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

On 28/06/2015 12:14, pete wrote:
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

So what was the DC over the battery in the 4 situations, battery idle,
battery being charged, battery powering inverter only, battery and
charger powering inverter ?

On Sun, 28 Jun 2015 07:14:43 -0400, pete wrote:

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.

Maybe you overdrew the battery?

A normal car battery has a power of maybe 5kW. It's normally run for a
few seconds which means it normally supplies, let's say, 10kJ of energy.
It's designed to release a few percents of the total energy stored within
itself. Lets say 2%. So a fully charged battery contains about 500kJ of
energy, however only a small percentage of that is repeatedly
recoverable. If we say a car battery can be discharged to 10% repeatedly,
that gives us 50kJ to work with. If we draw that energy at a rate of
200W, it will expire in 500 seconds, which is 8.33 minutes and close to
your measurement of 10 minutes.

The critical question is at what internal charge level does the battery
start dying? If the voltage at the terminals starts dying when the charge
drops to 90%, that explains the performance of the extra battery. If the
charge has to drop to 30% before the battery starts to fail, that
explains the behavior of the in-the-car battery.

Obviously, my calculations assume undamaged batteries. If the batteries
were heavily used and were overdiven previously, that would lower the
total amount of energy present in them and ipso facto lower the amount of
recoverable energy.

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.

100% certain that the secret is in the battery.

For this scheme to work assuming lead-acid batteries, you want a battery
that can be severely discharged, a so-called "deep cycle battery". These
come in many varieties so shop around if you're interested. You can also
make it work with NiCd batteries. Some have also suggested NiFe batteries
that you can supposedly build yourself.

In article , says...

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

A good inverter will shut off to save your battery so you can start the
car later to recharge it.
Thank the those that were thinking in the design.

Jamie

the OEM alternator, cost effective, works only on the highway where rpm produces power. Generalizing, a Ford 120amp alternator supplies lights and air at 50-60mph. Add a stereo amp, way over limits. The negative threshold comes slowly with yellow lights after 2-3 hours of asking a very good battery for more discharge than charge.

A 200amp alternator (Summit Racing) claims production of 120amps at idle but give it 15-20 mph. The OEM needs 65mph to give 120amps.

The battery your using may not be quality or fresh. Charging takes power and voltage the system may not support but that the OEM alternator at 65mph does. The 200amp unit charges at 45 mph in abt 20 miles.

drivers 'charging' dead batteries at idle after jump starting are not getting their $$$ worth.

On Sunday, July 19, 2015 at 7:05:07 PM UTC-4, wrote:
the OEM alternator, cost effective, works only on the highway where rpm produces power. Generalizing, a Ford 120amp alternator supplies lights and air at 50-60mph. Add a stereo amp, way over limits. The negative threshold comes slowly with yellow lights after 2-3 hours of asking a very good battery for more discharge than charge.

A 200amp alternator (Summit Racing) claims production of 120amps at idle but give it 15-20 mph. The OEM needs 65mph to give 120amps.

The battery your using may not be quality or fresh. Charging takes power and voltage the system may not support but that the OEM alternator at 65mph does. The 200amp unit charges at 45 mph in abt 20 miles.

drivers 'charging' dead batteries at idle after jump starting are not getting their $$$ worth.

++++++++++++++++


Google Images offers a menu of chart information or search your alternator

https://goo.gl/vvXQXM

https://goo.gl/X9bapx

Powerstream under 'technical resource' offers a wire size calculator


http://www.powerstream.com/