USB car chargers (USB-A or USB-C) and 12V solar systems

[DamonHD]

Hi,

What has anyone's experience been of using USB car chargers designed to plug into a (12V) cigar/cigarette lighter socket?

Rgds

Damon

[Bruce S]

Damon;
I have several.
For several types of USB devices including the newer USB-C .
I get the dual units that include standard and 2A side.

A lot of the newer computers also have "Power-Share" option in the BIOS too. The newer Dells even have a USB-C port.

What's your new experiment ?

Hope this helps
Bruce S

[Mary B]

I bought a board with 4 ports(China, where else) that is built into my radio desk. Lets my plug in phones etc. Runs off my 12 volt radio buss that is running off the 24 to 12 volt converter and the solar bats.

[richhagen]

We added 12V female cigarette type sockets and car USB phone chargers to several of the light kits we installed in the Philippines and other places back in the day.  They ran off either 6 cell 12 sealed lead acid batteries or 10 cell 12V nicad battery packs.  The batteries were charged with a 5 or 10 watt solar panel through a 3 amp charge and load controller, which powered a light.  The LVD also disconnected the power to the cigarette lighter 12V socket.  Some of the phone chargers were USB adapters with USB phone charging cords.  Worked fine as long as one did not plug in anything too large.  We added a dc push circuit breaker for that eventuality. The lower voltage of the discharging cell did not seem to bother the dc-dc buck circuits in them that I am aware of.  Back then they were probably only USB 1 or 1.1 though and only drew 1 amp at 5V max though. 

[taylorp035]

I've used quite a few of the 12v to USB converters.  The 0.5A ones don't even charge your phone, especially when you have navigation going.  You can get them up to 3.4A I believe, but it depends what you are trying to do.  I'm using a 1 amp single port one for my Christmas windmill project to charge my phone off of 3s li-ion setup.  It draws about 0.81 amps @ 12 volts, so it's not very efficient, but uses almost nothing when it's not being used (I think 0.03 amps to power the LED).

[DamonHD]

Damon;
I have several.
For several types of USB devices including the newer USB-C .
I get the dual units that include standard and 2A side.

A lot of the newer computers also have "Power-Share" option in the BIOS too. The newer Dells even have a USB-C port.

What's your new experiment ?

Hope this helps
Bruce S

Not so much an experiment as a mini "Have I gone mad?" crisis!  I've had four 12V USB car chargers fail in fairly quick succession when used on my 12V system, the last two within seconds of one another.  In fact, I think I heard the magic smoke escape (faintly) from the last two.

I don't think I'm doing anything stupid.  At least 2 or 3 of the 4 claim to be rated up to 24V input, and nothing on my system gets close to that.  Plus other 12V / car things have been operating happily for years on my system, so I doubt that spikes from (say) my PWM secondary solar charger can be at fault.

But somehow ~£100 / USD125 of kit just died no apparent reason.

I'd like to replace my current 2A-max 12V-to-5V converter that powers my Raspberry Pi 2B to something a little more off-the-shelf and powerful for my RPi3 (2.5A to 3A).

Latest news: may be downgrading' to a 3B from a 3B+ for power and heat reasons: http://www.earth.org.uk/note-on-Raspberry-Pi-3-setup.html#Downgrade

Rgds

Damon

[DamonHD]

Thanks for all the feedback.

From here and on Twitter I think that I'm not doing anything weird expecting to use 12V automotive stuff safely on a 12V solar off-grid system:  https://twitter.com/EarthOrgUK/status/1272968307122020359

Rgds

Damon

[Mary B]

I use something similar to this https://www.ebay.com/itm/12V-Dual-Port-USB-Charger-Socket-Car-Boat-Red-LED-Voltmeter-Rocker-Switch-Panel-/401315021670 2.1 amp per USB device.

[DamonHD]

Thanks Mary.

I have one of these due to show up tomorrow, which may do the trick for me:

    https://smile.amazon.co.uk/gp/product/B06XSCCLCD/

Rgds

Damon

[SparWeb]

Those are interesting Mary.  I've never seen that before but looks like something I'd like to use.  My old car's current USB arrangement is very awkward.  Thank you

[Bruce S]

Damon;
Hope you don't mind the questions about the PI3 here.
I did see where you were talking about passive cooling for the PI3 and see where it does exceed to 70C point.
Are you doing anything about increasing the passive cooling heat sink?

Cheers
Bruce S

[dnix71]

A lot of the newer computers also have "Power-Share" option in the BIOS too. The newer Dells even have a USB-C port.

That's part of the modern problem with usb C. The first two versions had low power limits. Version C may use up to 15 watts just for downstream power. That would suck a laptop battery dry fast if the bios didn't have that option.

https://en.wikipedia.org/wiki/USB-C

BMW's and other overly complicated cars use all the available wiring as a data bus. If you steal the radio on a VW, the car will not run. No aftermarket theft protection is approved by BWM. Even the dealer is not allowed to modify the wiring. I watched a neighbor mechanic fix a BMW with engine damage. he had to reset all the codes several times. Even changing the battery required reprogramming. The computer refused to adapt. If something changed you were forced to acknowledge it or the car would only limp home.

