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**sam_sam_sam** · 07-07-2021, 05:31 PM

Re: Battery problem handheld scope fn1rs1-5012h

What does the battery pack says about the battery pack voltage is suppose to be
My guess is that it suppose to be 4.2 volts or 3.2 depending on what type of battery it is which means that it is low on charge the protection board has locked out the fast charging and only doing a slow charging

But you need to know what type of battery you are dealing with to know how to proceed
You might need to remove the heat shrink tubing from the battery pack if does not have the information about what type of battery it is

Here is the data sheet for this ic chip

https://www.addicore.com/TP4056-Char...le-p/ad310.htm

According to the data sheet when the battery voltage is below 2.9 volts it is only trickle charging and will continue to do this until the battery voltage goes above 3.0

You might want to leave it on charger for 24 hours and see if it comes on voltage but I caution you that you need to check the battery temperature often while charging this battery to make sure that it does become warm if it does do not continue to charge it do not use it anymore

I hope this helps you

**eccerr0r** · 07-07-2021, 05:40 PM

Re: Battery problem handheld scope fn1rs1-5012h

Can't gauge how thick it is from the picture but making assumptions, it's probably no more than 1.5Ah. And yes neglecting li-ion cells is a fast track to requiring replacement earlier than expected... Chances are, this is a regular lithium ion and not a lithium ion-iron phosphate cell.
Measure the open circuit voltage of the pack, if it's less than 3V or so, consider it toast if the slow charge doesn't recover it.

**budwich** · 07-07-2021, 07:41 PM

Re: Battery problem handheld scope fn1rs1-5012h

thanks for the info. There is no writing anywhere on the outer plastic "shell" which I have taken down to the "last layer". I feel like its some form of battery like a tablet / phone which from reading is a "lipo". I have seen in places that 2.5v is a "cutoff" voltage for operation so that is why its not operating on battery. Can I "force" the charge "off board" with some form of cells plus resistors to get the voltage up to see if it will start charging or is that a "NiCAD" thing with the "zap" to get the cells to work again? I will leave it on charging for a while to see if it improves. The pack is about 1.75 in X 2 in X 1/4 in thick with a cordless phone type connect (two pin).

**sam_sam_sam** · 07-07-2021, 07:58 PM

Re: Battery problem handheld scope fn1rs1-5012h

Originally posted by budwich View Post

thanks for the info. There is no writing anywhere on the outer plastic "shell" which I have taken down to the "last layer". I feel like its some form of battery like a tablet / phone which from reading is a "lipo". I have seen in places that 2.5v is a "cutoff" voltage for operation so that is why its not operating on battery. Can I "force" the charge "off board" with some form of cells plus resistors to get the voltage up to see if it will start charging or is that a "NiCAD" thing with the "zap" to get the cells to work again? I will leave it on charging for a while to see if it improves. The pack is about 1.75 in X 2 in X 1/4 in thick with a cordless phone type connect (two pin).

Do this as a last resort I would just leave it on the charger and monitor it temperature for 24 hours and see if the voltage comes back to above 3.0 volts because if it is a pouch type battery you need to very careful about how you charge this type of battery you can make it puff up and make the battery useless

I have had it happen to me several times before so I use extreme care when charging them with out a protection board I do not recommend you try this on the only battery you have for this device

I have done it with a bench power supply before and you decided to go this route charging current should not be more than 200 milliamperes at the most but you have to set the voltage to no more than 4.00 volts but less voltage would prefer maybe more like 3.5 then let the device to charge it the rest of the way but remember that you need to monitor the battery temperature

**eccerr0r** · 07-07-2021, 08:15 PM

Re: Battery problem handheld scope fn1rs1-5012h

No, do not zap, unless you're not worried about

unlike NiCd cells...

**stj** · 07-07-2021, 09:15 PM

Re: Battery problem handheld scope fn1rs1-5012h

get a 5v source and a 75ohm series resistor.

here is a table i created a few years back:
--------------------------------------------
input 5v
output 3.7v
current >65ma
resistor: 75ohms
.1v - 65.3ma
.5v - 60ma
1v - 53.3ma
2v - 40ma
3v - 26.6ma
3.7v - 17.3ma << tops out and wont charge higher.
4.2v - 10.6ma
-------------------------------------

i use it to recover 18650's enough to put in a desktop charger.
as you can see, it can push a maximum current of 65mA into a dead cell - not enough to start a fire.
and at 3.7v the maximum current is pretty much non-existant.
so if you leave it running a couple of days it wont matter.

incidentally, i have recovered cells with as low as 1v like this so-far!!!
i think the super-slow aproach eliminates any type of crystaline punchthrough.

