I’m considering putting a home assist setup on my boat to monitor a few things. I have a Peplink cellular router on board so it would be easy to monitor a few sensors.
First off, what is the smallest device you can run Homeassist on, rPi?
Second, I’d like to monitor how often my bilge pump is running, not sure what kind of a sensor that would be but I’m sure something exists.
Lastly, any sort of battery/power monitoring options?
Thank you!
Read → https://www.home-assistant.io/integrations/zha#knowing-which-devices-are-supported as well as https://www.home-assistant.io/integrations/zha#how-to-add-support-for-new-and-unsupported-devices
Tip to new Zigbee users: Checkout blakadder’s unofficial Zigbee Device Compatibility Repository. Anyone can help maintain the site by submitting device compatibility information to it. The repository contains independent community member’s reports or device-specific pairing tips for several home automation gateway/bridge/hub software, including open-source Zigbee implementations, such as ZHA, Zigbee2MQTT, and Tasmota (Zigbee2Tasmota).
However if planning to use Zigbee2MQTT then best to check out their device list → | Zigbee2MQTT
Recommend get Home Assistant Green (though Raspberry Pi 3 Model B should also work if not planning to put too much stress on it), alternatively if want to have cameras then consider Home Assistant Yellow.
Home Assistant Green (or Raspberry) will also need a Zigbee Coordinator, see → Zigbee buyer's guide
If it is a 100-240 volt AC system then can use any any clamp amp meter, see example → https://smarthomescene.com/reviews/tuya-zigbee-single-clamp-energy-meter-review/ …or alternatively a smart power plug with energy measurement which will also allow you to switch it off and on.
If it is 12 volt DC system then probably best to use some kind of single clamp amp energy meter made to measure for 10-24 volt DC, but note that most you will find are probably made for 100-240 volt AC.
Not even sure if there are any Zigbee variants of such 10-24 volt DC so might need to build your, like using Zigbee shield for Arduino to make a custom DIY sensor, or check out → https://ptvo.info/
If have WiFi then ESPHome is perfect for such project → CT Clamp Current Sensor — ESPHome
There are probably a few out there, see example → Battery sensor - ZigBoat™
See this older thread → Zigbee or Tasmota Based 12v Battery voltage monitor wanted!
Off-topic; ZigBoat also sell this Bilge Flood sensor → https://www.zigboat.com/product/bilge-flood-sensor/
PS: You should probably also consider Zigbee for smoke detectors and alarm system components 
There is a thread in the forums where someone installed Home Assistant on a Raspberry Pi Zero-W.
The pump is probably a 12V device, and a sealed submersible unit, so you can’t simply detect the voltage at the motor. As an alternative, just monitor the voltage at the pump where it connects to the boat’s 12V bus. When the pump comes on, the voltage on the 12V bus will drop slightly.
Or you could monitor the sump water level. When it drops, then the pump came on. You could even put a not-to-exceed level and an automation to alert you if the pump should be on but the level in the sump isn’t dropping.
Thabk you for these very thorough replies! Everything is 12v except for the onboard charger.
I should have been more clear about the bilge pump, I don’t need to monitor its power usage, I just want to be able to see if it’s on or off and a history of it turning on/off.
Is it possible for these sensors to all be wireless? I could probably do wired for the bilge if I tapped into the bilge switch.
Yeah, that is understood and you can do that by monitoring its power usage 
Set up automations that trigger if is using more than X amount of power.
Do you mean to ask if they can be battery-powered or if they have to be mains-powered, or are you askin asking if they use wired or wireless communication? The term “wireless” in this context should only be used when referring to communication and not power. Zigbee sensors always use wireless communication.
Zigbee is low-power and most Zigbee sensors are battery-powered but if you have a Zigbee sensor that will constantly monitoring power usage then the Zigbee sensor itself probably needs to be connected to either mains-power or a larger battery than avarge power.
PS Again, WiFi devices generally use much more power than Zigbee, (so WiFi sensors can practically almost never be battery powered) but be aware that if you can not find a commerical Zigbee product that fit your needs out-of-the-box then it generally much more complexted to build your own custom DIY Zigbee device compared to builing your own custom DIY WiFi device using ESPHome or Tasmota on a ESP32 development board.
Wireless communication, I know batteries are essential. I’d definitely use zigbee not WiFi for communication. Are there any good online resources or stores for zigbee sensors?
Not stores but there are at least a few good online resources, re-read my first reply post above
Read → Zigbee Home Automation - Home Assistant as well as Zigbee Home Automation - Home Assistant
Tip to new Zigbee users: Checkout blakadder’s unofficial Zigbee Device Compatibility Repository.
