Simple battery pack set up?

[gr1nch]

Hi,

I've been assembling parts for a discreet dashcam install (a JooVuu X) and going to fit tomorrow. I just wanted to check the experience of others who have got similar setups, i.e.

Car USB <---A---> battery pack <---B---> dashcam

A - charging only when the engine is
B - always on power, parking mode enabled

Like many others I want to avoid exhausting the car's battery such that it would cause an issue, but also without 3rd party battery protection gear. Any issues with this?

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[gr1nch]

So put the complete system in with the power back in the armrest box where the USB slots are. I was able to conceal it under the overhang inside the box, using double sided tape (the kind used for securing number plates)

but the connectors accessible and charging LEDs still visible.

I checked that power is not supplied to the battery pack when the car is empty and locked (my preference as I can't risk the car battery being depleted). Parked up overnight and a couple of road tests showed the dashcam operates continuously as desired with the power bank in the power chain.
I had to swap the new 22Ah unit with my two year old 28Ah unit (both Ravpower) as the first one supported passthrough power, but turned *off* power output to the dashcam when the car was locked and then no power supplied to it's input by the USB cable. Ouch. Luckily the older unit does not have this undesirable feature.

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[gr1nch]

It turns out I hadn't looked closely enough and the powerbank's battery is actually rated 20.1Ah. I measured the dashcam's amp intake in record mode at an average rate of 0.4Ah, which implies a theoretical 50 hrs of power.

However I'm doubtful there's enough input current (measured at max 0.8Ah) from the car to recharge the powerbank fully when driving. That's half (0.4Ah) for the dashcam via pass-through and half for net topping up the battery. So 1hr of ignition on to power the dashcam for every 1hr of ignition off.

So I'll probably have to periodically remove the powerbank for an overnight charge at home where I can put 1.2-1.6Ah into it. Hence, the powerbank shouldn't be stuck directly to the glovebox. Thinking about the best system, I think stone kind of rigid plastic plate stuck to the glovebox with Velcro straps to hold and restrain the powerbank.

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[dash riposki]

3M Duallock?

The somewhat translucent, 'super' plastic velcro.

I'm just curious if daily use will shorten the life of the power bank?

I think I'd lean toward one of the power bank cases you put your own 18650 batteries in, at least the batteries could be changed easily.

 

[SawMaster]

LiPo and LiIon batteries like to be used more heavily versus lightly so this usage will not hurt the powerbank at all, though a lack of good charging might shorten it's lifespan somewhat. Of course the capacity (and therefore the runtime) will be less with a pack which isn't fully charged. Powerbanks are neat and easy but I'm still of the mind that best would be an AGM or wet-cell deep-cycle battery for long term cam operation. Perhaps a voltage-sensing circuit could be implemented with 2 powerbanks for longer runtimes and so that the 'idle' bank could receive a greater charge while driving Same as with the cam itself there is no one perfect solution here though this one is impressive and should work well enough

Phil

 

[gr1nch]

3M Duallock?

The somewhat translucent, 'super' plastic velcro.

Not heard of it before, but looking it up on Amazon, it certainly looks strong, but probably a little too much for what I have in mind. I'm looking for

* Double-sided sticky tape to permanently fix a backing plate (likely plastic) to the furry felt material on the glovebox over wall. This number-plate tape might be ok, though the powerbank came loose after the first drive.

* 2 x Velcro loops threaded through the backing plate that will secure the powerbank.

I'm just curious if daily use will shorten the life of the power bank?

It doesn't seem to have done on the trusty powerbank I mentioned which has been in daily use for the past two years, including passthrough once or twice a week.

I think I'd lean toward one of the power bank cases you put your own 18650 batteries in, at least the batteries could be changed easily.

If you end up doing that, post pics! At this stage, on my first foray into dashcams and battery systems, it's easier for me to remove a single unit for full recharging.

However it would be pretty cool to be able to "hot swap" individual batteries in an array (like HDDs) whilst preserving current flow from the rest to keep the dashcam on. Similar to this - https://m.aliexpress.com/s/item/32791112853.html

From the specs, can't tell if there was a hot swap function, though the individual battery level meters suggest the circuitry could provide aggregated power.

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[SawMaster]

Individual LiIon cells should be matched when used in parallel, and absolutely MUST be matched when used in series or you can easily end up having a cell vent with flames (think 'hoverboard fire' ) Thus no 'hot-swapping' cells unless you swap them all with another matched set, which kind of renders the point moot You'll also need a good charger with these, and know how to test and maintain them as they may wear differently over time. LiIon cells are generally safe when used correctly but when things go wrong the consequences can be extreme, so I'd highly recommend staying with factory-made powerbanks of good quality as the easiest way to avoid the potential hazards here.

