# I want to be able to monitor my car battery voltage using Zwave LR long range **URL:** \ **Category:** Smart Relays\ **Created:** [May 26, 2026, 10:15pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805 "2026-05-26T22:15:47Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 26, 2026, 10:15pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/1 "2026-05-26T22:15:47Z")
I want to be able to monitor my car battery voltage using Zwave LR long range… I don’t need to see the voltage on the device itself that attaches to the battery, but I do want it to connect to my home controller which in this case is a UDI EISY with a Zmatter Zwave dongle. ---
**Author:** ![OhioYJ](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/ohioyj/32/267_2.png) [@OhioYJ](https://www.zoozcommunity.com/u/OhioYJ)\ **Post date:** [May 27, 2026, 12:13am UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/2 "2026-05-27T00:13:11Z")
> [@johnstonf](#): > > I want to be able to monitor my car battery voltage I’m sure someone will chime in with a way to do this, but I have to wonder why out of curiosity (if you don’t mind)? Wouldn’t it just be much easier to leave the vehicle hooked up to a quality automatic charger? I have several vehicles in that sit in the garage frequently, so they are always plugged in as soon as I pull them in. I use smart plugs, then I run a routine, and it turns on the correct chargers. I have a couple of these stations on the walls in the garage: ![chargers1](https://canada1.discourse-cdn.com/flex003/uploads/zoozcommunity/original/1X/ed5cbfa481144a39eddfcae326d9cdcffefedb61.jpeg) ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 12:32am UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/3 "2026-05-27T00:32:41Z")
Thanks for replying, and I already do that with all my DeWalt tools and garden battery operated stuff, but for what I need for vehicles that are outside in different spots I’m looking to monitor those in the alarmed when the voltage is dropping too low, such as a trailer, garden tractor, van wheelchair ramp surdeploy system battery, etc ---
**Author:** ![darren.stp](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/darren.stp/32/217_2.png) [@darren.stp](https://www.zoozcommunity.com/u/darren.stp)\ **Post date:** [May 27, 2026, 1:22am UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/4 "2026-05-27T01:22:50Z")
I don’t know of one directly, however I wonder if one could be constructed. Maybe something like this ? - a configurable voltage relay module with upper and lower limits, to open or close a set of contacts to signal a discharge condition. Then connect that to the device of your choice - I’d use maybe the input of a ZEN58 (which can operate on 9-40v ac or dc). The only problem is the ZEN58 itself will draw some of that same power unless you have a separate power source. In my testing the ZEN58 pulls about 5mA at 9v. (I haven’t tested power draw at 12v.) so that may be acceptable. > **[Voltage Relay Module DC 0‑99.9V 12A with Upper Lower Limit Detection and Battery...](https://www.amazon.com/Voltage-Module-Detection-Control-BatteryDischarge/dp/B0CTKFGLQ5)** > > Voltage Relay Module DC 0‑99.9V 12A with Upper Lower Limit Detection and Battery Discharge Timing Control Over Voltage Protection: Amazon.com: Industrial & Scientific This would not report the voltage via zwave, just alert you when the battery degraded to a certain threshold. ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 1:44am UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/5 "2026-05-27T01:44:08Z")
Good thought if there isn’t a more direct approach… tx ---
**Author:** ![OhioYJ](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/ohioyj/32/267_2.png) [@OhioYJ](https://www.zoozcommunity.com/u/OhioYJ)\ **Post date:** [May 27, 2026, 10:41am UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/6 "2026-05-27T10:41:09Z")
> [@johnstonf](#): > > that are outside in different spots Ah I see now, it’s for things that can’t be plugged in. So you want to be warned that it’s times to charge them before they go dead. I’m on the same page now. This is actually a pretty good idea, I’m surprised there isn’t something for this. ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 1:53pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/7 "2026-05-27T13:53:03Z")
Ya, exactly! Fred Johnston [fred.c.johnston@gmail.com](mailto:fred.c.johnston@gmail.com) Mobile: 519-373-2100 ---
