power tools from inverters?

[rhett]

Great information, just another factor to consider.

Alternator Output ?
most vehicle alternators have a rated output of around 60 amps (max output), a little above idle much less amp output. Also alternator voltage output should be between 13.5 and 14.8 volts.

For a fresh Delco ST10 (64 amp) alternator lets say 40 amps @ 14.4 volts (40 x 14.4 = 576 watt output). So, any device using more than 576 watts starts using the stored battery amps causing a Duty Cycle effect. Alternators are rated at a 100% Duty Cycle.

Deep Cycle batteries are designed to be drained no lower than 11.9 volts (discharged). Battery life is increased by reducing amount of discharge, lets say 50% discharge (12.24 volts) will double the batteries recharge life cycle, and so on. So yes, more than one battery is recommended for frequent use.

Also wattage does directly relate across voltages to calculate amperage.
Example:
600 watts divided by 12 volts = 50 amps
600 watts divided by 120 volts = 5 amps
From the above examples, notice higher voltage more efficiently carries usable power.

Lots more for me to learn, please correct me if need be.
Thanks

 

[SPYDERLK]

Great information, just another factor to consider.

Alternator Output ?
most vehicle alternators have a rated output of around 60 amps (max output), a little above idle much less amp output. Also alternator voltage output should be between 13.5 and 14.8 volts.

For a fresh Delco ST10 (64 amp) alternator lets say 40 amps @ 14.4 volts (40 x 14.4 = 576 watt output). So, any device using more than 576 watts starts using the stored battery amps causing a Duty Cycle effect. Alternators are rated at a 100% Duty Cycle.

Deep Cycle batteries are designed to be drained no lower than 11.9 volts (discharged). Battery life is increased by reducing amount of discharge, lets say 50% discharge (12.24 volts) will double the batteries recharge life cycle, and so on. So yes, more than one battery is recommended for frequent use.

Also wattage does directly relate across voltages to calculate amperage.
Example:
600 watts divided by 12 volts = 50 amps
600 watts divided by 120 volts = 5 amps
From the above examples, notice higher voltage more efficiently carries usable power.

Lots more for me to learn, please correct me if need be.
Thanks

Clarification ... That would be a no load - or very lightly loaded - voltage.
larry

 

[rhett]

Thanks SPYDERLK,

Oh, I guess that is why most inverters have a Shut-Off at 10.5 volts. I still do not understand why such a low voltage though.

I have yet to figure out how to get accurate battery condition readings with a load, varying loads or with the charge system operating. I have learned to let the batteries sit idle and stabilize four a few hours after charging before testing the voltage. Maybe one day I will find the information or proper tool to do so on the fly.

Presently I am trying to setup an Off-Grid Power System and only know how to plug in the estimated power usage numbers for a general needs guesstimate. One neat thing I found was Epicenter and their How To for a Gas/Diesel 12 volt battery charger. I am putting together a 6hp with TWO Delco ST12 (94 amp) Alternators charging Two Battery Banks supplementing the Solar Panels as my array grows in size ($$,$$$.00) and for Rainy Days.

Thanks Again, On a side note for the original poster. It takes about 30 minutes to an hour to fully charge a drained 100 amp hour battery with an alternator charging.

 

[SPYDERLK]

Thanks SPYDERLK,

Oh, I guess that is why most inverters have a Shut-Off at 10.5 volts. I still do not understand why such a low voltage though.

I have yet to figure out how to get accurate battery condition readings with a load, varying loads or with the charge system operating. I have learned to let the batteries sit idle and stabilize four a few hours after charging before testing the voltage. Maybe one day I will find the information or proper tool to do so on the fly.

Presently I am trying to setup an Off-Grid Power System and only know how to plug in the estimated power usage numbers for a general needs guesstimate. One neat thing I found was Epicenter and their How To for a Gas/Diesel 12 volt battery charger. I am putting together a 6hp with TWO Delco ST12 (94 amp) Alternators charging Two Battery Banks supplementing the Solar Panels as my array grows in size ($$,$$$.00) and for Rainy Days.

