12 volt portable cooler off rear lighter plug?

Cuzoe

Veteran Member
Joined
May 24, 2017
Location
Los Angeles
TDI
MK7 Golf S
The 12V sockets are fed by a 20A fuse so the theoretical max is 240W. Obviously we'll not get that in practice but if we conservatively aim to stay below half the theoretical max that's 120W. And you're well under half that at 45W.

I wouldn't be concerned with startup wattage (current, really) even if it was near the fuse rating of 20A (240W, theoretical). A 20A fuse can take 20A for a few moments no problem. Just wouldn't want to run 20A through it continuously.

That being said, the fuse protects the wiring (and by extension the socket). So if the thing you're plugging in drastically underrates the actual power draw you'll just blow the fuse.

And if you really wanna see what you're up against buy a few fuses and test them. For instance, plug in a 5A and see if it blows. If it does then you know the cooler is doing more that 60W. Then try a 10. If that doesn't blow (it shouldn't, if the cooler specs are correct) is doing less than 120W. At that point I wouldn't think twice about running it since the factory setup is capable of double that.

To be super safe you could just run with a downrated fuse all the time, a 10 or 15. By design the fuse is the weak link. You can add additional safety margin by making it a weak-er link.
 

gearheadgrrrl

Veteran Member
Joined
Dec 15, 2002
Location
Buffalo Ridge (southwest Minnesota)
TDI
'15 Golf DSG, '13 JSW DSG surrendered to VW, '03 Golf 2 door manual
Actually, the "weakest link" is the cig lighter plug, which will melt at anything over 10 amps or so continuous. As a licensed amateur radio operator I used to run a 150 watt VHF amplifier in the truck at work which probably drew at least 15 amps continuous using FM mode at full power. After a few minutes this would melt the power plug, so I made a power plug with just the positive lead and used a wire and clamp to any available metal in the cab for a ground. worked pretty well, with 150 watts I could routinely access repeaters 100 miles away.
 

Cuzoe

Veteran Member
Joined
May 24, 2017
Location
Los Angeles
TDI
MK7 Golf S
That makes sense, since one fuse is feeding three 12V plugs. I'm not interested in testing to find the limit... but I wonder if the manual says anything about max wattage total and/or per plug. It really should unless one plug is capable of handling the full, let's call it 150, wattage safely.
 

bigb

Veteran Member
Joined
Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
Thanks for the input, just need to decide which one is best for us to use across 2 vehicles. No size limit when in my truck but need to be careful about the size in the VW.
 

amsoiltek

Active member
Joined
Mar 3, 2023
Location
Phelan, Ca
TDI
2015 Golf SEL White
Actually, the "weakest link" is the cig lighter plug, which will melt at anything over 10 amps or so continuous. As a licensed amateur radio operator I used to run a 150 watt VHF amplifier in the truck at work which probably drew at least 15 amps continuous using FM mode at full power. After a few minutes this would melt the power plug, so I made a power plug with just the positive lead and used a wire and clamp to any available metal in the cab for a ground. worked pretty well, with 150 watts I could routinely access repeaters 100 miles away.
Hey good info to know, I have my Yeasu FT-7800 in the trunk and was trying to avoid running a power cable up to the front, max amp draw on the radio on 2mtrs is about 9 amps. That may change if I decide to put an HF rig in the car, but just in case I'll install a buck converter.
 

gearheadgrrrl

Veteran Member
Joined
Dec 15, 2002
Location
Buffalo Ridge (southwest Minnesota)
TDI
'15 Golf DSG, '13 JSW DSG surrendered to VW, '03 Golf 2 door manual
FM seems to draw the most current, SSB draws less as the average power output is lower between the peaks. I've run 25 watt VHF FM and 100 Watt PEP HF rigs powered through cig lighter plugs with no problems.
 

amsoiltek

Active member
Joined
Mar 3, 2023
Location
Phelan, Ca
TDI
2015 Golf SEL White
FM seems to draw the most current, SSB draws less as the average power output is lower between the peaks. I've run 25 watt VHF FM and 100 Watt PEP HF rigs powered through cig lighter plugs with no problems.
The HF rig I want to use is the Icom IC-7100 and I know Icom's don't like voltage drops at all, I have a IC-7000 in my work van and if the motor is not running it will trip out. No way will my rig be as loaded as Scott's car over at StealthGTI, but I'm impressed and going to borrow some of his tricks.
 

codyayrton

Veteran Member
Joined
Jun 16, 2014
Location
Bend, Oregon
TDI
2011 Jetta Sportwagen TDI 6M (sold to VW), 2015 Golf S Sportwagen TDI 6M
Anyone tried running one of the 12 volt coolers off the 12 volt power outlet in the rear? I seem to recall that it is good for 150 watts? Looking at this one: https://www.amazon.com/dp/B07L3FLBQ...ZCCSNW5ED&ref_=list_c_wl_lv_ov_lig_dp_it&th=1 which claims 45 watts but not sure about startup current. One reviewer said 80 watts startup but it's not officially listed anywhere that I could find.
I use one nearly identical. Lower storage capacity at 35 liters but is 45 watts like the one you are looking at. I've had zero issues since buying it September 2022. Great for road trips and bringing home ice cream from the grocery store in July.

 

Rickstah

Veteran Member
Joined
Feb 5, 2002
Location
Yukon, Oklahoma
TDI
NB, 2002, green, Eurotek STG1
My old 2002 NB shows the rear plug to be on its own 30A fuse (#35 slot) I have run one of those older version thermos coolers many times from a 500 watt inverter plugged into that receptacle and as long as your A/C keeps the inside cool it works great and I had an old large 12v compressor that would dim the lights so if I recall it would pop a 15 but no worries using the plug. I guess they have made changes but I always thought it was smart to have that one separate from the two up front. My older cooler had about .35 amp demand while initially cooling down but then dropped to 10w or less. Way to go, NOW I want one again, lol.

From an Amazon review for yours: "(3) while the compressor works, it pulls about 28w-39w for a minute or two to bring down the temperature. During maintenance, it pulls only 2w-5w or so."
 
Top