I'm very impressed with Voltaic Systems and their products (and also their tech support). I bought the ARC 20 system (20W folding solar array and V88 power bank). Also the USB-powered Touchlight. Delivery was quick and easy to track.
I had a couple of questions about the hardware, and submitted those via Voltaic's support page; before the end of the day I had a friendly, helpful, and knowledgeable response.
The products themselves look and feel rock-solid. I bought the Voltaic products instead of other, cheaper alternatives primarily because of the many product reviews from photographers, journalists, Peace Corps volunteers, and others who clearly have put these products to real-life use in some difficult environments and who were uniformly pleased with the performance. I was not disappointed when my devices arrived: this is clearly "professional grade" hardware, not the cheap stuff.
Just to satisfy my own curiosity, I fully charged the V88 power bank and then discharged it (at about a 10W rate) while monitoring the outgoing power. I expected to get significantly less than the nominal 88 W-hr energy rating [my experience with batteries is that you NEVER get the rated power]. To my surprise I got 88.4 W-hr from the V88 before the last capacity indication bar started flashing. [I quit there--I didn't want to run the battery all the way down to undervoltage shutoff.]
I like that the unit uses [I believe] pouch-cell lithium polymer batteries, which I understand are much less likely to short out, overheat, burn or explode than lithium ion cells, especially if a manufacturer tries to eke every last mA-hr out of a Li-ion 18650 cell rating.
During the first week of September (and at about 40 deg N latitude) on a clear hot day, from about 8 am to 3:30 pm, I saw maybe 10W average, 14.3W max of power delivered with the array lying horizontal (i.e., not optimal orientation). By momentarily tilting the array toward the sun (by hand ... I need to build a structure to do this) I got a maximum of 14.5W. That's less than the 20W nominal rating, but [as with batteries] I realize that it's difficult or unusual to achieve actual "rated" performance with arrays. It's possible the V88 was limiting input power near the end of charging, and of course the sunlight would be more direct (more overhead) on June 21 than early in September [and also more direct if one were at the equator!]. So the array may be capable of more than the 14.5W I observed. At any rate, I am satisfied with the observed performance and delighted with the product quality.
I do have a couple of items I'd put on a "wish-list" of product features, but they are fairly minor:
1. The labels for the input/output connectors are low-contrast and printed on the back side of the device (opposite side from the LCD display). Once I accidentally connected input power to the output [they have identical connector types]. Fortunately, no harm done--the unit took this in stride. I've since made labels and put them on the front side.
2. I'm spoiled by my cell phone which reports battery state-of-charge (SOC) in percent. I don't know how truly accurate that cell-phone SOC number is, but it's satisfying to get a "full precision" value at a glance. The 6 bars showing the SOC of the V88 power bank are certainly adequate for the job, but a numeric display would be even better. I did a crude test, discharging the V88 from full charge and watching where the bars jumped down. [SOC determine by reading accumulated W-hr on a USB meter and assuming 0% corresponded to 88 W-hr discharge.] The V88's bar-graph "meter" appears to be very nonlinear. Here's what I observed (very approximate):
1 bar shows whenever SOC is greater than ~0%
2 bars when >2%
3 bars when >15%
4 bars when >35%
5 bars when >50%
6 bars show whenever SOC >75%
I labeled the front of my V88 with these numbers for future guidance, but all the more reason why a numerical readout for SOC would be easier and more satisfying.
3. This isn't a problem, just something I didn't find (well) documented. As is documented, you can hold down the power button when on and set the V88 for "always on" mode [so it doesn't turn itself off when little or no power is drawn]. However, if you power cycle the unit, it will then default (or so it appears to me) back to "Auto Off" mode. You need to manually set "Always On" every time you power the V88 on. That's a perfectly acceptable behavior, I just didn't see that mentioned in Voltaic's paper or online documentation [maybe I missed it?]
Bottom line, I'm delighted with this clearly rugged hardware, and if I had any reservations about whether it would be worth the extra cost, I have none now.
| Brand | Voltaic |
|---|---|
| Material | Monocrystalline Silicon |
| Item Weight | 3.25 Pounds |
| Connector Type | Usb |
| Included Components | Car Charger Socket, Laptop Output Cable, Set of Standard Laptop Adapters, and 18V AC Charger |
| Maximum Voltage | 12 Volts |
| Maximum Power | 20 Watts |
| Manufacturer | Voltaic |
| Part Number | 1001BPACK.GR |
| Item Weight | 3.25 pounds |
| Product Dimensions | 10 x 0.15 x 6 inches |
| Item model number | V88 |
| Batteries | 1 Lithium Ion batteries required. |
| Is Discontinued By Manufacturer | No |
| Size | With Battery |
| Color | With Battery |
| Style | Usb,Battery |
| Power Source | Solar Powered, Battery Powered |
| Voltage | 18 Volts |
| Wattage | 20 watts |
| Item Package Quantity | 1 |
| Special Features | Portable,Travel,Foldable |
| Batteries Included? | No |
| Batteries Required? | No |
