[Nezil]

I've posted on this forum previously about my install of a BlackVue DR750S-2CH with a BlackVue Power Magic Pro, and in general, I've been quite happy with the results that I've seen.

I've expanded the system with a free LTE hotspot (FreedomPop) so that I can monitor the car when I've parked it, or while it's being serviced ;-).

Although I've found that the parking mode activates automatically, and the PMP keeps the power going to the unit for a few hours, I've also run into an interesting issue that I thought I'd post up here in the hope that a) others have seen something similar, and b) hopefully someone will have a solution!

In summary, the issue is that I cannot get parking mode to operate for longer than 6 hours.

When I first encountered this issue I contacted BlackBoxMyCar, where I bought the equipment from, and they suggested turning off WiFi in parking mode, which is not something I want to do, because I use the WiFi for remote monitoring, and also for downloading files when my car is in the garage (see my other thread for how I've automated this).

I couldn't believe that the battery was truly going below the 12.0v that the PMP was set to, so I started investigating other options.

I tried taking voltage readings of my battery the morning after the camera had switched off during the night, and got a reading of 12.35v pretty consistently.

I tried leaving the trunk open to see if the voltage at the fuse that I was tapping off for permanent 12v was actually being switched off, but it too was at 12.35v in the morning.

Getting a little more serious, I removed the PMP and tested the voltage behaviour of the device out of the car. I used a bench power supply and slowly turned down the voltage until I got the PMP to switch off power, and found it to consistently switch off at 12.04v ~ 12.05v. A little high, but the device is rated at +/- 0.1v, so it's safely within spec, and shouldn't be an issue.

Finally, I decided to set up a full test, where I logged the battery voltage at 1 second intervals. I got the camera set up to run in parking mode, and then started logging data... and this is what I found:

Obviously this is a compressed chart, starting around 11pm, and finishing at around 9am. The tell-tale issue occurs, in line with the time when the BlackVue disconnected at around 5am. The timings on the chart are from the start of logging, not the actual time, so that's why the issue is labelled at around 5.56 - 5 hours and 56 minutes after I started logging. So there's this temporary drop in battery voltage that occurs pretty consistently 6 hours after you stop the car! This causes the PMP to disconnect power from the dashcam, and after that, the voltage rises slightly, and is pretty stable.

Zooming in on the drop in voltage, the voltage transient is about 2 minutes long in duration, so it's not a sudden drop, though I imagine that there must be a very brief drop that wasn't logged that goes below 12.05v at some point, in order to have the PMP switch off.

So what to do to eliminate this? A BlackVue Celink B battery pack might work, but I hate the fact that this is only connected to the accessory power, and if you do short journeys, it's going to go flat pretty quickly. Clearly my battery has plenty of capacity in it, so what's needed is some way to smooth this fluctuation.

A low cost DC-DC convertor would smooth out the voltage, but then I'd loose the battery protection which is the point of the PMP in the first place...

Any electronics geniuses out there that can suggest a solution? I don't mind soldering something up, but my electronics design is rusty!

[ZPrime]

Is your logging done directly off the + post of the battery, or from the "always-on" fuse location that you are tapping?

I ask because modern BMWs (and Audis), do all sorts of stuff in the background to "conserve" battery (because they actually do a lot to drain it when the car is off, so they then monitor voltage and shut down "consumers" so you can still start the car the next day). There may be one or two exceptions, but in general, stuff is going to get powered off over time. The only way you've got a guaranteed "permanent" +12V is to go straight off the battery, or off the jump terminals in the engine bay.

If you were taking your readings directly from the battery... ugh. I have no idea WTF it might be trying to do at ~6hrs "dormant" to suddenly choke the voltage like that. Only thing I can think that might happen after sitting for a long time would be for the telematics to check in with the mothership, but I wouldn't think some LTE/4G usage would eat the battery that badly. Was the car locked with the key away from it during this period? Or did you have the trunk open the whole time (which I assume would prevent it from locking)? I ask about the lock state because in a modern German car, locking it typically tells all of the electronics that they should go to sleep / idle / off sooner, while leaving it unlocked keeps the car in a "higher state of readiness," assuming that you might get in at any minute and want to drive away.

[Nezil]

Originally Posted by ZPrime

Is your logging done directly off the + post of the battery, or from the "always-on" fuse location that you are tapping?

