kawayanan
New Member
Background:
I am planning on getting a dual camera dashcam, probably a Viofo A229 duo (or possibly a A129 plus duo). I would like to use parking mode, but a very hesitant to use my vehicle battery (either running the battery low or shortening its lifespan). The vehicle is a hybrid, and may be a bit finicky about drops in battery charge (warning/error/issues). I know there are dedicated battery systems made for this purpose, but they are >$300 which is more than I am willing to spend. The dedicated systems seem to be LiFePO4 battery packs of around 6-8Ah (12V). I enjoy DIY projects, but don't have experience with battery systems or LiFePO4. I wanted to run what I am thinking past more experienced people to know if I am way off base on what is needed or missing important safety issues.
From reading everything I can find on the intranet, I think I understand how hardwire kits work (thanks ephestione! - your post and YouTube video were helpful). Assuming you do fuse taps (battery and acc), it appears that the power is always run through the battery tap (always hot), and the acc tap (only on when the car is running) simply help the dashcam know if it should be in drive or parking mode. I was hoping that it used the acc tap for power when driving, and the battery tap just for parking, since that would seem easier wire an extra battery to, but is seems that is not how they work.
Plan:
I would like to make a system using available 12V LiFePO4 batteries in the 6-10Ah range (this or this seem to be well popular on Amazon). These appear to have integrated BMS to prevent some issues like overcharge, over-discharge, over-current, and short circuit, but my research also suggests that you shouldn't count on these alone. They also can draw much more current charging than I want to pull from the vehicle systems (fast charge). I also want to isolate the vehicle battery so that is won't potentially discharged when the vehicle is shut off. I was thinking about something like this (DC to DC boost/buck converter) to serve as a charge controller. This should hopefully do a few things: 1) make sure that the voltage from the vehicle is correct to charge the LiFePO4 battery (i.e. 14.6V), 2) limit the amperage to the battery (2-3A to be in the 0.2-0.3C range for these batteries?), 3) make sure the LiFePO4 battery is isolated from the vehicle system when the vehicle is shut off (output anti-backflow). My idea for the wiring would be that the boost/buck controller would be wired to a vehicle fuse that is on only when the car is running. This way the LiFePO4 batter would only be charging when the car is operating. It seems to make sense to me to set the boost/buck controller to constant voltage at 14.6V, with a amperage limited to 2-3A. My thinking is that this would protect both the LiFePO4 battery (not tryin to charge to fast), as well as keep from trying to draw too much power and overtaxing the vehicle alternator (or blowing fuses). The dashcam would be wired to the LiFePO4 battery for constant power (to power the dashcam for driving and parked operations). The acc tap would be used a normal to let the dashcam know when to be in drive mode vs parking mode. I am aware that one potential problem will be the charging time for the battery if I limit the input to 2-3A. Depending on how long the parking mode is run and how depleted the battery is, my 35-50 min commute may not be long enough to top off the battery. If this is a problem, I would need to use a different boost/buck converter with a higher amperage capability (I would rather not go above 5A though for safety and heat)
This brings up to my lack of knowledge. First if I connect the battery and the power to the dashcam after the boost/buck converter, can I both charge the battery and power the dashcam at the same time? Do you see any issues with this idea? is my understanding of how LiFePO4 batteries should be charged and used correct? Is this all reasonable and safe for my car and the battery?
My additional thought is that future possibilities would be to add one of the small 10-20W portable solar panels that could be placed in the windshield if I was to be parked for a long period of time. I assume that this would be attached to the boost/buck converter (input side) to trickle charge the LiFePO4 battery and or power the dashcam for parked mode. Would this work? Can the battery handle power the dashcam in parked mode at the same time it might accept the solar panel power (assuming it produced more than the dashcam needed)? Any extra wiring/controller needed for this? Would the boost/buck converter need to be disconnected from the vehicle fuse or not? (the fuse would be one that is unpowered when the vehicle is off). Thoughts on these ideas?
