Magnum Energy hybrid inverter and a 15k BTU A/C

Marginal generators do not have enough cajones to START a roof air. For five seconds or so the power needed to start the AC can not be met by the generator alone. But once they get running, the AC draws far less power, and this means the generator MAY have enough power to support the Air Conditioner plus hotel loads.

But couple them TOGETHER for that five or so seconds and the Magnum inverter will supply enough vitamin supplement to generator power to start the roof AC. The trick is: Does your genset have the guts to run the AC and hotel loads (hotel loads are AC power to loads in your rig) WITHOUT RELYING ON THE INVERTER TO KEEP SUPPLYING POWER. Even a battery bank the size of the Chase Manhattan Bank is going to run down sooner or later if the inverter has to keep supplying power to keep the roof air going.

The start boost is ONLY to start the roof A/C then the game ends. The inverter reverts back to battery charger mode and generator power supplies the whole shebang.

Get a ferroresonant line voltage correction device or "Hughes Autoformer" if campground voltage is low. In a campground the inverter won't do a damned thing for you if voltage is low. If you connect to 100 volt shore power don't expect the inverter to have ANYWHERE NEAR the battery charge amperage potential as listed on the package.

mlts22 wrote:
One quick note -- the 4000 watt model is 24 volts, so it is 3000 watts only for this inverter model series for RV use.

Unless you're 2oldman. :)

One quick note -- the 4000 watt model is 24 volts, so it is 3000 watts only for this inverter model series for RV use.

You set a current threshold - it can be different for each of the 2 AC inputs.



Imagine a generator starting a compressor or some motor load. Before the load is applied, the generator is running fine at 120 volts. A huge load is suddenly applied (ac compressor, gas dryer motor, etc.) For a short time 30A is required, but the gen can only supply a max of 22 amps. The gen will bog down trying to service this load and the voltage will drop. Without help, it may or may not recover. The inverter supplies current, but it does not raise the voltage. The generator no longer has to service the large current draw, so the generator voltage will rise and the inverter will see the voltage back over some threshold and stop providing input current.


I think this is from a Magnum employee:

GBaxter wrote:

All the MS and MSH model sync with the incoming ac waveform before they transfer to make sure the loads stay on the same phase during transfer and will stay synced until they hit the low voltage dropout setting.

The way all the MSH models load support is by monitoring ac input current. When the shore (or grid input) amp setting is reached the inverter will automatically start to pull current from the batteries and add to the input current. In some cases it may help hold up the voltage depending on the source. If the source is grid then there is no way a 4kw inverter and some batteries are going to raise the voltage on the whole grid, if it could we wouldn't need substations on the grid.

If the source is a small generator then it may help stabilize the voltage but remember the inverter is always synced to the incoming waveform and it will try to follow that waveform as long as it stays connected. The way it can help a generator and the way the Trace SW series helped (it could not raise the voltage either) was it will load support and try to take some load off the generator in hopes the generator can pick up its voltage running less load.

The MSH will continue to Load Support until it reaches .5 VDC above the inverter Low Battery Cutout setting. It will then return to charge mode to bring the batteries up to charge.

I hope this helps,

Gary

Hi,

If it does not support voltage how does it "know" that the power needs to be supplemented?

That is good to know. I should have stated a 13.5k as the biggest, but if it can handle a 15k BTU A/C, that cannot hurt.

I definitely won't be running the A/C directly off the batteries, but having the ability to essentially have an online (not standby) UPS that feeds all components a clean voltage regardless of what is on the other end of the wire is nice. This means not having to worry about an autoformer, although a surge protector is still a must. If the CG voltage is low and the batteries are making up for some of the load, I can always plug a second multi-stage charger into the 20A outlet and have the batteries charge via that.

mlts22 wrote:

I'm also wondering if its surge capacity, 3900 watts for five seconds, 3800 watts for 30 seconds would be enough to handle the inrush current for a 15K BTU A/C.

I believe that surge capacity represents the amt of power generated from the batteries, so in a CG with low voltage, it **may** help with the AC since it will be additive to the shore power being provided.

As I understand it, these will not *fix* low voltage though. They will syc with the shore power (or generator) signal and add current, so if the shore power voltage is low it will allow you to have more power, but will not "fix" the low voltage.

If you have a small generator, I think it would "fix" the voltage, by allowing the gen unit to recover(from compressor startup) since the load that is bogging down the gen is reduced because of the current supplied by the inverter.

In the cg low voltage case, the source isn't likely to "recover" from just your inverter helping.


Magnum tech support is very good. I would send them an email explaining exactly what problem you're hoping to solve and they should be able to give you some insight as to what to expect.

mlts22 wrote:
Any opinions good/bad/ugly on this inverter/charger?

This is a relatively new product... I haven't read any first hand reports yet. However Magnum inverters are very highly regarded! If my ProSine 2.0 ever gives up the ghost, I'll be replacing it with a Magnum MSH3012M.

I'm also wondering if its surge capacity, 3900 watts for five seconds, 3800 watts for 30 seconds would be enough to handle the inrush current for a 15K BTU A/C.

This inverter should have no problem starting (and running if you had enough battery capacity) a 15K btu A/C.

Does Magnum/Victron really boost voltage?

Would like to hear a story of running the air on 105 volts. Then flip on the inverter and voltage is 115/120.

How much of that will come from the battery? Does not seem sustainable.

Magnum makes great products. You can't go wrong IMO. I would also consider Victron like PT mentioned.