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 > blowing a 20a and 30a fuse instantly

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blaczero

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Posted: 10/06/21 06:27am Link  |  Quote  |  Print  |  Notify Moderator

hey guys, I plug in a cigarette lighter 200w inverter into this...

https://www.amazon.com/gp/product/B01MTBXHEV

and it immediatly blows a 20a or 30a fuse. I wired this up with 12awg.

by my math, it should be drawing nowhere near 30a

the back of the inverter says 200w peak 150w sustained. Nothing is plugged into the inverter when I plug it in, and it works in my truck fine.

Any ideas?

wanderingaimlessly

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Posted: 10/06/21 07:02am Link  |  Quote  |  Print  |  Notify Moderator

Sounds like plugging something into the outlet is causing it to short internally. Try plugging something else into it, to see if it instantly trips.

blaczero

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Posted: 10/06/21 07:59am Link  |  Quote  |  Print  |  Notify Moderator

Plugged a USB charger into cigarette port, works fine

wborst

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Posted: 10/06/21 08:39am Link  |  Quote  |  Print  |  Notify Moderator

Are you sure that the outlet is wired correctly? Another possibility is that the inverter has a large capacitor that takes a large surge current to get charged.


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lryrob9301

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Posted: 10/06/21 08:40am Link  |  Quote  |  Print  |  Notify Moderator

Check your wiring, I think you have something wrong.


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Gdetrailer

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Posted: 10/06/21 10:48am Link  |  Quote  |  Print  |  Notify Moderator

blaczero wrote:

Plugged a USB charger into cigarette port, works fine


Recheck the wiring to the cig port, it still can be reversed and a plug in USB charger still work. Plug in power port USB chargers may have the ability to operate with reversed polarity since they could be used in older vehicles with a positive ground.

Your inverter however may not work at all with reverse polarity and may have a reverse polarity diode which acts like a short when reverse polarity happens..

Looking at the back of your power center it is easy to switch the pos and negative wires although this one I picked does have pos (+) and neg (-) markings.

[image]

You need to ensure the center connection inside the power port is correctly connected to the positive of your 12V system.

You can verify the correct polarity with using a DVM set to volt meter if you have one by touching the red lead to the center of the port and the black lead to any 12V ground. The voltage on the DVM should read positive and should not indicate (-).

blaczero

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Posted: 10/06/21 11:11am Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

blaczero wrote:

Plugged a USB charger into cigarette port, works fine


Recheck the wiring to the cig port, it still can be reversed and a plug in USB charger still work. Plug in power port USB chargers may have the ability to operate with reversed polarity since they could be used in older vehicles with a positive ground.

Your inverter however may not work at all with reverse polarity and may have a reverse polarity diode which acts like a short when reverse polarity happens..

Looking at the back of your power center it is easy to switch the pos and negative wires although this one I picked does have pos (+) and neg (-) markings.

[image]

You need to ensure the center connection inside the power port is correctly connected to the positive of your 12V system.

You can verify the correct polarity with using a DVM set to volt meter if you have one by touching the red lead to the center of the port and the black lead to any 12V ground. The voltage on the DVM should read positive and should not indicate (-).


Thanks!!!

Every bronze connector on the panel is ground, except the cigarette lighter. I had the wires on wrong!

Good info on the multimeter, I had tested it but didn't know which should be + (side or all the way in).

Gdetrailer

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Posted: 10/06/21 11:26am Link  |  Quote  |  Print  |  Notify Moderator

blaczero wrote:



Thanks!!!

Every bronze connector on the panel is ground, except the cigarette lighter. I had the wires on wrong!

Good info on the multimeter, I had tested it but didn't know which should be + (side or all the way in).


Excellent!

[emoticon]

I had thought about mentioning the brass color may be positive which would typically follow other electrical guidelines but was concerned not all were marked that way..

Max fuse size also should be selected to protect the wire.

12Ga = 20A fuse..

10Ga = 30A fuse..

While there may be a few exceptions to that rule, it is very wise to follow typical recommended fusing sizes for the wire size in use. You really want the fuse/breaker to pop before the wire over heats and causes a fire.

Just be aware 20A at 13.8V is 276W max your inverter will be able to supply. Might handle a quick surge above that before fuse blows but that should be fine.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 10/06/21 03:28pm Link  |  Quote  |  Print  |  Notify Moderator

Blows both a 20 and 30 amp fuse instantly.
200 watts of inverter is 20 amps. the starting surge shoudl pop a 20.
Not sure how big the starting surge is but popping a 30 is not beyond belief.

I"d hard wire teh thing via a 40 using at least 10ga or 8ga wires. or even 4ga (battery cable) and keep 'em short.


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blaczero

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Posted: 10/07/21 06:14am Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

blaczero wrote:



Thanks!!!

Every bronze connector on the panel is ground, except the cigarette lighter. I had the wires on wrong!

Good info on the multimeter, I had tested it but didn't know which should be + (side or all the way in).


Excellent!

[emoticon]

I had thought about mentioning the brass color may be positive which would typically follow other electrical guidelines but was concerned not all were marked that way..

Max fuse size also should be selected to protect the wire.

12Ga = 20A fuse..

10Ga = 30A fuse..

While there may be a few exceptions to that rule, it is very wise to follow typical recommended fusing sizes for the wire size in use. You really want the fuse/breaker to pop before the wire over heats and causes a fire.

Just be aware 20A at 13.8V is 276W max your inverter will be able to supply. Might handle a quick surge above that before fuse blows but that should be fine.


Thanks to you and the others for the feedback. Learning something every day here.

The panel is in and working great, one more step toward everything on DC

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