Small AP suitable for automotive use

I’ve been out of touch with OpenWRT for a while - everything I have runs beautifully and painlessly. Now I have a new project, connecting gadgets in a vehicle

Anyone know of a small access point that can be used as a client, runs on 12V, and doesn’t use much power? I need something to bridge a powerful AP to a small gadget that has a built in AP to be used in a car.

i'd say that most consumer-grade wifi-routers run on 12v dc[Power+supply*~]=12+VDC

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WR902AC (version 1)

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Automobile electrical systems are not friendly to electronics without a good deal of buffering. The voltage can run close to 15 V at times, and typically is around 14.4 V. The noise on the line and spikes can cause problems ranging up to killing a device.

I'd either make sure you've got a 12 V regulated supply between the two, or recommend that you look at one of the devices powered off 5 V and use a "phone charger" to power it (native, cigarette lighter adapter, or hacked/wired in). (See the "cheap devices" list for some choices and opinions on devices.)

"Suitable for automotive use" can be understood as "the device fulfills all automotive requirements regarding transient overvoltage / transient undervoltage".

Excerpt from (sorry, in german):

Impuls 1: -25/50/75/100V, Anstiegszeit 1us, Dauer 2ms, Innenwiderstand 10 Ohm,

Wiederholrate 0,5 (Ford EMC Pulse E) 5s, Prüfdauer 5000 (Daimler 120, GM 500)


Impuls 2a: +25/50/75/100V, Anstiegszeit 1us, Dauer 50us, Innenwiderstand 2 Ohm,

0.2-5 Sekunden

BMW nimmt 75V statt 50V und 4 Ohm

Daimler nimmt 100V statt 50V und 10 Ohm und testet 0.5s

Ford nimmt 37V statt 50V und Anstiegszeit 10us

VW nimmt 75V statt 50V und 4 Ohm

Impuls 2b: +10/10/10/10, ansonsten wie Impuls 1

Impuls 3a Impulspakete aus Impulsen mit -25/50/100/150V bzw.

Impuls 3b +25/50/75/100V, Anstiegszeit 5ns, Dauer 0.1us, Innenwiderstand 50 Ohm,

Wiederholrate 100us, Paketdauer 10ms, Pause zwischen Paketen 90ms, 1 Stunde

Prüfdauer. Daimler testet 600000 Impuls, GM 10 Minuten, VW 2 Stunden mit 10 Hz.

Impuls 4: Absacken der Spannung um -4/5/6/7V über 0.1 Sekunde und -2.5/6V um

20 Sekunden.

Impuls 5: 40-400ms langer Puls von 26.5/46.5/66.5/86.5V mit 0.1-10ms

Anstiegszeit, Innenwiderstand 0.5-4Ohm

ISO 16750-2 4.6.4 Test A/Load Dump: +101V 0.5 Ohm, 10ms Anstiegsteit, 400ms Dauer

Daimler +105V und 300ms,

Ford EMC Pulse G1 open circuit: +60V und 300ms

Ford EMC Pulse G1 loaded: +30V und 150ms

ISO 16750-2 4.6.4 Test B/Clamped Load Dump +35V 0.5 Ohm, 10ms und 400ms

Daimler Pulse #5B: +38V

GM GMW3100: +34V, 10 Wiederholungen

Ford EMC Pulse G2: +21.5V, 150ms

VW TL81000: +30V

jump start/starting aid: 32V für 60sec, charging: 17V für 60min

Also worth reading: ST Application note:

-> Feeding a router / AP directly from the vehicles 12V supply is not a good idea.

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If you want cheap/simple I would second the suggestion for a 5V phone/USB charger along with something small like a GL-Inet product.

One thing you might want to remember/keep in mind is that most consumer/cheap APs and equipment are not designed for cold enviroments, so if your goal is to make this a full time always working solution and you live in an area with cold winters you will want to do some testing on that first. After all, your car will warm up when you start it and drive it, but if the device locks up/doesn't boot because of the initial cold, chances are you would have to manually reset it to get it live, which is not exactly "automatic/always on" ideal ;o)

That's just speaking from my own experiences doing OpenWRT in my Jeep for the last 15 years though.