…
However if planning to use Zigbee2MQTT then best to check out their device list → | Zigbee2MQTT
And for DIY, see:
Not even sure if there are any Zigbee variants of such 10-24 volt DC so might need to build your, like using Zigbee shield for Arduino to make a custom DIY sensor, or check out → https://ptvo.info/
Summery:
Retail/commercial Zigbee products for home automation:
DIY Zigbee:
DIY low-power Wi-Fi using ESP32/ESP8266
Just keep in mind that if there is not an existing Zigbee device that will fit your needs out-of-the-box then you should probably consider looing at a non-Zigbee solution as it is not easy to make custom DIY Zigbee devices. Instead Ethernet (wired) communication solutions based on either Arduino or ESP32/ESP8266 is usually relatively much easier if you need to make your own custom DIY devices, specially ESPHome and/or Tasmota when using Home Assistant.
If you can not find a retail/commercial Zigbee product to fit your needs then you should still consider looking at ESPHome and/or Tasmota if need to build your own power meter DIY solution to measure DC current, as thinking about it you could use ESP32 development board Ethernet and pull such a cable instead of having to use WiFi. so tip there might be to use a PoE-powered ESP32 development board as then you can just get an 802.3at compatible PoE+ switch to power it remotely over Ethernet → https://www.google.com/search?q=esp32+AND+poe and that same PEO which could potentially also be used to power a Raspberry Pi with a POE+ HAT → https://www.jeffgeerling.com/blog/2021/review-raspberry-pis-poe-hat-june-2021
Anyway, if you search then you should be able to find multiple DIY ways to build your own DC power meter sensor using either ESPHome and/or Tasmota.
My boat isn’t huge, so I could definitely run ethernet or necessary wiring.
There is an existing solution by a company called Siren Marine that has all the necessary sensors and gateway, but is $1500 for the kit. I would put money on it that their wireless sensors are zigbee, as they run on a small coin cell battery. Do you think they could be hacked to work with HA?
For $1500, I’ll come to you to make a solution for your boat. Seriously, what state is your boat berthed in?
I am amazed at how complex a solution that some people want to make from a simple requirement. What is the make and model of your bilge pump? (Is there a web page with specifications? Also, what is the website of the $1500 solution?
Check it out - https://sirenmarine.com/
I think they were recently acquired by Yamaha. There are other solutions as well. I already have a Peplink router on board so I don’t need that which is why HA would be perfect for me.
Here’s another one:
Also, this one, but it’s an Italian company and they don’t have any sensor setups for me.
I looked at a couple of the Siren install videos. I am pretty certain that they are Bluetooth devices.
The prices blow me away, but they are going into a hazardous environment.
Prices:
But let’s get to your specific requirement- sense the pump turning on.
Where Is the float switch that turns on the pump?
If it’s external to the pump then just measure the voltage across the switch. 12-volts means the pump is off, near 0-volts means the pump is on.
If it’s internal to the pump you are left with few options. As I said above, just monitor the voltage at the pump with a voltage divider on the ESP Analog port. When the pump turns on there will be a dip in the voltage that should be easy to detect. But I would need to know more about the pump. You could also put a current sensing shunt resistor (usually less than one-ohm) in series with the pump and measure the voltage across the shunt. 0-volt is pump off, anything >0 is pump on. Again, I would need to know more about the pump to advise further.
A DC clamp-on sensor would be an easy solution, but those tend to be expensive.
The float is built into the pump. The other option is, under the helm where the server would live, I have access to the fuse panel and bilge switch. The bilge switch controls both stern and midship bilge pumps. Regardless, we have a few options. I would prefer if it didn’t live in the dampness that always exists in bilges.
How much are DC clamp on sensors? Define expensive…
Also, are the clamp sensors for current or voltage?
Lastly, could something like this be used and hardwired into the server?
This device is simply a voltage divider. Two resistors. As I said above, if you just want to know when the sump pump turns on, monitor the voltage at the pump. When the pump turns on, the voltage will take a brief dip because of the start current. The Velman board should work for this. But if you have other intermittent loads they might also cause a brief voltage dip.
I would still investigate a separate bilge water level monitor. (Don’t even try using the cheap resistive sensors. They come in contact with the water and corrode to uselessness quickly).
If you search for DC Clamp On sensors, you only get hand-held test instruments coating more than $100. AC clamp-on is easy to build as it is a simple transformer. A DC clamp on requires a Hall Effect detector to detect the strength of the unchanging magnetic field.
To measure current in a DC circuit, it easiest to put a small precision resistor in series with the load, then measure the voltage across it. An ESP device can easily do this on the Analog input. (Google shunt resistor for an explanation).
