I would like to know if it is possible to supply the “Sixfab Power Management & UPS HAT” by the J4 power input connector with a PoE 15v-12w injector.
If so, do you think this will be enough to charge the battery (li ion 18650 battery 3.7 v 2400mah) and power a RaspberryPI 4 ?
It is not possible.
Power HAT only supports DC voltage input.
Sorry, I’m not sure to understand your feedback.
For me, a PoE injector provides DC type power (15v or 48v depending on the model) over the Ethernet cable to the RaspberryPi Ethernet interface. And the RaspberryPi PoE header can transmit this DC power.
So, if I directly connect the PoE header from the Raspberry to the J5 input of the Sixfab Power Management, then I respect DC voltage input exigence.
Thank you in advance for your clarification.
Hi again @adm ,
First, as you said, the PoE injector transmits power between 15-48V but it must oscillate to transmit DC voltage over long distances over the ethernet cable(about 45-55V). The bridge rectifier is required to convert this oscillation to a constant DC voltage. UPS HAT doesn’t have it.
Secondly, Even if the voltage is constant, Raspberry pi does not support the input value in the range of 5-21V. POE is injected into the cable at a voltage between 44 and 57 volts DC, and typically 48 volts is used and this is above acceptable value.
As a result, it is not possible to directly connect the POE pins on the RPi to the UPS HAT but you can use Rpi + UPS HAT by transmitting power over ethernet with this converter. Using it directly would be a nice feature for UPS HAT. We will consider this in the next HW versions. If you want to use POE, we recommend using this product.
Thank you for your attention.
“the PoE injector transmits power between 15-48V but it must oscillate to transmit DC voltage over long distances over the ethernet cable(about 45-55V)”
I now understand why you said that “Power HAT” only supports DC voltage
“POE is injected into the cable at a voltage between 44 and 57 volts DC, and typically 48 volts is used and this is above acceptable value”
On this point I do not totally agree: indeed it is possible to find PoE injectors with voltages of 15V (Ubiquiti PoE Adaptater ref. POE-15-12W). But your 1st remark invalidates my solution
If you add PoE functions in a future version of your “Sixfab power hat” then I will be very interested.
Despite your feedback, I couldn’t resist to test my proposal to use a 15V-12W PoE injector. But rest assured, I did not insist for fear of destroye the HAT or the RaspberryPI.
I so tried to power the “Sixfab Power Management & UPS HAT”, the “Sixfab 3G / 4G & LTE Base HAT” and my RaspberryPI. Everything seems to be working properly with the “Power Management & UPS HAT” and its features.
But unfortunately, the network interface not works in this configuration. And I don’t understand why. Perhaps my system network configuration must be changed !
I return to the default configuration while waiting to understand, and for no break my HW.
With “802.3af/at”, PoE the powering device tries to determine if the device plugged into it needs power or not, and this usually works OK.
But with passive PoE, the power is just there (often controlled by managing the device) and can damage things not expecting power to be there. So the Ethernet port of the Raspberry PI 3B+ and 4B not intended to be PoE 15V powered terminate the connection.
So you must force the ethernet interface to 100Mbit in full duplex and with “autoneg” to off. This allows you to force the configuration of the RaspberryPi ethernet interface without dialog with the source interface.
You can do this with :
ethtool -s eth0 speed 100 duplex full autoneg off
Now the Eth0 interface is UP and Power supply the “Sixfab Power Management & UPS HAT” by the J4 power input connector with a PoE 15v-12w injector.
And everything seems to be working well.
To be continued …