Go Back   Computer Forums > General Electricals
Click Here to Login
Join Computer forums Today


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-21-2017, 02:26 PM   #1
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Car/battery inverters with computers and related parts.

Any of you have experience with this?

I'm using a 300W modified sine wave inverter thru the cig. lighter to power my laptop (batter disconnected) and it works just fine. I did that in ~4 hour sessions so far with the engine running, the A/C and the sound system.

I'm planning to get a pure/true sine wave inverter (my search say it's needed for TV's and lights) for small camps/picnics to to power, in addition to the laptop, 2.1 speakers, a 27" LED monitor and a couple of power saving lights, to game for 4-5 hours.

Any idea what requirements needed here? According to my calculations, the above devices use a pessimistic max of 220W.

My car has a 115A alternator and, if it's important, a 88A battery. Dunno what current that alternator can give at idle, but some people say about 65A.
__________________

__________________
Smart_Guy is offline   Reply With Quote
Old 02-22-2017, 07:28 AM   #2
Fully Optimized
 
strollin's Avatar
 
Join Date: Mar 2011
Location: USA
Posts: 2,672
Default Re: Car/battery inverters with computers and related parts.

If you want to use more than 140W or so then you need to wire directly to the battery with heavy gauge wire and avoid the cig. lighter socket which lacks the current carrying capability to handle more wattage.

It is recommended to mount the inverter as close to the battery as possible and keep the length of the DC cables as short as possible. If the power need is not close to the battery, use an extension cord on the AC side.
__________________

__________________
strollin is offline   Reply With Quote
Old 02-22-2017, 08:06 AM   #3
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

Agree with Strollin. I had a 3KW one on my boat fed by a bank of four 120amp/hour leisure batteries. That worked okay but my laptop wasn't overly keen on it because It wasn't a true sine wave inverter. Be careful with "pure sine wave" inverters. If you think about the way they convert DC to AC they can in no way be "pure." Ac is normally generated in a power staion or from some form of hydro electric plant. This meands that the generators are rotary machines and generating a "pure" sine wave voltage is easy. An inverter converts DC voltage to AC voltage by chopping the voltage electronically. The more a DC voltage is sampled digitally then the closer it will come to being a pure sine wave but it will never be truly pure.

You are right that a pure sine wave inverter is needed for televisions and LED lights and some laptop power supplies.

The location of the inverter and the size of the 12 volt supply wires is critical as Strollin has quite rightly pointed out. Have a look at Land Rover restoration web sites or any Camper/caravan/boating site. Loads of info on those.
__________________
pete.i is offline   Reply With Quote
Old 02-22-2017, 11:42 AM   #4
BSOD
 
Join Date: Feb 2016
Location: US
Posts: 963
Default Re: Car/battery inverters with computers and related parts.

I have a second house in the mountains that is off grid and power it with solar recharged batteries and a 1500 watt inverter. I run everything I use there.
__________________
Technician is offline   Reply With Quote
Old 02-22-2017, 11:45 AM   #5
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

Cool!

Yeah, I forgot to mention that I'm gonna use it directly from the battery as the thread name suggested. The cig. lighter in this car uses a 16A fuse but that's probably to run for couple of seconds to light the lighter only, not to run continuously. The laptop is 120W.

I'm planning on putting a volt reader to monitor the battery too. I don't want it to drain. I believe 13.5-14V reading means the battery is being charged and things are just fine. Is that correct?

I thought true sine wave is the same as pure sine wave! The other two lesser types I know are modified and square since wave. But basically anyway, if the wave is full wave, does that mean any computer device can run of it just like it does at home? With basic preparations taken care of of course.
__________________
Smart_Guy is offline   Reply With Quote
Old 02-22-2017, 12:00 PM   #6
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

Quote:
Originally Posted by Technician View Post
I have a second house in the mountains that is off grid and power it with solar recharged batteries and a 1500 watt inverter. I run everything I use there.
Does that include mechanical devices like fans and a washing machine? What sine wave type does it produce?
__________________
Smart_Guy is offline   Reply With Quote
Old 02-22-2017, 12:27 PM   #7
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

A true sine wave is what you would get from a continuous rotary type generator. Inverters digitally convert DC to AC and because that entails chopping the DC to do the conversion it cannot ever be as pure as domestic AC. It is damn close to be fair and 99% of devices are quite happy with it but some, and these are mostly devices with some sort of processor, will baulk. A really cheap inverter will actually give a square wave AC. Again a lot of devices don't mind that but processor controlled devices wont like it.
__________________
pete.i is offline   Reply With Quote
Old 02-22-2017, 06:03 PM   #8
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

I guess the one I have now is in the middle then. I took pics of it:





And it comes with a cig lighter connection:


and a battery clamps connection:

that can just screwed on.

