Reddit mentions: The best component testers

You mentioned the basics... how about electricity? I'm specifically thinking of a portable solar arrays, and some multipurpose chargers, batteries devices. Here are a few links of interest:

Super portable 21Watt version that has USB outs:
http://www.amazon.com/dp/B012YUJJM8/

Bigger model but capable of charging 12Volt batteries (I'm thinking trickle charging a car battery):
http://www.amazon.com/Charger-Backpacking-Battery-Foldable-Cellphone/dp/B00VBSFT74/

Multimeter for displaying power output:
http://www.amazon.com/dp/B00J3JSEG6/
(useful for positioning the solar cells for best power)

ThruNite U1 charger and battery; acts as not only a charger for NiCad, NiMH, and Li-Ion cells of varying sizes, but also (drum roll) can be used as a USB powerpack:

http://www.amazon.com/ThruNite-Charger-1x3400mAh-Multifunction-Portable/dp/B00WFXWUOE/

Then, standardize on lights that use 18650 cells as they're way, way better than NiMH (higher power, better capacity, longer life):

http://www.amazon.com/Bundle-Nitecore-Rechargeable-Flashlight-EASTSHINE/dp/B00VG1J8S2/

Oh, random idea... small stove that'll burn wood and comes with a backup alcohol burner:
http://www.amazon.com/dp/B0088FVZZI/

As suggested, circuit analysis equipment such as digital multimeters, oscilloscopes, and waveform generators are all good ideas. Some of these, if they're good quality, can be quite pricey. If you're not looking to break the bank for a nifty gift idea, I would suggest a tesla coil. It has very unique capabilities and is a neat ass toy/tool to own as an electrical engineer. They have a wide price range so you've got a good bit of variance to choose from depending on your budget.

For example:

$35 smaller one

$80-$90 medium-ish

Is he into guns? Some companies manufacture these things called coilguns. They use electromagnetism to shoot projectiles which he might find interesting. They're nowhere near the strength of traditional firearms but still pretty useful when keeping squirrels out of the bird feeder.

Don't know if this site sells them but this will give you insight as to what they are.

Hope this helps, let me know what you decide on!

Edit: Also, voltage/current measuring USB sticks

I'd just put the biggest marine deep cycle battery I can fit as my starting battery, (probably group 31) and get a $100 lithium jump pack in case I ran it down.

Or

You can build your own goal zero type portable battery setup for$200-400. The Yeti 400 is a 33ah 12v AGM deep cycle battery with 300w sine wave inverter and a 12v plug in. It also has features like low battery alarm, displays power usage, and comes with an AC charger. You won't save much $ making it smaller/less powerful, but it will weigh less if you'd like to use a smaller than 33ah battery.

$50-150 for an AGM deep cycle 12v battery, 33ah

$75-150 for a 300w pure sine wave inveter, you can save more money if you don't need pure sine wave or 300w, or don't mind an always on fan

$25-50 for a 12v trickle charger to charge the battery up at home, if you don't have a charger already

$15 for a male to male 12v adapter to charge it from your car, or use your jumper cables.

$10-20 for a 12v socket or two, or a USB charger socket

$10-50 for a battery case to hold the battery and mount the inverter and sockets on

$30 on misc parts like voltage display, wire, and fuses

I suppose this homeassistant needs speaker, microphone, maybe a screen or lights? You want to make sure that EVERYTHING drawing power from a 2.5A supply fits within that at all times, and try to keep a margin like 2.3A max just to be sure. There are some nice USB power meters that can help confirm this.

I just let my timelapse script run last night until the 1500mAh battery powering it died. It probably wasn't fully charged, but a Pi model B with just a USB camera attached taking pics every 10 seconds went for 2.5 hours.


There's ways to turn off nonessential accessories on the pi to save power including the HDMI & USB ports. Also, shutting the pi down correctly instead of letting it die will help keep the sd card from being corrupted, some good info here. I've got one of these on the way to really tell how much power I'm using before I figure out a battery solution. Mopi is another option to manage power and automatically turn the pi off before it dies, and I think the mopi can turn the pi off and turn it back on at certain times to extend battery power even further with the addition of a real time clock.

OP, it’s possible your current sensor isn’t getting data through properly. How fast does it actually charge? It may be useful to pick up a cheap USB current & voltage meter. I got a nice one and I have used it countless times.

