Any idea how much load I can put on a 1000w inverter on an 80 amp supply? - Page 1
Forum section: electronics / general

author: XOIIO
author_rank: Super Contributor
timestamp: July 12, 2016, 03:54:59 pm
content: Hey all, so I got this 1000w inverter for only $10 on local classifieds, because it wouldn't power up. Checked the fuses and they were good, so checked the next most obvious thing, and yup, it was the power switch.Swapped that out with one from an ATX power supply and it works perfectly, though sadly it's modified sine wave (I also drove around a bunch trying to find a switch, and then when i got home I realized I could just salvage one the right size, also changed out the pretty low visibility green LED with one of the new diffused blue ones I just got)Now it has a nice permanent home in the trunk of my car, replacing the police power point that was there. Not a big issue since I can still connect to it if I need to power anything else from it, but removing the old terminal connectors let me mount it in a good spot and saved me $20 on wires.Now, this power point is fused at 80 amps, and unfortunately, the manual for this doesn't have much, all it mentions is to use a circuit fused at 150 amps. The manual also does mention that it is capable of delivering 2000w surges.I've send an email to the manufacturer, but figured I'd check with you guys to see what sort of load you think I could put on this safely. Upgrading the wiring isn't an option right now, and honestly I likely won't really use this much, if ever, aside from charging up a laptop on the go, but it would be good to know.It won't be 100% efficient I know that, but with a surge rating of 2000w and a 150a fuse, maybe 80 amps would actually be enough to power 1000w continuously, if it's linear.

author: Kilrah
author_rank: Unknown
timestamp: July 12, 2016, 05:27:45 pm
content: A rough estimation for an inverter on 12V is 10A of input current for 100W out, so yeah you should be able to draw maybe 600-800W... BUT there's still a risk to blow the fuse even when connecting a much lower load if it causes a huge inrush current.

author: XOIIO
author_rank: Super Contributor
timestamp: July 12, 2016, 05:33:35 pm
content: Quote from: Kilrah on July 12, 2016, 05:27:45 pmAlright, I had first guessed around 800w, that's a 6.5 amp load or something, so hell, I could power my entire server rack off of it, which is plenty good.I figure it might work well with a mini fridge during a road trip or something lol, though it might get too warm in there, idk. I don't go on road trips anyways.

author: Kilrah
author_rank: Unknown
timestamp: July 12, 2016, 06:37:07 pm
content: Don't know your truck battery capacity, but of course you realise that drawing 800W on your battery is likely to only be good for an amount of time best counted in minutes...

author: rx8pilot
author_rank: Super Contributor
timestamp: July 12, 2016, 06:45:08 pm
content: Quote from: Kilrah on July 12, 2016, 06:37:07 pmTrue - yanking 80-100A from an automotive system is no joke. It looks like the unit is in the rear trunk too meaning the cables are likely rather long too. If that is true, the voltage drop will be substantial without massive cables. A long high-current run also has a lot of fire potential in a vehicle.

author: XOIIO
author_rank: Super Contributor
timestamp: July 12, 2016, 07:00:17 pm
content: Quote from: Kilrah on July 12, 2016, 06:37:07 pmIt's a car, and yes, it is trunk mounted, but for any load beyond a laptop charger I'd have it idling. The car has a 200a alternator to supply enough juice for any police equipment that would be installed, so it should be able to supply the inverter without any issue, from what I recall lightbars can draw 50 amps or so, and they often leave those on with the car parked.

author: rx8pilot
author_rank: Super Contributor
timestamp: July 12, 2016, 09:55:04 pm
content: That is a solid alternator for sure! Now all you need is some very heavy gauge cable to deliver the current with a workable voltage drop. 4AWG would drop around .6V and dissipate 60 watts at 25ft I think. 8AWG would jump to 1.6V drop and dissipate 160 watts! Startup inrush currents may cause it to shut down with that kind of loss.

author: XOIIO
author_rank: Super Contributor
timestamp: July 12, 2016, 10:00:25 pm
content: Quote from: rx8pilot on July 12, 2016, 09:55:04 pmI'll have to check the cable, I'll check the voltage at the battery and the inverter itself but I imagine it should be adequate, it was put in these cars specifically for police equipment, so I'd reckon the cable should be good for 100a and they just fused it at 80 for safety.

author: XOIIO
author_rank: Super Contributor
timestamp: July 12, 2016, 10:23:01 pm
content: Can't find my calipers at the moment, and this didn't have any load on the system aside from the trunk light, but the battery was at 12.600, and the trunk was at 12.551. I'm not sure if it would drop more with a fair load on it, it probably would, but that seems pretty good to me.

author: rx8pilot
author_rank: Super Contributor
timestamp: July 13, 2016, 12:20:11 am
content: The load will determine the drop.Sent from my horrible mobile....

author: XOIIO
author_rank: Super Contributor
timestamp: July 13, 2016, 09:11:36 pm
content: It's actually going to see a fair bit of use, or at least hopefully, whenever I go out to do a tech job, I'll stick my case in the trunk, take the netbook out and charge it as I drive there so that I'm sure it has a full, or at least more full, battery, since it's a pretty crap one that's on it's way out.

author: SkyMaster
author_rank: Frequent Contributor
timestamp: July 13, 2016, 10:17:55 pm
content: Quote from: XOIIO on July 12, 2016, 10:00:25 pmI also have the same model of Xantrex 1000 inverter; designed in Canada, made in China. Mine came from Canadian Tire.Hold on, the manual reads to use an input cable with amaximumlength of5 feet. Theminimumgauge should be2 AWG.According to the manual, below 11.0 V a low voltage alarm will sound. Below 10.5 V the inverter will stop.At 1000 W, the inverter should draw about 90 A.That being said, I could be wrong but from your pictures, it seems that wires powering your inverter are nowhere near 4 or 8 AWG.What was originally powered by this cable in the trunk?

author: XOIIO
author_rank: Super Contributor
timestamp: July 13, 2016, 10:35:10 pm
content: Quote from: SkyMaster on July 13, 2016, 10:17:55 pmIt would be general police equipment, computer systems, or certain dash cam setups, misc. stuff they would have back there, sometimes on an equipment shelf. Not sure if the light bar was hooked up to these or another point, depends on the setup.I forgot I also took pictures of the wires with a 10mm socket near them as I was reinstalling it with the carpet in, first is the 10mm socket below them, second is with it resting on them. they are powered by two 50 amp fuses, one for each of the positive wires I'd assume, so I'm guessing ford counted on 10a being lost due to the length/resistance of the wires or so. (or maybe it's just extra since the point itself is rated at 80a max.It does seem a tad on the small size, though the negative is one solid wire. (that's a 3/8th ratchet by the way)