DIY Goal Zero 12v charger concept - fail

[deanwards]

I'm hoping someone much smarter than me can shed some light on this experiment.

Goal Zero Yeti Lithium 1000 inputs are rated at 14 - 22 volts. So, I bought a 5 amp 12v to 19v step-up converter to connect with a 100ah LiPO battery. On paper this should deliver about 95w to the yeti from the battery. I wired it up and tested it with a multimeter and sure enough 5.4 amps at 18.99 volts, well within the specified range. Plugging it in to the Yeti PWM, I get nothing, no lights, nada. Plugging it into the MPPT does register, but the wattage jumps around between 46 and 53w and doesn't stabilize. Out of curiosity I plugged it into a Jackery 500 and got a steady 41w.

I was under the impression that 5a x 19v = 95w. Is it not that simple? Is there some other factor at play here? Shouldn't 19v be in the typical range of a solar panel output? BTW, The Goal Zero chargers (Their 12v step-up, and ac charger) output around 4.6a at about 15.5 to 16v.

Scratching my head why this ain't working. Any thoughts would be appreciated.

 

[boondox]

At a guess, the boost converter (step up) isn't playing well with the Yeti. A boost converter may not provide a very steady power supply for the Yeti. I have never tried such a scheme, others here may have and may have a more information for you. If you have a solar panel or another, more stable power supply, try that.

 

[MisterSandals]

Do you have the means to test the LiFePO4 battery voltage while the step up converter is trying to feed the Yeti?
Similarly, should that show sufficient volts, can you test volts output from the step up converter?

 

[deanwards]

boondox - I'm thinking you're right that the components just don't play well together
Mr Sandals - The LiFePO4 battery was at a full charge at the time, 13.6v. I tried it again at about 50% charge, 13.1v, and got the same results. I didn't test the actual voltage going into the converter, it was the battery monitor voltage readout. The converter is consistently putting out 18.99 volts though.

I'll just stick with Goal Zero's step up converter, even though it only has 5a and 10a options @ 12v. For $25 it was worth a try.

Thanks Folks.

 

[MisterSandals]

It sounds like you are relying on the displayed voltage on your devices. I think you should use a digital meter to check voltages independently; batteries and converters under load cannot be accurately measured.

 

[deanwards]

I see, I didn't check converter in and out under load with the multimeter. I'll do that. Thanks Cap'n O.

 

[deanwards]

So I checked the voltage under load and it explains why the Goal Zero isn't recognizing the converter. The input going to the converter is 13.69v at 3.68a, coming out of the converter it's 13.57v at 3.57a - actually lower than the input. I wonder if I have a bad converter?

 

[MisterSandals]

Is the buck converter reversed?
or
What does the converter output voltage read when not connected to anything?

If you have a pic, maybe someone can see something that might help.

 

[Oggie]

Just checking in... has your GZ charging concept worked now with the external battery and boost converter?

 

[Oggie]

So I checked the voltage under load and it explains why the Goal Zero isn't recognizing the converter. The input going to the converter is 13.69v at 3.68a, coming out of the converter it's 13.57v at 3.57a - actually lower than the input. I wonder if I have a bad converter?

Follow up: did you find your converter is defective? Or that it does not produce a consistent 19vdc under load? Curious since I'm attempting a similar set up using a 19v 285w converter and battery

 

[Daedalus]

Hi all,
Along the same lines i've assembled a frankenstein of non-GZ panels (USB only) running into a USB Boost circuit 5v in - 22v max out, running into a lenovo 7.9mm nib (GZ compatible input) this runs into my current sherpa and Yeti 150 until i get my 60W 18v panel adapted for GZ input.