Possible to source brand new battery and connect up to old mobile phone? - Page 1
Forum section: electronics / general

author: gizmo1990
author_rank: Newbie
timestamp: January 22, 2021, 09:08:58 am
content: Hi everyone. I'm new to the forum and wasn't sure where to place this question, so I thought I'd play it safe and post it here. I'm gradually building my understanding of electronics with little projects here and there. I have an old Sony CMD-Z5 (circa 2000?) mobile phone which I still use daily as my foreign phone.It has a rather unique battery design in that the battery is built into the back compartment itself, which snaps out to be replaced. I changed the battery about 8 years ago from new old stock, but obviously its hold of charge is pretty crappy.Since buying any new old stock again would only be buying a battery which was already old, I was wondering could I crack open the battery compartment and wire up a brand new battery? The battery used is a Li-ion 3.6v 600mAh. Is something like this even possible?Any advice much appreciated.

author: ace1903
author_rank: Regular Contributor
timestamp: January 22, 2021, 12:54:00 pm
content: From the pictures seems that the battery is connected only with two wires. So no smart ID chip.You can use a brand new battery that has the same capacity. Do not try to put a battery with a larger capacity because the internal charging circuit will not be capable to charge it properly.Nice to see a phone from that era that still works properly.Hope that GSM and 2G will not be abandoned soon as is the case in some countries.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 22, 2021, 01:03:11 pm
content: Quote from: ace1903 on January 22, 2021, 12:54:00 pmNot true, worst case if you fit a battery far larger than original the charger will time out and you won't get a full charge, but derating a battery will help to make it last longer.

author: gizmo1990
author_rank: Newbie
timestamp: January 22, 2021, 02:15:45 pm
content: Thanks for the replies everyone. I think I’ll open one up and see what’s inside then.The main problem looks like being able to source a li-ion battery which is this slim. All the ones I’m finding currently are quite thick. I’m guessing a li-po battery couldn’t be used?

author: amyk
author_rank: Super Contributor
timestamp: January 22, 2021, 02:18:55 pm
content: It's almost certainly a standard lipo cell with 4.2V maximum charge voltage. Measure the dimensions, you can probably get a larger capacity one in the same size now.

author: ace1903
author_rank: Regular Contributor
timestamp: January 22, 2021, 02:20:54 pm
content: I worked on phones design cca 2007 in companies related to Sony.Some of the earlier designs used linear circuits instead of switching to charge batteries and relied on battery internal resistance.Charging circuit with timeout on charging I think came later than 2000. I might be wrong but I said just to be on the safe side.I would not recommend the usage of different battery chemistry than the original.

author: gizmo1990
author_rank: Newbie
timestamp: January 22, 2021, 04:48:32 pm
content: Quote from: ace1903 on January 22, 2021, 02:20:54 pmWould that mean that using a li-po battery would be out of the question?

author: ace1903
author_rank: Regular Contributor
timestamp: January 22, 2021, 10:13:04 pm
content: Found service manual on net:"The safety concept protects against:Over voltage: The charging is stopped when Battery Voltage (Vbat) reaches (4.24 V- 4.3 V). The charging resumes when Vbat falls below(4.06 V – 4.15 V).Under voltage: When the cell voltage drops below (2.5 V – 2.7 V) the cell is disconnected for discharging.Charging is still possible.2-5 Battery Capacity:Standard Battery 620 mAh typical Li-ion QN-Z5BPSExtended Battery 1000 mAh typical Li-ion QN-Z5BPE"Seems that this model supports larger battery. There is no time out in charging logic.Lipo should be possible to use although this 4.3V upper limit.Maybe best option is to upgrade with new lipo battery that has internal overvoltage protection circuit.

author: amyk
author_rank: Super Contributor
timestamp: January 23, 2021, 02:21:45 am
content: Quote from: ace1903 on January 22, 2021, 02:20:54 pmthat doesn't make sense, lion cells have sub-ohm internal resistances...

author: tom66
author_rank: Super Contributor
timestamp: January 23, 2021, 11:53:23 am
content: Quote from: ace1903 on January 22, 2021, 02:20:54 pmMaybe you're talking about Ni-MH but nobody charges Li-Ion with the battery internal ESR, it is sub 100mohm and does not change until the cell is way overcharged!

author: gizmo1990
author_rank: Newbie
timestamp: January 23, 2021, 12:54:14 pm
content: Would a battery like this be suitable? It looks like it has overcharge and discharge circuitry.thttps://uk.rs-online.com/web/p/speciality-size-rechargeable-batteries/1251266/

author: tom66
author_rank: Super Contributor
timestamp: January 23, 2021, 03:39:34 pm
content: It has a cell protector, which should stop the battery from being put into thermal runaway if you overcharge it, or reduces the damage by over-discharging it.You still need to take precautions during charging, but hopefully the old phone will charge the cell quite slowly, so it should be OK - but I'd definitely do the first charge on something non-flammable and watch it carefully, in case it has an odd charging behaviour.

author: drussell
author_rank: Super Contributor
timestamp: January 23, 2021, 04:34:06 pm
content: Tons of places sell new and rebuilt batteries for that phone... Why don't you just buy one of those?

author: gizmo1990
author_rank: Newbie
timestamp: January 23, 2021, 06:14:09 pm
content: Quote from: drussell on January 23, 2021, 04:34:06 pmI’ve not found any such new or reconditioned batteries for this phone at all? All I’ve found is expensive new old stock, which will already have poor performance because of their age. Do you have any links to the ones you’re talking about?

author: gizmo1990
author_rank: Newbie
timestamp: April 25, 2021, 06:30:09 pm
content: Thought I'd just bump this as I finally got round to opening up the battery. It's obviously very compact indeed with a thickness of 4mm too. I'm not sure an off the self lipo of similar dimensions is even available, I've been looking around and not found any yet.Does anyone know of any batteries which might fit the bill?

author: drussell
author_rank: Super Contributor
timestamp: April 25, 2021, 06:43:23 pm
content: Quote from: gizmo1990 on April 25, 2021, 06:30:09 pmDid you eventrygoogling QN-Z5BPS?You can apparently buy one for under £2