**redwire** · 07-07-2021, 11:03 PM

Re: Battery problem handheld scope fn1rs1-5012h

Most Lithium battery chargers BMS will not initiate charging if the battery is too dead, its voltage it too low.
You have to trickle charge the battery manually, I use 1/20-1/10C so a 700mAh battery gets 35-70mA limited to 4.2V and you can use a resistor to limit charging current. 5V is okay if you don't forget about it.
I've had many "dead" laptop batteries that the BMS refuses to charge, but manually connecting a power supply, I can bring up the dead cells and then the pack's BMS will work fine.

The TP4056 IC will trickle charge until the battery gets to around 2.9V then it goes full charging current. It seems to charge anytime.
So there might be another problem, with the battery or IC? I would disconnec tteh battery and try manually charging it.
I don't have luck with pouch batteries, they seem to be junk. High self-discharge and they are always dead.

**budwich** · 07-08-2021, 05:36 AM

Re: Battery problem handheld scope fn1rs1-5012h

thanks again for the guidance / info. I left it charging over night. Still does not appear to doing much charging according to the usb monitor dongle. I might have damaged the pack trying to get it unstuck from the glue that held it to the case... :-( I haven't been monitoring the actual voltage close enough to know if its actually charging... meaning the second and third digits of a DMM... just noticing "2.4,,," but maybe it was 2.41 and now its 2.46... maybe.

An interesting thing happened though. I unplugged it from the board to measure the voltages. I could see some changes in the usb dongle current readings... it flashed towards 1amp or so... then settled back to a few ma as before. After measuring the pack, I then plugged the battery back in and the higher current reading showed up again and stayed there. I will let it sit for a bit and keep an eye on things. Maybe some level has been hit to allow things to function... hopefully.

IF not, I guess the one question that I have is, if I can't recover this pack, and try to find a "equivalent replacement", does the voltage matter?... ie. some indicate 3.6, some indicate 3.7... hence the question.

**eccerr0r** · 07-08-2021, 05:55 AM

Re: Battery problem handheld scope fn1rs1-5012h

That battery sounds like it's a goner.

As long as the battery chemistry matches, has the same number of cells in series, and physically fits you're fine.

**stj** · 07-08-2021, 07:12 AM

Re: Battery problem handheld scope fn1rs1-5012h

the tp4056 is a lion charger,
the cell will be a solid one probably intended to be used in old phones.

i'm 100% sure if you strip it it's not a polymer pouch.
what do you think they did with all the 3rd party replacement nokia batteries?
they just found new uses for them - like 2way radio's and bluetooth keyboards and radio's (like tecsun PL330) and so-on.
nothing goes to waste in china

**budwich** · 07-08-2021, 08:03 AM

Re: Battery problem handheld scope fn1rs1-5012h

you are probably right as it does seem a bit thick compared to lipo packs. The good news is that its currently drawing about .6 amps according to the usb monitor AND now if I turn on the unit with the battery connected, the unit does power up so there is some semblance of charge in the battery. This has been after about 2 hours charging at some "high current" as opposed to 6-8ma. The pack does not seem to be hot at this point which is good. In terms of the types of batteries for a replacement, space is not a problem as it sits on the back cover and the backside of the circuit board is flat. Thickness might be an issue overall. I will check it against a normal AA cell to see if it clears with the back on. I guess the one lesson might be to plug it in when I see the battery symbol starting to look "low". Fingers are crossed that it is operational again.

**budwich** · 07-08-2021, 09:41 AM

Re: Battery problem handheld scope fn1rs1-5012h

charging amps are down to .3 amp. Left "non-charging" for a while to "stabilize" the battery voltage. It reads 4.1v which is kind of like some of the camera batteries that I have which indicate 3.7 "pack spec". The instructions are somewhat poor in and around charging and do not seem to specify any indicators that would be displayed when the unit is fully charged. Thanks again for the comments and help. I am glad this neat little device is fully working again... now to get back to some real electronic repairs. :-)

looking at ebay... this listing picture looks like the same battery but with labeling.
https://www.ebay.ca/itm/184612532062...oAAOSw5GJf-EJV

while this amazon listing suggests that the "same battery" (ie. 904260) is a lipo based battery.... hmmm????
https://www.amazon.ca/3000mAh-polyme.../dp/B08FB3VD91

**stj** · 07-08-2021, 10:49 AM

Re: Battery problem handheld scope fn1rs1-5012h

does a magnet stick to the pack?

**budwich** · 07-08-2021, 12:47 PM

Re: Battery problem handheld scope fn1rs1-5012h

good question / point. Nope, magnet does not stick to the pack any where.
update on the charging, its now down to .15amps so it looks like the charging system is functioning and the battery itself has some form of charge holding capability for now.

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