This coming from an experienced LiIon cell user with the equipment to use them correctly, it is advice I would follow my own self

Phil

 

[dash riposki]

That's roughly the same type of 18650 case/charger I was suggesting.

 

[Rajagra]

It turns out I hadn't looked closely enough and the powerbank's battery is actually rated 20.1Ah.

Just a quick observation, that's 20.1 Ah at 3.7V. They've added up the Ah capacity of the individual cells.
It says 74.3Wh.
20.1Ah x 3.7V=74.37Wh.

The capacity at 5V is 74.3Wh/5V=14.86Ah

I'm sure most battery packs make claims about capacity in a similar way. Which is a bit naughty considering the user only sees 5V. The 3.7V is a hidden internal technicality.

 

[jokiin]

standard practice to advertise the biggest number you can claim, would work well as a power supply for all the cameras with 170° lenses

 

[Rajagra]

Yup, my Anker PowerCore+ does the same. It claims 96.48Wh and 26.8Ah.
96.48Wh is 26.08Ah at 3.7V, or 19.3Ah at 5V.

I have a no-name pack that's more honest, it is printed with: "Capacity: 3.7V/25000mAh/92.5Wh" which is spot on.
But of course it is marketed simply as a "25000mAh Portable Charger."

 

[gr1nch]

Just a quick observation, that's 20.1 Ah at 3.7V. They've added up the Ah capacity of the individual cells.
It says 74.3Wh.
20.1Ah x 3.7V=74.37Wh.

The capacity at 5V is 74.3Wh/5V=14.86Ah

I'm sure most battery packs make claims about capacity in a similar way. Which is a bit naughty considering the user only sees 5V. The 3.7V is a hidden internal technicality.

Ah ha! Thanks for that, I'd not given it a thought. So that'll bring down the anticipated hours quite a bit, nearer to a day and a half if I've got my sums right this time [emoji16]

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[SawMaster]

There's also something lost in the conversion of 3.7V at the cells up to 5V at the USB port- boost converters aren't totally efficient. 85%-90% is common in the cheaper ones. Only actual testing can tell you what you'll get in real-world runtimes, the math will only get you close

Phil

 

[DavidUK]

@gr1nch - is your set up in your opening post one where you leave all the cables permanently attached between car>battery pack>cam?

If so, I researched this to the nth degree over a year ago and decided it wouldn't work, after being "told off" by many knowledgeable members here: https://dashcamtalk.com/forum/threads/battery-pack-with-12v-socket-plug-in.21939/

There are two main points:
1/ The battery pack won't charge whilst discharging - i.e. the pack will become depleted.
2/ It is unwise to try and charge whilst discharging - i.e. it is unsafe.

Have a read through the whole thread, especially post #49.

My conclusion was that I could charge a battery pack from one 12v car source whilst driving , power the cam from another, then physically switch the cam's power cable from the car 12v socket into the battery pack when I wish to continue to record with the car switched off, but to leave the cabling in place as you propose would not be a solution.

 

[gr1nch]

@gr1nch - is your set up in your opening post one where you leave all the cables permanently attached between car>battery pack>cam?

If so, I researched this to the nth degree over a year ago and decided it wouldn't work, after being "told off" by many knowledgeable members here: https://dashcamtalk.com/forum/threads/battery-pack-with-12v-socket-plug-in.21939/

There are two main points:
1/ The battery pack won't charge whilst discharging - i.e. the pack will become depleted.
2/ It is unwise to try and charge whilst discharging - i.e. it is unsafe.

Have a read through the whole thread, especially post #49.

My conclusion was that I could charge a battery pack from one 12v car source whilst driving , power the cam from another, then physically switch the cam's power cable from the car 12v socket into the battery pack when I wish to continue to record with the car switched off, but to leave the cabling in place as you propose would not be a solution.

Thanks for the link, it makes interesting reading, despite the unnecessary clashes within it. Surprisingly it got me thinking about designing a better powerbank! I posted it there [emoji16].

As for my set up, I have the dashcam USB cable terminating in the glovebox next to the car's native USB socket, of which there are two. So I can power the dashcam directly from the car if wanted.
Next to the car USB socket is my powerbank. It does support pass-through power and has been doing so for 2 years indoors whenever I felt like it, with no adverse affects. I trust this particular powerbank.
Now to the risks. The only time in the car that the powerbank is passthrough charging, is when I am in it with the ignition on. High temperatures are generally not an issue as I live in Lincolnshire, a fairly windy, cool county.
If I wanted to completely avoid passthrough power, the dashcam powered when parked by a fully charged powerbank and for the powerbank to never leave the car (e.g. for fast home charging), then the only solution I can currently think of is 2 powerbanks. When driving one powerbank getting charged over USB (at about 0.8Ah in my car), with the dashcam on direct car power over USB. When parked the other powerbank would power the dashcam. Fiddly to swap the USB cable ends in the glovebox, but that's all.

