Roadtrek Zion - Promaster based Class B Motorhome

[booster]

I think the running of the air conditioner off the engine alternator, if it is big enough to run it at all, would be more limited by the durability and quality of the factory alternator. Once alternators get to much over 50% of their maximum output for longer periods, they can have heat and durability issues. Heat will reduce the output and efficiency and accelerate wear. I think Marco figured at least 100 amps at about 14 volts would be needed a while ago, by the time you inverted it.

If you are willing to run the motor to run the AC, you can always just use the dash air, which is larger and more efficient, unless you need to run both to get cool.

[cjscott]

Looks pretty cool. The sofas in the back would have to have seatbelts tho, do they? Really like that you can put your bikes in the back. Actually think I may like the white cabinet color also (would have to see in person). Remember the white cabinets from a number of years in some of the B's and liked them as they felt more open. Not sure about the large bathroom wall behind driver tho. Like the back, but wish the front was closer to the MB Pleasureway FL which gives u more space behind driver, with a TV and a small cabinet, but I think that one is 22 ft long. I also like the new Travato 59K which looks interesting but would have preferred 2 reclining sofas with seatbelts, than 2 separate twin beds, which only allow you to take 2 passengers.

[gerrym51]

Originally Posted by booster

I think the running of the air conditioner off the engine alternator, if it is big enough to run it at all, would be more limited by the durability and quality of the factory alternator. Once alternators get to much over 50% of their maximum output for longer periods, they can have heat and durability issues. Heat will reduce the output and efficiency and accelerate wear. I think Marco figured at least 100 amps at about 14 volts would be needed a while ago, by the time you inverted it.

If you are willing to run the motor to run the AC, you can always just use the dash air, which is larger and more efficient, unless you need to run both to get cool.

my thinking on this issue. if your tooling down the highway going over 40 miles per hour your getting most of the output of the 220 amp alternator.

a 2000 watt inverter is about 145 amps. having the extra alternator(280 plus 220-500 amps) is way overkill with this battery

[wincrasher]

I guess I don't understand why Gerry is saying the battery is so key. If I understand correctly, one could run the engine generator (or alternator) and power the AC from the inverter even if there was NO coach battery in the van. If you are putting amperage on the bus, whether it comes from the battery or the alternator is irrelevant, no?

[booster]

Originally Posted by gerrym51

my thinking on this issue. if your tooling down the highway going over 40 miles per hour your getting most of the output of the 220 amp alternator.

a 2000 watt inverter is about 145 amps. having the extra alternator(280 plus 220-500 amps) is way overkill with this battery

If you are going down the highway with all the lights and accessories on, and dead batteries charging, you might get to max output of 220 amps, but it would only be for a short time because the alternator would heat up and lose output, probably to something like 180 amps.

If everything is charged up, not much accessory running, going down the highway, the alternator will be only putting out maybe 20 amps. The load determines the output, not the alternator, which is basically a constant voltage generator with an upper limit on output. Alternator designs count on them being at high output a very small percentage of the time, unless they are application specific one.

I guess the question would be why abuse the alternator, run and inefficient inverter, and a noisy roof air, if you can just run the dash air?

[Davydd]

We stopped yesterday for a couple hours in 80 degree weather and left our cat in the van with five window vents open and running the MaxxAir fan set at 30% (fairly quiet). It worked well. I'm guessing in that situation leaving a van unattended with both an air conditioner and generator running would attract an awful lot of attention.

[wincrasher]

Originally Posted by booster

If you are going down the highway with all the lights and accessories on, and dead batteries charging, you might get to max output of 220 amps, but it would only be for a short time because the alternator would heat up and lose output, probably to something like 180 amps.

If everything is charged up, not much accessory running, going down the highway, the alternator will be only putting out maybe 20 amps. The load determines the output, not the alternator, which is basically a constant voltage generator with an upper limit on output. Alternator designs count on them being at high output a very small percentage of the time, unless they are application specific one.

I guess the question would be why abuse the alternator, run and inefficient inverter, and a noisy roof air, if you can just run the dash air?

I've not found that the dash air will provide enough cooling for the volume of van. Probably enough to keep a pet from expiring, but certainly not enough for human comfort.

[booster]

That is interesting, as we have found our Chevy to do very well on the dash air, at least as well as the Coolcat. Remember that most of current dash air conditioning do all the thinking for you (not a good thing), so the only way to get them to recirculate the van air and not keep pulling in hot air, is to have them on max air or whatever setting they happen to call it. We run ours there 95% of the time, with the fan very low, and it works much better than when it is taking in outside air.

[avanti]

We generally find the dash air in our Sprinter adequate for the whole van when traveling. It helps to have a window or vent cracked open in the back in order to facilitate airflow through the length of the vehicle.

