I thought I could use the RavPower battery as a kind of UPS. Power the CHIP from the battery and
connect a USB powersupply to the battery at the same time.
However, it appears that this silly battery does not allow that! When I plugin the charger, it drops the
output voltage and my CHIP turns off.
I tried running the CHIP from only the (fully charged) battery, and it appears it can sustain it for only
about 6-7 hours (I kept a tail -f /tmp/messages open on an SSH session so it is not exact).
Now I would need to charge it again (with the receiver OFF) and then can do another 6-7 hour run.
How useful is that? I think it is imprtant for the operation of a receiver like this to be online for as
much time as possible, preferably 24h/day. So a “UPS-like” operation would be useful for those that
have unreliable power, but a charge/use/charge/use cycle is not.
The battery came with my kit, actually I was not careful during ordering and got the deluxe kit for $20
more, but I seriously question the usefulness of this battery!
Especially now that I have found that the CHIP can actually work off a directly connected bare LiPo cell.
Wouldn’t it be much better to provide a bare cell and a USB cable (and maybe a charger, but that
could be tricky due to national differences) with the deluxe kit instead of this RavPower battery?
Off course to keep the Swing charged, you have to supply external power either thru the USB port (top right next to the lights) or via the appropriate pins on the left side connector.
In this configuration (which is the Lantern), or on a do-it-yourself (DIY) bread board, the CHIP/LNA/SDR/PATCH will work without AC power using the Swing battery for about 6 hours then recharge itself when the AC comes back.
What I don’t know is if you can rewire the RavPower with a connector to plug into the CHIP’s battery port, and have the CHIP recharge it. Do you know @Syed ? Ken
No, the RAV4 is not only a three-cell power pack, it also has it’s own charging circuitry. The JST connector on the CHIP is meant to be used for a plain, single-cell lithium-ion battery. It must be only one cell.
Good - - now we know. Therefore, back to the original thought.
So it appears the RavPower can’t operate a CHIP and recharge itself at the same time. Jesse’s post makes most sense to provide that single cell JST connected battery support for the CHIP. Ken
We have spent tremendous engineering time on validating power issues / power sources and capabilities for CHIP. We came across EMI issues on the single cell CHIP battery usage (remember: 19+19+20 dB LNA gain in proximity of CHIP!) probably this is why still the powerbank still the practical solution for the kit.
It’s really hard to find such ups usb powerbank solution because for regular users this is not a selling point… so even the powerbank is capable of such ups feature the sellers doesn’t indicate that.
I haven’t found any reason why NTC specifies only one cell. As long as your battery is a Li-ion/Li-po with nominal voltage of 3.7v you should be able to use as many cells as you want. However CHIPs charge rate is only about 500ma so a pack the size of the RavPower bank would take about 22 hours to charge. If anyone knows why we are suppose to only use one cell with CHIP let me know.
In RC modeling terms you can only us 1S and any P. So if you want a longer run time you could use a 1S3P battery that is still in the 3.7 V range but may have 3000mAh capacity. But it may take forever to charge…
Ok but I would think that once you have found one (see the links) and you have tested the RavPower
battery, you know what to supply. Frankly I don’t see the use case for a battery that alternately can be
used and be charged, in an application like this.
For EMI on the LNA, it would probably help a lot when you properly shield it. I am going to put the
LNA in a tinplate box when I have the parts for my outdoor antenna stup complete. That, and the
5m cable between antenna+LNA and the other parts will probably kill any EMI problems.
I wrapped min in some “bubblewrap” and covered it in Aluminium foil ( ensuring the foil is “bitten” by the connector when I screw the ant on). Cheap, easy and seems to have stopped it from pick up stray noise effectively
I guess it would be possible to accidentally create weird capacitance doing it like that, so there is a “Fiddle Factor” involved
As for the RAV battery I was supplied… I have found it to be pointless with outernet unless I intend to only ruinn it for a few hours at a time… It is a nice power pack for other things though
Ok but I would think that once you have found one (see the links) and you have tested the RavPower
battery, you know what to supply. Frankly I don’t see the use case for a battery that alternately can be
used and be charged, in an application like this.
Good point! Although if we would know exactly what to develop and sell months ago we probably could estimate winner lottery numbers too Also there are other constrains in the background like component sourcing, price, lead time, which makes decision matrix quite complex.
For EMI on the LNA, it would probably help a lot when you properly shield it. I am going to put the
LNA in a tinplate box when I have the parts for my outdoor antenna stup complete. That, and the
5m cable between antenna+LNA and the other parts will probably kill any EMI problems.
No! The un-shielded LNA picks up 5% noise the antenna from its nearfield picking up 95% noise as it’s also in the proximity of the digital components. Although we using a narrow band pass SAW filter, it’s really hard to filter out the in-band noise like the spurious of the ARM CPU VCO etc.
Again, it’s called development cycles / iterations what might not spectacular from externally but we non stop making new PCB versions, testing them and improving them to provide you guys better and better devices.
@zoltan
I found (when using HDSDR and looking at the spectrum) that I was getting occasional busts of noise from something local. using the shielding method I described above, on the LNA I reduced the amplitude of these bursts dramatically, as well as some background noise…
Currently I have the LNA attached directly to the SDR and then coax to the antenna, as I moved the LNA inside when I was having severe signal issues, and I have been away since the.
I will probably move the LNA back to the antenna end of the coax (where it should be) today
That is one of the reasons I will put only the antenna+LNA outside and the RTL-SDR and CHIP indoors,
this will reduce the digital noise near the antenna not only for Outernet but also for my other antennas.
As radio amateur I have experience with weak-signal receiving and while an everything-in-a-box setup
appears attractive for user convenience it is not really compatible with good performance.
For example, WiFi link equipment is often causing lots of interference as well, due to the same
construction.
Shielding the LNA should help against introduction of noise and other signals behind the filter.
For example, I am occasionally transmitting on 1296 MHz a few meters away from the antenna.
I’m still a bit puzzled that Outernet isn’t packaging a single cell lithium ion battery pack with the JST connector as Jesse used above with its DIY kits. Then the CHIP would recharge it, and you would have an uninterrupted power source. Is there some reason for that @zoltan?
Also, I’m still concerned about the power issues related to USB wall warts and USB cables. I have found (as others have) that some USB cables won’t work with the CHIP based products in the DIY kits and Lantern. In fact, I found another “bad” USB cable yesterday setting up my antenna test platform. By “bad” I mean it works with other devices around my home, but it would not power on the CHIP
Yes I know production cost is an issue for Outernet, and to include an “approved” charger and USB cable could maybe add $20 to the package cost. (That’s allot) But when you drop Lanterns in remote places, people are going to scrounge around to find chargers and cords and may not come up with good items. Ken
Also there are other constrains in the background like component sourcing, price, lead time, which makes decision matrix quite complex.
Ken