[Mikrotik] 28v over-voltage protection - $2.75 solution

Randy Cosby dcosby at infowest.com
Mon Nov 2 16:49:31 CST 2009


I came up with a solution for this problem for now.

I use West Mountain Radio Rigrunners ( 
http://www.powerwerx.com/west-mountain-radio/rigrunner-4005.html ) to 
distribute my voltage and protect my devices on solar installs.  Makes 
for a nice clean, easy-to maintain and troubleshoot install.  They go up 
to 38 volt, even though they don't say that in the descriptions.

I bought some radio shack 276-1143 diodes - 200V 3 amp ( 
http://www.radioshack.com/product/index.jsp?productId=2062578 ).   I 
crimped a red Anderson powerpole connector  ( 
http://www.powerwerx.com/anderson-powerpoles/powerpole-sets/15-amp-red-black-anderson-powerpole-sets.html 
) on each end of the diode after shortening the leads a little bit.  
Then I put that inline between my Rigrunner positive terminal and the 
cable that feeds my Mikrotik device.  I label the end that goes to the 
Rigrunner - the side of the diode without the white stripe - with yellow 
tape so I don't end up putting it in backwards later. 

I use one for each device.  Drops the voltage around .6 - .8 volts, 
enough to give me the margin I need on my radios.  On routerboards that 
are very close by (no voltage drop due to ethernet cable length) I put 
two of these devices in line to drop it 1.2v.   I'm cleaning out the 
local radioshacks and building a bunch of these for future use.

Randy


Dave Crim wrote:
> Ah, that would make some sense.  My 493 is directly attached using the
> power port, whereas the 433 is connected over POE with about 30' of
> cable.
>
> My solar charger puts out about 28.8V max.
>
> We're converting that whole site to AC (ran 915 feet of conduit with
> wire to the bottom of the hill), so our DC woes will soon go away.
>
>
>
> -----Original Message-----
> From: mikrotik-bounces at mail.butchevans.com
> [mailto:mikrotik-bounces at mail.butchevans.com] On Behalf Of Randy Cosby
> Sent: Wednesday, October 28, 2009 2:59 PM
> To: Mikrotik discussions
> Subject: Re: [Mikrotik] 28v over-voltage protection - just say NO
>
> How far from the power source is the 433?  Long ethernet cable runs will
>
> drop the voltage.
>
>
> Dave Crim wrote:
>   
>> I ran into this same problem and thought that I had two defective
>>     
> RB493
>   
>> boards.  That was after first installing a RB192. The board would
>>     
> "die"
>   
>> at a random time during the day.  When I brought it home, it worked
>> fine.  I finally put two and two together.  Then someone posted on the
>> Motorola list regarding this same problem.
>>  
>> I currently use the Packetflux DC to DC converter:
>>
>>     
> http://www.packetflux.com/index.php?main_page=product_info&cPath=4&produ
>   
>> cts_id=9
>>
>> It's cheap and works well.  I have it set to put out about 18V minimum
>> (which means about 22V max).
>>
>> Strange thing here is that I have a RB433 at the same site, running
>> straight off battery for almost 2 years.  They must have added the
>> over-voltage protection in the newer units.
>>
>>
>> -----Original Message-----
>> From: mikrotik-bounces at mail.butchevans.com
>> [mailto:mikrotik-bounces at mail.butchevans.com] On Behalf Of Randy Cosby
>> Sent: Wednesday, October 28, 2009 10:06 AM
>> To: Mikrotik discussions
>> Subject: [Mikrotik] 28v over-voltage protection - just say NO
>>
>> http://forum.mikrotik.com/viewtopic.php?f=3&t=36191&start=0
>>
>> I'm pulling my hair out and wasting all kinds of money on voltage 
>> regulators to make sure my solar and dc-powered sites don't cause 
>> mikrotik routerboards to go into over-voltage protection when the 
>> batteries get charged over 28v.
>>
>> I'm begging (and asking for you to join me) Mikrotik to:
>>
>> 1. Upgrade the over-voltage protection to 30v or higher on 24 volt
>> products.
>> 2. Never EVER make another routerboard that runs has over-voltage 
>> protection at 28v
>> 3. Change the over-voltage behavior to cause the device to reboot when
>>     
>
>   
>> the voltage drops to acceptable levels, instead of requiring a 
>> power-cycle to bring it back to life.
>>
>> Will you join me on this and let Mikrotik, your distributor, etc. know
>>     
>
>   
>> your thoughts on this? This is not a new problem, it has been
>>     
> discussed 
>   
>> repeatedly on the lists and forums.
>>
>> Thanks!
>>
>>
>>   
>>     
>
>   

-- 
Randy Cosby
Vice President
InfoWest, Inc

435-674-0165 x 2010

http://www.infowest.com/


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