Car Inverter - saan maganda bumili

**2youta** · November 6th, 2009 12:00 PM

bro, try nyo sa RAON in Manila mura lang dun, that's were i bought my inverter 1500 watts for only 1600petot. Kaya niya TV, personal ref., laptop and desktop pc. 4 months na sakin and ok na ok pa rin.

**arnielbenz** · December 2nd, 2009 07:50 AM

Mga sir here is mine kabibili ko lang kanina, I hope na okay eto. Para sa laptop (65W) and cellphone.

150W
Versatile socket
Soft start function
Product protection (short circuit, low voltage and overload)

**lgp** · December 24th, 2009 11:20 PM

Mga Sirs, probably the biggest reason why your inverters get busted is that you are assuming your load is small.

I am an EE and I have read earlier posts regarding calculating the load from the output. We have been trained to follow the 'best practice' approach in estimating loads in order to design good overcurrent protection as well as a safe operating environment.

When estimating loads, the input power should be the one taken into consideration as the input power always exceeds the output power, never the other way around. If the product states 220V 1.0 A, then it is assumed that the product draws a max current of 1Amp therefore it peaks at 220W.

If, on the other hand, the product is free voltage (which is common nowadays as you see more and more "100-240V" specs) it is assumed that the max current is drawn at the lower voltage (it is a fact that for power to be equal across the voltage range, the current drawn is greater at the lower voltage then at a higher voltage, which is why we transmit electricity at thousands of volts in order to utilize smaller wires carrying smaller currents)

Therefore, the common practice is to multiply the rated max current by the lower end of the voltage range, to give the wattage. Now, in these days where a lot of china made products with no quality control abound (I'm not saying everything made in china has no QC, just that there are a lot), it is safer to assume that the specs rated are more or less approximations, therefore, the safe way to assume the power draw would be to just multiply the current by the higher voltage in the range, thereby making sure that the power source you will be using won't be overloaded.

Oh, and another thing, someone mentioned the ref to be around 100W, while this may be true when the ref is at idle (depending on the construction) it may have slipped the poster's mind that a motor's starting current can surge to 250% of its rated power input. In addition to that, I don't think there are ref motors rated less than 1/4HP, and 1HP = 746W so 100W is way too low. Just an added info.

I hope this helps make it clear regarding power draw.

**traker** · December 29th, 2009 07:44 PM

I bought a 300W Panther inverter. I had it tested and was working when i bought it. However, when I plug it in to my car's 12v power socket (with a 120 watt max output) it won't power up fully I guess, as its fan is spinning but the power on indicator won't light up.

Anyone can help? Thanks in advance.

**woohoo** · December 29th, 2009 08:22 PM

Originally Posted by lgp

When estimating loads, the input power should be the one taken into consideration as the input power always exceeds the output power, never the other way around. If the product states 220V 1.0 A, then it is assumed that the product draws a max current of 1Amp therefore it peaks at 220W.

If, on the other hand, the product is free voltage (which is common nowadays as you see more and more "100-240V" specs) it is assumed that the max current is drawn at the lower voltage.

Therefore, the common practice is to multiply the rated max current by the lower end of the voltage range, to give the wattage.

Thank you for this info. Now I understand my LG LCD TV's 1.5A rating. It's the only brand among the most common ones which specifies Amperes instead of Watts, and it gave me some apprehension when I calculated 220V * 1.5A = 330W :shocked2:. Little did I know that since it's autovolt (100-240V), I should've gotten 100V * 1.5A = 150W.

Oh, and another thing, someone mentioned the ref to be around 100W, while this may be true when the ref is at idle (depending on the construction) it may have slipped the poster's mind that a motor's starting current can surge to 250% of its rated power input. In addition to that, I don't think there are ref motors rated less than 1/4HP, and 1HP = 746W so 100W is way too low. Just an added info.

I hope this helps make it clear regarding power draw.

Perhaps the Wattage ratings on refs reflect their AVERAGE consumption. My side-by-side Samsung ref (19cu.ft.) states its consumption as 150W only. That's below the minimum figure you mentioned (746W / 4 = 186.5W = 1/4 HP).

**speed unlimited** · December 29th, 2009 08:28 PM

Originally Posted by mick25

san location ng alexan?

Malapit sa divisoria El Cano st.

**lgp** · December 29th, 2009 09:42 PM

Glad to have cleared some things.

Originally Posted by woohoo

Perhaps the Wattage ratings on refs reflect their AVERAGE consumption. My side-by-side Samsung ref (19cu.ft.) states its consumption as 150W only. That's below the minimum figure you mentioned (746W / 4 = 186.5W = 1/4 HP).

Oh yes, that's right -it's the average consumption that is rated on some appliances. It's like the audio industry's RMS vs PMPO thing, sometimes marketing tells manufacturing to place what looks better on the product in order to 'entice' buyers. In the case of some appliances, the average is placed so as not to turn conservative buyers off if they see a high max consumption.

I forgot to mention that the equations given are not for exact consumption, but for circuit protection and safety requirements, that is, if you assume the 186.5W load, then a load of 150W can be safely carried. Then again, you'll have to account for the 250% surge everytime the motor starts, that is on top of the 186.5W continuous load.

**woohoo** · December 30th, 2009 02:22 AM

Originally Posted by lgp

Glad to have cleared some things.

Oh yes, that's right -it's the average consumption that is rated on some appliances. It's like the audio industry's RMS vs PMPO thing, sometimes marketing tells manufacturing to place what looks better on the product in order to 'entice' buyers. In the case of some appliances, the average is placed so as not to turn conservative buyers off if they see a high max consumption.

I forgot to mention that the equations given are not for exact consumption, but for circuit protection and safety requirements, that is, if you assume the 186.5W load, then a load of 150W can be safely carried. Then again, you'll have to account for the 250% surge everytime the motor starts, that is on top of the 186.5W continuous load.

Yup. Most end-users consider only the bottom line, after all, i.e., how much will they pay for the electricity. :D

**jut703** · December 31st, 2009 12:16 AM

Originally Posted by woohoo

Yup. Most end-users consider only the bottom line, after all, i.e., how much will they pay for the electricity. :D

Perhaps the reason for this is that a lot of people assume that their socket can take whatever is plugged in it, so overcurrent issues are not taken into account.

For home use, it really isn't much of an issue. As long as the electrical wiring in your house is of good quality, it can power whatever appliance you have. However once you start plugging in AVRs and the like, the specifications of the AVR must be taken into account.

For car use it is particularly important because of the 12V socket's limited capabilities.

It actually just takes one of the simpler equations taught in high school physics to approximate power draw, P = VI, where P is power, V is voltage and I is current.

**lgp** · December 31st, 2009 02:21 AM

Originally Posted by jut703

...

It actually just takes one of the simpler equations taught in high school physics to approximate power draw, P = VI, where P is power, V is voltage and I is current.

It would be safe to assume that, unless the load you are plugging into the inverter has a motor. For example, one has a 100W inverter, tapos yung load na ip-plugin relfects 90W upon using the "PIE" formula, one would assume "pwede ito", then again without taking into consideration the surge current, magtaka siya kung bakit pumutok yung inverter samantalang kaya naman nya yung load.