Yeah, I made a mistake before. It's 400W continues.

Here's the attached guide:


It's weird that it includes small TV's VCR's, lamps and fans. I guess this is expected from a Taiwan made inverter (?). Could the used modified sine wave scale in this model have a good number of steps on it to actually run those devices safely enough? That's the only explanation. Having many steps on the modified wave form could give closer performance to pure sine wave that less steps, I believe.

Is it safe to experiment on it with my subject devices? Non of them use motors. And if yes, should I just forget about testing the lights on it?
__________________
Smart_Guy is offline   Reply With Quote
Old 02-23-2017, 04:25 AM   #9
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

Problem is you cannot really tell how good or bad they are without scoping the output. You are right that the less steps there are in the output waveform the closer it will be to a clean sine wave. The problem is that a square wave is made up of lots (we were told "all" in training many moons ago) of different frequencies. All equipments will take an average of the produced waveform and the average frequency of that waveform could be a long way away from what the device needs to work. The less square bits in the modified waveform the better and the closer the average frequency is to what the device needs.
__________________
pete.i is offline   Reply With Quote
Old 02-23-2017, 04:30 AM   #10
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

Again the problem with experimenting with your devices is that who knows what will happen. Chances are that they will work, in fact a very good chance. BUT I would hesitate to recomend testing that way. Best way is to scope the output and see how clean the wave form is. There are other items of test equipment that can be used but these are expensive and really you are going down the road of lab testing then. In that case it, probably, is cheaper to risk your dosmestic devices. But don't forget mains voltages are highly dangerous and low voltages can cause fires so make sure that you are going to do any sort of testing SAFELY.
__________________
pete.i is offline   Reply With Quote
Old 02-23-2017, 05:37 AM   #11
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

I'll keep a fire extinguisher at hand

This whole idea started to worry me and bring other stuff into it. I tested the battery and charging with my some how traditional car battery tester and got a reading of 12V for the battery and a frequency of 13-13.25V at supposedly full load (turned on the aux fan to full, head lights, fog lights, full A/C, read defroster, music with sub-woofer, and cabinet light on).

Guess I'm gonna have to make sure the charging system is fully functional first.
__________________
Smart_Guy is offline   Reply With Quote
Old 02-23-2017, 12:29 PM   #12
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

Quote:
Originally Posted by Smart_Guy View Post
I'll keep a fire extinguisher at hand

This whole idea started to worry me and bring other stuff into it. I tested the battery and charging with my some how traditional car battery tester and got a reading of 12V for the battery and a frequency of 13-13.25V at supposedly full load (turned on the aux fan to full, head lights, fog lights, full A/C, read defroster, music with sub-woofer, and cabinet light on).

Guess I'm gonna have to make sure the charging system is fully functional first.
Yeah thats the problem with doing all this stuff. It's a bit like googling your symptoms. By the time you finish you been dead for two weeks LOL.

I'm not sure about the bit I have highlighted in red in your quote. That would be the voltage not the frequency. This is a DC voltage so no frequency. Also those voltages are low, in fact if I saw 12volts on my boat battery I would consider that to be a discharged battery. I would expect to a charging voltage, that is with the engine running, of 14.4 to 14.8 volts on a modern car. Much older cars had a charging voltage of 13.8 so even by older standards your charging voltage is well down. Those voltages I would measure directly across the battery terminals with everything switched off and the engine running at a fast idle. 12.8 volts across a battery not on load and not being charged is considered to be a half charged battery in the boating world. Ah just reread your OP and you had everything turned on. Turn everything off and run the engine at a fast idle and read the voltages again. If everything is okay then you should get readings close to what I have quoted.
__________________
pete.i is offline   Reply With Quote
Old 02-23-2017, 03:59 PM   #13
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

Quote:
Originally Posted by pete.i View Post
Yeah thats the problem with doing all this stuff. It's a bit like googling your symptoms. By the time you finish you been dead for two weeks LOL.

