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se232
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Battery driven RB get bricked

Mon Jun 14, 2021 11:53 am

Hello *.*

I have a satellite location, which is only powered by solar (no other current available). Very cloudy or rainy days cause a later voltage decrease below the working voltage.range during the night.
Until now, I have already 2 routerboards bricked at this location in short time (2 month).
hAP lite (powered by USB voltage)
SXT SA5 HP (sticker/label not readable any more)
Why are the RB get into that state?
Can it be, that even the BL is damaged/erased by voltage drop ins.
How can I flash a firmware/booloader back on these dead devices? (Netinstall is not showing anything)
What RB HW is stable or designed to be solar/battery power driven?
 
mada3k
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Re: Battery driven RB get bricked

Mon Jun 14, 2021 7:04 pm

Hmm. Strange. RouterOS does write on startup/shutdown, so very frequent reboots will wear out the flash memory. But two months?

I also think that a DC/DC converter can have problems and get damaged with very choppy and unstable supply voltage (the compensation/feedback-loop will break down)
 
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TomjNorthIdaho
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Re: Battery driven RB get bricked

Mon Jun 14, 2021 9:16 pm

IMO , although most DC powered Mikrotik devices show a voltage range for operation , you should avoid running your Mikrotik at the lowest voltage.
If you are operating at the lowest voltage , then you are border-line of being below the proper voltage and you can create problems.
The Mikrotik will often write to the Flash system. If the Mikrotik is writing something to flash and the voltage drops below operating voltage , then it is possible to corrupt the flash system with garbage.

A Mikrotik that is sending ( transmitting ) WiFi will always require more power ( amps/watts ) than a Mikrotik that is idle. When a Mikrotik is idle and operating at the lowest operating voltage , a WiFi transmit operation can temporarily use more current which can reduce the operating voltage - and if during this time the Mikrotik writes ( and or possibly reads ) flash, the flash can get corrupted because the operating voltage is to low.

I would suggest , two things.
- Don't use PoE ( Power over Ethernet ) to power the Mikrotik - instead use 14 or 12-gauge wire directly to the power connector on your Mikrotik. The larger wire will help reduce voltage loss.
- Consider , instead of running your Mikrotik directly from battery power to instead use battery power to power a voltage regulated DC-to-DC power supply. You might want to consider something like the now discontinued Mikrotik mUPS ( battery backup PoE injector ). You might want to also consider something like an ALGcom 24-Volt DC-UPS.

* The mUPS connects to a 12-Volt external battery and 24-Volt power supply. When there is 24-Volts from the AC power supply , there is 24-Volts to your Mikrotik. When the AC power is removed , the mUPS then outputs about 20 to 21-Volts to your Mikrotik. Note - the mUPS is not very powerful , so only power one device with a mUPS.
** The ALGcom 24-Volt DC-UPS uses an external 24-Volt battery system ( two 12-Volt batteries in series ). When AC power is applied , you get 24 Volts. When AC power is removed , you still get 24-Volts out , until your external batteries drop to somewhere about 21 Volts. The ALGcom power supply will simply just shut off when the battery is to low , which helps protect your equipment from operating at to low of a voltage.

By keeping your supply voltage to your Mikrotik devices regulated above the minimum operating voltage , I suspect you will no longer brick your DC-powered Mikrotik routers.

North Idaho Tom Jones
 
se232
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Re: Battery driven RB get bricked

Tue Jun 15, 2021 7:52 am

Thanks for the replies!
I have already a DC/DC converter installed for the SXT 5HPnD from >=9V to 24V, but somewhen in the middle of the night the battery runs out of energy and the 24V supply will drop in anyhow.
So the Mikrotik devices do not check the input voltage and have a predictable behavior when the voltage is below the minimum voltage level, they still try to continue working with all side effects? (Example: driving the SXT - having a voltage range of 5-30V - at 4.5V will cause unpredictable behavior, even damage of the device?).
For the proposal to avoid PoE: Neither the SXT nor the hAP lite have a power connector (SXT can be only supplied via PoE, hAP has only a micro-USB power plug).
Question to the system technicians: Does it help when I install a circuit which interrupts the power supply quickly, when the battery reaches a critical voltage level (e.g. 10V), instead of smoothly going down with the voltage (as it is in the current situation)?
 
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mkx
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Re: Battery driven RB get bricked

Tue Jun 15, 2021 8:41 am

IMO whenever one runs some device off a battery, it's good thing to install under-voltage cut-off device. Not to protect powered device but to protect battery itself. None of battery chemistries (lead-acid, nickel, lithium) don't like being completely depleted and one has to protect them from getting depleted. If batteries get completely depleted, they might get damaged, specially so if batteries are constructed from a series of cells (e.g. lead-acid battery with nominal voltage of 12V is constructed from 6 basic cells in series) because it easily happens one of cells has a slightly lower capacity and completely depleting the battery means reversing polarity of that cell.

So if you use 12V lead-acid battery as power bank for your 9-24V -> 24V DC-DC converter, you really should use under-voltage protector which cuts off battery when voltage drops below around 10.8V ... which is still fine for the DC-DC converter. The detriment effect on batteries is even worse if you're using two 12V batteries in series (making them 24V battery pack) if you allow them to deplete completely.

