110 watt LED Lamp/ 100 amp/hr Battery: How Long Can It Run?

[wrenchtech]

I am just making my first foray into battery power and then hopefully into solar. I have a 120v LED work light that is said to draw 110w. If I understand Ohm's law, that translates into .91 amps. I have been reading in this forum of people using 12v batteries with 100 amp/hr rating, so let's use that for this question. And I know that if the battery is a lead acid deep cycle type I won't want to draw it down past a certain point. So how long could I run this light on said battery? And what size inverter should I use?

If anyone can direct me to a good resource for learning this stuff, please do so.

[john61ct]

Problem here is the different voltages.

First off, get a multi LED light designed to run off 12V, otherwise you need to run an inverter as well, which is silly wasteful.

But ignoring that, 100Ah is usually called 50Ah usable storage

at 12V is 600Wh, divided by 110W load

So, running for 6 hours, will leave 45Ah, much lower if done regularly, you'll start reducing your battery's lifespan.

[wrenchtech]

I bought two light stands today off of Facebook marketplace for $10. I really lucked out. They are quite a bit beefier than the ones pictured here. I am ordering four 12v automotive accessory/off-road style LED lights to mount on top of them (2 on each), to light my off grid outdoor work area. I will also buy an AGM deep cycle battery to power them. If I like the results I will think about adding a few more lights. I’d like to work my way up to being able to run power tools and eventually a welder. Of course serious welding requires 220 V if I want to power an off-the-shelf stick welder, But I am thinking there may be something I can make that would work with direct current right off of the batteries. And of course, I will have to ad solar panels and an inverter as I progress.

[john61ct]

Check out Zena, make high powered alternators for pumping kW into deep cycling banks, and

also convert into stick welders powered by your vehicle

[Native]

It would seem to me that you may need the solar a lot sooner than "as I progress", unless you have a generator to charge the AGM battery.

[wrenchtech]

Originally Posted by Native

It would seem to me that you may need the solar a lot sooner than "as I progress", unless you have a generator to charge the AGM battery.

I have an older 4600 watt generator that I picked up for $100 at a garage sale. Could use it to run lights or charge batteries, but I don't like the noise. Would rather hear coyotes yodeling and yipping while working after dark. Can also take the batteries to another location to charge off the regular grid power.

[Native]

You only have to run the generator long enough to charge the battery. Then use the battery for another 5 hours.

[john61ct]

To fully charge a depleted lead battery will take 5-7 hours no matter how much current is available.

So solar is required if you want your deep cycle battery to last.

[wrenchtech]

It is also going to be interesting to test the claims made by the sellers of these lights. The units pictured above are supposedly rated at 480 W and put out 47,000 lm. This, is a light that you can buy for $13. I will be wanting to test these lights to see how much they’re really drawing.I have an inexpensive DC clamp style amp meter. I haven’t used it much though, and I don’t remember it being that sensitive. Any recommendations on the best way to measure how much these lights pull?

[o1marc]

Originally Posted by wrenchtech

It is also going to be interesting to test the claims made by the sellers of these lights. The units pictured above are supposedly rated at 480 W and put out 47,000 lm. This, is a light that you can buy for $13. I will be wanting to test these lights to see how much they’re really drawing.I have an inexpensive DC clamp style amp meter. I haven’t used it much though, and I don’t remember it being that sensitive. Any recommendations on the best way to measure how much these lights pull?

Plug it into a kill-a-watt.
I just went out to plug my dual row LED 5000L light into the K-A-W and it's kicking the breaker, something shorted in it. time to swap it out at WM.

Do you have a link or model number for those lights? The closest I find to anything with those numbers run $2300 and use 500W of power.

[wrenchtech]

Originally Posted by o1marc

Plug it into a kill-a-watt.
I just went out to plug my dual row LED 5000L light into the K-A-W and it's kicking the breaker, something shorted in it. time to swap it out at WM.

The kill-watt devices I've seen are for 120v AC. The lights are 12v.

[o1marc]

Originally Posted by wrenchtech

The kill-watt devices I've seen are for 120v AC. The lights are 12v.

A link to them?
Found them, 400w, only 12k lumens.

[wrenchtech]

Originally Posted by o1marc

A link to them?

12v LED Work Lights

[o1marc]

Originally Posted by wrenchtech

12v LED Work Lights

Those are not the same as what is posted before. I doubt the lumen figure.

[john61ct]

ammeters are only instantaneous

decent DC coulometers (Ah totalizers) in the sub-100A range are ~$30 plentiful on all the usual suspect platforms. Bigger ones like 500A or 1000A will be less precise for small loads

Hall type may give a bigger range?

[wrenchtech]

Originally Posted by john61ct

Check out Zena, make high powered alternators for pumping kW into deep cycling banks, and

also convert into stick welders powered by your vehicle

For around 20 years I have been watching another company called Premier Power Welder manufacture and sell modified alternators and controllers for work trucks and off road vehicles. I just looked at their website and I was amazed at how far they have come. From offering a limited set of solutions based on one model of alternator, it now appears that they have solutions for many applications, foreign and domestic. I just counted five pages of products! If car stereo enthusiasts can fit multiple alternators to their SUVs and pickups it should be possible for a medium duty diesel. I am imagining powering, in combination with solar and battery power, mini-split A/C units as I'm going down the road in a 40' bus. Having a very good welder as part of the deal would be icing on the cake.

premierpowerwelder.com

[wrenchtech]

Originally Posted by john61ct

ammeters are only instantaneous

decent DC coulometers (Ah totalizers) in the sub-100A range are ~$30 plentiful on all the usual suspect platforms. Bigger ones like 500A or 1000A will be less precise for small loads

Hall type may give a bigger range?

When you refer to Hall Effect measuring, am I correct in thinking that a clamp meter is an example of the Hall effect in action? Are the coulometers installed in-line in such a way that all of the current passes through the device or a part of it? Thanks

[john61ct]

Hall effect vs shunt are just the two detection technologies, and yes clamp type is the former.

https://www.fluke.com/en-us/learn/be...t-clamp-meters

Tracking amps is drawing the curve from left to right, just the line juggling up and down,

Coulomb / Ah-counting is getting the area underneath, like integration in calculus, or "totalizing" tracking the overall energy used per period of time.

[PNW_Steve]

Originally Posted by john61ct

ammeters are only instantaneous

decent DC coulometers (Ah totalizers) in the sub-100A range are ~$30 plentiful on all the usual suspect platforms. Bigger ones like 500A or 1000A will be less precise for small loads

Hall type may give a bigger range?

I have a Trimetrc SC-2030 battery monitor that has worked out well. I was looking at one similar to what John mentioned on eBay for $18 when it occurred to me that I had the Trimetric sitting on the shelf.

[john61ct]

Yes Bogart makes **excellent** stuff.

That Trimetric can coordinate 2* 30A controllers, even though PWM give superb control over the stop-charge via endAmps.