Solved - What to Do When the A119 Battery Finally Dies?

[Kremmen]

Like a QuadHD running at 60fps

 

[SawMaster]

Yeah, in 5 years time there will probably be much better cams available making an upgrade worthwhile. I still like not wasting an easily repairable cam which could be used on the sides or rear, or gifted to someone who does not have a cam.

Phil

 

[murcod]

View attachment 48592

Does anyone know how the bottom of the RTC battery is attached to the circuit board?

 

[murcod]

Does anyone know how the bottom of the RTC battery is attached to the circuit board?

Never mind. I thought both those solder pads came off the top of the battery. A clearer picture shows one lead goes to the top of the battery and the other comes from underneath. So it should be relatively easy to solder with a fine iron.

 

[murcod]

There's also a high temp version which is rated to 85C, with a slightly higher capacity (and slightly larger diameter) https://www.sii.co.jp/en/me/datasheets/ms-rechargeable/ms920t/

... and one twice the capacity with a slightly larger diameter https://www.sii.co.jp/en/me/datasheets/ms-rechargeable/ms920se/

 

[jokiin]

There's a few different options, the one I posted the link to is likely a different one to what they used but it's the same type of battery

 

[murcod]

I was going to try the high temp rated version, but cheap sources are hard to find.

So, instead I've ordered the MS920SE which is twice the capacity of the MS621FE (on the theory it starts with twice the capacity so should last longer as it's capacity reduces with age/ use.) Also the DOD (depth of discharge) will be less with the higher capacity battery - see below for the effects of DOD on battery life. Possibly a flawed theory but there looks to be a bit of space around the stock battery so why not go a bit larger?

On another thought- would a third super cap work if there was enough space? It's a bit annoying that a camera promoted as using super caps still has a lithium rechargeable battery in it that will fail.

The specs only give a life of 100 cycles for 100% DOD, 1000 cycles for 20%. So under 3yrs life for 20% discharge and then you've got to throw in the high temps in cars that would reduce the life.

 

[jokiin]

You can't just add a super cap, the caps have no role in keeping the time anyway

Sent from my moto g(7) plus using Tapatalk

 

[murcod]

You can't just add a super cap, the caps have no role in keeping the time anyway

A super capacitor in place of the RTC battery.

 

[reverend]

Those capacitors will fail at some point anyway, when they do it's an easy replacement, just desolder and remove the old and solder in new.



Batteries and capacitors all have a lifespan in these scenarios, as has been said when they die you have the option of replacing low cost components or just buying a new (possibly) more capable camera from that era.

 

[jokiin]

A super capacitor in place of the RTC battery.

just replace the battery with the correct type, a cap in it's place wouldn't last long enough to be practical

 

[Nigel]

I was going to try the high temp rated version, but cheap sources are hard to find.

So, instead I've ordered the MS920SE which is twice the capacity of the MS621FE (on the theory it starts with twice the capacity so should last longer as it's capacity reduces with age/ use.) Also the DOD (depth of discharge) will be less with the higher capacity battery - see below for the effects of DOD on battery life. Possibly a flawed theory but there looks to be a bit of space around the stock battery so why not go a bit larger?

On another thought- would a third super cap work if there was enough space? It's a bit annoying that a camera promoted as using super caps still has a lithium rechargeable battery in it that will fail.

The specs only give a life of 100 cycles for 100% DOD, 1000 cycles for 20%. So under 3yrs life for 20% discharge and then you've got to throw in the high temps in cars that would reduce the life.

After those 100 cycles, the battery isn't dead, it just means that it no longer has the specified capacity, I imagine the camera will keep working for 10x longer than that.

There shouldn't be much of an issue with heat, that battery is at the bottom where it doesn't get particularly hot, totally different to using a lipo main battery where it is recharged fairly quickly while positioned a few mm from the processor.

Are you replacing it because it isn't keeping the date and time? Or just because you can?

 

[murcod]

just replace the battery with the correct type, a cap in it's place wouldn't last long enough to be practical

Are you saying it wouldn't work from an electrical or space perspective? Given the low current drain specs of the RTC battery a supercap should be able to supply the required current. The RTC charging circuit may not like it though?

Are you replacing it because it isn't keeping the date and time? Or just because you can?

It's not something I'm doing because I can. The RTC started losing the date/ time over 6mths ago. It came good over Winter, but with the weather warming it has died again. If I have to fix something I'd like to make sure the same problem won't occur anytime soon. The Aussie Summer heat is most likely the cause. The CPL filter turned orange on the same camera.

 

[Nigel]

Are you saying it wouldn't work from an electrical or space perspective? Given the low current drain specs of the RTC battery a supercap should be able to supply the required current. The RTC charging circuit may not like it though?


