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rfc1149
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Running hardware portably using DC battery power

Thu May 21, 2020 1:17 pm

Hi everyone, this is my first post! Long time MikroTik fan.

MikroTik devices are really modular when it comes to power so I've been looking into a portable solution for fun.
The keyword here is "portable", it has to be easily transported, not involve solar power and not require dragging around a 12V car battery. :D
The devices I'm testing this with are an LtAP LTE6 and a hAP ac.

I've seen this done with a different TalentCell power pack that outputs 12V DC, powering a hAP ac² and a homebrew USB power-hub.

My thoughts for a setup involve using a TalentCell PB240A1 and a barrel plug to a two port barrel plug connection to the devices (like the twitter post).
Since I stack the connections to the DC output via a single port and the devices connect to it in parallel, the amperage draw from the battery increases, not the voltage.
If my math is correct, there should be more than enough power for both devices [the battery specs state the output at (29.4V-21V) / 3A].

What I'm looking for from the community is any advice on additional safety measures, fuses, or even a tried and tested setup direct to a battery without any middle-ware.
A better setup to me looks like a direct connection to a battery, with just a fuse. No circuitry or step-up/down converter in between except for maybe an undervoltage/overvoltage protection circuit.
I could also add a current measuring device inline to the cable and set alarm triggers when it hits about 80% use. A direct connection would offer way better efficiency in all cases.
I'm aware of the PowerBox and PowerBox Pro but it seems slightly unnecessary for a portable setup. A more expensive option would have been with a GoalZero battery.
However, GoalZero made the Sherpa 100AC without a 12V output compared to the older versions. It does have a built in inverter (modified sine wave) but again... efficiency!

Anyone who has tried this before, I would love to hear about your setup!
Last edited by rfc1149 on Thu May 21, 2020 5:08 pm, edited 1 time in total.
 
mada3k
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Re: Running hardware portably using DC battery power

Thu May 21, 2020 2:43 pm

I run a accesspoint and router on a 27.2V float charge voltage supply with two 12V SLA batteries. 2A battery fuse. Both the AP and router has voltage monitor and detects and logs and notifies when voltage drops and goes to low.

Mikrotik is very suitable in this kind of setups with varying DC supply.
Manages some CCR's, RB750Gr3, RB922 and wAP's
 
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rfc1149
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Re: Running hardware portably using DC battery power

Sun May 24, 2020 12:04 pm

I run a accesspoint and router on a 27.2V float charge voltage supply with two 12V SLA batteries. 2A battery fuse. Both the AP and router has voltage monitor and detects and logs and notifies when voltage drops and goes to low.

Hey mada3k, that sounds awesome! Could you perhaps post a picture of the setup please and maybe share some technical info like the wiring? I am considering SLA batteries although they are a bit heavy and I have some concerns about the lifetime of the cells. Some of the maritime yacht/boat batteries are also quite promising for how much power they can store. It's tempting to build a power supply out of 18650 LG HG2's too. Li-ion batteries have better lifespans and capacity over time and I read somewhere that LG HG2's drop to 60% capacity after 500 250 cycles.
If I do go down the 18650 route, I want to make a battery pack that fits the grooves of the hAP ac nicely, and another one with a makeshift directional mount for the LtAP so that I can position it towards the tower. Although I might just make a directional mount for the mANT LTE 5o instead and run two SMASMA cables to the LtAP using two ACSMAUFL connectors internally.

Edit: capacity after n cycles correction
Last edited by rfc1149 on Sun May 24, 2020 12:34 pm, edited 1 time in total.
 
jebz
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Re: Running hardware portably using DC battery power

Sun May 24, 2020 12:24 pm

For surveying, a power source from a Makita tool battery pack works well. Here's an adaptor you can make -
https://www.thingiverse.com/thing:352094
Contact block -
https://www.thingiverse.com/thing:863257

Or you can purchase a clone Makita USB adaptor and modify it with a cable from the raw 18v battery -
https://www.makita.com.au/building-cons ... ng-adaptor
I've done this and it's great. A medium battery lasts hours and the new ones have a charge LED bar indicator (4Ah).
..
Makita_Battery_Adaptor.JPG
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Re: Running hardware portably using DC battery power

Sun May 24, 2020 1:01 pm

For surveying, a power source from a Makita tool battery pack works well. Here's an adaptor you can make -

Wow! This is exactly the sort of thing I was looking for. It seems like the Makita packs use 10 x 18650 batteries, and judging by the voltage the configuration might be 5S2P (5 cells in series, 2 parallel). Have you run them from full to empty? If so, how long did they last on average? Also is that the RB951G-2HnD I spy? :D

I have to decide at some point if I want to go for a prefab battery or whether there is a significant advantage in constructing a pack from high capacity cells. In the past, I've used LG HG2 18650 cells with an XTAR VC4 charger, which more than does the job for safe charging and reviving near-dead cells stored too long with low voltage. There's a new 8-port charger, the XTAR VC8. Either way, I'm going to post the projects progress here so everyone can weigh in and possibly copy the design.