**Author:** ![darren.stp](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/darren.stp/32/217_2.png) [@darren.stp](https://www.zoozcommunity.com/u/darren.stp)\ **Post date:** [May 27, 2026, 2:13pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/8 "2026-05-27T14:13:39Z")
> [@OhioYJ](#): > > it’s for things that can’t be plugged in. @Agnes This may be another related use case for the suggested battery powered sensor with external inputs. > [@darren.stp](#): > > (I haven’t tested power draw at 12v.) For what its worth, I just tested the ZEN58 at 12v dc - power draw is: 3.5mA when relay is open 26.3 mA when relay is closed Slightly higher pull when booting (max 27.3 mA) or when including into the zwave network (about 1.2mA more than numbers above during inclusion or interview). ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 3:22pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/9 "2026-05-27T15:22:34Z")
that’s good information to know, and I’m thinking to break open one of these (ZSE41 800LR) door sensors, and I’m not sure if you’ve ever had any experience with bypassing the magnetic relay… I did it with old Insteon door sensors and work great… > **(attachments)** > > ![Screenshot 2026-05-27 at 11.13.42.jpg](https://canada1.discourse-cdn.com/flex003/uploads/zoozcommunity/original/1X/9b69ed35713b691edfc90ac964cb5b7bffcaeb11.jpeg) ---
**Author:** ![darren.stp](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/darren.stp/32/217_2.png) [@darren.stp](https://www.zoozcommunity.com/u/darren.stp)\ **Post date:** [May 27, 2026, 3:27pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/10 "2026-05-27T15:27:43Z")
> [@johnstonf](#): > > I’m thinking to break open one of these door sensors I’ve not done it myself (I have one right in front of me, and the solder pads are tiny). I’ve heard others have done this with a ZSE42 leak sensor instead, but I don’t have one on the bench to inspect. ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 3:35pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/11 "2026-05-27T15:35:28Z")
Is the actual magnetic switch large enough to solder onto each leg, if it were left on? ---
**Author:** ![darren.stp](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/darren.stp/32/217_2.png) [@darren.stp](https://www.zoozcommunity.com/u/darren.stp)\ **Post date:** [May 27, 2026, 4:03pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/12 "2026-05-27T16:03:06Z")
I think so… Here’s what it looks like, and I shorted the pins with 22 awg wire to show it working with the reed intact. [![](https://canada1.discourse-cdn.com/flex003/uploads/zoozcommunity/original/1X/a5d2abc2b0e8726168e49e2293bb2be09f19f781.jpeg "ZSE41 sensor contacts") ](https://www.youtube.com/watch?v=5A3sxfVSSUA) (Let me know if that video doesn’t show for you and I’ll adjust security) ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 7:37pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/13 "2026-05-27T19:37:16Z")
Thanks!, man, you and me need to get our heads together! ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 8:59pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/14 "2026-05-27T20:59:33Z")
Got all my parts ordered to test in a couple of days… ---
**Author:** ![Barkis](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/barkis/32/50_2.png) [@Barkis](https://www.zoozcommunity.com/u/Barkis)\ **Post date:** [May 27, 2026, 9:46pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/15 "2026-05-27T21:46:21Z")
> [@darren.stp](#): > > …maybe the input of a ZEN58 (which can operate on 9-40v ac or dc). The only problem is the ZEN58 itself will draw some of that same power unless you have a separate power source. In my testing the ZEN58 pulls about 5mA at 9v. (I haven’t tested power draw at 12v.) so that may be acceptable. This would be my choice. The drain of the ZEN58 on a battery supplying a motor drive sure wouldn’t be significant to, say, running the motor itself. If the device was recharged with any kind of regularity, this would be a simple solution not requiring surgery on the battery operated ZSE41 😄 FWIW, I use its sister product, the ZEN57, to monitor current drawn by my sump pump motor to indicate if it is running. The drain of the ZEN57 is miniscule compared to the current drawn by the pump motor. YMMV, of course, and it’s great to have choices! 😎 ---
**Author:** ![johnstonf](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/johnstonf/32/506_2.png) [@johnstonf](https://www.zoozcommunity.com/u/johnstonf)\ **Post date:** [May 27, 2026, 10:45pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/16 "2026-05-27T22:45:17Z")
I do want to be notified, because I do have quite a few batteries to monitor, and the drain on the ZEN58 would be worth the bit of time sooner, to need a recharge… Fred Johnston [fred.c.johnston@gmail.com](mailto:fred.c.johnston@gmail.com) Mobile: 519-373-2100 ---
**Author:** ![Agnes](https://yyz1.discourse-cdn.com/flex003/user_avatar/www.zoozcommunity.com/agnes/32/14_2.png) [@Agnes](https://www.zoozcommunity.com/u/Agnes)\ **Post date:** [May 28, 2026, 3:30pm UTC](https://www.zoozcommunity.com/t/i-want-to-be-able-to-monitor-my-car-battery-voltage-using-zwave-lr-long-range/805/17 "2026-05-28T15:30:29Z")
Thanks for that! I bookmarked this topic so we don’t lose sigh of it during the development process 🙂