I'm not sure about the bit I have highlighted in red in your quote. That would be the voltage not the frequency. This is a DC voltage so no frequency. Also those voltages are low, in fact if I saw 12volts on my boat battery I would consider that to be a discharged battery. I would expect to a charging voltage, that is with the engine running, of 14.4 to 14.8 volts on a modern car. Much older cars had a charging voltage of 13.8 so even by older standards your charging voltage is well down. Those voltages I would measure directly across the battery terminals with everything switched off and the engine running at a fast idle. 12.8 volts across a battery not on load and not being charged is considered to be a half charged battery in the boating world. Ah just reread your OP and you had everything turned on. Turn everything off and run the engine at a fast idle and read the voltages again. If everything is okay then you should get readings close to what I have quoted.
Ah, I mean frequency in the general sense. I meant fluctuation. English is not my mama tongue

Yeah, it was on heavy load. On fully warmed up no load idle it is 13.25V. My car is a 1992 that lacks the electronics of a modern car. It even has an over voltage relay!

I asked in my MB community and they said specifically for my car it should be 13.2V to 14.5V to keep the battery charging. Dunno why it is lower than other cars.

I wonder of something's up with the battery tester. I always wanted one of those fancy cig lighter digital volt readers.
__________________
Smart_Guy is offline   Reply With Quote
Old 02-24-2017, 12:59 AM   #14
BSOD
 
Join Date: Feb 2016
Location: US
Posts: 963
Default Re: Car/battery inverters with computers and related parts.

The only fans I have there are in the restroom and it's a DC fan. The inverter puts out pure sine wave AC. Most of the lights are also DC powered LEDs. I also power a (small) refrigerator and A/C unit and my TV and computer. Charging your computer up off the inverter and then running it on its battery will be a lot more efficient as in charge mode it will draw a lot less power.
__________________
Technician is offline   Reply With Quote
Old 02-24-2017, 11:11 AM   #15
Daemon Poster
 
Join Date: Nov 2014
Location: UK
Posts: 628
Default Re: Car/battery inverters with computers and related parts.

Quote:
Originally Posted by Smart_Guy View Post
Ah, I mean frequency in the general sense. I meant fluctuation. English is not my mama tongue

Yeah, it was on heavy load. On fully warmed up no load idle it is 13.25V. My car is a 1992 that lacks the electronics of a modern car. It even has an over voltage relay!

I asked in my MB community and they said specifically for my car it should be 13.2V to 14.5V to keep the battery charging. Dunno why it is lower than other cars.

I wonder of something's up with the battery tester. I always wanted one of those fancy cig lighter digital volt readers.
13.2 sounds a bit low even for an older car. Older alternators were usually regulated at 13.8. Newer car's alternators are regulated at 14.5 to 14.8. You could change the alternator for a newer one or you could change the regulator for a 14.5/14.8 one. Changing to a higher output alternator would be okay as long as you are sure that your battery is a reasonably new one. Changing the regulator is by far the cheapest option but a lot more work involved as the alternator will probably have to be stripped down. If your lternator did pack up then you would, almost certainly, get one with a higher charging voltage.

Having said all that if you do have an overvoltage relay then the charging voltage would be regulated by that.
__________________
pete.i is offline   Reply With Quote
Old 02-24-2017, 12:01 PM   #16
Fully Optimized
 
Smart_Guy's Avatar
 
Join Date: Oct 2011
Location: Saudi Arabia
Posts: 4,248
Default Re: Car/battery inverters with computers and related parts.

Quote:
Originally Posted by pete.i View Post
13.2 sounds a bit low even for an older car. Older alternators were usually regulated at 13.8. Newer car's alternators are regulated at 14.5 to 14.8. You could change the alternator for a newer one or you could change the regulator for a 14.5/14.8 one. Changing to a higher output alternator would be okay as long as you are sure that your battery is a reasonably new one. Changing the regulator is by far the cheapest option but a lot more work involved as the alternator will probably have to be stripped down. If your lternator did pack up then you would, almost certainly, get one with a higher charging voltage.

Having said all that if you do have an overvoltage relay then the charging voltage would be regulated by that.
Hmm, perhaps this hidden info make a difference: originally the stock alternator is 70amp that meets all needs of the car. This one is 115amp. Now that mention the over voltage relay, Is it possible it is lowering (balancing) the voltage because the rated current is higher to give an output similar to the original to avoid excessive output? If that's what you mean by your last line.

Original alternator: 70amp X 13.8V (standard reading) = 966W
This alternator: 115amp X 13.25V = 1,523W (my reading) (Covers the above, and even is much higher. My electrician warned my to never use a higher alternator)

Unless it does not work like that, of course. The battery is +1 year old now and on a turned off engine it reads a tick above 12V. Would the battery be dead now if my found 13.25V is lover than the standard?

I have an idea. The laptop seems to like my setup. I think I'll test it alone with a CPU power stress test and see the reading.
__________________

__________________
Smart_Guy is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -5. The time now is 08:27 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Friendly URLs by vBSEO 3.6.0
×