trouble with recent emergency battery, inverter, car set up

[pete]

I had a recent power outage that lasted for 3 days. Not having a generator on hand, I decided to try using what I did have for short term power purposes. The items consisted of the car, 500 watt inverter, and I had an extra car battery available.

I hooked up the inverter directly to the car battery in the car. With the car running, I was able to run the 46" LCD TV, and a couple of CFL lights which was all I really needed to do. However, I ran into some problems. If the car wasn't running the entire time, the items connected to the inverter would start flickering on and off after a period of time. If off of the car battery inside the car, this might be within an hour, but with the separate battery, maybe 10 minutes unless it was coupled to the car battery in the car with the car running.

All in all, I was disappointed. I'm wondering why the items wouldn't operate correctly unless the car engine was running. There certainly wasn't a lot of wattage being drawn.... the TV uses like 100 watts with the lights maybe 10 watts each, and there were 2. I had hoped to just use the battery in the car to occasionally "jump" and charge the separate battery when it got too low, but never got to that point as the attached items would start flicking on and off.

I see portable power packs with internal battery and inverter at places like Walmart. The inverter is usually 400 watts or so, so I know this method should have worked. Any ideas as to why my set up didn't work well would be welcomed. If it had worked this time, I had planned on maybe a 1000 watt inverter at some point which I had hoped maybe if this happened in the future to be able to run the house refrigerator from the inverter/ car battery set up, but not if I have to have the car running the entire time.

Thanks for your help.

Pete

[mike]

Are you sure your TV is only 100W? You're drawing too much current for a car battery to last long. Your extra batteries are shot.

Do the math. a 1000 watt inverter will draw 100 amps or so from a car battery. It won't last long.

A generator is WAY cheaper than the cost of a set of batteries to do what you want.

[pete]

According to the manual, the TV draws 100 watts. The extra battery was brand new and was rated 525 CCA.

Perhaps not, but the idea was to get the combination working well with the 500 w inverter first which didn't happen.

Well, the brand new battery was $65 and I already had the 500 w inverter. Since generators were all sold out locally at the time, I had to do my best to make the combination work which really didn't happen. Besides, generators have to be maintained periodically as they'll sit for long periods without use, something not done for inverters and we already have regular maintenance on the car.

[Terry Coombs]

The only maintainance my generator sees is an oil change periodically . I DO make sure I run the carb dry when I'm done with it , and only use non-ethanol gas . But then mine is a fairly expensive 5500 watt unit , not a HF $129 2-stroke POS . YMMV ...

[Stormin Mormon]

I'd be tempted to put ammeter on the TV and see what the real current draw is.

Car starting batteries some times have a "reserve capacity" listed, typically 25 amps for some hours and minutes. This will give you a better idea of capacity, compared to CCA.

Car batteries are designed for high current, very short time use. Like car starting. To use them for deep discharge can damage the batteries.

In such a setup, I think leaving the car running will give you better performance, and less chance of damaging the battery (s).

- . Christopher A. Young learn more about Jesus .

. .

[Stormin Mormon]

From my own experience with a ETQ 1200, they should not be run dry, they develop a piston rod knock, and then don't start worth a hoot after that.

With your 5500 watt unit, crank case oil. That one can run dry. The gas oil mixers should not be run dry.

- . Christopher A. Young learn more about Jesus .

. .

[bob_villa]

On Sunday, June 28, 2015 at 6:12:45 AM UTC-5, pete wrote: If it had worked this time, I had planned on

The items you are powering need a stable 60Hz...I think the inverter is below par for this. Sometimes CFL's are the only thing that flickers when you have a minute power fluctuation...and your TV may be CCFL (and not LED).

[philo]

With your car running, the inverter will be running with full input voltage.

With the car off, the battery voltage will eventually drop to the point where the inverter's output is low or unstable.

Your car battery is probably in good shape, but your spare battery is either weak or was not fully charged.

Also note:

A car battery is no designed for deep discharge...basically all it would normally need to do is supply a lot of current for a short period of time.

