24V-DC-Mod-on-CRS328-24P-4S+RM

WARNING - doing this mod will void your Mikrotik warrantee - if you do so - you do so at your own risk !

A little background info first:
I run a fiber-to-the-home ISP and a WISP. I have a dozen-plus remote towers and four mini-NOCs. My mini-NOCs and most of my remote towers do not have backup generator power - or they have backup generators needing repair from last winter to get the generators working again. (( I totally hate remote backup generators because they can fail during the winter when the snow is over 6-feet deep and a generator service company can't get to the remote mountian-top located generator to repair it )) -and- (( I totally hate AC powered UPS systems because they run down the battery after a few hours when the power goes out - sometimes hours to more than a week without power )). Sooo, I've been switching to only 24-Volt-DC devices were possible. It's good for me that my hundreds of outdoor APs are Mikrotik devices with PoE 24-Volt power. My problem is locating Mikrotik 24-Volt DC powered PoE out ethernet switches. ((( Yes there is the NetPower16-P , but that only has 16 PoE ethernet out ports and I need up to24 to 48 PoE out ethernet ports ))). Sooo, this is my first test mod on a Mikrotik CRS328-24P-4S+RM to convert it from AC power to DC power.

I wish Mikrotik would come out with an optional DC power wiring kit that does the same thing as my mod for their larger PoE switches.

This I performed on a Mikrotik CRS328-24P-4S+RM ( 24 PoE ethernet ports & four sfp+ ports )
My next mod will be on a Mikrotik CRS354-48P-4S+2Q+RM ( 48 PoE ethernet ports & four sfp+ ports & two 40G QSFP+ ports ) This mod will be for my mini-NOCs that do fiber-to-the-home (GPON) where I need/use 10-Gig or faster fiber connections

For my CRS328-24P-4S+RM DC-power mod I performed the following:
- remove the internal AC power supply
- created a DC wire harness for the CRS328-24P-4S+RM. ( externally I have connectors for external 24-Volt-DC operation and an optional external 48-Volt DC power supply.
-- Note; The CRS328-24P-4S+RM powers up and works fine on 24 volts only without the 48-volts connected. The optional 48 volts is only needed if you want to PoE power a 48-Volt device.
- For my external 24-Volt DC power supply, I am using an ALG 24-Volt-DC-UPS ( a 24 Volt power supply which will also has connectors to connect external batteries ). Thus when the power goes out , everything keeps running and the world still spins.
-- Note: My battery bank will be large enough ( Amp-hours ) to run a minimum of 1 week without utility power.

I have attached some pictures of my 24-Volt-DC mod on my CRS328-24P-4S+RM.

Oooo - I forgot to put the pass-through wire protective grommet where the AC power connector used to go. That will get done soon.

Also , the ALG 24-Volt DC-UPS is the SNMP network version. So I can get and graphs current loads, charge/discharge loads and utility-power/battery/DC-output voltages - and it also has a watch-dog reboot function.

Note: I used a 4-Pin trailer wire harness connector on my modified Mikrotik. Both outside wires are the common/ground/negative lead wire and the two inside wires are +24-DC and the optional +48-DC connectors. This enables me to quickly power-on/off the Mikrotik by disconnecting the connector ... fyi disconnecting the 110V-AC outlet on my power supply does nothing because it simply switches over to battery power ... In the ALG power supply picture , you can see the brown wire is not connected to anything , this is for the optional 48-Volt DC power if I want to power any 48-Volt PoE devices.

Move over NetPower16-P , here comes Tom's NetPower-24 ( this mod ), and soon to be followed by Tom's NetPower-48 !

North Idaho Tom Jones

That ALG power-supply look neat. I also run some stuff on 24V battery backed power. However I use the built in voltage sensor with some scripting to determine battery/utility status.

I think that Mikrotik should put a DC terminal block on all typical non-home devices (like the CCR/CRS'es)

Re: I think that Mikrotik should put a DC terminal block on all typical non-home devices (like the CCR/CRS'es)

Or offer an optional retro-fit wire harness to convert from AC power to 24/48 DC power - and include simple instructions explaining how to remove & replace the AC power supply with an optional 24/48 DC cable harness. Also include documentation stating the optional DC wire harness is for a negative or isolated 24/48 VDC ( aka never connect to a positive grounded DC power supply - such as telco 48 VDC positive ground. ). Also , a DC retro-fit wire harness could show a fully completed DC kit which shows some tested DC-UPS/battery-backup power supplies with and without the optional 48-Volt PoE DC power supply.

I suspect that Mikrotik could manufacture and sell a DC conversion kit for less than $25 in parts ( wire, connectors and a grommet for where the DC power cable will exit the chassis where the AC outlet used to be.

The DC harness after I installed the wire protective grommet.

North Idaho Tom Jones

24V-DC-Mod-on-CRS354-48P-4S+2Q+

Said I was gonna do it - and I did.
Now I have a 48-Port PoE out Mikrotik switch ( and four sfp+ and 2Q ) being powered by an external 24-Volt DC-UPS.
This is the perfect solution for one of my remote mountain-top towers where I need about 24 PoE ports and another 24-PoE-disabled ports and five 10-Gig fiber links.

This tower gets some deep snow over the top of the fence every winter. It's impossible to service the generator during the winter and in the past the utility power has been out for up to 10-Days. So now I have a solution and I also have the batteries to last over two weeks. ( good by 110-VAC UPS , you just don't have the efficiency to last weeks without utility power ).

I think I will call this one "Tom's-NetPower-48-4s+-2q"

North Idaho Tom Jones

I LOVE this. Keep up the good work Tom. If Mikrotik won't sell a DC power kit for these, you should! I'd buy!!

