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Hello all,
since I had the chance to thoroughly try the new AC50B I would like to write some thoughts here about this interesting piece of engineering.
I will write down below my notes and considerations about its capabilities, aware of the fact that, despite the length of the text, those interested in purchasing the unit will have no problem using a little time to inform themselves.
This is all more technical than imaginative since I would like to provide actual data more than dreams.
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I’m living off-grid for real, that means I don’t have any connection to the electricity grid, water supply, gas or telephone.
However, every day I make use of all the conveniences that our modern era makes available to us.
This requires access to a source of electrical energy, which is what primarily differentiates the Stone Age from the modern era of today.
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My main use of this unit is as a UPS, placed directly on my table and connected to the devices that serve me as a programmer and electronic engineer: 3 laptops, 2 monitors, different small devices. The unit internal fan is always off and very quiet if forced cooling is needed.
Due to its efficiency the unit does not heat up or make noise except for the few seconds it needs every now and then to keep the battery 100% charged.
Its efficiency is primarily coming from its bidirectional inverter technology, which means that the inverter which converts the battery voltage into mains voltage is able to work in reverse by converting the mains voltage in order to recharge the batteries.
That means the unit doesn’t have a separate charging circuit and this allows the unit to achieve an incredible level of efficiency and charging capability.
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The unit has a very bright screen that makes it clear from every angle and under sunlight. The screen can be easily turned on and off by pressing the power button once: during the evening this is very useful.
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The 2 USB-C 65W outputs are real 65 W outputs and both capable to keep up with the 65 W standard simultaneously. With my devices I’ve been able to reach 19.78 V at 3.24 A with both ports simultaneously.
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Cigarette plug DC output is providing 13.48 V which is the average voltage the same plug from a car will provide. I’ve been able to power on a small 5 kW diesel heater who draw 8.5 A with the voltage going down to 12.14 V while priming and that allowed the heater to power on without any issue.
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The AC output provides a constant pure sine wave of 230V across the entire output range in battery mode and it works in bypass mode while the unit is connected to the grid, that means voltage and frequency is passed from the grid to the AC output and AC devices are actually powered by the grid while the grid is providing clean power.
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The internal inverter is synchronized to the grid and can take immediately control of the AC output if grid input becomes unstable or missing, by using power from the battery. Being the inverter synchronized and ready-to-serve that provides a very fast AC switching time from grid to battery that is suitable for sensitive electronic devices to keep working without interruption.
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While charging, the unit has 3 charging modes: at 23 C ambient temperature, 20% SoC and 230 V AC input, those are the power and noise values I detected:
- silent charging: input at 166 W and noise 37 dB at 1 meter distance, barely noticeable.
- standard charging: input at 270 W and noise 41 dB at 1 meter distance, slightly noticeable.
- turbo charging: input at 568 W and noise 43 dB at 1 meter distance, not louder than my laptop fan while working.
It has a PV input which has a wide 12-28 V input range that I used a few times on my car. As the usual behaviour, the unit pulled 8 A for a total of 100 W from the cigarette plug of my car at 12.5 V.
What is interesting to understand about the PV input is that it is managed by a microprocessor who automatically detects the maximum current which is safe to pull from the source, for example by providing 18 V from a bench power supply which as a maximum current of 5 A the unit will start slightly ranging the voltage and current ending up sitting at 18 V and 5 A.
As a fundamental rule of electric current, for a given power supplied by a source, the increase in current over the maximum available always leads proportionally to a decrease in voltage. Through an algorithm it is therefore possible to determine a maximum input current determined by how much the voltage decreases, and that is very well implemented on the unit to avoid to pull too much current from the PV input.
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The unit has a charging algorithm which ramps down charging current from about 90% SoC to reach the optimum level of charging to 100%.
This is very important to allow the cells to absorb all the energy and reach the nominal EoC (End of Charge) voltage, avoiding reporting a full charge when this essentially does not reflect the real capacity.
This behaviour is perfectly comparable to pouring beer: If you pour it quickly, the foam will fill the glass and will not allow you to pour more, giving you the impression the glass is full while it’s not; if you pour it slowly, you will have a glass that is more efficiently filled with beer and this is exactly what a proper battery charger do in order to charge the battery more effectively.
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Since I often experiment, my AC mains sometimes fluctuates with out-of-spec voltage and frequency, and that repeatedly uncleaned AC input sometimes caused the AC50B to completely and safely disable the AC output until the next restart. This was unexpected and actually safely protected my AC device in bypass mode connected to the AC outlet and the unit itself which didn’t get damaged.
Furthermore, despite the error on the AC side the unit didn’t disable the DC side which continued to provide power like nothing happened.
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USB ports are fully protected against overcurrent and short circuits: connecting an USB cable that got pinched and is actually in a short circuit resulted in the unit to immediately shutdown the DC side with an alarm. The same happens while drawing more than 5V/3A from the USB-A port and 20V/3.3A from the USB-C ports.
AC output is protected against overcurrent even while in bypass mode and that adds another layer of safety to the devices connected to the AC50B.
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After the unit has discharged to 0% and AC and DC have automatically turned off, they will become available immediately as the battery begins to charge (from 1%), allowing the unit to get back up and running as soon as possible.
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I had many situations in which I used the AC50B to power up my table on battery while working at home electrical system and it perfectly did his job by using the 3 USB ports, 12 V and AC outlet at the same time for powering different devices.
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Honestly the unit blends in very well on my table and I often forget about it even if it’s actually powering up everything - the unit always does its job without bothering.
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Carrying it around is extremely easy thanks to its large handle and its relatively low weight. I often carried it around my property while I needed an AC source and sometimes forgot it outside turned on, finding it the next day still turned on with only a few % of charge lost overnight.
Honestly this is a device without a specific target and from which anyone could benefit, it is smart and could be used by anyone due to it’s large buttons, safety standards and a completely hassle-free configuration and usage.
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As a last note, essentially there is nothing negative I found so far in this unit except for the fact that personally I would have preferred to have a greater quantity of USB-C ports in an era where there are more and more devices to be charged every day.
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Thank you for reading and if you have any questions about the AC50B and would like me to try something with the device or get more information, please ask.
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Mett
