Size & Brand Inverter

[ImagesThatSing]

Good Morning!

We need to run a laptop, desktop, printer, tv vcr and some lights in our travel trailer under a worst case scenario. I have a 4 golf cart battery setup, and use a battery charger to recharge when I run the 5K generator. I need to know what size of inverter to buy to handle this load comfortably, what brand is the best, and should I buy an inverter that charges faithfully from the generator, or is my monitoring with battery charger, amp/volt meter good enough... . and , OH yeah, am I crazy {{{grin}}}. thank you for your experienced input fine folks.

 

[LandShark]

I'm using a 400 watt (800 surge) inverter, from Sam's, to run a laptop, printer, and a couple of cell phone chargers. It also powers a coffee grinder. My 150 watt inverter wouldn't quite handle the load.



You really need to add up the watts of each item you plan to run and buy a suitable inverter based on that.



Inverters that are combination chargers are very expensive.



Don't run lights off the inverter if you have 12v lighting available.

 

[ImagesThatSing]

Originally posted by LandShark

I'm using a 400 watt (800 surge) inverter, from Sam's, to run a laptop, printer, and a couple of cell phone chargers. It also powers a coffee grinder. My 150 watt inverter wouldn't quite handle the load.



You really need to add up the watts of each item you plan to run and buy a suitable inverter based on that.



Inverters that are combination chargers are very expensive.



Don't run lights off the inverter if you have 12v lighting available.

Yes the lights run directly off the batteries, I made an error there. I have a 400/800 watt unit that runs my laptop fine, but this weekend when I added my printer, it went into red light overload. -- I checked the voltage and it was at 11. 8v so it was not a low battery condition. The reading I have done indicates that that combination should only be about 150 watts. I can do the calculations, but it seems that they do no good if a 400 watt inverter cannot handle 150 or 200 watts demand with a more than adequate charge.



Also I wonder if this GO Socket inverter is a good brand



http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3041917767&category=32814



I just want to have more than adequate power since the ratings don't seem to hold the practical appliaction for power demands.

 

[y-knot]

Mr. G.



I run a FREEDOM 2000 in my trailer, so far it has worked just fine. I just it to run the frigerator while traveling (120v frig) and it handles that just fine (not a huge draw 1. 1 A). I also use it for the microwave, tv, coffee maker, it will even run the air compressor. I like the remote mounted switch with both battery and load indicators. I have it set up with two optima red top batteries, and a auto triple charger(other battery is the break-away, and the two red tops). There are several good converters out there, XANTREX, PROSINE are two I know of. When looking don't just get one that bearly meets your needs, you don't want to run it at 100% all the time, give your self at least 25% margin.

 

[klenger]

You also need to decide if you want a true sine wave inverter or can get by with a modified sine wave inverter. I had a modified type that I used for several years with no problem. When I got a new 14" TV, the set had lines on the screen from the inverter, so I changed it out for a 250 watt true sine wave inverter. No problems with it, but you pay a lot more for true sine wave.



In my case, the 250 watt unit is plenty because I have a generator for large loads. It seems like most RV 115 vac appliances fall into two catagories: small loads line TV, SAT Rec, Laptop, etc, and large loads like the microwave, A/C, toaster, hair dryers, etc. I decided to get a good unit with lower power and use the generator for the high power stuff. Running the high power stuff from an inverter will kill the batteries pretty quickly anyway, so you still have to run the generator.



See my RV web page in my sig for information on inverters and other RV systems.

 

[Skydiver]

What Klenger said is best.

For a good cheap lifetime warranty inverter go to www.sportsmansguide.com

do a search.

I have been thinking about buying their 1kw 2-cycle import generator for camping to charge the batteries. any comments?

Tim

 

[SilverFox]

I checked the voltage and it was at 11. 8v so it was not a low battery condition



If your battery only had 11. 8 volts it was dead! A fully charged 12 volt battery has 12. 6 volts after being charged and then rested for 24 to 48 hours. When the voltage drops to 12. 3 volts it has 50% charge and should never go below this. 12. 3 volts is considered a deep cycle and the battery has a very limited number of deep discharge cycles in its life. Your present inverter seems more that adequate.

 

[ImagesThatSing]

Originally posted by SilverFox

I checked the voltage and it was at 11. 8v so it was not a low battery condition



If your battery only had 11. 8 volts it was dead! A fully charged 12 volt battery has 12. 6 volts after being charged and then rested for 24 to 48 hours. When the voltage drops to 12. 3 volts it has 50% charge and should never go below this. 12. 3 volts is considered a deep cycle and the battery has a very limited number of deep discharge cycles in its life. Your present inverter seems more that adequate.

Your comments sent me back to the research that I had from some RV Guru person who is often quoted and referred on this site. And it is true that I am allowing the batteries to discharge more than I should. Some how I mistakenly thought that allowing up to an 80% discharge equated like the straight math . 80 or its compliment . 20 x 12 volts or anything above 2. 4 volts was ok. "hitting myself in the forehead" dummy me. Mark Nemeth provides the chart below which i am now printing and will carry with me in the travel trailer.



Mark S. Nemeth

Voltage State of Charge

12. 6+ 100%

12. 5 90%

12. 42 80%

12. 32 70%

12. 20 60%

12. 06 50%

11. 9 40%

11. 75 30%

11. 58 20%

11. 31 10%

10. 5 0%

As this chart indicates, assuming its validity, I can allow a discharge down to 12. 42 volts only--oops, I am going to have a lot of charging to do this weekend to get those 4 golf cart batteries up to where they need to be. Good news is that I will be up there Friday through tuesday and will have plenty of time to help them recover. l



Thank you so much forpointing this out, or I would have destroyed these guys in short order. Maybe there has already been irrepairable damage, and if so, that is the cost of my error.



Thank you again for the heads up.



REgards

Ron & Jodi

ImagesThatSing.com

 

[SilverFox]

I have seen Mark's chart and at the time wondered where he got it and if it were new or old. Most charts I have seen do not agree "exactly" with Mark's chart. If Mark's chart was way off from all the other charts I have seen I would post the source (provided I could find them) of the slightly different charts. At any rate I think we have found the source of your problem and hope your present inverter will handle your needs.

 

[ImagesThatSing]

Well, I am not sure it still isn't the inverter getting old, then. The reason I say that is that the inverter says it will only show the red indicator which is an overload/low voltage indicator when the charge reaches something like 10. 5 or 11. 5 volts (I cannot right now remember which). What I am going to do, is to first charge the batteries fully using house current and a charger, then when I get up on site, will recheck the voltage after the 4 batteries have become stabalized. Top them off if necessary, and then check to see if it will run my 2 computers. I can turn on the generator for using the printer, but according to all of the ratings I have seen, one laptop, and one desktop + monitor should be less than a 400 watt draw. I will just then have to monitor the status of the units and recarge when appropriate.



This has been a quite useful, informative, and remindfull discussion.



Once again, I tip my hat to the collective gifted, and sharing nature of those here gathered.

 

[willyslover]

here is a link to a battery page. . one of the best user friendly pages I have seen... it's to a specific page , use home page and browse this site. .





http://www.uuhome.de/william.darden/carfaq4.htm

 

[SilverFox]

It's possible the inverter's instructions are referring to the voltage reaching the inverter. Depending on the wire size and distance between the battery and inverter the voltage could easily be 10 or 11 volts if the voltage at the battery was below a 50% charge. Remember that 12 volt systems drop fast depending on length and size of wire. After it is inverted to 115-120 volts length of run is not as important.