If you discharge a car battery too often it will die prematurely.

To run an inverter it's best to use a battery specifically designed for deep discharge...such as a trolling motor battery.

[makolber]

Op, Here the answer to your problem. Most inverters have a low voltage cut off that will turn them off When the input voltage gets below something like 10 volts.

A good car battery puts out 12 volts which leaves you only 2 volts margin. You MUST use heavy cables and connectors to connect the inverter to the battery. 100 watts at 12 volts is almost 10 amps so it is easy to drop a volt or more in the Cable and connectors.

A running car CHARGES the battery which means there is almost 14 volts across the battery. That extra 2 volts makes up for the drop in your cables.

Get some HEAVY cables and try it again.

Mark

[trader_4]

I agree it sounds like the inverter didn't run as long as you'd expect. If your load calc is right, you had 120W. Allowing for some losses, let's make it 150W. That's 1.25A on the AC side,

12.5A on the battery side. I would think a typical car battery would be able to deliver 12A for a lot more than an hour. How long were the extension cords linking this together? Was it wired to the battery with cables of sufficient gauge? Another factor would be the age of the batteries used. A new battery and a 5 year old one are going to perform differently. Also possible there is something wrong with the inverter and how well it works may depend on whether it's a quality one or a cheap Chinese one off ebay.

Did you take any voltage or current readings while this was happening? That would have provided some relevant data.

OK, so we know that one of the batteries is brand new. Generators seem to generally do OK without maintenance when just sitting, provided you empty the gas, run it dry.

[trader_4]

All good points. If he bought a new battery for this use, it should be a deep cycle type. Starting type batteries don't last long when you deep discharge them. Each discharge takes more life out of them than it would a deep cycle battery. And letting them sit for any period discharged is very bad too.

[bob haller]

check date code on new battery, it might have been sitting on a shelf for a year, was the new battery load tested before use and then charged?

my GF was thinking of buying and renovating a abandoned home. she wondered about the wiring.

i stumbled onto a near giveawy deal on CFs.

so i replaced nearly all lightbulbs thru the entire home, and feed a extens ion cord from the inverter to the homesmain braker panel. i managed to powe r up the entire home.

i did this during the day and returned with her about dusk that evening. pl ugged in the home it lit up nicely. some neighbor must of noticed and calle d the police. lots of questions like how did you get the power on?

about this time the diming began the OP reported.

kinda unreal standing in the living room of a abandoned home talking to pol ice with the lights dim and brite. the inverter was over heating from being slightly overloaded, and the short 12 volt cables had the inverter really close to the raditor fans exhaust, it was unreal hot when i pulled the syst em down.......

interestingl we were at that home yesterday, the community is sending my GF a letter aboutpurchase price.. we orignally stumbled onto it years ago.

of course it needs a lot of work, all copper gone, and some CPVC all frozen and broke. who cares thats what PEX is for:)

will need a new roof soon, new furnace and air, some wiring upgrades. it ha s romexall with ground wires but 2 prong outlets, no biggie replace all out lets and switches i have done lots of wiring, needs windows, the old steel casements werent a big loss neighbor hood kids used a neighbors river rock garden a a ammo dump.

someoe tore down the kitche cieling to steal the copper.

i enjoy fixing up homes, just wish my knee didnt hurt.

when we were there yesterday I discovered the ceramic tile kitchen was real ly glued on plastic tile. home will need a new kitchen and the old tile w as ugly. GF thought it was ceramic.

i am stuned the home wasnt really vandalized. we found a letter from someon e pushed thru a window wanting to rent it.. neighbors are nice and must be keeping a eye on things. hopefully purchase price is very low. i would enj oy the project.

years ago we removed all the trash from the place......

its aquired a name the ivy house. since ivy grew up the outside wall enter ed into the master bedroom and over time grew across the rooms and out ano ther window on the other side

[Stormin Mormon]

abandoned home. she wondered about the wiring.

home, and feed a extension cord from the inverter to the homesmain braker panel. i managed to power up the entire home.

dusk that evening. plugged in the home it lit up nicely. some neighbor must of noticed and called the police. lots of questions like how did you get the power on?

home talking to police with the lights dim and brite. the inverter was over heating from being slightly overloaded, and the short 12 volt cables had the inverter really close to the raditor fans exhaust, it was unreal hot when i pulled the system down.......

is sending my GF a letter aboutpurchase price.. we orignally stumbled onto it years ago.

