Electrical Help pls

[maria_bettina]

Hi! I bought a 250 Watt Electric Heater to stave off the chill at night (the tag says it uses 2.1A). We have solar panels to charge our 200A battery (I don't think that matters, but just in case).

Before the trip, I plugged the 250 Watt Heater into the 300 Watt inverter, and the inverter is plugged into the cigarette lighter in the camper. (The wire that runs from the cigarette lighter to the battery sized for 10A.) It worked fine. But now that my son and husband are on their trip, when they plug in the heater, the 10A fuse blows that is at the cigarette lighter. Twice.

They are able to play a DVD and TV by plugging it into the inverter. So everything works for the DVD and TV.

Nothing else is being charged or used on that inverter, nor at the cigarette lighter.

Note: There is an electric fridge/cooler, and it's being powered by the same auxiliary battery, but it's not on the same fuse (if that makes sense; I know I am not using the correct terminology).

My hubby just got to a campsite that has a power supply, and the heater works fine. So at least he is able to use it now without blowing fuses.

Any suggestions as to where we can start looking for the issue(s)?

TIA.

[pianotuna]

maria_bettina wrote:


Yes, I am bummed.

How many amp hours is the battery bank?

The rule of thumb is multiply amps by 10 to get the draw at 12 volts. This is due to inverters being at best about 88% efficient.

If the voltage on the battery is low, the inverter may well draw even more amps, causing the fuse to die.

Generally the inverter may be sized to do 125% of the load. 250 x 1.25 = 312.5 watts (so the inverter is busting its heart out trying to run that heater).

There are a couple of solutions.

1. connect the inverter directly to the battery posts. That will eliminate the fuse and amperage issues.

2. Use a 50 heating pad instead. You could run two.

3. There are 12 volt heaters available.

In any event the batteries are not going love running the heater for long periods of time.

My first battery bank was 875 amp-hours. Heaters were not an issue.

[CA_Traveler]

maria_bettina wrote:
But if that same 250 Watt heater was DC, that's a whole different story. Electricity is like magic. Totally boggles my mind! Haha

Nope a 250W DC heater: 250W/12V = 20A+, ie It will draw 20A+ DC amps.

Plus the cig plug is likely rated for 8A, you need to connect the inverter more directly to the battery. About 4 hours of run time and more with solar cranking.

[maria_bettina]

stevenal wrote:
Once the fuse blowing issue is solved, I expect you'll be dealing with battery capacity. Heating appliances will draw your battery down very quickly.

Yes, I am bummed. I don't know how to heat ourselves at night. Below 40-degrees and it's downright uncomfortable. We have a Little Buddy heater, but not for sleeping. We have Reflectix around the vinyl (we have a pop-up TC), but that's not enough.

Back to the drawing board.

[maria_bettina]

time2roll wrote:
Inverter should draw power direct from the battery using #8 wire minimum. 250w is close to 25 amps at 12 volts.

If I bought a new inverter and connected it to the battery directly, I am still looking at 25A. Which is crazy. We have a 200Ah battery, so 4 hours of continual use (before I reach 50% battery charge)? But if that same 250 Watt heater was DC, that's a whole different story. Electricity is like magic. Totally boggles my mind! Haha

[maria_bettina]

shastagary wrote:
this is what it says on the amazon page of that inverter that i also own. it can easily draw more than 10 amps with the heater load

If the rated input of any connected AC devices exceed 150W, please use battery clamps to directly connect to your vehicle's battery as most vehicles' 12V cigarette lighter ports are rated for 150W. Do not use to power high power electric devices such as hair dryers, electric heaters, which might blow a fuse.

😮 guess we will count ourselves lucky with a couple blown fuses.

I better relook at the DVD and TV wattage. Thanks for pointing this out.

[maria_bettina]

2112 wrote:
I'm curious toi know what heater you are using. The link you provided directs me to the inverter.

I fixed the link..thanks for pointing that out.

https://smile.amazon.com/gp/aw/d/B00I4UVGHO?psc=1&ref=ppx_pop_mob_b_asin_titleHeater

[stevenal]

Once the fuse blowing issue is solved, I expect you'll be dealing with battery capacity. Heating appliances will draw your battery down very quickly.

[time2roll]

Inverter should draw power direct from the battery using #8 wire minimum. 250w is close to 25 amps at 12 volts.

[shastagary]

this is what it says on the amazon page of that inverter that i also own. it can easily draw more than 10 amps with the heater load

If the rated input of any connected AC devices exceed 150W, please use battery clamps to directly connect to your vehicle's battery as most vehicles' 12V cigarette lighter ports are rated for 150W. Do not use to power high power electric devices such as hair dryers, electric heaters, which might blow a fuse.