Since SXT 5HPnD is rated to take input anything between 5V and 30V, you should actually replace your DC-DC converter with undervoltage protector (unless your battery pack can run with voltages over 30V, in that case you still need DC-DC converter to protect SXT from overvoltage).

I don't think there are many mass-production electronic devices that would include under-voltage protection (or over-voltage protection for that matter) and user/owner has to ensure that power supply works inside rated supply voltage interval at all times.
 
pe1chl
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Re: Battery driven RB get bricked

Tue Jun 15, 2021 12:28 pm

Yes I agree with the above, it is usually no problem to simply cut the power to the RB750, but to slowly decrease the voltage below the minimum really can trigger issues.
So as recommended, change the circuitry so that when the battery is below some minimum voltage, the load is suddenly cut.
(and make sure it is powered on only when the voltage is above some much higher value, e.g. 10.8v OFF, 12.5v ON. or else it could end up to be blinking OFF-ON-OFF-ON because when you switch off the load at 10.8v the battery voltage will rise a bit)
 
RogerWilco
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Re: Battery driven RB get bricked

Wed Jun 16, 2021 4:45 am

Similar thing happened to me with SXT LTE running on solar/battery. It was a faulty the battery that bricked the device each morning. Netinstall recovery worked.
 
MikeKulls
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 9:19 am

Thanks for the replies!
I have already a DC/DC converter installed for the SXT 5HPnD from >=9V to 24V, but somewhen in the middle of the night the battery runs out of energy and the 24V supply will drop in anyhow.
I am running a Mikrotik off a battery and solar. It sounds to me like you just need a bigger battery and bigger solar. Reality is you should never flatten a battery below 12V and ideally about 12.2V. I use a 100W panel and 100Ah of battery. The batteries are old so I'm not sure how much capacity is left but some days they struggle. Recently after a poor day of solar the voltage got down to 12.2 V at the battery and 11.5V at the Mikrotik. I have monitoring installed that reads battery voltage every 10 seconds to a raspberry PI. Not sure if this will work but here's an image. I can see the solar working and see how well the solar worked for a particular day. I can also see the voltage drop via the ethernet cable. The yellow line starts half way through the graph as I only just implemented it.

Image
 
MikeKulls
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 9:40 am

I would add I tested my setup as using 10Ah per day. That is with the mikrotik with wifi and 4G, a cheap switch, 1 security camera, a raspberry PI zero and a wemos board. If you're just running the Mikrotik only then usage might be lower depending on model. You only really need to get through 16 hours of dark in most locations so that's about 6Ah. So a brand new 24Ah battery might do the job. You aren't meant to take a battery below 50% capacity so that only gives you 12Ah of usable capacity. For solar I think you'd want at least a 50W panel but more is always better. If you want some more details of the battery monitoring I'm happy to give you some pointers. It only required a raspberry PI zero to run. They use about 1Ah per day
 
pe1chl
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 10:18 am

What you need is a good charge controller, that will have 3 ports: solar, battery, and load. It will charge the battery from the solar, and it will cut the load
when the battery voltage becomes too low. That will protect the battery, and it will solve the issue with the MikroTik device that results from slowly ramping
down the voltage into the area where its behavior is undefined.
 
marekm
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 12:26 pm

While a good charge controller is needed, MT devices shouldn't be possible to brick that way - they should cut off when supply voltage is out of range, and never have any undefined behavior. The issue can also happen with poor quality mains power, during thunderstorms etc. A proper supply voltage monitor circuit is not expensive, and usually needed anyway as EMC tests that every device needs to pass also include supply voltage disturbances.
 
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mkx
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 3:58 pm

I've yet to see a main-stream ICT gadget with active power supply monitoring and self-management. The best I've seen so far is monitoring. It's up to site engineer to provide stable power supply, mostly in form of more or less sophisticated UPS.

If you're designing your own site (with the list of equipment present you definitely are), you'll have to take care of power supply yourself. Chineze are trying to sell you all sorts of building blocks, including DIY under-voltage protectors and what not.
 
pe1chl
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Re: Battery driven RB get bricked

Thu Aug 12, 2021 4:51 pm

A proper supply voltage monitor circuit is not expensive, and usually needed anyway as EMC tests that every device needs to pass also include supply voltage disturbances.
Adding many inexpensive features to an inexpensive device will make it expensive.
It is something that is not relevant under normal operating conditions (a sudden sag in voltage is handled OK) and it seems reasonable that the very few installers that encounter this situation solve it externally to the device.
 
MikeKulls
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Re: Battery driven RB get bricked

Sun Aug 15, 2021 2:46 am

A proper supply voltage monitor circuit is not expensive, and usually needed anyway as EMC tests that every device needs to pass also include supply voltage disturbances.
Adding many inexpensive features to an inexpensive device will make it expensive.
It is something that is not relevant under normal operating conditions (a sudden sag in voltage is handled OK) and it seems reasonable that the very few installers that encounter this situation solve it externally to the device.
I feel like this sort of functionality is best left to be off board. That way it can be built to suit the system powering it. For example if it's a 24V battery we don't want it cutting off at 8V and then coming back on at say 10V.

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