It violates the warranty and may cripple the car add any device that might inject a signal back into the car's electrical system. The dash power port (not the one in the back or glove box) is also frequently an unsafe place to plug stuff in. I helped a neighbor change a flat tire in his 2006 Chevy. The temporary spare needed inflation, so I plugged in a small 12v air pump. Magic smoke came from under the dash and the body control module wiring burned up. The car had to be towed away. No fuses blew. It was a known issue, but GM refused to fix it.

[JW]

BMW's and other overly complicated cars use all the available wiring as a data bus.

I hate to specify my Google listing. Check out my google reviews-

https://www.google.com/search?q=auto%20repair%20gatlinburg%20tn&rlz=1C1CHBF_enUS773US773&oq=auto&aqs=chrome.0.69i59j46j69i57j46j0l4.6275j0j15&sourceid=chrome&ie=UTF-8&sxsrf=ALeKk02f9kDbLrqmOEb2xKFZ8WE8DtG5Gw:1593049303670&npsic=0&rflfq=1&rlha=0&rllag=35814074,-83552820,15544&tbm=lcl&rldimm=12876846943694322452&lqi=ChlhdXRvIHJlcGFpciBnYXRsaW5idXJnIHRuWigKC2F1dG8gcmVwYWlyIhlhdXRvIHJlcGFpciBnYXRsaW5idXJnIHRu&ved=2ahUKEwiI7uqO65vqAhVQm-AKHYHkA7sQvS4wAHoECAsQIQ&rldoc=1&tbs=lrf:!1m4!1u3!2m2!3m1!1e1!1m4!1u2!2m2!2m1!1e1!1m5!1u15!2m2!15m1!1shas_1wheelchair_1accessible_1entrance!4e2!2m1!1e2!2m1!1e3!3sIAE,lf:1,lf_ui:2&rlst=f#rlfi=hd:;si:12876846943694322452,l,ChlhdXRvIHJlcGFpciBnYXRsaW5idXJnIHRuWigKC2F1dG8gcmVwYWlyIhlhdXRvIHJlcGFpciBnYXRsaW5idXJnIHRu;mv:[[35.8270195,-83.2985309],[35.6797857,-83.65021209999999]];tbs:lrf:!1m4!1u3!2m2!3m1!1e1!1m4!1u2!2m2!2m1!1e1!2m1!1e2!2m1!1e3!3sIAE,lf:1,lf_ui:2

put a bad review on there and I will get you!!


Anyway I have seen my 3rd Tesla, recently I was having my coffee in the morning and someone dropped it off by a tow truck in the middle of the parking lot. I got a a phone call about 9am from this smoking hot chick named Jill, the owner of the Jet Black Tesla... I grabbed the cordless walked out to the car and was talking... I said the door is locked, she said try it now/ Oh I just unlocked it with my cell phone- smile.... Im like OK how do you drive this thing. She said take the Tesla credit card and set it on the center console. Put your foot on the brake and select the shiftier. Im thinking ok this is cool. and it started to roll then stopped cold Im like what happened its dead now? She said is the the door all the way shut, im like well your right, then things went smoothly and I was like all right I just drove a Tesla

Im like this reminds me of a 840 BMW...

JW

[SparWeb]

It's supposed to make you feel like the car knows more about driving than you do.

Harrumph.

[DamonHD]

Damon;
Hope you don't mind the questions about the PI3 here.
I did see where you were talking about passive cooling for the PI3 and see where it does exceed to 70C point.
Are you doing anything about increasing the passive cooling heat sink?

Cheers
Bruce S

No problem about RPi questions.

I'm not attempting significant passive cooling since I have an expansion HAT board on top (real-time clock + GPIO + ADC, etc) that would get in the way.  I have stood the case on its side, though, since that does help.  That's quite passive!

(I can put up a pic ot two, if of interest.)

I'm also happy to let the thing run slow, against a lowered thermal limits, as there is nothing that needs doing very fast, even in hot weather such as now (31C outside, 28C inside).

Rgds

Damon

PS. I'm using the JZK Car Power Converter as bought from Amazon, and it seems to be OK, running cool.  I needed to buy a specially meaty micro USB lead to stop the RPi3B undervolting when I fired up all the CPUs!

[Bruce S]

Makes perfect sense on turning sideways.

Running them slower is similar to turning down the current on LEDs or TEGs.

[DamonHD]

I got local supply voltage monitoring just upstream of the JZK working.  It's not perfect - single-ended and the analogue ground will shift under it when there is significant draw by the RPi3B for example - but it is capturing data.

And that data suggests that either I need to beef up the wiring upstream of the JZK or check what is happening with the ground and maybe compensate - the measured voltage drops horribly from reality (even as measured by the RPiB at effectively the same point) when the CPU is doing something.  I suspect that it's much more bursty than the RPI2B.

