Minibox PicoUPS-100 12 volt DC micro UPS system

http://www.mini-box.com/core/media/m...14ef1d9762cd03

Pros:
-Works as advertised, never missed switching between power sources

Cons:
-Voltage input requirement makes product totally usuitable for automotive use
-Unbelievably long charging time, even at recommended voltage is not suited for car use


The PicoUPS is an rather odd device. It's basic function is to operate as a uninterruptable power supply for a car PC. Connect a second sealed lead acid battery to it and when you shut your car off, it switches power from the car battery to the second battery and continues to power the PC. When the car is restarted, the second battery is recharged by the car's power and it is ready for another cycle. Thus, all 'car-off' functions are taken up by a secondary battery, not your vehicle battery. Slick!

The rather odd part about the PicoUPS is that it is completely unsuitable for in-car PC use because the circuitry requires a much higher voltage than the standard car alternator can put out in order to charge the secondary battery! Not only that, but the rate at which it recharges the alternate battery is quite low, meaning you have to drive your car around quite a bit (hours) to charge the battery enough to run the computer for minutes!

An odd device, indeed. More on that i just a moment. First, here's an explanation of how the PicoPSU works:

1. On one end of the PicoPSU are two inputs. One attaches to your secondary sealed lead acid battery. the other goes to the switched part of your car's electrical system. This can't be the accessory line, though, because it has to carry all the juice to run your PC. An appropriately sized relay is required. You would think that this would be included on the PicoUPS, but it isn't, so include it in the cost calculation if you purchase one.

2. At the other side of the PicoPSU is the output. This feed your PC's +12v and ground for the power supply.

Operation of the PicoPSU is transparent. A multi-colored LED signals when the system is charging or discharging and if it is receiving power at all. When the car is on and supply power from the alternator, the PicoPSU uses the car as the source of power to feed the PC and also charge the secondary battery. When the car is turned off, the PicoPSU seamlessly switches to the secondary battery to supply the PC for operation.

In practice, the PicoPSU works perfectly. I connected it to my benchtop power supply (a 10 amp 13.8volt AC-DC converter) and also to a 12 volt 9 amp-hour sealed lead acid battery I bought from Interstate batteries (item SLA1088). I ran the outputs to my Mini-ITX system's (Intel D201GLYA) power supply and hit the start button for the PC. It started as normal and ran perfectly. I then cut the power from the benchtop power supply and the system switched over without interruption to the SLA1088 battery.

Switching the power supply back on and off several times, I found that the PicoPSU did a fine job of keeping the computer from crashing when switching between supplies, with no issues whatsoever.

The description of the PicoPSU on Mini-box's site says that it is designed to switch between a DC input source of 15-18 volts. Uh-oh. Car alternators usually only put out 14.5 volts at best. I decided to run a series of tests on the usability of the PicoPSU and here's where the oddness of this product's suitability for the car PC market begins to creep in.

[IMG]http://www.mp3car.com/vbulletin/imag...d5b55e2e53.jpg[/IMG]

Using a digital multimeter, I connected it to the alternate battery and recorded the voltage every 5 minutes for several cycles. From the left side of the graph to the right:

1. First, I just turned the car (my benchtop power supply) on to charge the battery. It took about 3 hours to raise the voltage from 11.82 to 12.06, about .24 volts.
2. Next, I started the computer and then shut the 'car' off. The PicoPSU switched to the alternate battery smoothly and ran for 12 minutes before the voltage was too low to keep operating the computer.
3. I then turned the 'car' power on and left the computer off to give the secondary battery a quicker charge. About an hour after charging, I started the computer and ran it for about 30 minutes with the car power still on. This caused the voltage on the secondary battery to drop slightly and then level out.
4. I then shut off the car power and ran the PC on the secondary battery. It lasted for about 9 minutes before shutting down.
5. I then restarted the car power and also the computer and operated it like that for 30 minutes.
6. I shut the car power off and left the computer on. It lasted for just under 2 minutes before shutting off.

Conclusion

This product is not suited for car PC applications. A larger secondary battery would have extended the run times but also extended the already excruciatingly long charge time. No wonder, since the specs call for 15 volts or more to adequately charge a battery. My results reflect that. Unless you drive your car for hours in between stops, you won't get a very long run time from your battery and short runs of 30 minutes or so barely charge the battery. The manual for the PicoUPS calls for a 6-12 hour charge time between uses for a 7ah battery at 12 volts - the same rating as the battery I tested with.

I have to wonder what this product is for at all. It cannot take a 24 volt input (too high), which means it is not intended for the marine market. It would only be suitable in applications where a specially designed power supply is used. That leaves the automotive market out.

Minibox's description says that it is for uninterruptable power supplies for mission critical applications like servers and so forth. Which is fine, but they better not draw much power. The max the PicoUPS can deliver is 6 amps. At 12 volts X 6 amps, the PicoUPS can power a 72 watt system and no more.

I think this product would be good if you set your computer to go into standby when the ignition is off. This way, it runs off the second battery providing standby power for very long periods of time, without worry of draining your main battery. And it has the smarts to recharge your standby battery while the car is running.

Obviously the product was not designed for the application for which you are trying to use it. The product is designed as a true UPS system, where the main power is active almost all of the time, and it only needs to switch to backup power only occasionally.

-- Kevin

So what is the point of this product when you can just get a battery isolator instead for a dual battery setup? Probably would cost around the same, yet still allow high charge currents to the secondary battery. If the battery isolator was a diode based unit, you also wouldn't have to worry about voltage dips during crank.

old thread i know, but i am looking for a product just like this, only i want to charge a lithium ion battery pack.

i figure i can just hook up a 14.4v pack to the battery leads on this pico-ups, because since it will always stay above 13v the ups wont try to charge it anyway. i wonder how safe it is though. the charger for the lithium ion battery would just be run by a standalone a/c d/c tabletop charger that i would build into the case.... that way when i plug the computer into a/c power the battery would still charge, but when i unplug this little pico ups would switch to the lithium-ion pack.

(not for my carpc, its for a boombox project)

Yeah - there are a few simpler solutions for that pico application - like keeping the PC power connected until manually off'd (via a push button) or from a low-voltage signal plus/or timer. (It's the addition of a couple of 20c diodes ad a push button to the exiting power relay, plus a $20 battery protector (low voltage cutout) and maybe a few more diodes, and optional timer circuit, plus LED indicators etc).

But to charge Li-ion, you need a specific charging regime - ie, a charger for the job (though they are not as critical as LiPO batteries (that can explode & flame)).

A dc-dc converter can boost the input voltage if needed.

well thats what i was planning...

basically, i want to make my own 'laptop'... or 'portable pc' and sell off this $700 HP proprietary laptop.

the case i plan to use will just be a red 19" metal toolbox. ill cut in 5" car speakers in the front, and mount a usb monitor in the lid (make it removable so i can place the screen on a table) and cut in a volume knob and stop, play, rew/ff buttons on the front. this way you can still select music tracks with the lid closed. the car speakers can be powered by a simple 25Wx2 amp.

itll run a dual core nano with ion graphics, and i figure with ~7ah of battery life it would run maybe 2 hours with moderate volume. i still might just go SLA for the battery, but the weight would be very uncomfortable. i can save over 5lbs by just using lithium batteries...

but it would be really nice to have a computer i can just pack up, close the lid and take anywhere. my laptop does that of course, but it needs its own case to travel and i dont like how i cant upgrade or add anything really. toolbox pc is where its at!