[gerrym51]

i don't know if an alternator can feed an inverter directly. i have googled this repeatedly and cannot find an answer,

however when the Roadtrek 'engine generator' came out it was for the e=trek 8 6 volt batteries 880 amps battery pack.

the the '1/2 trek package-440 amp hour battery pack-same 280 amp alternator.

now the zion-186 amp hour battery pack. same engine generator size. as Mark said a 1/4 trek.

my opinion-and this is my opinion- at 186 amp battery engine generator is far less useful. if you want to leave the van for a period of time for any reason the zions battery pack is not big enough for the air conditioner for more than 20 minutes. so choice is leave engine running-a nono for me-use no air conditioner-or use the ONAN-loud and unpleasant.

if i did not have the cats i would not have gotten either generator-on the zion. however we do and we might need it.t i should have also said at 40 miles per hour the alternator is capable of putting out 220 amps-not that it would be needed.

the air conditioner aside-if your battery is 186 amps and at 50 percent 93 amps(obviously) 500 amps of alternator not needed


i researched again the direct to alternator. although it might be theoretically possible every inverter and inverter/charger site i look at says they are made to have a battery connected in the loop.

[avanti]

Originally Posted by gerrym51

i don't know if an alternator can feed an inverter directly.

When your rig's isolation relay is closed, the alternator is DIRECTLY CONNECTED to your inverter. It is also directly connected to the coach battery and the chassis battery. They are all in effect on a single bus. The simple answer to your question is "yes". HOWEVER, automotive electrical systems are designed to have a battery in the system at all times. It acts kind of like a huge capacitor to smooth out the supply and demand of current. But, even if you didn't have a coach battery, you would still have the chassis battery to serve this function. So, the complete answer is "Yes, but...". It really depends on what you count as "directly". But, assuming adequate capacity, the alternator/battery system can provide power to your inverter just as it does to any other load in the vehicle.

[gerrym51]

Originally Posted by avanti

When your rig's isolation relay is closed, the alternator is DIRECTLY CONNECTED to your inverter. It is also directly connected to the coach battery and the chassis battery. They are all in effect on a single bus. The simple answer to your question is "yes". HOWEVER, automotive electrical systems are designed to have a battery in the system at all times. It acts kind of like a huge capacitor to smooth out the supply and demand of current. But, even if you didn't have a coach battery, you would still have the chassis battery to serve this function. So, the complete answer is "Yes, but...". It really depends on what you count as "directly". But, assuming adequate capacity, the alternator/battery system can provide power to your inverter just as it does to any other load in the vehicle.

i think wincrashers question about this was does it make any difference what size the house battery was versus the inverter.

just as an example. say a house battery is 100 amp hours. if you have 300 amp alternator would it power the inverter to it's full power?

2000 watt inverter uses a bout 146 amps. would the alternator power it no matter what size house battery?

[booster]

Originally Posted by gerrym51

i think wincrashers question about this was does it make any difference what size the house battery was versus the inverter.

just as an example. say a house battery is 100 amp hours. if you have 300 amp alternator would it power the inverter to it's full power?

2000 watt inverter uses a bout 146 amps. would the alternator power it no matter what size house battery?

Steady state, the alternator would be able to do it fine, but whether that would be OK in practice is less certain. Most of the inverters will cut off if the voltage drops to low, maybe 11 volts or so, so if you have a high starting load on the inverter, you may pull too many amps for the alternator to react fast enough to hold voltage. At that point, a big battery bank would hold up the voltage enough to get it through the startup surge. Soooooo--maybe.

[avanti]

I agree with Booster's analysis, although my tone would probably be a little more optimistic. Any reasonably sized house battery has a lot of amps with which to buffer brief surges. And even if it didn't, you also have the chassis battery in the loop as well, as I mentioned above. My prediction is that it would be fine in practice. But, there are many moving parts here (such as the chemistry of the battery which determines its ability to provide fast, deep draws, and so on). Also, a lot of upfitters scrimp on the size of the wire from the alternator to the chassis. (Davydd's ARV has 4/0 the length of the vehicle!) So, yes, the answer is "maybe".

This all assumes, of course, that the alternator is indeed capable of providing the requisite amps in the steady state.

[wincrasher]

Originally Posted by booster

Steady state, the alternator would be able to do it fine, but whether that would be OK in practice is less certain. Most of the inverters will cut off if the voltage drops to low, maybe 11 volts or so, so if you have a high starting load on the inverter, you may pull too many amps for the alternator to react fast enough to hold voltage. At that point, a big battery bank would hold up the voltage enough to get it through the startup surge. Soooooo--maybe.

Well if you are right on that, then even a small battery should level out the voltage just fine, if it even needs that kind of buffer. That buffer would only be needed for a very short time until the alternator could spin up with the load. I would like to know more about cooling of these alternators, or even if it really a legitimate concern. Some are set up with a "ram air" thru the airbox, which would be fine going down the road, but I don't see how that does any good parked at camp.