Rgds

Damon

[Bruce S]

Damon;
I know you pay close attention to the wiring bits, but, the ground shouldn't lift, unless you're really into polyphase power-shifting like they're doing on cars these days (BMW, VW, MB , they're doing this on their higher end vehicles) keeps thieves at bay===sorta.
 
Is it possible there's a floating ground somewhere? Or a wire strand that's going ?
Possibly you'll need to back trace from the JZK to source.

Cheers
Bruce S

[DamonHD]

There simply is going to be significant impedance in the wiring from the incoming supply GND star point through the USB supply and cable and micro-USB power connector to the ADC ground which os on the other side of the big CPU current eater and a connector and finer traces.  I haven't actually measured this yet, but I will when I get a chance.  I have some ideas.  The peak current draw is nominally 2A to 3A.

It's good enough for government work for now, but fixing this (eg by reinforcing the ground path) may also fix the undervoltage warning I get during every single boot.

Rgds

Damon

[Bruce S]

I understand the Voltage drop from my years of using NiCd and NiMih , but don't normally see any issues with Li or Fe based batteries.

Once I have a spare second, I may go back in your battery setups and have a look see too.

Cute podcasts too  . Can I get on the autograph list  ?

Cheers
Bruce S

[DamonHD]

I suspect that much of the drop is in the last few inches inside the kitchen cupboard and through the USB wiring!  It took many goes to get an adequate USB power cable, and was one reason to downgrade from 3B+ to 3B, since the 3B peak draw is less I think.  I do attempt to compute the values on the fly, like this:

Code: [Select]

Verbose mode ($Id: powermng.cpp 25520 2018-09-11 06:13:20Z dhd $).
Sleep before power measurement.
LOAD POWER (mW): 6977
SS-MPPT-15L Vb_f slow battery voltage (mV): 12778
SS-MPPT-15L Adc_il_f load current (mA): 546
Input flag DUMPING is set.
System dumping for 100m.
SS-MPPT-15L Adc_ic_f battery charge current (mA): 0
NET battery charge current (mA): -546
SS-MPPT-15L T_batt (C): 21, temperature compensation -15mV.
Estimated LA battery impedance: 83mohm.
Estimated LA battery sag/(-rise) from internal impedance, and nominal internal voltage, effective w/ temp comp: -45mV, 12823mV, 12838mV.
Estimated actual battery sag from load (mV): 45mV.
LA/B1 dynamic threshold adjustment for load current -45mV.
ADC command 6a 80
ADC (6a 0) response 1347 (5 43 0)
Battery voltage 1 local (LA) 12638mV.
Supply drop B1 to BV 140mV; implied supply impedance 256mohm.
Adc_vl_f load voltage (mV): 12778
Supply drop B1 to controller load terminals 0mV; implied controller impedance 0mohm.
Supply drop controller to BV 140mV; implied wiring impedance 256mohm.
Input flag EXTERNAL_BATTERY_NOTVHIGH is set.
Input flag EXTERNAL_BATTERY_NOTFULL is set.
Battery voltage 1 basic compensation -60mV.
Battery voltage 1 'very low' threshold 12200mV (raw 12200mV).
Flag EXTERNAL_BATTERY_NOTVLOW is set.
Flag EXTERNAL_BATTERY_VLOW is unset.
Battery voltage 1 'low' threshold 12390mV (raw 12450mV).
Flag EXTERNAL_BATTERY_LOW is unset.
Battery voltage 1 dump margin threshold 12390mV (B1 delta 150mV, sag for dump load 107mV).
Battery voltage 1 'not high' threshold 13405mV (raw 13450mV).
Flag EXTERNAL_BATTERY_NOTHIGH is set.
Flag EXTERNAL_BATTERY_HIGH is unset.
Battery voltage 1 'very high' raw threshold 13600mV.
Flag EXTERNAL_BATTERY_NOTVHIGH is set.
Flag EXTERNAL_BATTERY_VHIGH is unset.
Flag EXTERNAL_BATTERY_NOTFULL is set.
Flag EXTERNAL_BATTERY_FULL is unset.
Input flag FORECAST_PV_GEN_GOOD is unset.
Battery extra USoC reserve for poor forecast / VHIGH and FULL not recent 5%.
Battery 1 effective/usable SoC 100%, dump thresholds min 60% higher 80% (uncompensated USoC 100%).
Setting sampling_down_factor to 50.
Setting up_threshold to 60%.
Setting sampling_rate to 25000.
Input flag NODUMP is unset.
External flag file /rw/docs-public/www.hd.org/Damon/Env/_gridCarbonIntensityGB.red.flag is absent.
Input flag GBGRIDPEAK is unset.
Dumping driven by external factors.
Flag DUMPING is set.
Flag DUMPINGEND is unset.
LASTDATA: 2020/07/01T19:41:03Z AL 0 B1 12778 B2 -1 P 6977 BV 12638 ST OK D e A1P 0 B1T 21 UC 100

Glad you like the podcasts: you just doubled my audience.  You can even be in one since I'm itching to test Zencastr for real!

And of course you can have an autograph, possibly on a check/cheque from my US checking account to give it some real value!  B^> 

Rgds

Damon