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Could someone fill me in: why do people want to monitor their 12V battery? Is it just a proxy for “you seem to have left your light on”? It honestly feels like

Could someone fill me in: why do people want to monitor their 12V battery? Is it just a proxy for “you seem to have left your light on”? It honestly feels like a way to spy on family/company vehicles. Powered by the battery… knowing its voltage just being a side effect. But I guess that’s only if the app also tells you these data.

blibble 3y ago
over covid my battery went flat a couple of times I ended up using a multimeter but an app would have been more convenient
- jxramos 3y ago
  same here, I bought a Battey Tender solar charger and hardwired some SAE connections to my batter. I bought one of these to spot check the voltages at will CHAFON Motorcycle USB Fast Charger SAE to USB Adapter with USB C 18W PD,QC3.0 Quick Charge https://www.amazon.com/gp/product/B087JCWX5Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B087JCWX5Q/ref=ppx_yo_dt_b... These types of gadgets are useful too in my other car where I can spot check the voltage when on the road and when charging USB devices 12V USB Outlet Qidoe Dual 18W Quick Charge 3.0 Port & 20W PD 12V USB C Car Charger Socket with Voltmeter and Power Switch, Waterproof Multiple Car USB Port Adapter https://www.amazon.com/gp/product/B0B1WJ3W5X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B0B1WJ3W5X/ref=ppx_yo_dt_b...
Arrath 3y ago
Less often used equipment/vehicles (say, boats or weekend motorcycles) are often put on battery tenders when not in use, to keep the battery fresh for when you do want to use it. Just yesterday my FIL was relating how he put his motorcycle on a tender because it had some parasitic drain that would flatten the battery in 3 days of sitting, for example. This product seems to be a bit of an in-between, not having the ability to trickle charge the battery, but you can keep any eye on it and charge or jump it as needed.
- Syonyk 3y ago
  Yeah, I got tired of replacing batteries and now keep just about everything infrequently used on a battery tender. Lead acid as used in cars doesn't like being deeply discharged, so a couple good deep charges will trash them. A battery tender and extension cord is an awful lot cheaper than batteries, and a $30 unit will save you a lot more in battery replacement for infrequently used vehicles. Also, they make the tractor a lot happier to start in the winter. :)
- SV_BubbleTime 3y ago
  I was in a warehouse of supercars recently. Stuff you had no idea existed. 10 offs, things like that. Every vehicle was on a trickle charger, for a few reasons. But one reason I especially liked… The La Ferrari CAN NOT run the batteries dead. If it does, and it’s locked, you are in trouble. Like call a Ferrari rep to come fly out and partially take it apart to get it charged and running again trouble. Same with some Bugati I had never heard of. Everything down to McCarens and lower. These aren’t vehicles that will run after sitting for a month let alone a few. Some might top at a week.
  - wkat4242 3y ago
    Wow that's surprising, especially considering most buyers would buy these things to drive a few times a year. It's not really something you get to drive to work or do you shopping :)
    - SV_BubbleTime 3y ago
      Every supercars owner knows to leave them on chargers. Or rather, everyone responsible for super cars leaves them on chargers. One time, I had to change the oil on a McClaren… it has no dipstick, no oil pan, and you need to remove ~50 bolts and two skid plates to access anything. They are art and engineering pieces that you get inside. They are not cars per se.
x1sec 3y ago
I know someone who actually has a few of these devices - they are big into their FWD'ing - they have solar panels on their roof and spend days 'off the grid'. Another (more common) use case is people that take their caravan out on the road. Many have a plug into the car that keeps the caravan fridge powered on when driving. For me, I wanted to keep track of the voltage of the battery in a caravan when not connected to mains power.
hsbauauvhabzb 3y ago
Even if it is, the attitude of ‘don’t install this app as it might track you’ is not a viable solution for it that classes of app. Reducing risk is one thing, but until regulation occurs there’s nothing to stop every app you use doing the same thing.
thepasswordis 3y ago
It’s useful if you have a lot of vehicles and don’t drive all of them every day.
XorNot 3y ago
I'm currently looking for something to do this (bought one of these, it was junk and didn't work so I took it off) so I can have my Home Assistant installation keep an eye on it and notify my phone when it gets below some threshold. Still looking for a solution, by the way, if anyone knows of something which will work (kind of thinking I want to go with ESPHome now though).
- briHass 3y ago
  Renogy sells a 10A charge controller (https://www.amazon.com/Renogy-Wanderer-Amp-12V-24V/dp/B07NPDWZJ7 https://www.amazon.com/Renogy-Wanderer-Amp-12V-24V/dp/B07NPD...) that frequently goes on sale for around $10. It has a RS232 port, and there are libraries for ESP devices and/or ESPHome that can read all of the (modbus) data from the controller. You need a serial adapter or level converter to adapt the serial voltages to 3V and a RJ-12 (6p6c) wire... or you could just buy their bluetooth module that does it for you. Typically used for solar panels, but you could always hook up a 18-20v power supply and let it manage/charge your battery. The nice thing about these controllers is that they can handle multiple battery types and have multi-stage charging algorithms.
- x1sec 3y ago
  I've written a basic Python script [1] to read the battery voltage from this device. More details here [2]. Could easily integrate with Home Assistant. Might give it a go actually. It reads the real time voltages, not voltages stored in the embedded device's memory (for when there is no BLE connectivity while it's running). If there is interest, I can work out this part too. [1] https://gist.github.com/x1sec/3af7efdcd3465aac09093081c32ba321 https://gist.github.com/x1sec/3af7efdcd3465aac09093081c32ba3... [2] https://doubleagent.net/hardware/ble/bluetooth/2023/05/23/a-car-battery-monitor-tracking-your-location-part3 https://doubleagent.net/hardware/ble/bluetooth/2023/05/23/a-...

