As unsightly as I anticipated, but Plasti Dip applied. For those not familiar, it can be peeled off later.
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To be fair, I’d bet that Yellow (if you can find one to match) would work almost as well. And if you find one, do that top of the core as well. Heat from there goes right into the battery compartment as well.
The question is - how much impact does the white have? Can’t wait for results.
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Prolly right. Just going for the color that clashed the most. 
They do make a yellow
I don’t expect more than a 1-2 degrees C while discharging, but every degree lower is another 10-15 min of full charging power before its starts throttling.
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I’ve been collecting some data on this with some sensors and esp32, this graph shows the temperatures before and after I added a single layer of white vinyl over the battery cover.
Surface temperature would peak around 140F before, and 120F after, with some change to the internal temperature as well. It’s not a cure but it does help - I’m working on some other methods to cool it down.
General observation - cooling the top does help so it isn’t “preheated” before charging, and during charging the bottom of the battery temperature will outpace the top temperature. Getting some airflow at the bottom may help.
Things I’m going to try:
-
more layers of vinyl, and cover the core section not just the battery cover
-
Add 1mm thermal pads to the bottom corners of the battery to lift it off the deck, it may improve airflow, but may affect charging (it’s just metal on metal right now)
-
Blower style fan with a hose routed to the battery (there’s room through the core to do this)
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That’s some great data and confirms what I expected - It helps a little.
I’m curious if isolating the battery from the frame will have an impact. I can see a case for it helping or hurting heat dissipation.
It hasn’t been hot here the last few days so I haven’t tested yet.
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Great data. What temp sensors are you using for your esp32s?
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Sensor part # was my next question. I have a bunch of extra ESP32s waiting for something to do 
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That’s cool! This forum is getting geekier each day!
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Ditto…
The sensor on top of the battery cover is this one Soil Temperature Humidity Sensor Probe SHT45 Stainless Steel Plastic I2C Interface DC3.3V Integrated PTFE Filter Membrane Operating Condition IP67: Amazon.com: Industrial & Scientific
The sensor inside the core is a one-wire dht22/am2302 Teyleten Robot DHT22 / AM2302 Digital Temperature Humidity Sensor Module for Arduino Replace SHT11 SHT15 (3pcs): Amazon.com: Industrial & Scientific
The sensors under the battery and on top of the battery are one-wire DS18B20 Weewooday 4 Sets DS18B20 Temperature Sensor Module Kit with 1 m/ 3.2 Ft Waterproof Digital Stainless Steel Probe -55 to +125 Degrees Celsius, Compatible with Raspberry Pi: Amazon.com: Industrial & Scientific ?
I can share an esp32 yaml file if you want.
I picked the first sensor due to it being exposed to the elements and I wanted humidity readings, for inside the core I just used what I had on-hand, any DHT3x/4x would work fine in there. The other one-wire sensor I had on hand and just collect temperature data. It would have been nice to have all SHT45’s but that’s what I had on hand
I’m running it with a seed studio esp32s3 and a 12v integrated solar panel+battery
I’d like the yaml if you don’t mind sharing.
And the battery you use, how much run time do you get out of it?
I am using this Amazon.com : Folgtek Trail & Game Camera Solar Power Bank Solar Charger Monocrystalline Solar Panel 3W 8000mAh Output 12V/1A, 9V/1.5A, 6V/2A, Input 5V IP66 Waterproof Portable Outdoor Power Supply with Bracket : Patio, Lawn & Garden with the 12V out going to a step down converter Amazon.com: PlusRoc Waterproof 12V/24V to 5V Converter DC-DC Step Down Module Power Adapter Compatible with Raspberry Pi 4, Cellphone, Car (USB Type-C Connector) : Electronics that powers everything.
I haven’t run out of battery and it’s been running continuously for 8 days. A small battery pack would probably last quite a while. They’re tricky since that esp32 draw so little power the power banks like to turn off thinking there is nothing connected.
