Sunday, May 18, 2014

Problems with Goal Zero Sherpa 50 and 220 V Inverter

I have again been developing my outdoor power system, with the goal of eventually being able to work remotely. With the Goal Zero portable solar system, my success has been more than zero, but still lacking.

Some two years ago, I purchased the Nomad 7 and the Guide 10 power pack. They have been proven great for charging AA batteries, cell phone, and such while hiking or kayaking. However, I'd like to be able to power a laptop, even a small one, so that I could communicate, write, and perhaps even work while on the go.


Last year I experimented with a 27 W folding panel and the Sherpa 50 v2 power bank. While they worked somewhat well, I was not completely satisfied. The 27 W panel was not able to power even my small Acer Aspire One D270 netbook, which takes around 15W power. Well, the sun is not so bright in Finland, but I had expected better than that.


So, I went on and purchased the newer 13 W folding panel. With it, I seem to get enough power for the netbook, and even my ThinkPad T420 seems to work at midday, although just barely. The laptop should take around 25 W when it's not charging, and more when it is.


Unfortunately, I have not yet found proper connectors, so that I could hook up voltage and ampere meters to the solar panels to measure their real power output. That is something I intend to do in near future.

Broken Inverter


I also purchased a 220 V inverter for the Sherpa 50 power bank, so that I could power devices that want more than the 5 V 1 A, 12 V, or 20 V that the power bank gives out by default.

Unfortunately, after using the inverter for just a week, it broke down. I had used it just to power my camera battery charger, so the load was very light, and when it broke, it wasn't even charging. After breaking up, it seemed to short-circuit the power bank so that it gave out error status.

Fortunately, the German dealer replaced the inverter without question and I did not even need to send the broken one back, which would have been a bit expensive overseas. So, that was great.

This also gives me the possibility to open up the inverter and see what might be broken, but I haven't had time for that yet.

Oddly Behaving Inverter


Now, trying the new inverter, it mostly seems to work. I have tried it with my different laptops and curiously, it seems to give power even better than through the 20 V laptop connector, which should have less power loss.

Well, the only way how I can measure that it is to see whether the power bank's indicator flashes to indicate that it's charging from the solars, while a load (a computer) is plugged into it. I'm not quite sure how reliable measure it is.

The trouble now is that the new inverter seems to heat up quite a bit. I can't measure the exact temperature, but it's quite hot to touch and especially the attachment screw is so hot that I can't keep my finger on it for even just a second. The inverter has a cooling fan, but it's not working even when it's that hot. Well, perhaps it doesn't need to, as the electronics could take it, I don't know. Nevertheless, I'm worried about that.

What I'm even more worried about is that the power output seems to vary greatly. When I attach a power meter to the inverter's output, and attach my laptop to it by it's 230 V power plug, the power output fluctuates wildly between 0-60 watts. Using the inverter when it's cool may make it a bit more steady at around 19-21 watts most of the time, but nevertheless occasionally dropping to zero.

Reading the voltage output, it is not 220 V, but varies between 170-200 volts!


Attaching the power meter to wall outlet says 232 V and it gives a steady 25-27 watt output to the laptop. So, the problem does not appear to be with the meter.

So, it partially works for now, but I'm rather worried that it could again break anytime. It is entirely possible that the problem is with the power bank, even though it otherwise works fine. For example, it could cause the trouble if it does not give enough power to the inverter.

I'll need to study the problems further. Seem like Goal Zero has had some quality problems at least in the past. An owner of the previous version of the Sherpa 50 power bank reported horrible quality of the electronics, with a lot of bad solding and such. I don't know if that is the problem with the inverters as well, but it seems bad.

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