Additional charging option/experiment

I’ve been meaning to test this for a few days, and finally got around to it today, and can report it seems to work great!

I’ve got an omnicharge 20+ power bank which has a bi-directional barrel jack with the same dimensions as the MNT reform classic’s v2.5 power input (I cant remember if it’s 5521 or 5525, but regardless). It can be used to charge the omnicharge from a solar panel efficiently (it’s got an MPPT charge controller), but can also be set as a DC output source. The USB C to barrel jack cable I got from adafruit is rated 20v/5a and that seems to work fine, and that’s the max setting the omnicharge also has.

So, I’ve hooked it up and it is happily charging. The omnicharge says it’s outputing about 45 watts and can do that for about 1.5 hours.

The omnicharge is using lion cells internally, so not a super great solution for long term usage, but I’m happy it’s all DC and solar chargable.

It’s 5521.

That sounds like more than 6 hours of normal operation at around 10 W of power draw, nice!

Do you have photos too? :smiley:

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I’m not sure we can trust it’s time estimate – when i checked around an hour later, the omnicharge was drained and when I booted the mnt reform the OS thought it was at about 83% charge (from around 15%). I should pay more attention. I’ll try again, though.

And yes, such as it is!

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Slightly updated data!

tl;dr – draining the mnt reform classic to the point the system shut down (system controller battery menu indicated 2.x volts for the various batteries), then charging the reform only from the omnicharge which started at 100% and went to it’s zero-point, resulted in ~4:41 minutes of runtime.

Usage of the machine during this time was light web browsing (mastodon, forums, etc), a little scripting (wrote a dumb cronjob to dump uptime every minute), and a few hours of youtube playback.

The battery is several years old with regular usage, so probably not actually at it’s rated 20,000 mAh capacity. I charged it back up to full today with a 40 watt ETFE folding solar panel lying flat with a 5521 DC output in about 2.5 to 3 hours of mixed clear and broken clouds in Minnesota’s late morning (9-ish to noonish) sun.

Although I’ve had it for awhile, now, there’s something wonky with the mnt reform’s battery reporting. I trust the voltage displays in the system menu, but the “percentage full” reading is still usually ???, with occasional 100% after a lot of charging.

In the OS, the swaybar display often reaches 0% and then wraps around to 100%. Or, like just now, after dying and being plugged into power, when rebooted to check the timestamps in my dumb cronjob “how long have I been up” script, it displayed 100%, despite me literally just plugging it in.

I may have damaged my batteries when I first received it, putting a few of them into a charger without setting it to lifepo4 mode first, but they seem to be working.

Regardless. I have seen closer to 5-6 hours runtime, typically, depending on usage and length/type of charging – I think most likely the 4 & 1/2-ish hours I got out of this does test NOT correspond to the reform having a full charge in it’s batteries. It’s indicative of the amount of charging the omnicharge can provide – somewhere around 75 to 80% of the actual capacity of the reform’s batteries.

I’m not really doing rigorous testing here, this is more “gut check” and “how can this work?” testing. I have a 300 watt-hour LiFePO4 power station with 5521 DC output – I should check that and see how it handles things. I can also compare/contrast the direct DC 5521 connectivity of that and the omnicharge and the same batteries using the USBC to 5521 cable I have (both the omnicharge and the power station have USB C output in addition to their DC output capabilities).

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Hm. The power station’s 5521 output is 12v/10a – not sure I want to put 10a into the mnt reform directly. I may stick to using the USB C to 5521 cable.

It won’t draw 10A unless there’s a short, and the DC input jack is protected by a fuse. It’ll be fine.

The most I’ve seen mine do is ~4A, and I regularly charge my Reform off a 13.8V 50A power supply for my ham radio stuff.

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