[Cheap](USB Meter, DROK Digital Multimeter USB 2.0, Multifunctional Electrical Tester, Capacity Voltage, Current Power Meter Detector Reader with Dual USB Ports, LED Displahttps://www.amazon.com/dp/B00J3JSEG6/ref=cm_sw_r_cp_api_i_ss8IDbE6C7JCJ)

[The one I have with unlimited useful tools. ](AVHzY USB Meter Tester Multimeter USB Load Current Tester Voltage Detector DC 26.0000V 6.0000A Test Speed of Charger Cables Capacity of https://www.amazon.com/dp/B073R7YRM9/ref=cm_sw_r_cp_apip_Gc6nVKprYh32G)

Get yourself one of these if you want to know what your charger is doing. Use a current monitoring widget to see if it is getting to the phone. I have had good luck with Anker chargers in general, but for a Quick Charge capable device it has to be the real thing. Qi chargers are cool, just watch the temperature. They can get hot. Letting you phone sit around at 100% too much is not great for the long time life of your battery.

5 should be safe. 10 probably work ok too. The elite-c has the same chip as a Pro Micro, it will draw the same amount of current.

I have one of these cheap USB power meters. https://www.amazon.com/gp/product/B00J3JSEG6 Useful to see how much power is being drawn.

> My Pi has connected 1 USB mobile 3g modem, 1 motion sensor over gpio, and (hopefully) 2 i2c sensors.

I'll assume you don't have a USB inline meter doodad to measure the current draw? (they can be had for $3-4 if you can wait 4-6 weeks for shipping from China)

In that case, could you please provide the manufacturer/model numbers for the 3G modem, the motion sensor and the i2c sensors so I can find their datasheets and figure out their maximum current draw?

I'm hopeful 24 hours is doable with a cheaper USB battery, say in the $25 range rather than $50.

Usually different USB ports on the same external battery have completely different amperage outputs. I guess just make sure that you are always using the highest amperage output. One thing that you could do is buy a voltage and current meter from Amazon they're like $7 to watch the power flow through your USB and you could test.

DROK® Dual USB 2.0 Digital Multimeter Ampere Voltage Capacity Power Meter 7 Modes Monitor for Fast Charging Data Sync DC 3.2-15V 0-3A Volt Amp Charger Detector Mobile Solar Panel Alignment Tester https://www.amazon.com/dp/B00J3JSEG6/ref=cm_sw_r_other_awd_XzJDwb5JV4VB4

you can measure resistance with a regular multimeter using the 4-wire method. If you have a regulated digital power supply (like a lithium battery charger with lcd) it's as simple as putting a constant current relatively high amp load on the wire, measuring the voltage drop and dividing by current. you could also use a good quality USB power meter ($10, amazon), or a dedicated ~15 watt meter. i've used an incandescent light bulb for this and got fairly accurate results.

you can also use the same process to test USB cables' resistances. I'll use 2x usb power meters (one on each end of the cable) and a powered off cell phone//other electronic as the load. most modern power banks will also display voltage out and current.

edit: here's some more info, and is quite accurate if done correctly.

USB Volt/Ammeter's are surprisingly useful.

The Bosch solid state voltage regs aren't all that expensive, CIP1 has them for $20.99

Sounds like the camera is a little flaky, but in theory the usb adapters should be protecting it.. might pick up one of these and see how well the USB adapters are doing delivering the 5V they're spec'd for.

Could always try one of these, I don't think those dashcams typically draw too much power.

I used one of the original Electronics Australia (EA magazine) kit meters hundreds of times a day for a decade at least, rarely failed me.
That was what they called the bob parker design and it still gets made https://www.amazon.com/Blue-ESR-Tester-Fully-Assembled/dp/B00O0BMIYQ

Not that one seems stupidly priced but they might still be available cheap.

Edit : here is the original, the only mod I did to it was add 2 back to back 1n4001 across the input to protect it from charged caps and also stuck a resistor in series with the 7 segment cathodes as there are no segment resistors and it was far too bright and chewed battery's originally.
http://www.bobparker.net.au/esr_meter/esrhints.htm

These are pretty handy and not too expensive.


https://www.amazon.com/gp/aw/d/B00J3JSEG6/

Adapters have different amp ratings. Purchase one of these usb testers to know exactly what’s going on.

I use it all the time on chargers attached to my iPad, iPhone and watch. It’s interesting how different they all are.

To anyone interested, similar multimeters go on sale for $1-3 every now and then. I've gotten two from different brands from watching SlickDeals.

