Goal Zero Yeti power supplies

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Comments and screenshots by Michael Gordon

Goal Zero Yeti 1000x Lithium

Acquired November 2022.

Summary: Great for portable radio operation. Expensive, solar powered, simple.

Energy storage: 1000 watt-hours (hence the model number). The battery itself is about 80 amp hour, 12 volt. Lithium-ion NMC (nickel-manganese-cobalt) cells made by LG (a top-notch, Tier 1 battery manufacturer)

As with any lithium battery you can discharge this deeply with little consequence as compared to AGM or gel-cell batteries that suffer greatly shortened lifespan (charge cycles) from deep discharges. Also lithium batteries allow much higher discharge currents that can be important in radio operation.

This is an important feature upgrade from the Yeti 1000 Lithium. Of significance to amateur radio operators is the 12 volt ports now offer 13.4 volts regulated (boosted) DC instead of simply tapping the battery voltage typically between 11 and 12 volts depending on the state of charge. The "X" models also offer USB-C ports with higher charge voltages and currents, in addition to normal USB "A" ports 5 volts 2 amps.

The "X" models include MPPT charge controllers (Maximum Power Point Technology). Solar panels tend to be current limited and can deliver 7 amps at 20 volts but still 7 amps at 12 volts or even 7 amps at zero volts into a short circuit. Obviously, the higher the voltage and still 7 amps is higher power. So the MPPT hunts for the highest voltage that achieves maximum power, which is typically 17 to 20 volts, and transforms this through a switching regulator down to 12 volts, but more amps, for the battery. It is a no-brainer BUT the MPPT charge controller can be a significant source of RFI.

Another difference is that the maximum DC input voltage is now apparently 50 volts instead of only 22 volts.

Advisory for actual use with 100 watt 12 volt DC radios: The DC port cannot deliver the 20 amps needed by a typical 100 watt radio (Icom IC-7300 being example) but SSB voice modes peak at 20 amps but averaged is only around 5 to 7 amps. So I use a large capacitor (1 Farad) to smooth the current demand and it works great. I am still working on a way to not expose the Yeti 1000x to a discharged capacitor that it will see as a short circuit. Probably a relay that introduces a 5 ohm resistor while charging the capacitor would allow the in-rush current to be about 2 amps and when its voltage is significant, close a relay that connects the capacitor in parallel. Until then I just charge the capacitor from an AGM battery before connecting it to the Yeti 1000x.

The presence of "boost" regulator could mean an additional source of radio frequency interference or RFI but so far I encountered no interference in VHF or HF (40 meter band) operation.

Obviously, the high efficiency sine wave inverter can also be a source of significant RFI and in earlier models seems to have been pretty bad. But the new "X" series appears to be well shielded and/or filtered and not a noticeable source of RFI.

The Sine Wave inverter is high efficiency and features soft start, which is to say the AC voltage ramps up over a time span of about 400 milliseconds (0.4 seconds) which ought to reduce surge current demand into inductive and capacitive loads PROVIDED that the load is connected while the inverter is turned off, so that on turning on the inverter, the load sees the ramp or soft start.

FFT reveals some harmonics of 120 Hertz, or in other words, likely a glitch in the zero-crossing and indeed when you suspect this is the case, you can see it on the oscilloscope. It is barely noticeable but doubtless a product of turning off the opposing half-cycle completely before turning on the other half. It would be bad to have the output driver MOSFETs driving both positive and negative at the same time. It would probably explode, catch fire or something were that to ever happen.


Yeti 1000x Inverter soft start


Yeti 1000x Inverter sine wave. Notice slight wiggle at the zero crossings.


Yeti 1000x Inverter sine wave FFT. Small harmonics at 120 hz intervals above 60 hz.


Yeti 1000x DC port starts abruptly and regulated at 13.4 volts. It also has a capacitor so stopping it is not abrupt.

Notes on Measurement. I used a Keysight DSOX1202g oscilloscope. Manual trigger, rising edge, 200 ms per horizontal division, single trace. This scope waits for a trigger. It is actually recording the signal but starts the display only when the triggering event happens. When it has completed a single sweep it stops and waits. So I have the inverter turned off, start the sweep. Turn on the inverter. As soon as the scope sees the trigger voltage it displays everything up to that point on the left of center, then continues the sweep to the right and then stops. With a USB memory stick iserted, push the SAVE button for a screen shot.

