Solar Charging and Battery for Dash

Posting this to share a little of what I have learned. Understandably, there are no more solar shields left from the kickstarter. So, have been trying to decide on a solution based on solar chargers for my little project. I researched the panel being sold at Adafruit, and that led me to Voltaic.

Check this out… two of their battery packs have a ‘always on’ mode, so you do not have to worry about the sleep/snooze on the dash making a ‘power pack’ shut off:

I am ordering this one:

Should be plenty for my Dash at the frequency I will collect and upload data. Will report back.

Hey, that looks like a good one. We are actually planning to do another production run of the solar shields, but it may be a couple months.

Will I simply use the USB connection on the Dash to connect to that battery pack? I had it in my head that snooze() was more about the battery connector than power via USB.

Interesting product and solution!

I had a look at your Thingspeak implementation as well, well done there, for sure.

One quick comment: I went to the solar charger site, and I see, like most of these devices, that they are only capable of providing a maximum of 1A. Several scenarios apparently exist where the Dash may definitely use more than 1A, and in certain cases can get close to a 2A draw.

Is peak draw from the radio while transmitting? In my specific scenario, I make SerialCloud.println() calls with < 300 bytes of data. I don’t think I own the equipment needed to test the draw for my scenario. Unless a voltmeter will do it :stuck_out_tongue:

How can I test the draw/amps that the Dash will need in my specific scenario? I have is a simple multimeter (INNOVA 3320)

Fortunately, the dash will always be in the same place in my scenario. So cell tower distance, power required to transmit should be mostly constant. Also, the amount of data I plan to send from the dash is very small so that also should be consistent.

Hey, Soggy, I ended up using one of those little USB power meters. Goes inline with whatever your USB is powering. They only cost about $20 or so from Amazon; it’s one of the best little devices I’ve ever bought. Tells actual USB volts; amps, power, and energy on a little 4-way display.

Turns out that powering the Dash via the battery is a “good thing” as far as power management – the power spikes are nicely handled by the battery. Powering solely through the USB 5V (as you’re looking at doing through the solar kit) means the 5V Dash MAY demand up to 2A. Hard to say for how long; but certainly your small data sets are a help. From the TINY bit I know about cellular, the power draw is highly proportional to the strength of your local cellular connection – “more bars” means the radio in the Dash ramps down the transmit power, (please, somebody tell me if this is not right in general and/or on the Dash).

Having a consistent location for the Dash will for sure be a big help – if it works once for your location with a 1A source, odds are it will work going forward, too.

It’s also fun to see what the actual cell reception in your area is for the Konekt SIM – I put my Konekt SIM into a (SIM-unlocked) iPhone; discovered that I had decent reception, and that Konekt was preferentially locking onto T-Mobile in my area (even though my IPhone is via AT&T, also with decent reception in my area).

Ok, I ordered the more expensive kit that allows a 2A draw. This may be obvious, but do I just connect to the USB connector on the Dash? It is a battery, so what about the battery jumper? Also, Snooze(), does it work the same way when connected to a 5v source?

That sounds correct to me! The Dash will see the solar kit as a fixed 5V source, so put the jumpers in the “non-battery” position (both jumpers farthest away from the power connectors). I’ll do a check sometime this weekend to verify if there’s a power input drop at the 5V connector when snooze is used.

Yeah, @MichaelM that’s correct. Use the non-battery mode since you won’t be using the Dash’s battery charging circuit and will be using a 5V input.

1 Like

Hi @Reuben, I have a Dash Pro sitting on the Solar Shield. If the Solar Shield connects to a Solar Panel, charging a 3.7V Lipo battery at the same time. Should I configure the Dash Pro jumper wire in the non-battery mode. It seems that the 3.7V battery is connected to the R01 pin. Will it damage the Dash Pro?

Am I right to say that the USB power is not connected to either the R01 (Batt) nor the L01 (5V) pins? In whatever mode, I can connect an USB cable with no risk.

It should be in non-battery mode since the battery is getting charged by the Adafruit part and not the Dash.

Noted with thanks, @Reuben. Are you saying that if jumper is in battery mode, Dash (or DashPro) is charging the externally connected battery? I have been thinking that it is the battery powering the Dash in this mode.

It’s both. The jumper should be in the battery position whenever the battery is connected directly to the board in order to enable the charging circuit and allow the board to properly be powered by the battery.

(On the solar shield, you’re not connecting the battery directly to the board so that’s why you don’t use the battery position)

Thanks, @Reuben. I think I am slowly getting it :slight_smile: Still need some more confirmation on the following questions:

  1. If I connect the solar shield to a solar panel, and I also connect a battery to the solar charger board (which is plugged onto the solar shield) so that the battery can be charged by solar to be used at night. As the battery is not connected directly to the Dash/DashPro, I should set the jumper in non-battery mode.

  2. Whether I connect a battery to the solar charger, or to the Dash/DashPro, or use solar panel to directly power Dash/DashPro, I am ok to connect the USB port to a PC to run Arduino IDE. The only exception is when I use an external 5V source to connect to L01. Correct?

Hi @Reuben, I did not see your reply to my 2 clarification questions below. In any case, the following observation is making me nervous about inserting Dash/DashPro onto the solar shield with charging board: The DC power or solar panel power is fed to the input adapter of the charging circuit board, the voltage also appears on R01 (VBATT) pin and not the L01(USB_5V) pin. From all the messages above, I thought the power is going to the L01 pin!

So if I leave the jumper in non-battery mode, isn’t it going to cause a problem if Dash/DashPro is inserted on the solar shield?

Also, the specs says that the VBATT pin in battery mode is from 2.2V to 4.4V. This must be when using the battery charging circuit inside the Dash/DashPro in battery mode. When an external charging board is used, and 5V or more appear on this bin even if no battery is on the Dash board, any bad things will happen. Because of this uncertainty, I still dare not plug in Dash/DashPro onto the solar shield with action external charging board.

Hi @Reuben, I have been waiting for your reply for a week. Could you please drop me a note? Thanks.

Hi @juipin - A few things based on your questions above outlined below from our hardware team. Thanks for reaching out:
When the Solar Shield is connected, power is supplied to the Dash on pin R01, which is labelled “VBATT” on the schematic. That’s correct based on your observation.
So - VBATT is connected to the output of the battery charger circuit and to the Battery connector on the Dash 1.1. It is also what is used as the voltage to create the 3.3 V internally for the rest of the Dash.
The trick is to get the Battery Charger to not put a voltage on VBATT when the solar adapter is connected.
And, to do this whether or not the USB connector is plugged in. The only way to do this is to remove the jumper completely off. When there is no connection on the J2 USB/Battery jumper, the +5V from the USB (USB_IN) goes nowhere (mostly = it only goes to a pin on the uBlox which isn’t used)

The key here is that there is no conflict on the VBATT pin (R01) when J2 has no jumper in place.
Also, the Solar Shield has it’s own battery connector; and that should be used to charge any battery, and not the one on the Dash 1.1 if running with a battery.

Let me know if you have any further questions.