Parking Battery-Power Station, 3X capacity and 3X cheaper than dedicated options + extra functionality

[DigitalCorpus]

The voltage will drop under load, but for a 10 W load, it won’t be significant on 12 V systems.

 

[GPak]

I am having difficulty working out what you mean, are you saying that the hardwire kit that you connect to the 12V output has 85% efficiency while the Power Station's voltage regulator is only 76% efficient?

The numbers are for the Necespow 161Wh Power Station ONLY, extrapolated for 322Wh version (assuming the same ratio/efficiency).

Efficiency is calculated as a ratio between real tested (useful capacity), vs. manufacturers rated capacity, which is always pure battery capacity.
Here is my testing data:

 

[GPak]

There has been a bit of arguing about this in the past. The 3Wh left cutoff is good, but I suspect that is only true at room temperature, if the power station gets down to 5°C in the winter, it will leave a lot more power in the battery since the battery voltage under load, drops with temperature.

I checked this at 10W discharge rate, exectly as @DigitalCorpus mentioned, checked at room temperature, and I doubt at 5°C with the same 10W discharge rate there would be noticeable difference:

Going from 12V to 11.2V takes about 30 minutes and corresponds to approximately 5Wh.
Going from 11.8 V to 11.2 V takes about 18 minutes and corresponds to approximately 3 Wh.

Many power stations have so called DoD (Depth of Discharge) cut off protection, Bluetti for example cuts power at 90% capacity, basically keeping battery at 10% charge.

Here is more detailed test data to check how accurately the bar status is displayed. As you can see, the lifespan of the last bar is short, and it will be beneficial for the battery if the HK4 stops discharging.

 

[GPak]

BTW, I have no means to test HK4 voltage regulator efficiency, If someone has done that please post here, it will be interesting to know.

Since this is essentially a low power step down buck converter, I'm guessing the efficiency would be around 90-95%, which I forgot to account for, and that would probably eat up some of the parking capacity benefit of the 12V system.

 

[Nigel]

BTW, I have no means to test HK4 voltage regulator efficiency, If someone has done that please post here, it will be interesting to know.

Since this is essentially a low power step down buck converter, I'm guessing the efficiency would be around 90-95%, which I forgot to account for, and that would probably eat up some of the parking capacity benefit of the 12V system.

I think it is about 93%, but I don't have a way of measuring it that I trust to be highly accurate, so it will still be more efficient than using the 5V output, but not quite such a big difference as you appeared to suggest.

Anyway, there is no confusion now, we know what your figures were and people can make informed decisions.

checked at room temperature, and I doubt at 5°C with the same 10W discharge rate there would be noticeable difference:

I've not tested it, but the graphs I found last time I looked into it suggested that temperature was far more significant than I expected, mainly because the discharge "curve" for these batteries is very flat, so a 1V change due to temperature makes a big difference to how much is left when it cuts off. 5°C isn't too bad, but for many people it is also not very cold! -20°C puts most of the discharge curve below the cutoff.

 

[GPak]

Here is what I found, if the data here is correct, then yes, the low temperature significantly degrades usable capacity of LFP batteries.

Marine lithium batteries in operation | Nordkyn Design

This article details the relations between voltage, state of charge, current and temperature for lithium iron phosphate (LFP or LiFePO4) battery banks.

nordkyndesign.com

11.8V cut-off farther lowers the usable capacity
This is why extra capacity is Good.

 

[GPak]

Per data above, the low temperature considerably degrades usable capacity of LFP battery.
I was not able to find different source to confirm it, and so I tested my Necespow 161Wh Power Station (PS).

I placed the PS into my freezer set to 1°F = -17°C for the night, but this morning, when I tried to start the test, PS did turn ON, but did not discharge and turned OFF shortly.
Amazingly, Necespow 161Wh does what it says in manual, i.e. operating temp range from -10°C to +65°C, so it will not operate/discharge below -10°C.

Because the temp display is just 2 digit, showing only up to -9°C, I waited a little and started the test at about -9°C.
I tested at 2.36A (0.19C) constant amperage, the same as I tested this same PS at room temperature to compare apples to apples.
(At the end, when test stopped and I tried to see the result PS actually started to discharge again, which initially confused me, but it lasted for a couple of minutes only, adding jus 1Wh, so I ignored that portion from the table)

Notes:
-Unlike pure LFP cell, PS also has an additional self-consumption for BMS, internal circuitry, display, and possibly some DoD limit, hence the results are not numerically the same to the data above, which is for pure LFP Cell, without any other loses and also at unknown discharge C rate. However the test shows the similar behavior/trend at low temperature.