The set of data I posted above was directly off the battery, but I re-did the test last night by taking readings directly from the fuse tap to see if there were any differences. See next post...

If you were taking your readings directly from the battery... ugh. I have no idea WTF it might be trying to do at ~6hrs "dormant" to suddenly choke the voltage like that. Only thing I can think that might happen after sitting for a long time would be for the telematics to check in with the mothership, but I wouldn't think some LTE/4G usage would eat the battery that badly.

I thought the same thing, and there might be a way to validate this that I've just thought of... The connected drive app tells you when the server last spoke to the car; maybe if I check this first thing in the morning, it will have a time synchronised with the battery voltage drop?!?

Was the car locked with the key away from it during this period? Or did you have the trunk open the whole time (which I assume would prevent it from locking)?

The car was locked, but the trunk was open for the first logging I did above. Last night however I both locked the car and simulated the trunk being closed (by closing the latch, even though it was actually open). As you'll see in my next post, the behaviour was no different.

[Nezil]

So I re-ran the test last night, but this time with a few changes:

• I took readings from the fuse point I use for the PMP permanent 12v rather than the battery itself as I'd done previously.
• I simulated the trunk being closed, by closing the latch, even though I didn't actually close the trunk, so the car thought it was totally closed and locked up
• I started with the battery at a slightly lower state of charge - I'd driven in the morning yesterday, and the car had been sat all day in parking mode, so the battery was already somewhat discharged from nearly 6 hours of parking mode that had already taken place that day.

As you'll see, the data this time stops at 6 hours, rather than continuing on. This deserves some explanation first...

The device I'm using to log the data is a Junsi iCharger 406Duo, which is a multi-purpose battery charger / discharger used primarily for fast charging and discharging (at up to 40 Amps) LiPo batteries for RC car racing. It has a built in logging function that can either log to an SD Card, or to a PC, which is what I was doing. I set the iCharger to assume it was connected to a Lead Acid battery with 6 cells, and to discharge at its lowest rate of 0.05 Amps until the voltage reached 2.0v / cell (12.0v). This level of discharge is so low that it's unlikely to affect my results, and it provides me a way of logging data 1 time / second.

Unfortunately, this time, the voltage must have dropped below 12.0 for enough time for the iCharger to stop discharging, and therefore also stop logging. The drop is still visible however, and it happens at exactly the same time - 5 hours and 57 minutes!

The other thing I noticed this time, is that I started logging just before I locked the car, and simulated closing the trunk. The voltage drop caused by locking (the first fluctuation in the zoomed in region below), and by closing the trunk, are significant - a drop of 0.15v from 12.16 to 12.01. Closing the trunk causes the tail lights to flash if the car is already locked, as it was in this case, and maybe some other things to happen, but the point is that it doesn't take much for the voltage to drop temporarily on a Lead Acid battery.

[ZPrime]

Very interesting... dug this up from the 2addicts section, and linked from there was this other thread where people were discussing tapping from the FEM module/ECU directly in hopes of avoiding any "external battery drain" warnings...

In that second thread, it was mentioned that when tapping directly from the FEM, it cuts the camera off after 6 hrs anyway.

I wonder if what is happening is that there is a ~6hr idle time in some of the main ECUs, after which they all wake up simultaneously to perform "final work" and then shut off more permanently? That flurry of activity could explain the voltage drop you see at the battery, which would then trigger the PMP to shut off.

Personally I don't think I care about a 6 hour idle time... About the only time my car is parked that long at a stretch would be in my garage at home, where I shouldn't have anything to record anyway. But if you are street parking or routinely sit out in a lot somewhere, I can see why you'd want the longer time and I'm curious to see if there is some way around this. You'd probably need to hack up an Arduino that has its own battery (to run through any voltage drop?) and then does a more comprehensive monitoring of power (average voltage over a 10-15-30sec period or something).

[Nezil]

Originally Posted by ZPrime

Very interesting... dug this up from the 2addicts section, and linked from there was this other thread where people were discussing tapping from the FEM module/ECU directly in hopes of avoiding any "external battery drain" warnings...

In that second thread, it was mentioned that when tapping directly from the FEM, it cuts the camera off after 6 hrs anyway.

That sounds a lot more invasive than a fuse tap, and something I'd rather not have to do...