Thanks Again, On a side note for the original poster. It takes about 30 minutes to an hour to fully charge a drained 100 amp hour battery with an alternator charging.

10.5V is a happy medium to let you stay on with a pretty heavy load on a well charged battery. Battery output voltage drops as load increases even with a full charge. This is an instant drop, followed by a further slow drop as the battery discharges. With a very heavy load -- starting a V8 on a cold morning the battery output may drop to 10v as soon as you hit the key because the starter has a huge draw as it comes to life under high load. An inverter that loaded it that much would kick off. Not a desired condition there ... but consider an inverter draining a battery at low load. Once the output of a lightly loaded battery drops to 10.5V it is pretty darn dead .. or has a a weak cell that has gone dead before the others. The 10.5 cutoff value protects that cell by preventing the chance that the strong cells will continue pushing current thru it. This would essentially be charging that cell backward and quickly destroy it.

If actually fully drained it will take 100A for a little more than an hr to charge it. Amps times hrs = amp hrs. Not 100% efficient charging. Thats why a little longer charge than shown by formula.
larry

 

[Soundguy]

yep.. 10.5v is a 'middle ground'

it's discharged for a 12v bat.. but mind you that 10.5v is a laoded reading... when not loaded usually comes up.

also.. any lower volts, and the current needed goes up to maintain wattage. quickly get away from circuit design paramaters quick that way.

soundguy

 

[handirifle]

Thanks for all the feedback info on inverters. Lots more to it than they tend to act like when you're buying one. Currently, I have no plans for any heavy duty usage, but I guess ya never know. I had figured, for my purposes, a 1KW would have been plenty, it may still.

I had figured on keeping this first one portable, and hooking it to whechever vehicle I needed to use, BUT, if I used a small one, say a 750w (assuming that's enough to power the tool, since I still haven't looked at them to see what the amp draw is) would it be over taxing the system of, say a riding mower, with about a 16 amp alternator?

As far as this use, it would be for about a 5 or 10 minute job. This setup is NOT meant to take on heavy projects.

 

[ultrarunner]

I've been running a Statpower 1800 Inverter since 1990 in my 85 Chevrolet Van.

So far, it has run everything I've needed with the one exception of the my circa 1990 Makita Cordless Charger... I switched to a 12 volt Makita charger for the cordless.

I've run my Spartan 300 Drain Auger, Microwave, Small Senco Air Compressor, Drills, Saws, and Sump Pumps.

I also put in a Delco 130 Amp Ambulance Duty Alternator and a second battery with a continuous Duty switched solenoid so I can combine both the vehicle and deep cycle battery when needed.

The reason for the second battery is I didn't want to have to run the engine all the time.

My inverter is old and for light duty loads I plug in a 25 watt incandescent lamp so the inverter doesn't go into sleep mode... I've found the current draw from the lamp is enough to keep the inverter powered up to handle surges from starting motors.

The Senco compressor doesn't take much... my small Emglo circa 1990 takes much more and is plumbed into the truck front, rear and side for easy access to air.

 

[Craig Clayton]

I used a battery booster / 120 Vac portable power unit to drill holes in my gate project that I need to post up as the project is now finished .
I also am planning on finding an LED portable light to plug into the booster / inverter as the Led will give me a long run time.
The wife brought it home because we had a power failure and I had no back up to my sump pump, which is now done right.
She was advised by a rep at a big box store that this would work, all I will say is he meant well as I have several trade licences.
The unit is rated at 650 watts Vac and is about the size of a large mail box and it weighs 20 pounds. It powered a 3/8 drill just fine. I now can run all my corded tools from this unit as long as I do not get power happy. If I want to run everthing at once then the 6000 watt generator comes along.
In Canada it is sold through Canadian Tire , In the states ??.