-When the voltage dropped below the lowest HK4 hardwire setting of 11.8V, I briefly lowered the amperage to about 7.7W discharge rate, equivalent to the most demanding 3ch DVR parking consumption at low bit-rate.
As a result Voltage went up by +0.6V and above 11.8V, hence this PS, at 7.7W draw rate, probably will maintain above 11.8V very close to the end.

-Even so the PS was seating inside of -17°C freezer, as soon as it started to discharge, internal battery temperature started to rise and reached equilibrium with freezer at about -4°C in average, for the duration of the test.
(In real life, parking follows driving, and the battery should be warm at the beginning of parking, and even at low sub-zero ambient temps, when left in a car, say for overnight recording, PS may never go sub-zero due to internal battery heating.)

Here is the summary table for low temp test compared to room temp test:
(Test videos will follow soon)

 

[GPak]

Here are the sub-zero discharge capacity test videos:

Here I accidentally disconnected the wires and at the end you can hear a beeping sound, but I immediately connected the wires and resumed testing.

Here, when the voltage dropped below the lowest HK4 hardwire 11.8V setting, I briefly lowered the amperage to about 7.7W discharge rate, equivalent to the most demanding 3ch DVR parking consumption at low bit-rate. As a result Voltage went up by +0.6V, hence this PS, at 7.7W discharge rate, will maintain above 11.8V very close to the end.

Here, after PS died, it then decided to live again, but it lasted for a minute or two, and I ignored this part from the final table

 

[Nigel]

-Even so the PS was seating inside of -17°C freezer, as soon as it started to discharge, internal battery temperature started to rise and reached equilibrium with freezer at about -4°C in average, for the duration of the test.
(In real life, parking follows driving, and the battery should be warm at the beginning of parking, and even at low sub-zero ambient temps, when left in a car, say for overnight recording, PS may never go sub-zero due to internal battery heating.)

Excellent testing, I'm surprised the battery got that warm, I do wonder if the cells were actually that temperature, maybe the thermometer is not among the cells, but clearly it doesn't matter since as you say, it is going to be a reasonable temperature when you park and is able to keep itself warm enough.

So the only real problem with cold weather is that the battery probably isn't going to charge during a normal length journey when the temperature is sub-zero °C and if it has become empty overnight. If it can survive the night without emptying then normally it will recharge because it has been keeping itself warm somehow.

Not sure what was generating the heat, since you were not using the regulated output?
Maybe it is well insulated, so didn't need much energy to get warm?

 

[GPak]

So the only real problem with cold weather is that the battery probably isn't going to charge during a normal length journey when the temperature is sub-zero °C and if it has become empty overnight. If it can survive the night without emptying then normally it will recharge because it has been keeping itself warm somehow.

That is why the extra battery capacity is so important!
In my case, Viofo Mini consumes about 2.5W in low bit-rate parking, so even 90Wh is enough for 90/2.5=36hr

 

[GPak]

Not sure what was generating the heat, since you were not using the regulated output?
Maybe it is well insulated, so didn't need much energy to get warm?

All power station self-discharge when they are turned ON, I guess BMS need power, USB circuitry is on and need power too, display needs power, and the battery itself generates heat wen discharging.
This particular PS has an aluminum shell so it is quite thermo-conductive.

 

[DigitalCorpus]

If it can survive the night without emptying then normally it will recharge because it has been keeping itself warm somehow.

Not sure what was generating the heat, since you were not using the regulated output?
Maybe it is well insulated, so didn't need much energy to get warm?

In order to cool, there needs to be an absence of thermal energy. In order to heat, there has to be a presence of thermal energy. Thermal energy is heat and technically speaking, there is no “cold”.

If the batter self-heated, then it has a self discharge problem. Keep in mind that the act of discharging the battery inherently means some movement of materials, which makes things harder to freeze. This is because, in a simplified manner, temperature is the average kinetic energy of the atoms of the material.

Also, despite the old days where alkaline batteries have a voltage recovery after they’ve been discharged due to a chemical process or some such, batteries cannot regarge themselves thanks to the laws of thermodynamics. Freezing the internals of a cell would precent it from functioning so it would appear dead, but it’s only frozen; things don’t move.