I wonder if what is happening is that there is a ~6hr idle time in some of the main ECUs, after which they all wake up simultaneously to perform "final work" and then shut off more permanently? That flurry of activity could explain the voltage drop you see at the battery, which would then trigger the PMP to shut off.

That's a great suggestion, and one that does make a lot of sense. I'm pretty sure that after six hours, the car does shut more things down, and it's interesting to me that the theory of locking doors or not doesn't seem to hold true with our cars... the same voltage behaviour occurs whether I lock the car or not. I'd heard it before, so it may have been a thing a few years ago, but no longer, probably because people have a habit of leaving their cars unlocked in their garage!

Personally I don't think I care about a 6 hour idle time... About the only time my car is parked that long at a stretch would be in my garage at home, where I shouldn't have anything to record anyway. But if you are street parking or routinely sit out in a lot somewhere, I can see why you'd want the longer time and I'm curious to see if there is some way around this. You'd probably need to hack up an Arduino that has its own battery (to run through any voltage drop?) and then does a more comprehensive monitoring of power (average voltage over a 10-15-30sec period or something).

Actually my use cases are somewhat complicated... I need it powered up in the garage at home so that I can pull files off with my automated script. This works great, and is totally seamless, but it does take a few hours to complete each day. 6 hours shut off in this situation is actually perfect, so I'm happy with the current behaviour in this most common of cases, and this is why it's taken me so long to investigate the problem.

My other use case however, is when I park at work, or in San Francisco for an all day meeting, or at the airport for a day trip to LA. In all of these cases, I am often away from the car for more than 6 hours, and it's also the time that I actually care about parking mode working.

I'm at the point now where I'm considering a Cellink B, even though it costs $199.00 currently. It's a lot of money for a battery, and I'm annoyed that it's not actually going to solve my issues entirely. It will work fine for my away from home situations, but when I am home, it will power the camera all night, and I don't think my 20 minute drive to work will be sufficient to charge the battery. I wish there was a way that the Cellink B could be used only when the battery dropped below the 12.0v, but I could switch it on when needed, and not when I don't. I'm still trying to get my head around that conundrum before placing an order for it, but it looks like it's the best solution at this point.

To be honest, I'm also thinking that our cars ECUs are pulling quite a bit from the battery during the 6 hour period before things truly shut off. I'm almost thinking that the PMP is actually doing the right thing, and going beyond 6 hours might actually be a bad thing to do; another reason why getting the Cellink B might be a good idea. I'm sort of happy with 6 hours with the PMP as it is, but am considering the Cellink for the times when I go beyond that.

[Nezil]

So I ordered the Cellink B from BlackBoxMyCar for $199 just before their Boxing Day sale ends... I wouldn't say I have buyer's remorse, but I'm not happy about having to spend so much money.

I believe it wouldn't be needed if I fitted a PMP to my wife's Honda Pilot, because I think it has less going on to mess with the voltage after 6 hours.

Interestingly I've seen both BMW and Audi users complain that they only get 6 hours, and many other users say that they get as much as 36 hours. I have a feeling that zee German auto makers have so much going on, and they're all seeing this 6 hour drop that I'm seeing.

I've decided what I'm going to do is fit the PMP in line after the Cellink, so that I can use its timer functionality rather than it's voltage detection functionality. This way I can set it to 6 hours under normal use, which should only discharge the Cellink about 25%, and my short drives to work would top this up in normal use. Then when I need to park for longer, I'll set the PMP to indefinite and let the Cellink run to empty, which should be up to 25 hours if you believe the specs.

My biggest concern is if it doesn't get to charge sufficiently and over time just runs lower and lower because I don't do a long drive to work and back. I really don't want the hassle of moving it inside to charge it or similar.

There is a new Cellink called the NEO, which at $270 is even pricier. It's a neater unit, and it has the capability of charging at 9A rather than the 'B' at only 7A. It might have been a better choice but I just can't justify $270 for this...

Now that I've said that, I'm going to get a hit and run when the Cellink goes flat aren't I!

[ZPrime]

The thing I don't like about the Cellink is that it's Lithium Ion (or LiPoly, or similar). Draining them to dead is not the best thing for their longevity... drain it dead a few times and you've halved the life. Seems like a stupid design choice for something that is basically designed to be drained dead (if necessary). Lead acid is actually a better choice.