The FFT function activates a continuous FFT and you can tinker with the span and center to zoom in on areas of interest. So the example is a 2k span centered at 1k, so from DC on the left edge to 2k Hertz. The vertical scale is db so these spikes are not actually anywhere near as strong as seems visually. As you can see from the sine wave itself, the zero-crossing glitches are barely noticeable.

Battery:
Cell Chemistry Li-ion NMC (nickel-manganese-cobalt)
Pack Capacity 983Wh (10.8V, 91Ah)
Lifecycles 500 Cycles to 80% capacity (Discharge rate: 1C, Full charge/discharge, Temp: 25C)
Shelf-life Charge every 3-6 months
Management System MPPT charge controller

Ports:
USB-A Ports (output) 5V, up to 2.4A (12W max), regulated
USB-C Port (output) 5 - 12V, up to 3.0A (18W max), regulated
USB-PD Port (input/output) 5 - 20V, up to 3.0A (60W max), regulated
6mm Port (output, 6mm) 12V, up to 10A (120W max), regulated
12V Car Port (output) 12V, up to 15A (180W max), regulated
12V High Power Por HPP (output) 12V, up to 15A (180W max), regulated
120V AC Inverter (output, pure sine wave) 120VAC 60Hz, 12.5A (1500W, 3000W surge)
Charging Port (input, 8mm) 14-50V, up to 10A (150W max)
High Power Port HPP (input) 14-50V, up to 50A (600W max)
Expansion Module port Covered port under the lid. To be used with Goal Zero

General:
Weight 31.68 lbs (14.37 kg)
Dimensions 15.25 x 10.23 x 9.86 in (38.74 x 25.98 x 25.04 cm)
Operating Usage Temp. 32-104 F (0-40 C)
Warranty 24 months


Goal Zero Yeti 1000 Lithium

Summary: Great for portable radio operation. Expensive, solar powered. Ought to be used with a battery booster.

Acquired May 2019.

Offers two AC sockets, 120 volts sine wave, 1500 watts continuous, 3000 watt surge.

12 volts DC on Anderson Powerpole also cigarette lighter socket. But it only rarely is actually 12 volts. Lithium batteries rapidly drop to 11-something volts and then stay at 11-something for a long time until nearly discharged. However, lithium batteries can deliver a lot of current without significant voltage drop and that's good for radios.

PWM charge controller standard. MPPT charge controller is an optional extra. You'll get around 20 percent more actual charge from a solar panel using MPPT, depending on solar panel voltage. You can charge from both PWM and MPPT inputs simultaneously. Max charge power 300 watts.

Maximum DC input voltage (from solar panel or charger): 22 volts.

Advisory for actual use with 100 watt 12 volt DC radios: The DC port cannot deliver the 20 amps needed by a typical 100 watt radio (Icom IC-7300 being example) but SSB voice modes peak at 20 amps but averaged is only around 5 to 7 amps. So I use a large capacitor (1 Farad) to smooth the current demand and it works great. I charge the capacitor initially from an AGM battery to eliminate the surge demand on the Goal Zero Yeti 1000 on initial connection. I then feed this into an MFJ Battery Booster to get 14 volts for the radio. The average power demand on transmit, but no audio, is 45 watts; maximum audio is 75 watts. So there's about 30 watts of AVERAGE actual power to the antenna when the radio is set to maximum power or 100 watts Peak Envelope Power (PEP). But you get that power only with full voltage! The IC-7300 uses battery voltage on both the driver stage and the power amplifier stage and so a reduction of voltage reduces drive AND reduces final power. A 2 volt reduction translates to about one-quarter power output. QRP radios appear less affected by this phenomenon. My Icom IC-705 2 volt reduction is still about 75 percent power.

4 USB "A" ports 5 volts 2 amps.

The Sine Wave inverter is high efficiency and features soft start, which is to say the AC voltage ramps up over a time span of about 350 milliseconds. Regulation is not quite as good as the 1000x model.


Goal Zero Yeti 400 Lithium

Acquired August 2017

Considerably smaller and lighter and handy for many things, but seems to have rather a lot of RFI when using its inverter.

Maximum DC input voltage (from solar panel or charger): 22 volts.

The 400 in the model number is the watt-hours of the battery. 300 watts continuous power delivery; claimed 1200 watts surge but I think nowhere near that surge capability.