I think the Zion setup is just fine considering their intent. The battery size is not to run the AC or the microwave for any length of time, or at all. The battery is sized adequately for the 12v loads in the van (lights, tv, pump, ventilator, furnace, etc.). If you want AC or the microwave, you need to idle the engine, no ifs, ands or buts. But you could do it for hours on end if need be. Sounds like it would work fine for 90%+ of customers. Certainly quieter and less to maintain than an Onan.

[gerrym51]

since Roadtrek won't tell-proprietary- i will assume my choice is correct


the question is based on the battery size and 2000 watt inverter-is a 280 amp extra alternator-based on this size battery.

[mumkin]

Wow... my question certainly set off a small firestorm of answers. Much of it is over my head, but let me re-phrase the question a bit... to a 'what if' situation.

It is summer... 85 degrees... I need to do something that will take an hour or two and have to leave the dog in the van. With the current Zion or 170 set-up and no generator, how long could I leave the van running using the dash air before it would overheat? (I have an extra key, so I can lock it up while it is running) In my experience, sitting in traffic with the AC on tends to make your car overheat. Or is this the olden days and it doesn't happen with modern computer-run engines.

Or would I need the under-the-hood generator to even do this - for either rig?

OK guys... fight it out and I'll be back later to see the consensus. I bow to your superior knowledge.

[gerrym51]

Originally Posted by mumkin

Wow... my question certainly set off a small firestorm of answers. Much of it is over my head, but let me re-phrase the question a bit... to a 'what if' situation.

It is summer... 85 degrees... I need to do something that will take an hour or two and have to leave the dog in the van. With the current Zion or 170 set-up and no generator, how long could I leave the van running using the dash air before it would overheat? (I have an extra key, so I can lock it up while it is running) In my experience, sitting in traffic with the AC on tends to make your car overheat. Or is this the olden days and it doesn't happen with modern computer-run engines.

Or would I need the under-the-hood generator to even do this - for either rig?

OK guys... fight it out and I'll be back later to see the consensus. I bow to your superior knowledge.

I have no idea. try it in your current van and see .if you want to walk away fron the van and no Onan i think one of the 1/2 trek packages in another roadtrek would be a better option

[dc83]

Gerrym51 stated
the Zion's battery -tppl and superior- as it is only has a 186 amp cpacity at 20 hours (although this special battery equates to about 220 amps standard agm). it's the battery capacity-in my opinion-that makes the zion not so good a choice for the engine generatorI have been reading and learning from you all sitting on the sidelines. Has been of great help in deciding what Roadtrek to buy. I am most interested in Gerrym51's
path in deciding what he was going to buy since I was also looking at the Zion. Am thinking of going the 1/2 Etrek path as Gerrym51 discovered the Zion battery is too small. But how do you get 220 amps equivalent from a tppl? Aren't amp hours equivalent? Please explain as I have much to learn. If batteries are rated at the 20 hour rate how can a tppl be different?

[gerrym51]

Originally Posted by dc83

Gerrym51 stated
the Zion's battery -tppl and superior- as it is only has a 186 amp cpacity at 20 hours (although this special battery equates to about 220 amps standard agm). it's the battery capacity-in my opinion-that makes the zion not so good a choice for the engine generatorI have been reading and learning from you all sitting on the sidelines. Has been of great help in deciding what Roadtrek to buy. I am most interested in Gerrym51's
path in deciding what he was going to buy since I was also looking at the Zion. Am thinking of going the 1/2 Etrek path as Gerrym51 discovered the Zion battery is too small. But how do you get 220 amps equivalent from a tppl? Aren't amp hours equivalent? Please explain as I have much to learn. If batteries are rated at the 20 hour rate how can a tppl be different?

http://buy.northstarbattery.com/p/sms-agm-400-battery


we have discussed this battery before-at 20 hours it's amps are 186. howver this is a special tppl battery. its RESERVE CAPACITY is 400 minutes(the 400 in its name). this is how they measure batteries in europe. reserve capacity is how long 25 amps per hour can be removed. in batteries the faster you use amps up the less amps you will actually get from them-something called peukets law(something likr that).

i went to the lifeline battery website and looked up the 25 amp per hour rates. the 12 volt 210 amp hour battery had 390 minutes 25 hour rate.
so the Northstar is equal to about 220 amp hour regular agms.

now thats 12 volt batteries. 6 volt batteries(220 amps) are 491 minutes. roadtrek uses 6 volt batteries in their other models-however the tppl Northstar compares very favorably to the 12 volt. tppl batteries have less resistance the standard agms so charging and discharging they waste less energy than standard agms therfore have better reserve capacity for equal weight/size. however 186 amps is still 186 amps.

heres the chart

http://www.lifelinebatteries.com/rvdeep ... teries.php

minutes of discharge is on right hand side. the 25 amp rate is the relevent column

now i also have to tell you other than the battery situation we LOVE the zion-and will not let the battery deter us. to us it has many more positives than the other models. i just want buyers to be aware