[Nezil]

Originally Posted by ZPrime

The thing I don't like about the Cellink is that it's Lithium Ion (or LiPoly, or similar). Draining them to dead is not the best thing for their longevity... drain it dead a few times and you've halved the life. Seems like a stupid design choice for something that is basically designed to be drained dead (if necessary).

Actually, this is where the Cellink really excels, so I hope not everyone is making the same assumption as you.

The Cellink has a LiFePO4, often shortened to LiFe by people that know about batteries, as opposed to LiPo or Li-Ion which is the more common battery technology found in laptops, cell phones, tablets and portable battery packs.

LiPo batteries have got to the point where they have by far the highest energy density (both by size and weight), as well as the lowest internal resistance which means they can be charged and discharged without getting too hot, even at very high current draw.

I have LiPo batteries for my RC Car racing, which are 2 cell (7.4v nominal, 8.2v when charged) 5,000mAh packs that can discharge at 100C - 50 Amps! I have also charged them regularly at up to 10C, which is 50 Amps, and takes about 10 minutes from empty.

So LiPo batteries are ubiquitious, and hugely powerful, but they're also somewhat fussy. They don't perform well at all at low temperatures, if you over charge them they explode, and if you over discharge them they explode. The big issue with battery packs of cells in series, is that if you don't monitor the individual cells, you could have one that's at a lower state of charge than another in series; your overall voltage is fine, but one could be about to explode both in the discharge and charge cycles. To make this more complex, the max and min charge voltages are affected by temperature, so a fully charged battery at room ambient temperature will affectively be an over charged one when it gets cold!

LiFe is less popular, mostly because its energy density is lower. It is however less fussy about temperature, still has pretty low internal resistance and can be charged and discharged fairly quickly, though not as high a rate as the best LiPo batteries. It can also be deep cycled 2 to 3 times more than LiPo.

EGen, the makers of the Cellink have deliberately chosen slightly more rare LiFe packs for the Cellink because these reasons, and it's for this reason that it's a) a bit more expensive than it's competitors, and b) it's the ideal choice for a dashcam battery given the usage scenarios (wide temperature usage range, deep cycles, lots of cycles, fast charge ability).

Lead acid is actually a better choice.

Standard Lead Acid (car battery) is actually a really poor choice because it isn't designed to be drained ever. It's more like a capacitor than a battery, because it doesn't like to be discharged much at all, hence the need for battery tenders etc.

[cookiesowns]

Hrm. I have a few ideas of this what might be.

1) The car more than likely runs the EVAP pump to test for fuel tank leaks right around the 6hr mark. If it activates the fuel pump this will explain current draw.

2) On cars with NBTEvo and connected drive the car actually sends data to BMW HQ with your FASTA data. It's not small at all, so 2 minutes seems plausible.

Where exactly are you tapping for this feed? You could also be getting an in-accurate read near the IBS sensor. The car may also be doing some funky stuff if it detects additional current draw from your dashcam.

If you drive your car a decent amount, i'd say just set the limit for the PMP to 11.9 or 11.8 or thereabouts. BMW can behave just fine in californian climates even with a battery that sits at 11.8V. provided its still new enough to deliver the amperage.

[Nezil]

Originally Posted by cookiesowns

Hrm. I have a few ideas of this what might be.

1) The car more than likely runs the EVAP pump to test for fuel tank leaks right around the 6hr mark. If it activates the fuel pump this will explain current draw.

2) On cars with NBTEvo and connected drive the car actually sends data to BMW HQ with your FASTA data. It's not small at all, so 2 minutes seems plausible.

Interesting suggestions for sure.

Where exactly are you tapping for this feed? You could also be getting an in-accurate read near the IBS sensor. The car may also be doing some funky stuff if it detects additional current draw from your dashcam.

I tried both at the fuse box (second result above) and at the battery terminals themselves (first data set), the results were practically identical.

If you drive your car a decent amount, i'd say just set the limit for the PMP to 11.9 or 11.8 or thereabouts.

The problem is that the PMP cannot be set to 11.9 or 11.8, it only has options for 12.0 and 12.5. Sometime along the way they modified the way that the dip switches work because the older versions did have different voltage settings.

I did think about trying an alternative battery monitor, but I do think it might be best to go with the additional battery pack now.

