Has anyone ran the ePMP 1000 AP’s on more then 56v?
I am asking because we have a site running both 2.4 APs ( ePMP 1000 GPS) and 450i 900mhz APs and its a 48 volt DC solar site. We are adding a new charger to the system for the generator and it has a 52v setting or a 56v setting for charging the batteries. The recommendation is to run it in the 56v setting for the heaths of the batteries. When we start it up I see the battery bank go to 56.1v. Has anyone put slightly more then 56v to the ePMP 1000 GPS ap?
I am looking into ways to step the battery bank down to a clean 48v but I would still like to find out if the APs can take it.
Warning! Not all e1k APs are 56v friendly. Check the lable for the acceptable power levels or contact cambium with your radio serial number and they can tell you if it is 56v friendly.
Considering the actual losses involved, I would consider a 48v to 24v buck converter with a large capacitor (think car stereo amplifier power capacitor) on the 24v side to power your e1k APs. We do this to power our tower switches which take 12vdc off our 24v systems. (Our solar and our regular systems are identical except for the power sources). Just make sure you keep the converter cooled either with a big heat sink or a small fan and add a input and output fuse based on your expected current rating.
Douglas,
Thanks for replying. I did end up putting in a converter to bring the voltage down to 48v for all the APs to run on.
If you have 802.3af compliant e1k APs, these are good between 36.6v and 60v (the total possible voltage range of 802.3af ). This we have tested with each AP series to ensure compatibility and holds true. It is unknow what the over voltage fail mode is as we only test the spec range for compatibility with our non-comunicating passive 48v systems, nor what the max allowable voltage before frying is. We do not send the PSE presense codes to the radios either, so they do not know what power supply they are connected to.
The problem with a 48v solar system is the battery voltage can range as high as 64v during equalization, which is definitely outside the 802.3af and 802.3at specs. The only way we have found to be reliable is to use a boost/buck converter to allow a steady voltage despite what the battery is doing.
Our sites are 24v, this allows more run time on battery for the same battery foot print, we use 500AH battery cells) versus needing to use 180AH cells to fit the same area. So we boost the voltage for the epmp3000’s that we have, which isnt that many as the 3000L provides more than enough for most of our locations.
This isnt to convince you to switch, there is some very good cases to supply 48v versus choosing a lower voltage. Switch manufacturers generally have a dc power supply for telecom use though those are just a robust switching buck converter in most cases any way. But you also gain 802.3af/at PSE services which you would have to work around with a different voltage like what we have done, Cisco switches are 12v inside and provide 48v connections for 802.3af/at if supported so it can be done too. We even have a i5 based computer acting as a iperf server that runs on 12v with a cheap ebay 12v to atx power card. The point is, dont think that you have to use an off the shelf product to get what you want/need, you can be very creative and it will be maintainable.