I LOVE this. Keep up the good work Tom. If Mikrotik won't sell a DC power kit for these, you should! I'd buy!!

For the heck of it , I started a battery run-down test using a new set of marine deep-cycle batteries that were not fully charged yet. I canceled the battery run-down test after two and 1-half day. The test was however only running at 36 watts. After the batteries are fully charged , I am looking forward to seeing what they can really do on battery only power.

fyi - the power supply I am using has a feature to switch to battery only power , then auto-switch back to AC charging power when the batteries are low.

For me in mu use - this is exactly what I needed. At some of my remote mountain top towers , the snow can get 6 to 12 feet deep during the winter. When running on generator power for that long , it's then impossible to re-fill the propane tanks. With this solution, I should be able to last about around a week without power ( and without generator ). Then when utility power is restored, who cares how long it takes to recharge the batteries , because recharging the batteries will be always quicker than waiting for summer when a propane tank can get to the tower.


Re: ... If Mikrotik won't sell a DC power kit for these, you should! I'd buy!! ...
The mod takes about two hours. If you have one of the two I have modified , I can post how to perform the mod. Simple simple simple

O - I also performed another set of DC mods today ...

Just wondering how these are doing, specifically PoE off them.

Just wondering how these are doing, specifically PoE off them.

All of the Mikrotik switches I have DC-modified are working great.
I especially love the 2 to 4+ days of DC-UPS battery fall back ability when the AC utility power goes out.
Most of my DC modified Mikrotik switches are located at remote mountain-top towers where they can be very difficult to get to during the winter.

North Idaho Tom Jones

Looking at replacing 8ish of our tower sites with the 24 or 48 port switches running 10-15 PoE ports off them constantly.
What the max you've used for the PoE output? We run some high power radios off the 3850s we are looking to replace.
I would love more information.

Looking at replacing 8ish of our tower sites with the 24 or 48 port switches running 10-15 PoE ports off them constantly.
What the max you've used for the PoE output? We run some high power radios off the 3850s we are looking to replace.
I would love more information.

I am using all Mikrotik AP PoE 24-Volt devices.

Re - high power radios ....
Check the specs on the specific Mikrotik router/switch and verify the PoE out power per port is sufficient for any high power PoE devices.
- One work around if you need more PoE than the switch delivers is to use a PoE injector and power it directly from your DC-UPS system - however I prefer when possible to PoE power using the switch because then I can PoE power-cycle and also use the PoE watch-dog settings to auto power-cycle a PoE port if a PoE devices stops pinging.

North Idaho Tom Jones

Note - What looks like black or red electrical tape is actually crimped, then soldered connections, then wrapped in electrical tape , then dipped in liquid electrical tape ( aka liquid rubber ).
I also used slightly over-sized DC power wires ( with fuses on the + and - power leads ( the - fuse is 5-Amps+ larger than the + fuse ) , so that I could have a long DC power cable and not have to worry about any voltage drops. If a fuse blows , I want the + fuse to go first, if all hell breaks loose than both fuses can blow.
With the Tik power supply removed, the Tik actually runs cooler now.

Hi Tom,
My 3 year old CRS328 (like yours) died yesterday - zero output from P/S.
A replacement CRS328 has been ordered to resume normality ASAP

However, I'm keen to try your DC conversion on the 'dead' unit so I have a) more ports and b) power redundancy.

I'd be most grateful for any further detail of your MOD than that contained in the Forum article.

I sent this also via Messenger on your FB page

The conversion of a Mikrotik AC powered router or switch to DC is pretty straight forward.

On the AC power supply , find your common , +24 and +48 wires.
Remove the AC power supply(s). Cut the power supply output wires somewhere that if needed , you can re-splice them together.
Note: The +48 volt stuff is only used for PoE out when set to high. If you are using 24-Volt PoE , then don't worry about the 48-Volts ... However , mark them so that you can later add a second 48-Volt power supply connection if you want to use 48-Volts later.

For my 24-Volt DC power supply , I use ALG 24-Volt DC external power supplies ( two external 100-amp-hour 12-Volt batteries in series to the ALG , then the 24-Volt regulated output from the ALG to the Mikrotik.

On the back of my Mikrotik , where the original AC connextors were located , I put a grommet(s) in the square holes ( made it look better and protects the DC power wires from getting cut on the case where your new power wires will pass through.

Optional , although you can wire directly from the now DC powered Mikrotik to your external power supply , I used some 4-wire trailer wire connectors. Two wires for common , 1 wire for 24 volts and 1 wire for 48 volts. This connector allows me to plug-in an extension cable if needed and also offers a quick way to power-off the Mikrotik ( by disconnecting the 4-wire connector ) - and I can quickly change DC power supplies or swap different DC modded Mikrotiks.

I soldered all the common wires together , also all the 24-volt wires together and all the 48-volt wires together. Then slide some shrink tubbing over each large bundle soldered wires. Then use some tie-wraps to fasten everything so that nothing could pull loose.

Estimate time for 1'st DC conversion is 1 to 2 hours. Additional mods on same model is 30-minutes each.

My DC modded Mikrotiks at my towers have worked flawlessly for years now. And I no longer have to worrly about generators or 30-minute to 2-hour UPS run time. Mine under full load can easily go 1 to 7 days , depending what what batteries I connect to my DC UPS.

*** I wish Mikrotik had optional DC wire harnesses for all of there AC powered Mikrotiks. No electronics need , just some connectors , then connect to an external DC to DC regulator then to your Mikrotik.

North Idaho Tom Jones

... Last night I ordered a 24v 20A supply locally ...

That 20 amp power supply should be plenty to power multiple Mikrotik's