It's not something I'm doing because I can. The RTC started losing the date/ time over 6mths ago. It came good over Winter, but with the weather warming it has died again. If I have to fix something I'd like to make sure the same problem won't occur anytime soon. The Aussie Summer heat is most likely the cause. The CPL filter turned orange on the same camera.

I think you have a voltage issue with a super-capacitor replacement, plus the charging is very different, you might damage the charger if it is not current limited.
My guess is that you had a faulty battery rather than a heat damaged one, no issue with using a larger battery of otherwise similar spec.

 

[murcod]

Yes, I'm aware of the charging characteristics of capacitors. The charging circuit limitations would be one thing that could be problematic. It wouldn't need to be a big capacitor- given the battery capacity looks to only be around 6mAh, so a "super" capacitor would be overkill as it's only needs to supply enough voltage/ current to the CPU to keep the date/time ticking over.

 

[jokiin]

Are you saying it wouldn't work from an electrical or space perspective?

electrical

 

[Nigel]

Yes, I'm aware of the charging characteristics of capacitors. The charging circuit limitations would be one thing that could be problematic. It wouldn't need to be a big capacitor- given the battery capacity looks to only be around 6mAh, so a "super" capacitor would be overkill as it's only needs to supply enough voltage/ current to the CPU to keep the date/time ticking over.

It would need to be a super capacitor, anything smaller will self-discharge to empty far too fast, there is a good reason Viofo used a battery!

 

[murcod]

An example of using super caps for RTC backup https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3816.html https://www.maximintegrated.com/en/design/technical-documents/app-notes/3/3517.html

supercap-powered RTC?

I'm designing a ATmega-based microcontroller test board. One of the features I want to include is a Real Time Clock with a Maxim DS1307 IC. Instead of including a traditional coin cell battery back...

electronics.stackexchange.com

So definitely possible if the circuitry supports it.

 

[murcod]

It would need to be a super capacitor, anything smaller will self-discharge to empty far too fast, there is a good reason Viofo used a battery!

Simplicity, price, they only require the camera to out last the warranty period.

 

[murcod]

So that type of RTC battery is a Manganese Lithium chemistry rechargeable battery. If some more specs were known this page can calculate the theoretical life span of the battery.

Manganese Lithium Rechargeable Cell Lifet - Maxim Integrated

www.maximintegrated.com

"For Manganese Lithium (ML) cells, the maximum number of charge/discharge cycles (cell life) is affected by the depth of discharge (DoD). This calculator estimates ML cell lifetime based upon a given depth of discharge. The calculator uses an estimated cell load to determine approximate backup time versus discharge depth.

As a ML cell is cycled, the capacity at full charge decreases. This means that that it will take less time to reach a given depth-of-discharge as the cell is cycled. This calculator does not take into account the reduced capacity during use, but is intended to serve as a first approximation of cell life."

Calculating ML Cell Life for an RTC Backu | Maxim Integrated

This application note discusses how to calculate the approximate cell life, based upon cell capacity, load, and depth of discharge.

www.maximintegrated.com

"ML secondary (rechargeable) cells are a relatively new technology, with some important advantages over primary (rechargeable) lithium coin cells (typically CR and BR). Some ML cells are capable of withstanding standard IR reflow profiles, while primary lithium batteries cannot. Using an ML cell can simplify the manufacturing process, eliminating the need to place the coin cell on a PCB post-reflow. A primary cell must either be sized to provide backup power over the expected life of the product, or provisions must be made for the cell to be replaced. While an ML cell has a lower energy density than a primary lithium cell, the ML cell can, in some applications, have smaller capacity, because it is recharged between uses. This allows for a smaller cell, decreasing the required PCB space. An advantage of the ML cell is its relatively low self-discharge rate (compared to capacitors, NiMH, and NiCad batteries) of approximately 1% per year, which allows extended life when the current load is small.

ML cells require a regulated-voltage charging source. Maxim has integrated the required charging source into a family of RTCs. The stand-alone DS12R885 has the charger on chip. In addition, there are module products that include the battery, charger, and RTC in a BGA package.

One issue with secondary cells is the number of charge/discharge cycles that they can withstand during a normal service life. For ML cells, the number of charging cycles is inversely related to the depth of discharge (DoD)."

"Figure 1 shows the effect that depth of discharge has on the number of charging cycles. The data are taken from the manufacturer of an ML614R battery. We can approximate the number of cycles for a given depth of discharge, and then calculate the approximate time to a particular discharge depth by multiplying the depth of discharge by the nominal cell capacity, and dividing by the load current. From there we can approximate the total life during backup (service life) by multiplying the calculated time by the number of expected cycles: total life = %DoD*(capacity/load)*cycles."