40 years ago, I was designing military electronics-avionics, for outfits
like SAC, DOD, NASA, NSA. Inverters and switching power supplies were a
somewhat troublesome area then and they still can be.
Today, components are better, but poor installations can cause problems.
Inverters sound simple; Open box and connect a few wires. True enough for
small inverters but a bullet proof HIGH POWER INVERTER installation is more
difficult to achieve, especially with 12 volt systems.
Some thoughts to consider:
1. All lead acid batteries last much longer if you never deep cycle them,
even those rated for deep cycling.
2. Overcharging batteries quickly reduces their capacity and life.
3. You get more power from a lead acid battery when you slowly discharge it
with less current.
4. Cycling batteries is inefficient because you put in about 20% more power
than you will get back.
5. Battery terminal voltage drops as load increases. Wire loss increases
with load. Inverter efficiency drops with load. Inverter efficiency drops
as voltage decreases. This all works against you with larger inverters.
6. To minimize wire loss use 2/0 cable and mount inverters as close as
reasonably possible to battery. Never depend on chassis grounds. Often
better to use both chassis and a 2/0 cable grounds.
7. Well engineered inverter systems tend to operate from 24 or 48 volts when
power levels are over 1,000 watts. Want to consider a 48 volt GMC house
system? Nothing comes easy, but eight golf cart batteries in series is
an interesting concept for boondockers.
8. Fuses at batteries are in your best interest. They protect lives, motor
home and maybe inverter.
9. Several different technologies are in use, so all inverters are not
created equal. This can affect weight, efficiency and reliability,
acoustical noise, noise in radios, output waveforms, noise on 12 volt buss,
etc.
10. Some are more fool proof, than others. I need all the help I can get in
this area.
A pair of NEW FULLY CHARGED Sears golf cart batteries will have about 11.5
volts at the terminals with a 150 amp load. They are obviously not happy
supplying this load which is about what a 1500 watt appliance requires.
At this power level, the golf cart batteries need help, We can either
install more batteries or start an engine.
Freedom of Choice is what America is about, so each to their own, in this
choice.
Idealists will install more battery capacity and enjoy the solitude of a
near zero noise environment while the microwave is cooking dinner and
draining their large bank of batteries.
Others view a large inverter system as a modern, light weight, more easily
maintained form of GENSET.
How can I properly stress this important option in inverter useage?
Think GENSET Think GENSET, like an Onan.
An engine is running and electricity is being produced as fast as we use it.
This conceptual difference is important and offers many advantages.
A small house battery IS practical, if our instruction book clearly states
the engine better be running and making adequate 12 volt energy with heavy
120 volt loads.
Instead of starting your Onan, you start your GMC. It fast idles at about
1200 rpm in neutral so your alternator supplies the necessary current.
The house batteries are now just along for the ride though they will be
charged if needed and they make up any shortage when load peaks exceed
alternator capacity.
With Flowmasters melodiously trumpeting through the woods, wildlife is
entertained, and 120v power is limited only by the size alternator and
inverter you are willing to purchase and install.
Without running your engine, you can watch TV, make early morning toast and
coffee. Your 4d or pair of golf cart house batteries stay happy supplying
these lighter or briefer loads.
Welcome to the future, though it's been around for over 40 years.
Cheers,
Don
75 Glennbrook
Shenandoah Valley of Virginia
like SAC, DOD, NASA, NSA. Inverters and switching power supplies were a
somewhat troublesome area then and they still can be.
Today, components are better, but poor installations can cause problems.
Inverters sound simple; Open box and connect a few wires. True enough for
small inverters but a bullet proof HIGH POWER INVERTER installation is more
difficult to achieve, especially with 12 volt systems.
Some thoughts to consider:
1. All lead acid batteries last much longer if you never deep cycle them,
even those rated for deep cycling.
2. Overcharging batteries quickly reduces their capacity and life.
3. You get more power from a lead acid battery when you slowly discharge it
with less current.
4. Cycling batteries is inefficient because you put in about 20% more power
than you will get back.
5. Battery terminal voltage drops as load increases. Wire loss increases
with load. Inverter efficiency drops with load. Inverter efficiency drops
as voltage decreases. This all works against you with larger inverters.
6. To minimize wire loss use 2/0 cable and mount inverters as close as
reasonably possible to battery. Never depend on chassis grounds. Often
better to use both chassis and a 2/0 cable grounds.
7. Well engineered inverter systems tend to operate from 24 or 48 volts when
power levels are over 1,000 watts. Want to consider a 48 volt GMC house
system? Nothing comes easy, but eight golf cart batteries in series is
an interesting concept for boondockers.
8. Fuses at batteries are in your best interest. They protect lives, motor
home and maybe inverter.
9. Several different technologies are in use, so all inverters are not
created equal. This can affect weight, efficiency and reliability,
acoustical noise, noise in radios, output waveforms, noise on 12 volt buss,
etc.
10. Some are more fool proof, than others. I need all the help I can get in
this area.
A pair of NEW FULLY CHARGED Sears golf cart batteries will have about 11.5
volts at the terminals with a 150 amp load. They are obviously not happy
supplying this load which is about what a 1500 watt appliance requires.
At this power level, the golf cart batteries need help, We can either
install more batteries or start an engine.
Freedom of Choice is what America is about, so each to their own, in this
choice.
Idealists will install more battery capacity and enjoy the solitude of a
near zero noise environment while the microwave is cooking dinner and
draining their large bank of batteries.
Others view a large inverter system as a modern, light weight, more easily
maintained form of GENSET.
How can I properly stress this important option in inverter useage?
Think GENSET Think GENSET, like an Onan.
An engine is running and electricity is being produced as fast as we use it.
This conceptual difference is important and offers many advantages.
A small house battery IS practical, if our instruction book clearly states
the engine better be running and making adequate 12 volt energy with heavy
120 volt loads.
Instead of starting your Onan, you start your GMC. It fast idles at about
1200 rpm in neutral so your alternator supplies the necessary current.
The house batteries are now just along for the ride though they will be
charged if needed and they make up any shortage when load peaks exceed
alternator capacity.
With Flowmasters melodiously trumpeting through the woods, wildlife is
entertained, and 120v power is limited only by the size alternator and
inverter you are willing to purchase and install.
Without running your engine, you can watch TV, make early morning toast and
coffee. Your 4d or pair of golf cart house batteries stay happy supplying
these lighter or briefer loads.
Welcome to the future, though it's been around for over 40 years.
Cheers,
Don
75 Glennbrook
Shenandoah Valley of Virginia