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[dzal67]

Thanks for the link, it makes interesting reading, despite the unnecessary clashes within it. Surprisingly it got me thinking about designing a better powerbank! I posted it there [emoji16].

As for my set up, I have the dashcam USB cable terminating in the glovebox next to the car's native USB socket, of which there are two. So I can power the dashcam directly from the car if wanted.
Next to the car USB socket is my powerbank. It does support pass-through power and has been doing so for 2 years indoors whenever I felt like it, with no adverse affects. I trust this particular powerbank.
Now to the risks. The only time in the car that the powerbank is passthrough charging, is when I am in it with the ignition on. High temperatures are generally not an issue as I live in Lincolnshire, a fairly windy, cool county.
If I wanted to completely avoid passthrough power, the dashcam powered when parked by a fully charged powerbank and for the powerbank to never leave the car (e.g. for fast home charging), then the only solution I can currently think of is 2 powerbanks. When driving one powerbank getting charged over USB (at about 0.8Ah in my car), with the dashcam on direct car power over USB. When parked the other powerbank would power the dashcam. Fiddly to swap the USB cable ends in the glovebox, but that's all.

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Do you think that would work? I would like to know before I destroy few cables.

 

[Rajagra]

The problem with that circuit with the diodes is that there is a forward voltage drop across each diode. A drop of 0.3v to 0.7v is typical and is a lot to lose if you're starting with 5v. It may or may not work. Using diodes on dual 12v supplies would be less of a problem.

I bought a couple of those power banks you can put 18650 batteries in. The good news is the batteries are not connected in parallel. They are tested and charged individually, and you can have any number of batteries fitted. I'd hope that when the power bank is supplying power it does so in a similarly clever way.

Time for some testing!

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[dzal67]

I'm not professional in that area I am not sure if diodes are required. It is possible (very likely) that phone charger and battery pack output is protected against reverse electric flow. No diodes would make it even simpler. Using high output dual usb phone charger, camera would be powered and battery pack would be charged while ignition is ON. With ignition OFF and no power to cigarette lighter socket, battery pack would kick in and power dash camera in parking mode. I hope I'm not missing something.

 

[gr1nch]

Thanks for the link, it makes interesting reading, despite the unnecessary clashes within it. Surprisingly it got me thinking about designing a better powerbank! I posted it there [emoji16].

As for my set up, I have the dashcam USB cable terminating in the glovebox next to the car's native USB socket, of which there are two. So I can power the dashcam directly from the car if wanted.
Next to the car USB socket is my powerbank. It does support pass-through power and has been doing so for 2 years indoors whenever I felt like it, with no adverse affects. I trust this particular powerbank.
Now to the risks. The only time in the car that the powerbank is passthrough charging, is when I am in it with the ignition on. High temperatures are generally not an issue as I live in Lincolnshire, a fairly windy, cool county.
If I wanted to completely avoid passthrough power, the dashcam powered when parked by a fully charged powerbank and for the powerbank to never leave the car (e.g. for fast home charging), then the only solution I can currently think of is 2 powerbanks. When driving one powerbank getting charged over USB (at about 0.8Ah in my car), with the dashcam on direct car power over USB. When parked the other powerbank would power the dashcam. Fiddly to swap the USB cable ends in the glovebox, but that's all.

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Do you think that would work? I would like to know before I destroy few cables.View attachment 35851

Could you clarify the question? I've not had to destroy any USB cables so farwith my set up [emoji6]

For a few weeks I've been running a single power chain successfully (if interested, you can see the detailed install in a previous post)

Car USB <> powerbank <> dashcam

Since the powerbank is not hard-wired to the car's electrical system, it only receives power when the key is in the vehicle, i.e. when I'm in it, so there is no unattended pass-through activity.

The powerbank acts (a) as a UPS so giving continuous recording, avoiding brownouts etc (e.g. turning engine off/on if waiting for someone, etc) and (b) as the dashcam's only power source in parking mode.

Often I don't need parking mode so turn off the dashcam either (i) by its own power button or (ii) by temporarily removing the USB cable end from the powerbank, which is accessible, but a little fiddly.

At some point (i) won't be practicable because I'll be fitting a custom made, hopefully seamlessly professional-looking, dashcam cover, hiding all buttons.

Getting to the numbers:
* Powerbank draws 800mAh from the car, when on
* Dashcam draws 400mAh from the powerbank
* Powerbank lasts in parking mode about 1.5 days

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