blibble 3y ago

over covid my battery went flat a couple of times I ended up using a multimeter but an app would have been more convenient

jxramos 3y ago
same here, I bought a Battey Tender solar charger and hardwired some SAE connections to my batter. I bought one of these to spot check the voltages at will CHAFON Motorcycle USB Fast Charger SAE to USB Adapter with USB C 18W PD,QC3.0 Quick Charge https://www.amazon.com/gp/product/B087JCWX5Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B087JCWX5Q/ref=ppx_yo_dt_b... These types of gadgets are useful too in my other car where I can spot check the voltage when on the road and when charging USB devices 12V USB Outlet Qidoe Dual 18W Quick Charge 3.0 Port & 20W PD 12V USB C Car Charger Socket with Voltmeter and Power Switch, Waterproof Multiple Car USB Port Adapter https://www.amazon.com/gp/product/B0B1WJ3W5X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B0B1WJ3W5X/ref=ppx_yo_dt_b...

Arrath 3y ago

Less often used equipment/vehicles (say, boats or weekend motorcycles) are often put on battery tenders when not in use, to keep the battery fresh for when you do want to use it. Just yesterday my FIL was relating how he put his motorcycle on a tender because it had some parasitic drain that would flatten the battery in 3 days of sitting, for example. This product seems to be a bit of an in-between, not having the ability to trickle charge the battery, but you can keep any eye on it and charge or jump it as needed.

Syonyk 3y ago
Yeah, I got tired of replacing batteries and now keep just about everything infrequently used on a battery tender. Lead acid as used in cars doesn't like being deeply discharged, so a couple good deep charges will trash them. A battery tender and extension cord is an awful lot cheaper than batteries, and a $30 unit will save you a lot more in battery replacement for infrequently used vehicles. Also, they make the tractor a lot happier to start in the winter. :)
SV_BubbleTime 3y ago
I was in a warehouse of supercars recently. Stuff you had no idea existed. 10 offs, things like that. Every vehicle was on a trickle charger, for a few reasons. But one reason I especially liked… The La Ferrari CAN NOT run the batteries dead. If it does, and it’s locked, you are in trouble. Like call a Ferrari rep to come fly out and partially take it apart to get it charged and running again trouble. Same with some Bugati I had never heard of. Everything down to McCarens and lower. These aren’t vehicles that will run after sitting for a month let alone a few. Some might top at a week.
- wkat4242 3y ago
  Wow that's surprising, especially considering most buyers would buy these things to drive a few times a year. It's not really something you get to drive to work or do you shopping :)
  - SV_BubbleTime 3y ago
    Every supercars owner knows to leave them on chargers. Or rather, everyone responsible for super cars leaves them on chargers. One time, I had to change the oil on a McClaren… it has no dipstick, no oil pan, and you need to remove ~50 bolts and two skid plates to access anything. They are art and engineering pieces that you get inside. They are not cars per se.

x1sec 3y ago

I know someone who actually has a few of these devices - they are big into their FWD'ing - they have solar panels on their roof and spend days 'off the grid'. Another (more common) use case is people that take their caravan out on the road. Many have a plug into the car that keeps the caravan fridge powered on when driving. For me, I wanted to keep track of the voltage of the battery in a caravan when not connected to mains power.

hsbauauvhabzb 3y ago

Even if it is, the attitude of ‘don’t install this app as it might track you’ is not a viable solution for it that classes of app. Reducing risk is one thing, but until regulation occurs there’s nothing to stop every app you use doing the same thing.

thepasswordis 3y ago

It’s useful if you have a lot of vehicles and don’t drive all of them every day.

XorNot 3y ago

I'm currently looking for something to do this (bought one of these, it was junk and didn't work so I took it off) so I can have my Home Assistant installation keep an eye on it and notify my phone when it gets below some threshold. Still looking for a solution, by the way, if anyone knows of something which will work (kind of thinking I want to go with ESPHome now though).

briHass 3y ago
Renogy sells a 10A charge controller (https://www.amazon.com/Renogy-Wanderer-Amp-12V-24V/dp/B07NPDWZJ7 https://www.amazon.com/Renogy-Wanderer-Amp-12V-24V/dp/B07NPD...) that frequently goes on sale for around $10. It has a RS232 port, and there are libraries for ESP devices and/or ESPHome that can read all of the (modbus) data from the controller. You need a serial adapter or level converter to adapt the serial voltages to 3V and a RJ-12 (6p6c) wire... or you could just buy their bluetooth module that does it for you. Typically used for solar panels, but you could always hook up a 18-20v power supply and let it manage/charge your battery. The nice thing about these controllers is that they can handle multiple battery types and have multi-stage charging algorithms.
x1sec 3y ago
I've written a basic Python script [1] to read the battery voltage from this device. More details here [2]. Could easily integrate with Home Assistant. Might give it a go actually. It reads the real time voltages, not voltages stored in the embedded device's memory (for when there is no BLE connectivity while it's running). If there is interest, I can work out this part too. [1] https://gist.github.com/x1sec/3af7efdcd3465aac09093081c32ba321 https://gist.github.com/x1sec/3af7efdcd3465aac09093081c32ba3... [2] https://doubleagent.net/hardware/ble/bluetooth/2023/05/23/a-car-battery-monitor-tracking-your-location-part3 https://doubleagent.net/hardware/ble/bluetooth/2023/05/23/a-...