@GPak is along the right line if thinking. Yes, the shell is aluminum, but there is air present. Then the plastic jacket around the cells. Then the cell’s walls, maybe an insulating layer, then the anode and cathode materials. Air is a crap cubsuctor, thus a good insulator and for thermal purposes, they are inversely proportional to each other. The BMS does have a slight discharge effect that prevents the battery from freezing, but I can assure you this isn’t due to a heating effect. I’ll elaborate more if desired, but for now, I’ll leave with a though experiment:

Stirring Tea

 

[kawayanan]

Necespow 322Wh Power Station is a good choice especially with the lowest sale price I have seen $116.
Please do post your setup, it is interesting and may be helpful to others.

I would recommend to run 12V system, which compere to 5V system has considerable advantages:

- Power Station’s 12V DC output efficiency is better than USB (85% vs 76% or 274Wh usable vs 244Wh, the difference is 30Wh or about 5 hours of parking recording for dual channel DVR !)
- 12V system is not affected by voltage drop due to long wires, plus often USB port output is less than 5V, which may cause DVR malfunction.
- HK4 Hardwire cable can be used “as is”, un-modified, and it provides about 5.6V to DVR. When set to 11.8V CUT OFF it only cuts the last 2.2% or 3Wh of usable capacity and that is good.
(That 3Wh is “falling from cliff” energy where voltage drops rapidly from 11.8V to 11.2V at which point power station will shut OFF on its own).

Sorry for the slow response. I was working on a reply and then the website seemed to go down (for me at least), then I was traveling for the holiday.

When I ordered, the 322Wh was at $116 and the 161Wh was around $96 I think. They are shifting though. I just checked and the 322Wh is $103 and the 161Wh is $50 No clue how they come up with the prices or why they seem to change so often. With the smaller PS being that cheap, I thinking of getting one for my wife's car.

I will post my setup once completed. I was planning on using the 12V out from the power station, mostly since I didn't want to chop up the hardwire kit. Glad to know that it should be a little better off that way too.

The one thing I will probably want to mess around with is the charging setup. I can't find any manuals or specs on the power station, only their description on Amazon. Is the 12V charging circuit slower than the USB-C or can the handle similar amount of power? (it claims 5-6 hours for one input, 2-2.5 hours if you use two). My plan was to do a 12V connection to a fuse tap, and I assume I will need to get the correct barrel connector to make that connection. To improve the charging though, it looks like you need to have two inputs (65W via USB-C and the 12V input). I would rather not keep something permanently in my cigarette lighter plug, and was contemplating how to setup a fuse tap to USB-C PD 65W connection. At first I was thinking an adaptor like you linked (https://www.amazon.com/gp/B09Y39K17Z) with a female socket (like https://www.amazon.com/gp/B07CQNX7XH), but then I realized that was silly. I can get a more purpose built things like https://www.amazon.com/gp/B0C8N56TR7 and connect that to a fuse tap. This one specifically states that it returns to the one position when the car is restarted, while some other similar ones say they remain off when the car restarts and need to be turned on to charge. Since I seem to often overlook good and simpler methods, anyone have a better idea for a fuse tap to PD 65W solution?

As a potential separate future project, I should also be able to pretty simply add a solar panel as a way to charge the power station. I have a pickup with a hard bed cover, that would be easy to attach a small set of solar panels to. That way I could use the car to charge while driving, or switch to solar while parked (depending on the solar, maybe that would be enough alone to keep the power station topped off).

 

[Nigel]

All power station self-discharge when they are turned ON, I guess BMS need power, USB circuitry is on and need power too, display needs power, and the battery itself generates heat wen discharging.
This particular PS has an aluminum shell so it is quite thermo-conductive.

I'm not surprised that it warms up, it is just the amount of warming that I was surprised by, to raise the temperature of something that size from -19°C to -4°C, I would guess takes a similar amount of power as the dashcam takes. Have you measured the power in vs power out on your battery? I'm just curious as to how much is being "wasted". In my experience, lithium cells hardly warm at all at those currents, it must be going somewhere else.

 

[DigitalCorpus]

I'm not surprised that it warms up, it is just the amount of warming that I was surprised by, to raise the temperature of something that size from -19°C to -4°C, I would guess takes a similar amount of power as the dashcam takes. Have you measured the power in vs power out on your battery? I'm just curious as to how much is being "wasted". In my experience, lithium cells hardly warm at all at those currents, it must be going somewhere else.

The sensor is likely not between cells, but between the case and cells.

 

[GPak]

I'm not surprised that it warms up, it is just the amount of warming that I was surprised by, to raise the temperature of something that size from -19°C to -4°C, I would guess takes a similar amount of power as the dashcam takes. Have you measured the power in vs power out on your battery? I'm just curious as to how much is being "wasted". In my experience, lithium cells hardly warm at all at those currents, it must be going somewhere else.