So, you considering moving into a place where the neighbors call the cops on you?

- . Christopher A. Young learn more about Jesus .

. .

[Ed Pawlowski]

Sounds like you are buying 4 walls and an umbrella. Would be nice to have it salvaged rather than left to fall down in time. Take lots of before and after photos.

[bob haller]

its a brick home the structure is solid, sure it needs work, much of whick i and some friends can do myself:), since i helped them they should return the favor.

while you learn new skills, and look with pride at what you accomplished...

besides its fun:)

besides this can make money wether you live in it, rent it out, or sell it in the future,, plus you removed a blight from the neighborhood.

I like the fact the neighbors are interested.

the back yard is surrounded on 3 sides by trees

[tony944]

Pete whenever you go into high current hook up be careful! Base on 500 watts inverter. Voltage = 14 V. Vehicle running. Voltage = 12.5 V Battery sitting alone. At 500 watts, input needed 14 VDC. @36 amps. Size of wire #8 requires. In charge Mode At 500 watts, input needed 12.5 VDC. @40 Amps. Size of wire #8 requires. Not being charge.

1000 watts at same Voltage input you need to double Current and size of Wire. At start up when Vehicle is cool and in charging mode normally will be 14.4 Volts, after warm up it may drop down to 13.8 VDC. So you can see, there is some difference on output when Vehicle is running, Voltage of Battery will fluctuate when is in charging mode. Hooking up that size of inverter ?do not use alligator clips you must have solid screw down to Battery post or you might have melt down of post, and needless to say fire or explosion. ******************************************************************************

I had a recent power outage that lasted for 3 days. Not having a generator on hand, I decided to try using what I did have for short term power purposes. The items consisted of the car, 500 watt inverter, and I had an extra car battery available.

I hooked up the inverter directly to the car battery in the car. With the car running, I was able to run the 46" LCD TV, and a couple of CFL lights which was all I really needed to do. However, I ran into some problems. If the car wasn't running the entire time, the items connected to the inverter would start flickering on and off after a period of time. If off of the car battery inside the car, this might be within an hour, but with the separate battery, maybe 10 minutes unless it was coupled to the car battery in the car with the car running.

All in all, I was disappointed. I'm wondering why the items wouldn't operate correctly unless the car engine was running. There certainly wasn't a lot of wattage being drawn.... the TV uses like 100 watts with the lights maybe 10 watts each, and there were 2. I had hoped to just use the battery in the car to occasionally "jump" and charge the separate battery when it got too low, but never got to that point as the attached items would start flicking on and off.

I see portable power packs with internal battery and inverter at places like Walmart. The inverter is usually 400 watts or so, so I know this method should have worked. Any ideas as to why my set up didn't work well would be welcomed. If it had worked this time, I had planned on maybe a 1000 watt inverter at some point which I had hoped maybe if this happened in the future to be able to run the house refrigerator from the inverter/ car battery set up, but not if I have to have the car running the entire time.

Thanks for your help.

Pete

[N. Cognito]

Take care of it and this will virtually last forever:

[clare]

Running a car to operate a 500, or even a 1000 watt inverter, is an awfull inefficient and expensive way to provide emergency power.

[clare]

I don't even have to drain the carb. I just plug it into the natural gas line. I also have the option of running it on 2 propane BarBQ tanks. Synthetic oil change every 50 hours of intermittent use, a few hundred hours of consistent running. (Full pressure filtered lub system)

[Mark Lloyd]

[snip]

During one power outage, I ran a TV (372W LCD with fluorescent backlight) with an inverter on a deep-cycle battery. It lasted over 4 hours without any flickering.