Memory battery for Canon A640 ?. - Page 1
Forum section: electronics / general

author: cleanworkbench
author_rank: Regular Contributor
timestamp: October 28, 2020, 12:29:29 pm
content: Does anyone know where the memory battery is in the Canon A640 camera and what code it is. I keep getting change batteries even when i put in new AA,s.Has anyone got any info or go to,s on this problem please or are there any Canon Powershot gurus here.Thank you.

author: DrG
author_rank: Super Contributor
timestamp: October 28, 2020, 05:22:43 pm
content: Quote from: cleanworkbench on October 28, 2020, 12:29:29 pmMe No Guru, but I have that camera and it is excellent IMO. Have used it for many years and still do on occasion.I don't know what the "memory battery" is nor, of course, its code. I have never found a service manual for the camera only a couple of operating manuals.The one complaint that I had was that batteries do not last long - in fact, by today's standards (e.g., my EOS SL2), the batter life is pathetically short. I invested in an AC adapter which is quite handy, here are the specs:I would suggest that you first clean the battery contacts well and insert some fresh batteries (correct orientation of course). If that is a no go, I would suggest that you find or make an AC adapter and see if that doesn't cure the low battery condition. If that doesn't work, I gotnutthinelse.

author: magic
author_rank: Super Contributor
timestamp: October 28, 2020, 08:01:35 pm
content: There are the main batteries and there is some sort of rechargeable button-style battery inside the articulated LCD module.The latter only powers the clock (when main batteries are not present) and the camera will work normally even if it's fully depleted. It recharges from the main batteries, of course. Settings are stored in some non-volatile memory somewhere, they aren't lost when the small battery discharges.If you get "change battery", it refers to the AA cells. If putting in fresh, unexpired, high quality cells doesn't help then something is probably screwed with the internal wiring or maybe buck converters or capacitors. Dunno, I have never repaired or studied that stuff.The DC input jack is in parallel with the battery compartment. Inserting a plug disconnects one pole (the negative IIRC) of the batteries to prevent charging them from the PSU. You don't need the dedicated PSU, it will run just fine from 5V if you can get a suitable plug. 4.0/1.7mm I think. If connecting a PSU doesn't help then something is surely screwed inside.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: October 28, 2020, 08:54:18 pm
content: Thanks for the replys , its a great little camera for sure. There are some older models where the button cell can be replaced , i have found nothing on a diagram for this camera .Maybe it is my AA batts losing capacity. They are about 5 years old now.I will defo look into the remote PSU supply though.

author: DrG
author_rank: Super Contributor
timestamp: October 28, 2020, 09:18:44 pm
content: Quote from: cleanworkbench on October 28, 2020, 08:54:18 pmI have found nothing about changing the battery that holds the settings like time and date other than a reference to an internal rechargeable lithium batteryhttps://support.usa.canon.com/kb/index?page=content&id=ART121461.You are getting the red icon on screen flashing indicating low battery - right? You are using rechargeables that are 5 years old? Yeah pop some new batteries in there and you may be good to go. If you have to keep setting time and date maybe you have other problems but until you try it with fresh, fully charged cells, you will not know.As for not having to buy a dedicated PS, I never said that you needed to buy a dedicated PS - in fact, what I said was "buy or make". Since they (used?) to sell a NiMH charger and cells for that cam and also say it is ok to use non-rechargeable batteries, obviously there is a voltage range there - nominally 4.8-5.0V. That their PS is rated at 4.3V out is notable. What is more important, IMO, is that it is also rated at 1.5A, which seems a bit hefty for a camera that operates on 4 AAs. At least in my view.If you look around you can still see posts with lots of dissatisfaction with the number of pictures you can take on a set of AAs and that is why - that camera sucks up a lot juice. For road trip work, I always used to carry a spare set of batteries. The PS, which did not cost much if I recall, is very nice for any kind of bench top or copy stand type work. It has an extra long cord (two actually).Hope it helps.

author: rdl
author_rank: Super Contributor
timestamp: October 28, 2020, 10:34:12 pm
content: This is apparently a known problem with some older Canon cameras. While technically they can run from NiMH they are actually intended to use alkaline. Using rechargeables the low battery threshold is quickly reached.

author: amyk
author_rank: Super Contributor
timestamp: October 29, 2020, 12:38:34 am
content: Quote from: rdl on October 28, 2020, 10:34:12 pmBatteriser to the rescue!

author: magic
author_rank: Super Contributor
timestamp: October 29, 2020, 07:05:17 am
content: A6xx series shut down in the vicinity of 1V per cell.Even the dedicated PSU supplies merely an equivalent of 1.075V per cell.Current is less than 0.5A in any mode IIRC including during exposure, but I may have missed peaks shorter than 0.3s due to my meter's sampling rate.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: October 29, 2020, 08:37:25 am
content: OK people thanks for the advice , looks like i,m going to buy a new set of batteries then and investigate the PSU plug in as well . Again yes , very little info on the internal battery , probably not even available on the street , who knows .