithium batteries, here's a bunch with reasonable diameters :https://www.digikey.com/short/fhqp4h87If both leads are on the same side, it could be this 1220 maybe?https://www.digikey.com/en/products/detail/panasonic-bsg/ML-1220-F1BN/2404068Check datasheet, discharge characteristics graph on first page, voltage is 2.5v for most of its useful life, and then slowly goes down

author: Peabody
author_rank: Super Contributor
timestamp: February 11, 2023, 06:52:27 pm
content: Here's what the manual says:> Built-in Rechargeable Lithium Battery> The camcorder has a built-in rechargeable lithium battery> to keep the date/time and other settings. The built-in> lithium battery is recharged while you use the camcorder;> however, it will discharge completely if you do not use the> camcorder for about 3 months.> To recharge the built-in lithium battery: Connect the> compact power adapter to the camcorder and leave it> connected for 24 hours with the camcorder off.I will have to check later to see if there are two cells stacked, but I think it's just one. Here's the disassembly video I've been working with:https://youtu.be/JVcChmZD2mY?t=451Anyway, in the end I'll just desolder it and see if I can find the part number. But it seems to me it has to be a 3V cell. That doesn't guarantee it's being charged to 3V, but I don't see anything on Digikey that looks like the one in the video that's less than 3V.

author: Peabody
author_rank: Super Contributor
timestamp: February 11, 2023, 07:01:33 pm
content: Quote from: mariush on February 11, 2023, 06:39:14 pmWell, the tabs are actually on the opposite sides of the cell, but the tabs are bent so they line up on the PC board. It certainly could be the 1220 or something like it. As long as it's supposed to be a 3V lithium, I should be able to find a replacement. So I'll desolder it and see if I can find the number. I was just having trouble with the 2.34V it's reading, but that could make sense on something like the 1220.

author: tooki
author_rank: Super Contributor
timestamp: February 11, 2023, 08:25:52 pm
content: Quote from: ConKbot on February 11, 2023, 04:55:55 pmJust a little FYI: the “C” in “CR2016” refers to the battery chemistry. (R means round cell.) So “CR” actually means “round cell with lithium anode, magnesium dioxide cathode, with organic electrolyte” (that is, standard 3V lithium non-rechargeable.). As such, a NiMH battery cannot be a CR cell since it’s a totally different chemistry.Though rarely (never?) used, the code for NiMH button cells is theoretically “HB”.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 11, 2023, 11:43:07 pm
content: Quote from: tooki on February 11, 2023, 08:25:52 pmSo if "R" means round cell why is the code for NiMH button cells not "HR"?

author: tooki
author_rank: Super Contributor
timestamp: February 12, 2023, 01:29:32 am
content: I don’t know with certainty. Ask the IEC, it’s theirsystem!(As best I can tell, they’re actually different systems for primary (non-rechargeable) and secondary (rechargeable) batteries.)

author: amyk
author_rank: Super Contributor
timestamp: February 12, 2023, 06:38:08 am
content: Quote from: karpouzi9 on February 12, 2023, 05:32:47 am2.4 nominal, 3V fully charged. But titanate is a bit on the exotic side for this application, and it's more likely the ML series manganese cells linked above are correct.

author: Peabody
author_rank: Super Contributor
timestamp: February 12, 2023, 06:35:13 pm
content: Ok, I desoldered it, and it is a Maxell ML1220 as mariush predicted. Digikey doesn't have Maxell, but has this Panasonic which is a match on the tab structure:https://www.digikey.com/en/products/detail/panasonic-bsg/ML-1220-F1BN/2404068It's a 3V cell, but even the cell I have that's still working reads 2.83v after being charged for 24 hours. That's on the camcorder with the dead LCD. I could move that cell over to the good camcorder with the completely dead cell, but I think it makes more sense to order a new cell. The cell that's still working is 10 years old.I guess Digikey is the place to order, but since it's a lithium battery it will have to travel by truck/rail from Frostbite Falls to Oklahoma. So I may see if I can find one on Ebay where the seller will just mail it normally.I haven't actually taken the good camera apart yet to see if there's any other reason why the coin cell isn't working (other than it being dead). But the battery and the SD card slot are serviced by the same ribbon cable, and the SD slot works fine. So I suspect the coin cell has just reached the point where it won't recharge at all anymore.

author: Peabody
author_rank: Super Contributor
timestamp: February 13, 2023, 05:38:41 pm
content: I opened the good camcorder, but couldn't see any reason why the battery isn't working. I think it's dead, Jim. So I ordered a new one from Digikey. Shipping was three times the price of the battery, but I needed a few other things anyway. So it should arrive later this week, and I'll install the new battery and see what happens. Film at 11.

author: Peabody
author_rank: Super Contributor
timestamp: February 19, 2023, 01:38:18 am
content: Just wanted to report that I desoldered the bad battery, and it measured 1.9V. But when I tried to charge it, it wouldn't accept any charge current. So it's dead, which is what I was hoping for. The replacement battery arrived from Digikey, and it seemed to work fine. So I soldered it in, and reassembled the camcorder, and now my settings are preserved when the main battery is removed. It will take me a while to confirm that the charging system for the backup battery is working, but I have no reason to suspect it isn't.