I can't find the articles I was reading but based on what I found - yes, the phone will use the full 27 watts. But there's a caveat with the whole quickcharge thing. I believe this is true for both USB-C PD and QuickCharge 1-4+.

No batteries in any Android or iPhones will quick charge from zero to 100%, which is why the marketing says "5 hrs of charge in 5 mins" or "50% charge in 15 minutes" and yet nothing about how long to full charge. When the battery is nearly drained and not too hot it will quick charge at max voltage for awhile, then somewhere between 30 and 50% it drops the voltage, then after awhile it drops it down some more. By the time you're at 80% it's charging at close to a standard 5v/2A rate.

The full explanation is pages long and gets into all that stuff with heat, electrolytes, anodes, dendrites, C-ratings, etc etc. So quick charging is nice but it's not everything the marketing implies. I'm going to have 2 quick chargers and then make do with a bunch of adapters for the normal ones already scattered all over the place.

edit:
If you want to know for a fact what charger/device/battery combo is doing what and when, you need one of these guys:
https://www.amazon.com/dp/B073R7YRM9/_encoding=UTF8?coliid=I1B17SFT39RCSC&colid=2K0VHPRC4OVAZ

I use and recommend this one for USB-A. https://www.amazon.com/dp/B00J3JSEG6

It sounds like you need a USB meter.

Can you borrow someone else's charger to test with? Perhaps your charger is losing its strength and needs replacing.

There are inexpensive little gadgets that you can plug into the USB to show the voltage and current. It would show if the power is "drooping" lower than what the 2i2 likes.

USB Meter: https://www.amazon.com/dp/B00J3JSEG6/

The hub working simply just as a hub, adding more ports and a conduit for the signals, is different from powering external devices. And so any hub will work with the pi. That being said, I run non powered $4 4 port hubs on a pi zeros and it can run keyboard, mouse, wifi dongle and web cam. I have never needed a hub for my B+, 2's and 3's doing all that as well. Short of running a dvd burner or charging other devices how much power do you really need? You can figure it out with one of these DROK meters. So all hubs work with the pi, the question is really how much power you actually need.

Just something to consider.

Try and plug your Wyze power adapter into a different electrical circuit in your home and also try a different brand of charger into other electrical circuits not controlled by the same circuit breaker. Sometimes a home electrical outlet may not have 110 volts due to various issues, which would result in a lower power output for two Wyze cams to operate when chained together with the line-losses from the two usb cables.

To verify, you need a device to measure the USB power with under load conditions.

Something like this:

From Amazon

USB Meter, DROK Digital Multimeter USB 2.0, Multifunctional Electrical Tester, Capacity Voltage, Current Power Reader with Dual USB Ports, 7 Modes

https://smile.amazon.com/DROK-Multimeter-Multifunctional-Electrical-Capacity/dp/B00J3JSEG6/ref=sr_1_6?keywords=USB+voltage&qid=1574890447&sr=8-6

I can confirm via a USB multimeter that non-Dash charging peaks at 1.5A with a quality charger and cable.

Use this

I bought one of these to see when it was actually charging: USB Meter, DROK Digital... https://www.amazon.com/dp/B00J3JSEG6?ref=ppx_pop_mob_ap_share
I just keep plugging the gotcha into the cord until I get a reading on the screen.

I'll give a dollar to the first person who hooks up with one of these and reports on the open-circuit voltage, voltage under load, and whether it does at least 2A.

Add one of these and you can see how much USB power is coming out!

https://www.amazon.com/DROK-Multimeter-Voltmeter-Capacitance-Charging/dp/B00J3JSEG6/ref=sr_1_1?ie=UTF8&qid=1469735078&sr=8-1&keywords=usb+amp+meter

I wound up buying this one. I think it's the older model, but was about the same price, had a ton more reviews and showed voltage on same screen.

https://www.amazon.com/gp/product/B00J3JSEG6/

Can you move to a different port? Maybe the RTL is drawing too much power? These's a USB test tool that will show you the voltage/current of a device. I use https://www.amazon.com/DROK-Digital-Multimeter-Voltmeter-Capacitance/dp/B00J3JSEG6/ref=sr_1_6?ie=UTF8&qid=1492270966&sr=8-6&keywords=usb%2Bvoltage%2Bcurrent&th=1

This is the particular one I used... https://www.amazon.com/dp/B00J3JSEG6/ref=cm_sw_r_cp_tai_1os3Ab1K742KB

Try powering off your phone and charging it. This will all but rule out a software problem. Also, one of these things might come in handy; I haven't found Ampere to be too accurate.