My brother is having issues with a 13500 btu A/C starting while using a 2000 watt inverter. This is installed on a cake delivery van. The fan motor will turn on but not the compressor. He is using two 12 volt batteries connected to the vans alternator. The breaker will trip on the inverter when be compressor tries to start. They were using a 2000 watt generator to run be A/C but don't want the hassle of the generator. He swapped out the inverter and is still having the same issue. Any ideas? Bigger inverter? I personally don't think the vans alternator will be able to keep up the batteries either.Any help would be appreciated.

I'll leave it to the experts whether this idea has any chance at all. But off the top it probably suffers from1. Inadequate inverter.2. Possible inadequate wiring between batteries and inverter3. Inadequately sized batteries in amp hour capacity4. Inadequate alternator capacityIs this roof air to be counted on for continuous duty during the day?

Yes that would be a huge load on the alternator, and probably would wear it out quickly.Do they have any idea how many amps they would be drawing at 12 volts DC to run the A/C unit? Just the fan motor is probably drawing over 50 amps at 12 volts! Is it a pure sine wave inverter? If MSW or some sort of pure modified sine wave, then it will not handle the high torque loads of the compressor motor.I would suggest something like the Pure Sine Wave Trace 2500 watt with a 5,000 watt surge capacity. That will require #000 wire from the inverter to the pair of batteries (4 golf cart batteries would be my recommendation) and #4 wire from the alternator +12 terminal to the + 12 volt terminal on the inverter. That way the inverter can draw 400+ amps from the battery, and 100 or so from the alternator while starting the compressor, and can draw just 50 - 75 amps from the batteries while the engine is running and the compressor is on, while also getting 100+ amps from the alternator.You might also consider a Outback inverter in the 3000 watt range, with a 6,000+ watt surge rating. SolarOnSale.com or SunElec.com might have one of the larger pure sine wave inverters.When my buddy had his MCI bus conversion, he found that his Trace 12 volt 4000 watt inverter struggled with his 13,500 Btu A/C unit. While the 24 volt inverter worked much better, and less amperage. He has a 300 amp 12 volt alternator and 100 amp 24 volt alternator, so either one is rated at plenty of power to run the A/C unit. His 8V92 engine is much larger than your minivan (at about 1,600 pounds for just the engine) it is 756 cubic inches! Good luck,Fred.

tpi wrote:I'll leave it to the experts whether this idea has any chance at all. But off the top it probably suffers from1. Inadequate inverter.2. Possible inadequate wiring between batteries and inverter3. Inadequately sized batteries in amp hour capacity4. Inadequate alternator capacityIs this roof air to be counted on for continuous duty during the day?Yes, he said they run it all day. He also said he is running the heaviest wire he could locate. I told him he would need 4 6 volt batteries and a charger at night as the alternator cannot keep up.

Halmfamily wrote:Yes, he said they run it all day. He also said he is running the heaviest wire he could locate. I told him he would need 4 6 volt batteries and a charger at night as the alternator cannot keep up.The 4 6 volt may work if the AC is run intermittently and the batteries hit a charging station a few times through the day.But if there's a 400-700 amp hour daily deficit from continuous duty and no recharges, he'll need even greater battery capacity, maybe 8 or 10- 6 volts.

I'm not surprised. That AC size will pull right around 2000 watts when the compressor kicks in, some a little more, some a little less. Sounds like his is a little more. Being right at the cusp, so to speak, is why sometimes folks can get a 13,500 btu AC to work on a 2,000 watt power supply, and sometimes they can't.Running an AC off a battery in any case is a bad idea because the total power load is so high. Much better is to use a generator, and I'd recommend at least a 2,500 watt one at that as a minimum, with 3,000 watt even better.

13500 A/C on 2000 watt inverter? | Good Sam Community

26 Replies

Chris_Bryant
Explorer II
Nov 11, 2015
They make engine driven systems that are purpose built for this.
time2roll
Nomad
Nov 10, 2015
Consider a transfer switch if you have power available at the shop or home where the van is loaded or sits overnight. If you could plug in a couple hours or all night to keep the van cool. It would sure help the cooling load during the day. Maybe even a small battery charger (15-20 amps) to make sure you are topped off before you head out. Utility power will be far lower cost than gasoline.
Halmfamily
Explorer
Nov 10, 2015
Thanks everyone for the advice. He is going to put a smaller A/C on and change out to 2 six volt batteries. He will also upgrade the alternator to 200 amps. His client is adamant about not going back to a generator. The inside of the van has also been fully insulated. Hoprfully he'll get this working.
Chum_lee
Explorer
Nov 10, 2015
otcfun wrote: never mind Moderators please, throw me out and ban me now!

