Vantare CruiseAir Voltage Monitor

[travelite]

I verified that CruiseAir Aft and Mid-R are powered by inverter 1 and Fore and Mid-L are powered by inverter 2. (Each of my 16,000 BTU CruiseAirs draws around 14A AC). What I don't understand is when I run from my generator or from shore power and I look at the voltage and current draw using the LED readouts for Leg1 and Leg2 power draw, running 4 CruiseAirs shows 45A on Leg1 and 15A on Leg2. Any ideas?

[Gil_J]

Assuming all 4 Cruise-Airs are on, let me make a SWAG. Inverter 1 (leg 1) is powering 2 Cruise-Airs and charging the house batteries. Inverter 2 is powering 2 Cruise-Airs with both shore power and inverted battery power.

Trace 4000s can augment incoming power if it detects low incoming AC voltage. Although this shouldn't be the case, it's the only scenario that comes to mind.

Keep in mind, this is justice a guess,

[travelite]

That's absolutely correct Gil, inverter_1 is in Bulk and inverter_2 is in Float. Inverter_2 (in Float) raises it's 120VAC voltage level slightly attempting to bring the battery voltage level down to 26.6V. Inverter_1 in Bulk is drawing charging current from the generator attempting to restore the battery voltage to 28.6V. The inverters are fighting each other. Leg_1 sees a higher load because it needs to power the 2 CruiseAirs and supply bulk charging current to inverter_1; Leg_2 sees a reduced load because inverter_2 is inverting battery power to augmenting the power to it's CruiseAirs. So much for distributing the CruiseAirs across both legs in an attempt to balance generator power. What's also interesting is that the generator doesn't seem to mind this arrangement. Both legs show roughly 120VAC so from a voltage standpoint the center tapped single phase generator is happy; from a reactance standpoint both legs see the same inductive load so phase shifts are in sync and again the genny is happy; the only imbalance is Leg_1 supplies more current than Leg_2 but the current vectors are in phase so the difference is taken up by the neutral wire. The generator is phase balanced across it's center-tapped single phase output, but hardly load balanced. I wonder what switches are available within the Trace SW4024 to better divide the load. I'm thinking of tweaking the float-to-bulk transition battery voltage on Inverter_2.

[Gil_J]

One thing I'm not fond of with the Trace units is that you can't turn off the charger function, or so I've been told by owners. My normal mode of operation is to turn off the charge function on one of my Freedom 458s. This prevents the chargers fighting each other and I don't normally need the extra charge current. I know there is a paralleling function supported by the Trace units, but I've never heard of anyone that has the interconnecting cable needed for the function to work. This might be the best way of setting them up.

Another option would be to divide the battery bank. The negative to this is you only maximize battery capacity if both legs have an equal drain on the batteries. That's not likely. If I split the bank I would install a manual battery paralleling switch between the split banks to allow you to get maximum inverter time if you are dry camping. With the switch on the split banks become one and function just like you have today.

You do have the option, as I recall, to turn off the inverter function. I assume you can also turn off the function that combines the shore/generator supply with inverter power. Either of these should fix the issue. The first option would require you to turn the inverters on manually when you lost shore/generator power.

As before, I don't have much hands on exposure to the SW4024s, so take this with a grain of salt.

[travelite]

Thanks Gil,

I can't turn off the chargers but I can back them down to a 1A draw which is easy and works well. By doing this the inverters are still drawing off each other; one in Bulk and one in Float, but the load of the four CruiseAirs is evenly split, two powered by Leg_1 and two powered by Leg_2. I have 16,000 BTU CruiseAirs and they draw about 17.5A AC each, or roughly 1.1A per 1000 BTU.

On a side note, if you have over-the-road and using the 1.1A per BTU or 132W per BTU and if your over-the-road is 150,000 BTU, then you're using 19.5KW if running at full tilt which translates to approximately a 26.5hp load on the Series 60. :)

[Gil_J]

If not mistaken, thecPrevost OTR air compressor is over 30HP; 37HP rings a bell. For the life of me I never understood why they didn't offer a much smaller (right-sized) OTR air option for RV shells. Ultimately, the RV conversion shells don't amount to enough shells for Prevost to add the option is my guess. The 8-12 passenger entertainer shells can probably use the over abundance of cooling, so smaller units would be solely for RVs.

BTW, how often does a Prevost OTR air compressor cycle? I've been told temperature is regulated by adding heat rather than cycling the compressor. That too, if true, adds to inefficiency. The good news is the OTR is COLD!

[travelite]

Wow, if they add heat instead of cycling the compressor that really sucks, but I believe it. The real catastrophe is when you're parked, which is the usual use case for a motorhome, the OTR adds nothing and it takes away a lot of basement space, especially in a slide equipped XLII where basement space is already a premium. In an H3 it's not so bad but it's still bad to have a lump of dead weight consuming an almost an entire basement bay. The other site plays up OTR and plays down CruiseAirs. I think they have it backwards. My 64000 BTU's worth of CruiseAirs do a marvelous job whether parked or on the move. My wife constantly asks to turn the t-stat up. The diatribe on the other site is that Cruisairs don't work on hot summer days because they pull hot air in off the payment. Well, mine work and I've been all over this country. Donny Myers cured the H1P5 fore CruiseAir problem and now it cools as well as the rest. Having lived with noisy throw away roof tops I couldn't imagine going back. As far as OTR, it's a waste and it's too bad that so many are swayed by bad advice. Jamie really needs to make this a free site so we can balance the wrong info coming from the other site. For instance, what's with the zeroing out bandwagon? Why throw away good parts? This site could offer a balance to the info coming from the other site if it were free.

[Donnie Myers]

David, did I not give you my cheat sheets with inverter settings and steps to take the inverter out of bulk and force to float at the end of a charge cycle? It's much better to get the batteries to the bulk voltage of 28.6 and let them go through the absorption cycle. Then, as you walk by and notice that one is bulk and the other is float, just simply go into the battery charge menu and drop the time down for absorption until "float" lights. Just remember to raise the settings back to original before exiting menu. The only way to prevent this issue is to use the series stacking cable on the Trace inverters. However, we found that not to be an option due to how many other issues it causes.


Something I find interesting is you say you forward Cruise Air is on inverter 2? Most of the the time, we ran Fwd and mid-left on 1 and aft with mid-right on 2.

[travelite]

Hey Donnie,

No I didn't get the inverter cheat sheets, but I'd really appreciate a copy. I like your approach of dropping the absorption time down and then raising it back before exiting. I'll give it a try. My forward, aft, mid-r, and mid-l are as you describe. When I wrote the initial post I was too lazy to go out to the bus to see how they were split so I guessed. Looking forward to visiting for an RTI upgrade. Everything you guys did is working perfectly. The shower is fantastic and the basement is bone dry! Thanks!