Ideally I'd like to see parking mode recording (without WiFi) for 48 hours. This is pretty much the limit of what I'd need, and even then it would be rare to be away from the car that long. I think 15 hours is more likely if I do a day business trip down to Hollywood and catch an early morning flight out and an evening one back.

Most days it would likely be:

• 15 minute drive to work
• ~9 hours parked outside the office (parking mode)
• 15 minute drive home
• ~3 hours needed powered on in the garage to download the files from the day

BMW can behave just fine in californian climates even with a battery that sits at 11.8V. provided its still new enough to deliver the amperage.

I'm sure that's true, but I don't really want to be caught not being able to start the car.

Fortunately the M2 has only an AGM battery rather than Li-Ion, so if it does fail it's quite a bit cheaper to replace.

For reference though, the battery in my 2012 Jaguar XF failed at 3.5 years and it was garaged every night in California just as the M2 is now. Fortunately that was covered under warranty by the dealer.

[cookiesowns]

Originally Posted by Nezil

Interesting suggestions for sure.



I tried both at the fuse box (second result above) and at the battery terminals themselves (first data set), the results were practically identical.



The problem is that the PMP cannot be set to 11.9 or 11.8, it only has options for 12.0 and 12.5. Sometime along the way they modified the way that the dip switches work because the older versions did have different voltage settings.

I did think about trying an alternative battery monitor, but I do think it might be best to go with the additional battery pack now.

Ideally I'd like to see parking mode recording (without WiFi) for 48 hours. This is pretty much the limit of what I'd need, and even then it would be rare to be away from the car that long. I think 15 hours is more likely if I do a day business trip down to Hollywood and catch an early morning flight out and an evening one back.

Most days it would likely be:

• 15 minute drive to work
• ~9 hours parked outside the office (parking mode)
• 15 minute drive home
• ~3 hours needed powered on in the garage to download the files from the day

I'm sure that's true, but I don't really want to be caught not being able to start the car.

Fortunately the M2 has only an AGM battery rather than Li-Ion, so if it does fail it's quite a bit cheaper to replace.

For reference though, the battery in my 2012 Jaguar XF failed at 3.5 years and it was garaged every night in California just as the M2 is now. Fortunately that was covered under warranty by the dealer.

Both the AGM battiers in my 7+ year old BMW's lasted right around 5-7 years. These cars don't get driven much but are garaged and occasionally trickle charged.

[ZPrime]

Originally Posted by Nezil

Actually, this is where the Cellink really excels, so I hope not everyone is making the same assumption as you.

The Cellink has a LiFePO4, often shortened to LiFe by people that know about batteries, as opposed to LiPo or Li-Ion which is the more common battery technology found in laptops, cell phones, tablets and portable battery packs.

LiPo batteries have got to the point where they have by far the highest energy density (both by size and weight), as well as the lowest internal resistance which means they can be charged and discharged without getting too hot, even at very high current draw.

I have LiPo batteries for my RC Car racing, which are 2 cell (7.4v nominal, 8.2v when charged) 5,000mAh packs that can discharge at 100C - 50 Amps! I have also charged them regularly at up to 10C, which is 50 Amps, and takes about 10 minutes from empty.

So LiPo batteries are ubiquitious, and hugely powerful, but they're also somewhat fussy. They don't perform well at all at low temperatures, if you over charge them they explode, and if you over discharge them they explode. The big issue with battery packs of cells in series, is that if you don't monitor the individual cells, you could have one that's at a lower state of charge than another in series; your overall voltage is fine, but one could be about to explode both in the discharge and charge cycles. To make this more complex, the max and min charge voltages are affected by temperature, so a fully charged battery at room ambient temperature will affectively be an over charged one when it gets cold!

LiFe is less popular, mostly because its energy density is lower. It is however less fussy about temperature, still has pretty low internal resistance and can be charged and discharged fairly quickly, though not as high a rate as the best LiPo batteries. It can also be deep cycled 2 to 3 times more than LiPo.

EGen, the makers of the Cellink have deliberately chosen slightly more rare LiFe packs for the Cellink because these reasons, and it's for this reason that it's a) a bit more expensive than it's competitors, and b) it's the ideal choice for a dashcam battery given the usage scenarios (wide temperature usage range, deep cycles, lots of cycles, fast charge ability).