Chum lee
otrfun
Explorer II
Nov 10, 2015
road-runner wrote:
I say load management is necessary. If the fridge is running on electric or the converter is pulling a lot of power, an eu2000i will not start or run an air conditioner. With a fully loaded 60 amp non-PFC converter and the fridge element running, you're already over the eu2000i's continuous rating.
For your scenario, yes, true. My premise is based on powering only a 13.5k BTU a/c with a 50 amp LRA.

Sure, those who love a/c 24/7, want to charge their batteries, and have very little budgetary concerns, are not going to be enthusiastic about performing any load management---I get that. But, someone who only camps occasionally, and/or can't afford/justify purchasing two EU2000i's or one EU3000iS, it's a welcome option to power a major morale & welfare item---their a/c--by spending $1000 vs. $2000.

FWIW, my generator outputs 23.3 amps and I still have to perform some load management--especially on hot, humid mornings when the converter is max'd out charging the batteries and we want to use the microwave, a/c, etc. all at the same time.
road-runner
Explorer III
Nov 10, 2015
I say load management is necessary. If the fridge is running on electric or the converter is pulling a lot of power, an eu2000i will not start or run an air conditioner. With a fully loaded 60 amp non-PFC converter and the fridge element running, you're already over the eu2000i's continuous rating.
otrfun
Explorer II
Nov 10, 2015
Chum lee wrote:
otrfun wrote: "All the Dometic and Coleman spec sheets I've seen typically show LRA's of 50 to 68 amps for their 13.5k BTU a/c's."

Yes, you are correct, for several microseconds during startup. Think about what you know! If it took 50 to 68 LRA'a to start a single 13,500 BTU A/C unit, then the smallest RV generators would be 6,000 to 8,160 watts. You know that is not true. As I previously said, under certain conditions you can run a 13,500 BTU A/C unit on a 2,000 watt genny, just not reliably without playing a bunch of load management tricks. If thats what like doing, more power to ya!

Chum lee
You appear to be contradicting yourself. You're saying I'm "correct", but at the same time you're saying the 50-68 amps of LRA "is not true"?

This 50-68 amps of LRA/inrush current IS real, alive, and does exist--even if it's only for a very short time--no smoking mirrors. I've measured it numerous times with a clamp-on, inrush current capable meter.

If one used a generator that had no (zero) inrush current capability, then yes, one would need a generator with 6000-8160 watts of "continuous" current to provide the 50-68 amps of LRA. However, that's not the case with an EU2000i.

A Honda EU2000i is capable of providing up to 54-55 amps of inrush current (Eco mode off; 50 amps with Eco mode on). This 50-55 amps of inrush current is sufficient enough to start (and run) more efficient 13.5k BTU a/c's with LRA's at the lower end of the 50-68 amp scale.

Bottom line, no load management tricks necessary if powering one of the more efficient 13.5k BTU a/c units with an EU2000i---it's simply a generator with massive inrush current capability (relative to its rated continuous current output).
wa8yxm
Explorer III
Nov 10, 2015
He needs both bigger batteries (Two pair GC-2 or more or two 4D 12 volt or more)

He also needs more inverter. 2,000 watts (normally it's peak rating) is not enougbn, I'd go with at least 2500 watts or 3,000 watts.

Or.. he might try a smaller A/C 13.5 is a bunch for a delivery van.
Chum_lee
Explorer
Nov 10, 2015
otrfun wrote: "All the Dometic and Coleman spec sheets I've seen typically show LRA's of 50 to 68 amps for their 13.5k BTU a/c's."

Yes, you are correct, for several microseconds during startup. Think about what you know! If it took 50 to 68 LRA'a to start a single 13,500 BTU A/C unit, then the smallest RV generators would be 6,000 to 8,160 watts. You know that is not true. As I previously said, under certain conditions you can run a 13,500 BTU A/C unit on a 2,000 watt genny, just not reliably without playing a bunch of load management tricks. If thats what like doing, more power to ya!

Chum lee
otrfun
Explorer II
Nov 07, 2015
TomG2 wrote:
otrfun wrote:
Chum lee wrote:
. . . The LRA (Locked Rotor Amps) or the required current to reliably START the AC unit is about 18 to 20 amps or 2160 to 2400 watts . . .
All the Dometic and Coleman spec sheets I've seen typically show LRA's of 50 to 68 amps for their 13.5k BTU a/c's.
Don't tell my Honda eu2000i, it has been starting them for years. I did upgrade to a Champion to avoid all the energy management required when using the Honda.
Odds are the a/c units you've been starting/running with your EU2000i have had relatively low LRA's.

Yes, the OP wants to power his a/c with an inverter, but the same principle applies. By choosing a more efficient a/c with lower continuous and LRA ratings, one can reduce the need for larger generators, inverters, and battery banks.