Why Won't My 1000W Inverter Run my 800W Coffee Maker?

TWZMYJP wrote:
Cable Sizes: Difficult to verify based on only being able to see the external cable insulation, cannot vouch for how thick the insulation is or how thick the copper is hiding inside?

We need to know this, and, not being able to access the cables is not a good thing.

YOu said two NEW "Deep cycle RV" batteries 12 volt.
I seriously doubt those are DEEP CYCLE. sound like MARINE/deep cycle compbo batteries (why do I doubt. 12 volt. is the key)

What size are they?
For a kilowatt you need at least 200+ amp hours of battery. Basically Group 31 pair should do it. or a pair of GC-2 in series (Those are 6 volt and TRUE Deep cycle)

NOTE: Deep cycle will not affect the inverter if they are full up when you start. Has more to do with how long (in years) the batteries will last you. In RV house service DEEP CYCLE often last close to 10 years. MARINE/deep cycle if you are lucky. half that. I was never that lucky.

A person would be astonished at the inrush of a tungsten filament light bulb.

This is why many devices list an inductive resistive and tungsten rating. Resistive and tungsten are not the same. Resistive does not saturate to >1,000c.

Straylight wrote:
Could be that you have a phantom draw (maybe your fridge?), could be that your coffee maker is higher wattage than you have been led to believe (especially during startup), but it also could be this thing I used to hear but now can find no evidence for: That some inverters and inverter generators really don't like appliances that generate heat in the same way a toaster or electric heater does. Something about the inverter seeing it as a short? Don't quote me on it.

Yes, AFAIK, OEM set-ups in new rigs like that are for a res fridge. They can do that. Once you try to do something else, you get in trouble. Could be the wiring is too thin for anything more than what the fridge pulls, or for several other reasons as given in this thread.

If it hasn’t been mentioned already, another thing to consider is that upon initial start-up your seemingly 800w coffee maker load is slightly inductive, meaning that upon initial start up, its likely of a greater (though brief) load that the posted wattage suggest, and your inverter is likely short on necessary headroom... Now consider other possible bottlenecks like battery size and condition, and often overlooked cable size and length of cable run snd you have the perfect storm...

landyacht318 wrote:
Even the best 12v flooded 'deep cycles' made by trojan, are rated at only have the 'lab cycles' of their golf cart batteries.

That's not true. The J-150 and J-185 12V ones are right there with the common T-105 GC. Although not on this chart, the T-1275 is, too. It's in the "1200 @ 50% DOD" table on Trojan's website. It's only the car battery sized ones which lack.

pianotuna wrote:
And the reason this is true is because the load per cell is 50% of what it is on the thick plates of the gc-2 jars. i.e. gc-2 is 12 cells and marine jar is 24 cells. So load per cell for 1000 watts would be 100 amps on the gc-2 cells and 50 amps on the marine jars. Plus thinner plats are "more reactive".

Yeah but, a typical 12V grp 24 FLA at 53lbs v.s. the GC2's 66lbs gives the GC pair a 26lb advantage. Wait, that makes the GC's look worse, nevermind! :)

HTH;
John

And the reason this is true is because the load per cell is 50% of what it is on the thick plates of the gc-2 jars. i.e. gc-2 is 12 cells and marine jar is 24 cells. So load per cell for 1000 watts would be 100 amps on the gc-2 cells and 50 amps on the marine jars. Plus thinner plats are "more reactive".

landyacht318 wrote:

That said a pair os 12v marine batteries should power a 1000 watt load through an inverter much better than a pair of 6v gc-2 golf cart batteries.

As a test, try boosting system voltage by having the engine running or the converter on and plugged in while the inverter tries to power only the coffee maker. Not sure how hard this would be to achieve in your rig.

The wire insulation usually is not ridiculously thick, unless one is buying drug store 10 awg jumper cables. What is its diameter and length from battery to inverter?

While there are a few brands which try and actually make a higher quality 12v flooded rv marine 'deep cycle' battery, they are not sold at a tire store, and are quite expensive compared to a wally world/tire store marine battery that will have the same general weight capacity and CCA.

Regarding 12v flooded 'deep cycle' batteries go, most seem to be exceptional junk, that retain poor voltage under load, and then require rather ridiculously high absorption voltages held for a ridiculous amount of time before specific gravity maxes out.
If they do not get this then they are doomed to seriously underperform during their brief lifespan.

Even the best 12v flooded 'deep cycles' made by trojan, are rated at only have the 'lab cycles' of their golf cart batteries.

A lab cycle is a 50% discharge followed immediately by a 100% recharge, which no batttery in actual use by an RVer is ever going to get.

That said a pair os 12v marine batteries should power a 1000 watt load through an inverter much better than a pair of 6v gc-2 golf cart batteries.

12V batts are usually 110 AH max. This is not good enough (in the long run), even if they are fully charged. Doesn't matter much what make, unless it's an AGM - those tend to drop less under load.

Coupled with some voltage drop due to thin cable from inverter, this could be enough to cause LVD.

Some cheesy 1000W inverter could struggle providing 900W.

So... updated homework to do:
1) find out the battery type, brand and AH rating
2) get somebody to check the cable size and length
3) find out inverter brand/specs, particularly - continuous power rating of inverter.

An alternative - add one more 12V battery and see what happens. You are going to need at least one more 12V anyway.