[2112]

I'm curious toi know what heater you are using. The link you provided directs me to the inverter.

[maria_bettina]

Mark- thanks for that explanation. I was wondering about the voltage early on, but couldn't get myself to believe the amps required for that small heater.

When I tested the heater in the TC, if the TC was "plugged in" it would be a trickle charger to the aux battery (and honestly I can't remember if we were charging the battery or not).

So if the issue that you described is the culprit, I suspect there is no way to use that 250 Watt heater in the TC. ????

PS just talked to my hubby. The Renogy is reading 22V late in the day. So that's it. I tested the heater when the sun was up and the solar panels were charging the battery. The voltage was high, higher than it would be at night.

Am I understanding that correctly?

[mbloof]

maria_bettina wrote:
Hi! I bought a 250 Watt Electric Heater to stave off the chill at night (the tag says it uses 2.1A). We have solar panels to charge our 200A battery (I don't think that matters, but just in case).

Before the trip, I plugged the 250 Watt Heater into the 300 Watt inverter, and the inverter is plugged into the cigarette lighter in the camper. (The wire that runs from the cigarette lighter to the battery sized for 10A.) It worked fine. But now that my son and husband are on their trip, when they plug in the heater, the 10A fuse blows that is at the cigarette lighter. Twice.

They are able to play a DVD and TV by plugging it into the inverter. So everything works for the DVD and TV.

Nothing else is being charged or used on that inverter, nor at the cigarette lighter.

Note: There is an electric fridge/cooler, and it's being powered by the same auxiliary battery, but it's not on the same fuse (if that makes sense; I know I am not using the correct terminology).

My hubby just got to a campsite that has a power supply, and the heater works fine. So at least he is able to use it now without blowing fuses.

Any suggestions as to where we can start looking for the issue(s)?

TIA.

No worries, a common misconception.

Technical: P=I*E, 250W=2.1A*120VAC ok?

The 'problem' here is to get 250W AC out of a inverter it may require 300W on the +12V side of things. (%80 efficient) which equates to: 300W/12V=25A - thereby blowing the 10A fuse on the cigarette lighter.

So why did it work at home? (assuming at home you were plugged into shore power)

With the additional current provided by the campers onboard converter charger the battery voltage would be higher than what it would be by itself.

Consider if the battery voltage was 13.8V the current for 300W would be 21.7A and if the battery was @ 14.4V the current would be 20.8A.

Since many converter chargers are designed to actually charge the onboard battery, I'd suspect your voltage while plugged in was ether 13.8V or 14.4V.


- Mark0.

[maria_bettina]

jimh406 wrote:
My first guess is the antenna amplifier is on. Many power outlets get their power from the same circuit the antenna amplifier is on. Turn the amplifier is off. Many have an LED to show if they are on or not.

Otherwise, check to see what else is off when the fuse blows just to make sure something else like a fridge etc isn't drawing a bit of power from the same circuit.

Also, it may make a difference at what the setting is on the heater for temperature. The difference in the surge could be different if you turn it all of the way down, turn it on, and then gradually turn the thermostat up.

I don't think we have an antenna amplifier. I had to google it to see what it was. We only watch DVDs with our little TV.

We will check the fridge, and I will ask my hubby about the circuits.

I, too, thought of that first surge. I texted him to see if he started the heater at 250 watts or on the lower setting. I think when I tested it at home, I started it on LOW and then powered it higher after a few minutes. That just seems logical to me.

Question: Because the inverter is only rated for 300 Watts, if the heater exceeded that 300 watts, would the fuse at the cigarette lighter blow, or would the inverter overheat? It seems that the 10A fuse should have been fine, even if there was a power surge because the surge likely couldn't have been more than 10A. But the bottleneck is at the inverter, so what happens when the inverter has to deal with more than 300 watts? A blown fuse (but I would think that the inverter would stop working)?

The fuse blowing happened immediately. Turn on heater and fuse blown. No time for anything to overheat.

Heater
Inverter

[jimh406]

My first guess is the antenna amplifier is on. Many power outlets get their power from the same circuit the antenna amplifier is on. Turn the amplifier is off. Many have an LED to show if they are on or not.

Otherwise, check to see what else is off when the fuse blows just to make sure something else like a fridge etc isn't drawing a bit of power from the same circuit.

Also, it may make a difference at what the setting is on the heater for temperature. The difference in the surge could be different if you turn it all of the way down, turn it on, and then gradually turn the thermostat up.