Here’s the yaml
substitutions:
update_interval_global: 15s
esphome:
name: esp32s3-yarbo-1
esp32:
variant: esp32s3
board: esp32-s3-devkitc-1
framework:
type: arduino
# Enable logging
logger:
level: VERBOSE
logs:
display: INFO
sensor: VERBOSE
component: INFO
# Enable Home Assistant API
api:
password: ""
ota:
platform: esphome
password: ""
wifi:
power_save_mode: light
networks:
- ssid: !secret wifi_primary_ssid
password: !secret wifi_password
- ssid: !secret wifi_failsafe_ssid
password: !secret wifi_password
#manual_ip:
# static_ip: 192.168.1.122
# gateway: 192.168.1.1
# subnet: 255.255.255.0
# dns1: 192.168.1.1
# dns2: 8.8.8.8
captive_portal:
i2c:
- id: i2c_bus_a
sda: 5 # green/white
scl: 6 # yellow/blue
scan: true
frequency: 100kHz
one_wire:
- platform: gpio
pin: GPIO2
id: one_wire_hub_1
time:
- platform: host
id: esptime
timezone: UTC
sensor:
- platform: wifi_signal # Reports the WiFi signal strength/RSSI in dB
name: "WiFi Signal dB"
id: wifi_signal_db
update_interval: 60s
entity_category: "diagnostic"
- platform: copy # Reports the WiFi signal strength in %
source_id: wifi_signal_db
name: "WiFi Signal Percent"
filters:
- lambda: return min(max(2 * (x + 100.0), 0.0), 100.0);
unit_of_measurement: "Signal %"
entity_category: "diagnostic"
device_class: ""
- platform: dallas_temp
one_wire_id: one_wire_hub_1
name: "Yarbo Core Battery Bottom Temperature C"
id: yarbo_core_battery_bottom_temperature_c
address: 0x2d3ce1d4437ee928
accuracy_decimals: 5
unit_of_measurement: °C
update_interval: ${update_interval_global}
- platform: dallas_temp
one_wire_id: one_wire_hub_1
name: "Yarbo Core Battery Top Temperature C"
id: yarbo_core_battery_top_temperature_c
address: 0xc23ce1d4439b8628
accuracy_decimals: 5
unit_of_measurement: °C
update_interval: ${update_interval_global}
# this is the AM2302 DHT22, similar case as the SHT30 but one-wire
# it is not weatherproof, and should not be directly exposed to rain
# it is routed to the interior of the core
- platform: dht
pin: GPIO1
model: AM2302
temperature:
name: "Yarbo Core Interior Ambient Temperature C"
id: yarbo_core_interior_ambient_temperature_c
unit_of_measurement: °C
accuracy_decimals: 2
humidity:
name: "Yarbo Core Interior Ambient Humidity"
id: yarbo_core_interior_ambient_humidity_pct
unit_of_measurement: "%"
accuracy_decimals: 2
filters:
- clamp:
min_value: 0
max_value: 100
update_interval: ${update_interval_global}
# this is a weatherproof edition of the SHT45 and sits on the surface/side
# to give ambient temperatures around Yarbo core
- platform: sht4x
i2c_id: i2c_bus_a
temperature:
name: "Yarbo Surface Ambient Temperature C"
id: yarbo_core_surface_ambient_temperature_c
unit_of_measurement: °C
accuracy_decimals: 5
humidity:
name: "Yarbo Surface Ambient Humidity"
id: yarbo_core_surface_ambient_humidity_pct
unit_of_measurement: "%"
accuracy_decimals: 5
filters:
- clamp:
min_value: 0
max_value: 100
heater_max_duty: 0.01
heater_power: High
heater_time: Long
address: 0x44
update_interval: ${update_interval_global}
1 Like
Yep. Share please. Saves time. What did you power the ESPs with when it was mowing?
the solar+battery combo rides along with it while mowing, mounted on the back (bolted onto the BBM but it could attach in a number of places back there)
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Awesome, thanks for the info. Very creative.
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this is what it looks like (the esp32 and everything are inside one of these Otdorpatio Project Box ABS Black Electrical Boxes IP67 Outdoor Waterproof box Electronic Junction Box Power Enclosure with Cable Glands for DIY Project 4.5 x 3.5 x 2.2 inch (115x90x55mm) - Amazon.com) and goes inside the core, plenty of room for it in there.
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Almost worth the purchasing the back brace…
i was just going to bungee it across the two handles, or try to re-use the trailer hitch but the BBM had the same size hole+thread as the solar panel, that was lucky!
A small usb battery pack would likely keep this alive for quite a while, I’ll have to give it a try and see what happens. I have a couple that can be put into low-power mode so they won’t auto-shutoff.
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Imagine having access to the api… We could also add a humidity sensor to the bottom of the robot… We link heat sensor to optimize charging times, humidity to stop or start mowing at the threshold we specify, etc… And with our community I’m sure we could end up with a third-party open source tool to get even more from our robot…
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Have you thought about heat sinks on maybe the sides or top of the plastic cover? A little thermal glue and a small series of sinks should pull heat out while it works (maybe not as much when it’s charging, but a good initial spot helps?)
1 Like