Standard Lead Acid (car battery) is actually a really poor choice because it isn't designed to be drained ever. It's more like a capacitor than a battery, because it doesn't like to be discharged much at all, hence the need for battery tenders etc.

I appreciate the battery education... I thought they were using Lithium Ion or Lithium Poly, which IME with tech stuff, doesn't like to be drained to dead. Good to know it's actually something better!

[dtmurf]

Originally Posted by Nezil

Most days it would likely be:

• ~3 hours needed powered on in the garage to download the files from the day

.

Assuming your car is not involved in a hit and run every day, why download the video every night? Storing 9+ hours of your car sitting there parked seems like a waste of memory...

[Nezil]

Originally Posted by dtmurf

Assuming your car is not involved in a hit and run every day, why download the video every night? Storing 9+ hours of your car sitting there parked seems like a waste of memory...

It doesn't download 9+ hours worth... the car only records on motion or on some form of impact. I guess if I parked on a busy street it might continuously record for 9 hours, but I don't.

Having said all of that, I have a 1TB drive hooked up to handle the data at home, and the process deletes the data once it's 2 weeks old so it's not just building up indefinitely. As you said, there isn't much use in the data until something happens, so I'd only check it if that were the case. I might not notice some damage for a day or so though, so I thought it best to keep the data for a couple of weeks so that I can go back and check on it if that is the case.

I have a Cellink B now, and plan to install it to make use of the PMP's timer functionality, if I need it. In normal use, I'll probably set it up with a 6 or 12 hour timer, and then extend the duration if I know I'm going to be parking somewhere for longer. So I'll have the Cellink connected to the same fuse I currently use for accessories only, followed by the PMP, and the camera connected to that.

I've seen some threads with people discussing letting the Cellink continue to charge while the car is stopped, therefore having the PMP on the input side to the Cellink. I think the idea there was that the Cellink would be more likely to be fully charged, and that's fair, but it would also ensure that the car battery is usually discharged, and that's less desirable.

I'll report back on how this works day to day once I've installed the Cellink and I have more experience with the setup.

[dtmurf]

Originally Posted by Nezil

... I might not notice some damage for a day or so though, so I thought it best to keep the data for a couple of weeks so that I can go back and check on it if that is the case.

Ah, make sense! I completely forget how it works in parking mode (only records when something happens) but you are absolutely right about maybe not noticing some damage for a few days so I can't fault your logic there.

This thread has provided quite the battery education so thanks for that!

Just picked up a DR750S-2CH, a PMP, a Cellink B and a hardwire kit for the M2. I have a DR650S-2CH in my daily but I just run it from the 12v outlet as I'm not much worried about when its parked. I want to hardwired the M2 so I need to do a little research on how to install it plus I don't want it to run in the garage so I'm thinking a switch somewhere convenient.

[Nezil]

OK, so I've done the install, and will post here on the findings, but I'm going to document the install itself in a new thread, so that if anyone is interested in the installation part, there is an easily searchable reference.

The link to that thread is here: http://f87.bimmerpost.com/forums/sho...php?p=22651100

[Nezil]

So I have some feedback on the run-times and charging of the Cellink. It's only initial findings, but I think it's valuable because it gives an indication of how much time it takes to charge the battery, and how long the battery lasts in regular usage.

Before install, I charged the Cellink fully inside the house with a 12v DC power source. So starting from full on Saturday night, after installation, the Dashcam ran for 12 hours and then shut off because of the PMP timer as intended - first time running for 12 hours in parking mode; wahoo!

By this time, the battery would have been discharged, but how much, is unknown...

By looking at the files from the Dashcam on Sunday, I can see when I drove, parked and drove again throughout the day. When I got home, I checked the status of the battery, and it showed that it was fully charged, so I assume that it finished charging at some point on the last drive.

- 12 hours discharging overnight -
09:35 - Started driving
- 29 minutes charging -
10:04 - Stopped driving <- at this point I checked the battery, and it was not fully charged
- 70 minutes discharging -
11:15 - Started driving (charging)
- 13 minutes charging -
11:28 - Stopped driving
- 47 minutes discharging -
12:15 - Started driving
- 34 minutes charging -
12:49 - Stopped driving <- battery was fully charged at this point
- 12 hours discharging -
01:57 01/15 - Disconnected (due to 12h PMP timer)

So in total, 76 minutes of charging, with 117 minutes of discharging resulted in a full battery.