The freezer temp was set to -17°C, however, briefly opening freezer to check the PS status lets warm air in, hence actual temperature inside freezer could be a bit higher during the test. Unfortunately I had no thermometer to monitor freezer temp.
I already provided discharge test results so here are charging test results, note that charging from included Wall Brick is very inefficient due to Wall Brick efficiency itself, charging with USB-C(PD) is very efficient. (assuming battery is out off all 161Wh, which I seriously doubt, I think when it is "empty" it still retains some energy)

 

[GPak]

When I ordered, the 322Wh was at $116 and the 161Wh was around $96 I think. They are shifting though. I just checked and the 322Wh is $103 and the 161Wh is $50 No clue how they come up with the prices or why they seem to change so often. With the smaller PS being that cheap, I thinking of getting one for my wife's car.

Is the 12V charging circuit slower than the USB-C or can the handle similar amount of power?

Thanks for the hint, I could not resist and ordered 322Wh version for $103

161Wh version DC input is limited to 2A (actual tested is about 1.85A) hence from cigar lighter will charge at about 12.7V*1.85A=23.5W charging rate
322Wh version DC input is limited to 4A, if actual is similarly 3.7A then 12.7V*3.7A=47W charging rate (could be higher if voltage higher)
Combined charge rate would be about 65W USB-CPD + 47W DC = 112W (using cigar lighter socket)

 

[GPak]

Look what I found, TechnoAmp N300, Power Station, review and Teardown!
It is in some Asian language, but English text comments help to understand essential info

Necespow N300 is improved version of TechnoAmp N300:
TechnoAmp N300 is using 32650, qty 16, 6.0Ah cells for 16*6Ah*3.2V=307.2Wh
Necespow N300 is apparently using 32650, qty 16, 6.3Ah cells for 16*6.3Ah*3.2V=322.56Wh

The review provides some answers, you guys been looking for:

@Nigel - Standby power used by the control board is 0.7W (AC inventor turned OFF)
@DigitalCorpus – No hanging thermo-sensor between case and battery pack, all wires are coming out from inside of Battery pack, at-list one of them must be thermo-sensor

 

[GPak]

Two things to note:

-For parking demand analysis, DVR parking consumption rate should be combined with PS self-consumption rate.
(In case of 2 x Viofo Mini2, in low bit-rate, that would be about (2*2.5W)+0.7W=5.7W, or about 14% more power)

-Moreover, N-150 PS will not auto shut-off for about 12 hr after DVR stops parking recording in accordance with time limit setting, hence, in the worst case scenario, it will self-discharge about 12h*0.7W=8.4Wh, before auto-shut-off.

 

[kawayanan]

When I ordered the N300 (322Wh), it wasn't on Prime needed about 10 days to be delivered. When I saw the 161Wh version on sale for $50 yesterday, I ordered it too, and it was fulfilled by Amazon (Prime - 1 day delivery). As a result, I got them both today. My only problem now is that I am pretty busy at work and won't have a chance to mess with them immediately. I'll post when I do though. The N300 just about fits under my front seat...

I did note that the two manuals are a good bit different. I'm not sure if people here have seen the N300 manual, and with all the discussion of cold temperature usage, I though that this might interest people.

N300 Manual:

Cold Temperature Usage
Cold temperature (-10-65°C) can affect the product's battery capacity due to chemical characteristics of the battery. If you'll be living off grid in sub-zero conditions, it is recommended to keep your product in an insulated cooler, and connected to a power source (car charger/AC adapter/solar panel). The natural heat generated by the product contained in an insulated cooler will keep the battery capacity at its highest level.

Nothing too surprising there, I just thought it interesting after the discussion above.

Edit - a few more observations:

Concerning the DC inputs - the N300 list this:

Adapter: 16V - 4A
Solar Panel: MPPT 12-25V/64W MAX
Car port: 12V - 4A 48W MAX

The AC adapter does get a bit warm when charging, but not too bad.

Overall, the N300 manual is better written and organized than the N150. I would rate it better than most Chinese manuals, and is pretty clear and informative. It does have a couple funny bits though.

The original car charger features a 10A protection tube to protect your car. You will know the machine is peing charged when the battery indicators blink.

The car cigarette adapter does have a fuse in it. I was checking this to decide if I would need to add something between a fuse tap and the DC input. I don't expect that the adapter has any features to limit the current (other than the fuse if it gets to high), so I assume that the BMS should limit it. Probably not a bad idea to have a fuse inline though.