Thank for the help!
I am planning on getting a dual camera dashcam, probably a Viofo A229 duo (or possibly a A129 plus duo). I would like to use parking mode, but a very hesitant to use my vehicle battery (either running the battery low or shortening its lifespan). The vehicle is a hybrid, and may be a bit finicky about drops in battery charge (warning/error/issues). I know there are dedicated battery systems made for this purpose, but they are >$300 which is more than I am willing to spend. The dedicated systems seem to be LiFePO4 battery packs of around 6-8Ah (12V). I enjoy DIY projects, but don't have experience with battery systems or LiFePO4. I wanted to run what I am thinking past more experienced people to know if I am way off base on what is needed or missing important safety issues.
From reading everything I can find on the intranet, I think I understand how hardwire kits work (thanks ephestione! - your post and YouTube video were helpful). Assuming you do fuse taps (battery and acc), it appears that the power is always run through the battery tap (always hot), and the acc tap (only on when the car is running) simply help the dashcam know if it should be in drive or parking mode. I was hoping that it used the acc tap for power when driving, and the battery tap just for parking, since that would seem easier wire an extra battery to, but is seems that is not how they work.
Plan:
I would like to make a system using available 12V LiFePO4 batteries in the 6-10Ah range (this or this seem to be well popular on Amazon). These appear to have integrated BMS to prevent some issues like overcharge, over-discharge, over-current, and short circuit, but my research also suggests that you shouldn't count on these alone. They also can draw much more current charging than I want to pull from the vehicle systems (fast charge). I also want to isolate the vehicle battery so that is won't potentially discharged when the vehicle is shut off. I was thinking about something like this (DC to DC boost/buck converter) to serve as a charge controller. This should hopefully do a few things: 1) make sure that the voltage from the vehicle is correct to charge the LiFePO4 battery (i.e. 14.6V), 2) limit the amperage to the battery (2-3A to be in the 0.2-0.3C range for these batteries?), 3) make sure the LiFePO4 battery is isolated from the vehicle system when the vehicle is shut off (output anti-backflow). My idea for the wiring would be that the boost/buck controller would be wired to a vehicle fuse that is on only when the car is running. This way the LiFePO4 batter would only be charging when the car is operating. It seems to make sense to me to set the boost/buck controller to constant voltage at 14.6V, with a amperage limited to 2-3A. My thinking is that this would protect both the LiFePO4 battery (not tryin to charge to fast), as well as keep from trying to draw too much power and overtaxing the vehicle alternator (or blowing fuses). The dashcam would be wired to the LiFePO4 battery for constant power (to power the dashcam for driving and parked operations). The acc tap would be used a normal to let the dashcam know when to be in drive mode vs parking mode. I am aware that one potential problem will be the charging time for the battery if I limit the input to 2-3A. Depending on how long the parking mode is run and how depleted the battery is, my 35-50 min commute may not be long enough to top off the battery. If this is a problem, I would need to use a different boost/buck converter with a higher amperage capability (I would rather not go above 5A though for safety and heat)
This brings up to my lack of knowledge. First if I connect the battery and the power to the dashcam after the boost/buck converter, can I both charge the battery and power the dashcam at the same time? Do you see any issues with this idea? is my understanding of how LiFePO4 batteries should be charged and used correct? Is this all reasonable and safe for my car and the battery?
My additional thought is that future possibilities would be to add one of the small 10-20W portable solar panels that could be placed in the windshield if I was to be parked for a long period of time. I assume that this would be attached to the boost/buck converter (input side) to trickle charge the LiFePO4 battery and or power the dashcam for parked mode. Would this work? Can the battery handle power the dashcam in parked mode at the same time it might accept the solar panel power (assuming it produced more than the dashcam needed)? Any extra wiring/controller needed for this? Would the boost/buck converter need to be disconnected from the vehicle fuse or not? (the fuse would be one that is unpowered when the vehicle is off). Thoughts on these ideas?
Thank for the help!