Overall, my concern is that if I do 12 hours of discharge every night, and only a few short drives in between to work and back, will the battery slowly but surely reduce in charge to the point where it won't last more than 12 hours.

In other words, if the amount of charging of the Cellink battery in a 24 hour period does not offset the amount of discharging.

[Nezil]

I've just pulled off the videos from today's not atypical day of driving to the office and back.

I wasn't at the office the whole day because I worked from home for a lot of it, but here's the data:

- 12 hours discharging overnight -
11:38 - Started driving
- 17 minutes charging -
11:55 - Stopped driving
- 122 minutes discharging -
13:57 - Started driving (charging)
- 15 minutes charging -
14:12 - Stopped driving
- 12 hours discharging (in progress) -

In this somewhat typical day, there was only 32 minutes of charging, and if you include the 12 hours overnight from the night before, that's 842 minutes (14 hours 2 minutes) of discharging.

In theory, the Cellink should charge at 7 Amps, and is a 6,000mAh battery. Charging at 7 Amps is a little over 1C, and that means it should be charged in around an hour at that rate, if totally discharged.

If 30 minutes of driving charged the battery 50%, this usage will be sustainable only if the dashcam discharges less than 50% in 14 hours... and I don't think that's likely.

If I set the timer to 6 hours, it might put me in a position where the battery is charged by the time I get to work.

All of this would be a lot easier if I had bought the Cellink NEO rather than the B; the capacity is the same, but the NEO charges slightly faster, and it has bluetooth so that you can monitor the state of charge.

[Nezil]

I decided to connect an Ammeter in series with the DashCam to see what the current draw was like. I'd read somewhere that it was around 300mA, but wanted to confirm that.

During boot up, the current draw ranges from 100mA to around 350mA, but then quickly settles at ~300mA once booted (confirmed by a 'connected' messaged from BlackVue Cloud).

Once in parking mode, the current draw sits at ~270mA while nothing is being recorded.

During 'live view' the current draw is ~290mA, and while recording in parking mode, the current draw fluctuates between ~270mA and ~300mA, presumably as the SD card is written to.

I didn't see the draw exceed 300mA, and I didn't see it drop below 270mA.

The only thing I've not yet tried is measuring the draw when WiFi is disabled, assuming that's possible. As I've said, disabling WiFi doesn't work for my use case, because I want files downloaded over WiFi, but it might be useful to extend the run-time if I'm parking for an extended duration, as I will be on Wednesday this week.

[Nezil]

So some maths:

Assuming the current draw is 300mA, and the battery is 6000mAh, the run time should be 20 hours (6000/300 = 20), if everything works at 100% efficiency, which it won't...

Running for 12 hours every night will drain the battery 60% (300mA x 12 hours = 3,600mAh) leaving 40% remaining.

If the battery charges at 7A, it would take about 31 minutes to re-charge (3,600mAh / 7000A * 60 = *30.86 minutes), again, assuming 100% efficiency, which it won't be.

If I were to run the camera for 6 hours however, everything would be halved, and the battery might just be charged by the time I get to the office... If I had a charge rate of 9A, like the new Cellink NEO has, this would almost certainly be the case.

[Nezil]

I just measured the current draw with WiFi disabled... When I spoke with BlackBoxMyCar.com previously, they suggested that this might extend the run time of the camera, so I thought it was worth a try.

Sadly, although it does reduce the current draw, it's fairly minor; here's the results:

WiFi enabled, recording to SD: 270mA ~300mA
WiFi enabled, transferring over WiFi, reading from SD: 280mA ~ 290mA
WiFi enabled, at rest, not recording, not transferring: ~270mA
WiFi enabled, live view (cannot be accessing the SD card at the same time): ~280mA

WiFi disabled, recording to SD: 250mA ~ 270mA
WiFi disabled, at rest, not recording: 240mA ~ 250mA

So at most, the effect of WiFi is only 30mA, which is about 10% of the overall drain. I guess it might be useful to eek out an extra few hours over a long parking stint, gaining you maybe an additional 2 hours of parking mode (22 hours vs 20 hours).

The last thing to test is the effect of running the dashcam with only the front channel active. If you reverse into your space, this might be worthwhile knowing about.