Cordless grinder

[EastTexFrank]

Seems to me that an inverter large enough to run a grinder will require a special and expensive alternator on your vehicle to feed it.

Using US standards:

A simple grinder uses 120 volts and at least 5 amps. (Pro grinders may use 11 amps). 120v x 5a = 600 va. And 600 va at 12 volts = 50 amps.

Most original automotive alternators are 35 amp or less. So with a 120v 5 amp grinder you will need the engine roaring and still won't stay ahead of the grinder's current draw.

That was interesting Cali. I've never thought of it before but I occasionally run power tools, usually an electric pole saw, off a 1500 watt (3000 surge) inverter connected to my Powerstroke. It has dual batteries but I have no idea what size (capacity) alternator it has. I think it's about 100 amp but I need to go check.

Thanks again.

 

[GreenWannabe]

Mith, air compressors run off the truck are used quite a bit by utilities folks here (electric, gas, etc.) . Two common brands are Ingersoll-Rand (compressor line now owned by Doosan Infracore) and vMAC. Probably quite a bit more expensive than the solution you are looking for, but gives you an idea of what is possible. Generators are also available as truck auxiliary equipment, brand names escape me right now. Good luck in your search.

Fred

 

[jwstewar]

A couple of unrelated thoughts on this thread.

First the cordless grinder. I have several of the DeWalt 18v tools including the grinder. It seems like anything that cuts (circular saw, recip saw, or the grinder) really sucks the battery, but the impact driver or drill something like that, they run forever on a charge. I thought I would use my DeWalt grinder to sharpen the mower blades. It was quite a bit slower than my corded DeWalt & Makita grinders. It only made it didn't quite make it through 1 blade before the battery was dead. I have 6 batteries, so I could have swapped batteries, but I just ended up getting the corded one out to finish the job. Incidentally DeWalt markets it as a Cut-off tool - not a grinder. When the wind blew Monica's greenhouse away, I made several cuts through the aluminum frame before the battery gave up. It is good if you only have to do a couple of minor cuts and don't want to have to drag a cord out to do it. I got mine free. Monica bought me a combo kit at Lowes. It was normally $399 and they had it on sale for $299 + a free tool by mail. I ordered the grinder/cut-off. Turns out the drill was bad on the combo so I returned. Thinking they would check the receipt for the return, I mailed the new receipt in and changed my mind and got the impact driver. Ended up getting both. The impact driver is now my favorite tool. I will never use (OK more than likely not) a cordless drill to drive a screw again. Not bad, 6 tools, 2 batteries, and a charger for $299.

As far as the truck compressor goes. Dad used to change tires for a living, he typically used a long anvil 1" drive impact wrench. When he first started working for the company he retired from, they ran compressors off the truck engine. He start in 1980 for this company, they had a '78 Chevy with a 3-speed on the tree. The odometer said less than 100k miles on it, but he figures the engine had closer to 600k. He would start the truck in the morning and it wouldn't shut off until he quit working that evening. As they started buying newer trucks, it started getting super expensive and hard to put them on the newer trucks as there was no room under the hood. They just started using the typically gas compressor in the bed of the truck. Harder to get started if it was cold and took some bed room, but other than that no drawbacks. Cheaper, easier to replace when it wore out and less wear and tear on the truck because it didn't sit and run all day. Especially duriing the summer sitting out in the field and getting it hot.

 

[Mith]

The air compressor is sounding attractive, I'll have to check with my insurance company how much it will add to my premium (its a modification so it adds).

The cordless grinder would be perfect if it weren't for the battery life. Do you reckon its just DeWalt that are so bad, or maybe Makita is better.
Maybe I'll ask for a demo, 15 mins per battery would probably do, but 5 mins just wont cut it (excuse the pun).

 

[California]

That was interesting Cali. I've never thought of it before but I occasionally run power tools, usually an electric pole saw, off a 1500 watt (3000 surge) inverter connected to my Powerstroke. It has dual batteries but I have no idea what size (capacity) alternator it has. I think it's about 100 amp but I need to go check. Thanks again.

I meant to show you this article last week but it was bookmarked on the home computer and I was at the ranch.

Prius powers home during outage

Apparently Prius uses 12 volts for the water pump, power steering etc so it has a 130 amp 12 volt alternator. This engineer learned he can charge the primary (200v) battery running the gas engine 5 minutes every half hour, and that will drive the alternator, for a net continuous output from his inverter of around 120v 1000 watts. Clever! He said he used only five gallons of gas generating about 17 kilowatt hours of energy over a couple of days. His math and his references to other articles might give you some ideas.

 

[cleatusj]

I use a 400w/600w surge inverter to run a Harbor Freight 4 1/2" grinder to cut bolts with out the engine running and have never ran down battery with 5-6 cuts. Any more and I crank the engine. If I was to replace the inverter I would go to a 600/800.

 

[Mith]

Well, I went with the Makita cordless in the end. I bought 3 batteries, and a 15 minute charger. I dont know what the other brands are like, but the charger for this thing looks like something out of mission control at NASA, flashing lights everywhere.
They sell a few variations on batteries and I went for the 18V 3Ah Lithium ones. I'm hoping I dont have to buy any more for a while, the batteries cost £120 (~$200) each on their own.
Not used it yet, but I'll report back on how it goes.

 

[Mith]

Well, I went with the Makita cordless in the end. I bought 3 batteries, and a 15 minute charger. I dont know what the other brands are like, but the charger for this thing looks like something out of mission control at NASA, flashing lights everywhere.
They sell a few variations on batteries and I went for the 18V 3Ah Lithium ones. I'm hoping I dont have to buy any more for a while, the batteries cost £120 (~$200) each on their own.
Not used it yet, but I'll report back on how it goes.

 

[olcowhand]

I use a 400w/600w surge inverter to run a Harbor Freight 4 1/2" grinder to cut bolts with out the engine running and have never ran down battery with 5-6 cuts. Any more and I crank the engine. If I was to replace the inverter I would go to a 600/800.

I got a 1200watt inverter a while back. It'll run my 4 1/2"er fine. I bought the inverter for short power outage times when no need to fire up generator , plus for easy portable AC.