LFP (LiFePo4) Battery for Parking, 192Wh (DIY)

[GPak]

This thread is the third one in a series of alternative parking batteries for dash cams.
Coming from these two threads, on ‘Power Stations for Parking’ and ‘LTO Battery for Parking’.

https://dashcamtalk.com/forum/threa...-dedicated-options-extra-functionality.49972/

https://dashcamtalk.com/forum/threads/lto-lithium-titanate-oxide-–-the-ultimate-battery-for-dash-cam-parking-recording-diy.50484/

I believe, we should not rely on car's starter battery to power dash cam in parking mode, stressing it with a constantly undercharged state, and sooner or later it will fail to start the car at the most crucial moment because of that.
Hence dedicated parking battery is ‘must’ in my book, perhaps with exception when the parking duration is short enough and/or daily driving is long enough.

I also must say, that the use of suitable LFP based Power Station is the simplest, the most affordable and probably the best option available for a Parking Battery.
It is safe, full of functionality and very easy “Plug and Play” installation.

Now,
After building couple of LTO Batteries the question is why LFP (LiFePo4)? The simple answer is a slight advantage in size and cost, but otherwise LTO is superior to LFP in every other aspects.
LFP chemistry has higher than LTO energy density, hence for the same battery capacity it will have less volume/weight, not by much, but still.
At the same time, LFP is safe enough, and is not far behind LTO in this regard.
So if the sub-freezing charging or very high rate of the charge is not ‘must have’, but smaller battery size is important, then LFP is preferred choice.

Here are some images showing the difference in size between the roughly equal capacity LTO/184Wh and LFP/192Wh batteries, (LFP is black).
They both are 145mm wide 250mm long (5.7” x 10”), the difference is in height, 54 mm for LFP vs 82mm for LTO. (LFP height is less by 28mm or 1.1”)

To be continued.

 

[kamkar]

I would for sure prefer a dedicated power pack, and not least if i had a need for longer duration parking guard.
But my needs are modest so i am OK leaning on the very small battery in my car.

 

[GPak]

Basic specs for this LFP Parking Battery:

- Cell Type: 33140, LFP (LiFePo4), 3.2V (nom), 15Ah, 48Wh per cell.
- Total Energy Capacity: 4 x 48 = 192Wh, (4S1P configuration).
- Battery Charge Rate: Up to 15A (1C)/216W max, I use 8A (0.5C)/115W (Charge Rate depends on car limitations, Cigar outlet limited at 10A in my case)
- Operating temperature: -20°C/+65°C discharge, 0°C/+65°C charge (based on Cell spec).
- Dimensions: 54 x 145 x 250mm (2.1 x 5.7 x 10”)

 

[GPak]

Building principles for the Parking Battery is the same no matter which chemistry.
The difference is only in a working voltages.
Since most DVRs are using 12V with hardwire kit (HK) or with 12V USB adapter, converting 12V to whatever voltage DVR needs, the optimal configuration for the LFP Parking Battery is 4S1P, at about 10.4V-14.4V range.
This is a standard configuration for 12V LFP Battery system, with this configuration there is no need for any voltage converters, farther simplifying the Battery.
Also, there is no need to regulate output voltage which helps with efficiency and usable energy capacity.
Note that for most Hardwire Kit’s, the lowest voltage cutoff is around 11.8V, hence approximately 2.5% of the battery capacity will not be used, although Viofo is working on a “No-cutoff” version of the HK.

Here are a few photos showing the main components, I'll explain some options and challenges along the way:

 

[GPak]

Here is the first video to show in a little more detail all the components in some cases alternate options and their purpose.

Next, I'll follow up with video to show the challenges of fitting them into the smallest possible box.

 

[GPak]

Here is the promised second video discussing possible arrangement options.