Edit: punctuation
 
mada3k
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Re: Running hardware portably using DC battery power

Mon May 25, 2020 1:15 pm

For mobility I would go for power-tool batteries as well. They are light and have great capacity.

SLA is for more suited for permanent installations where weight isn't an issue.
Manages some CCR's, RB750Gr3, RB922 and wAP's
 
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Re: Running hardware portably using DC battery power

Mon May 25, 2020 9:40 pm

I will start by buying a Makita 1840BL (4Ah) or 1850BL (5Ah) and an aftermarket USB converter to modify for power leads.
Will test the setup and post results here!
 
jebz
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Re: Running hardware portably using DC battery power

Tue May 26, 2020 2:40 am

Here's some internal pictures to give you a start.
.
Makita_Battery_Adaptor_PCB01.jpg
Makita_Battery_Adaptor_Wire_Routing.jpg
Makita_Battery_Adaptor_PCB02.jpg
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Re: Running hardware portably using DC battery power

Wed May 27, 2020 11:56 pm

I use a power bank with USB-C power delivery output. Combine that with a PD Buddy Sink and you are done.

The PD Buddy Sink even fits into a wAP (LTE) case - resulting in a powerful mobile access point.
photo_2020-05-27_22-53-20.jpg
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Manage RouterOS scripts and extend your devices' functionality: RouterOS Scripts
 
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Re: Running hardware portably using DC battery power

Thu May 28, 2020 4:19 am

Here's some internal pictures to give you a start.
Thank you for the starting point! Your setup seems quite apt and nice bit of engineering with the cable routing.
I'm making this my first setup. Got the batteries on the way and a new TS-100 soldering iron too.


I use a power bank with USB-C power delivery output. Combine that with a PD Buddy Sink and you are done.

The PD Buddy Sink even fits into a wAP (LTE) case - resulting in a powerful mobile access point.
That's awesome! What a snug fit. Does the PD source always rise to 20V?
I don't own a wAP... yet, but this definitely makes me want one.
 
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Re: Running hardware portably using DC battery power

Thu May 28, 2020 1:39 pm

That's awesome! What a snug fit. Does the PD source always rise to 20V?
I don't own a wAP... yet, but this definitely makes me want one.
You can configure the voltage (or voltage range with preference) your PD buddy delivers. It also depends on your power source, some do not support 20V...
The PD buddy itself does not rise anything, it just does the protocol handshake and passes through.

So if you configure PD buddy to deliver 20V it requires a power source that supports it. If the source does not support it you will have no output.
If you configure PD buddy to deliver anything between 12V and 20V it acts more flexible. I have a wall plug that supports 15V at most - that's what you have then.

BTW, I have one PD buddy with a Lenovo plug to power a pre-USB-C Thinkpad. Even that's possible.
Manage RouterOS scripts and extend your devices' functionality: RouterOS Scripts
 
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Re: Running hardware portably using DC battery power

Fri May 29, 2020 8:22 pm

I decided to avoid the Makita battery packs due to the cost/performance ratio. The original 5Ah pack contains 10 x 1000mAh Samsung INR 18650 cells.
For the same price as one of those packs, I can buy 10 x 3000mAh LG HG2 18650 cells. In 5S2P configuration @ 3.7V 18.5V, that's a 15Ah 6Ah pack.

I also discovered a solderless solution for constructing a battery pack. Couple that with a SKYRC IMAX B6AC V2 balance charger, and obviously some extra investment later, I have an elegant solution. This means a little bit more work, but a modular approach is highly efficient and easily serviceable. Even with the aftermarket (off-brand) Makita packs, the cells are untrustworthy at best. You're taking a gamble on packs that might be constructed with depleted cells and a pre-existing high cycle count. Worse yet, they may be very low capacity cells or unstable rejects, marketed with facetious capacity ratings.

DC-DC efficiency is still present in my approach and should play out nicely. One of the advantages of the Vruzend kits is that you can easily replace individual cells, as well as construct the pack in any shape you want. The spacing between the cells in the finished pack allows for decent cooling when coupled with a fan as well.

Lastly, my design considerations had to include balance charging since I didn't want the cells to be unevenly worn over time.

A rough breakdown of cost:
£60 for 10 x LG HG2 3000mAh 18650
£60 for SKYRC IMAX B6AC V2 balance charger
£40 for Vruzend 64pc 2.1 18650 battery pack kit in case I wish to expand the pack or build a larger one, 16 (2.1) / 28 (1.6) pc version goes for £20.

More updates to follow!

Edit: pack capacity of LG HG2 cells
Edit 2: my math was way off on the pack Ah.
 
jebz
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Re: Running hardware portably using DC battery power

Sat May 30, 2020 7:07 am

I decided to avoid the Makita battery packs due to the cost/performance ratio. The original 5Ah pack contains 10 x 1000mAh Samsung INR 18650 cells.

Edit 2: my math was way off on the pack Ah.
.
I agree if you don't have 18v battery Makita power tools or other similar tools this solution may not be a good solution.
I think you math is off too. A 3Ah Makita battery would have 10x 1500mAh cells and the 5Ah batteries would have higher capacity cells or more cells.

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