kawayanan
New Member
Hello! This is not a solar setup (at least not yet), but hopefully you are willing to help. This seems to be the place with people who have the knowledge and experience with LiFePO4 systems to be able to help.
Background:
I am planning on getting a dual camera dashcam, and they are able to do monitoring (time-lapse or motion activated) while the vehicle is parked. Obviously, this requires batteries. The simplest way is to use the vehicle battery, but this has the chance of running the battery down (can't start the vehicle) or damaging the battery over time (lead acid batteries not handling charge/discharge cycles well). A USB battery banks are also not well suited for the situation. There are dedicated battery systems made for this purpose, but they are >$300 which is more than I am willing to spend. (example of a dedicated solution). The dedicated systems are generally 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.
Dashcams like the one I am looking at generally get hardwired with two connections (usually through fuse taps like these). One connection is to a fuse that is only on when the vehicle is running (lets the dashcam know when it should be running in driving mode and powers it). The other connection is wired to a fuse that is always on. This powers the dashcam when in parked mode, and the dashcam knows to go into park mode when the other connection loses power. The wiring usually also has a battery monitor that shuts the dashcam down when the constant connection drops below as specified voltage level (to protect your vehicle battery from being depleted).
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. 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 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 dual wiring would be to a fuse tap that is on when the vehicle is running (to power normal driving operation), and to the LiFePO4 battery for constant power (to power the dashcam for parked operations when the vehicle is shut off). The dashcam should still sense the state of the vehicle (running or parked) as if it was connected to the vehicle battery, but utilize only the LiFePO4 battery when the vehicle is off.
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. This could be attached to the boost/buck controller (which would be disconnecting from the vehicle fuse tap) to keep the LiFePO4 battery charge while it powered the dashcam in parked mode. Would this work? Would it need to be disconnected from the vehicle fuse or not? (the fuse would be one that is unpowered when the vehicle is off) Another thought would be to also wire the LiFePO4 battery to LED lights and USB chargers that I may add to the bed of my truck (to be powered by the LiFePO4 battery when the truck is off). Thoughts on these ideas?
Thank you for you help.
Background:
I am planning on getting a dual camera dashcam, and they are able to do monitoring (time-lapse or motion activated) while the vehicle is parked. Obviously, this requires batteries. The simplest way is to use the vehicle battery, but this has the chance of running the battery down (can't start the vehicle) or damaging the battery over time (lead acid batteries not handling charge/discharge cycles well). A USB battery banks are also not well suited for the situation. There are dedicated battery systems made for this purpose, but they are >$300 which is more than I am willing to spend. (example of a dedicated solution). The dedicated systems are generally 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.
Dashcams like the one I am looking at generally get hardwired with two connections (usually through fuse taps like these). One connection is to a fuse that is only on when the vehicle is running (lets the dashcam know when it should be running in driving mode and powers it). The other connection is wired to a fuse that is always on. This powers the dashcam when in parked mode, and the dashcam knows to go into park mode when the other connection loses power. The wiring usually also has a battery monitor that shuts the dashcam down when the constant connection drops below as specified voltage level (to protect your vehicle battery from being depleted).
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. 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 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 dual wiring would be to a fuse tap that is on when the vehicle is running (to power normal driving operation), and to the LiFePO4 battery for constant power (to power the dashcam for parked operations when the vehicle is shut off). The dashcam should still sense the state of the vehicle (running or parked) as if it was connected to the vehicle battery, but utilize only the LiFePO4 battery when the vehicle is off.
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. This could be attached to the boost/buck controller (which would be disconnecting from the vehicle fuse tap) to keep the LiFePO4 battery charge while it powered the dashcam in parked mode. Would this work? Would it need to be disconnected from the vehicle fuse or not? (the fuse would be one that is unpowered when the vehicle is off) Another thought would be to also wire the LiFePO4 battery to LED lights and USB chargers that I may add to the bed of my truck (to be powered by the LiFePO4 battery when the truck is off). Thoughts on these ideas?
Thank you for you help.
