Roadtrek/Hymer Lithium/2nd alternator/Voltstart issues?

[BBQ-ClassB]

While the Nations alternator does have its multitasking limitations, I don't think the dreaded "death spiral" characterization accurately reflects the consequences which seem more aggravating than disastrous.

First, I don't think there is a spiral discharge effect at the battery because the remaining Voltstart sequences after the initial one will provide the same 35 minute recharge to the battery.

Second, when Voltstart completes its last sequence, very shortly afterward the BMS protected battery shuts off. With no battery voltage at its input, the inverter shuts off. With no inverter output, the AC shuts off. Sure, everything shuts down which would be a PITA, but I don't see any damage or death to any components.

When people say "death spiral",
I don't think they mean death, or anything died.

They simply point out that the battery is in a worse state than when the VS cycle began.

Which is not what any unsuspecting consumer would expect, nor want to have.

 

[Davydd]

Death spiral simply meant charging not keeping up with battery depletion when running air conditioning. ARV used the Nations alternator and discovered this early on with dog owners in the southwest. It happened despite the fact ARV also ducted air pass the alternator to keep it cool and allowed user programming to set each auto start time to run up to two hours, not just 35 minutes. After 5 auto starts you can reset another 5 simply by manually key starting which of course requires your presence. The Nations alternator simply drops in efficiency.

I think they solved it with the Delco alternator. I ran it steady for an hour and it charged at a rate above 280 amps without dropping. The test ended simply because full charge was achieved.

We travel with a cat. We also travel to follow the weather so to speak and rarely travel anywhere needing air conditioning. So opening all the windows and running the Maxxfan has been sufficient for short periods of time. Only once so far did we go anywhere where air conditioning was needed and that was in Palm Springs when we planned to be away most of the day with friends. When something like that happens the smart thing to do is seek a shore power campground. Which we did. ARVs are well insulated and have a more efficient air conditioner than most Class Bs. That helps.

In regard to auto start. That is a rare occurrence for us. I've forced it in testing but it has never happened on its own other than some unexplained occurrences such as accidental "butt" starting with the Dronemobile key fob ARVs come with.

Keep in mind, away from a campground such as in a public place like a parking lot an unattended Class B that is running with no one around is going to attract a lot of attention and if a dog is barking even with a cooled B you might get unwanted attention. I don't think it is a smart solution to rely on.

In campgrounds sleeping with air conditioning on is something we have never done. I find it rather obnoxious lying right under one running. Having auto start come on in the middle of the night can be very disturbing to others. The noise level of a diesel engine is as bad as an Onan generator. Idling might not be allowed anyway.

I probably could do without the need for auto start (Voltstart as RT calls it and Autogen as ARV calls it). However, I do believe having 800ah of lithium ion batteries and a second alternator is the way to go. We rarely drop below 50% SOC so have more battery than we need but a lot of no-brainer worry or need to conserve comfort. In our two years we camp off-grid 95% of the time and don't bother to plug in if staying at an electric site most of the time. We leave our inverter on and use our B electrically exactly the same way as if plugged into shore power which means we have all time use of our microwave, induction cooktop, electric coffee maker and all the 110a VAC plugs. We have no propane on board. In effect we live transparently the same way no matter where we stop. My wife will often brew two Keurig cups of coffee in the time it takes me to fill the diesel at a service station.

 

[booster]

The "death spiral" is pretty much what the name implies. The state of charge range of the batteries "spirals" downward with each subsequent recharge cycle, until the batteries are "dead", be it from low voltage cutout or totally out of energy.

In the reality of the situation, the biggest issue is the the portrayal of the alternator sizes, primarily the DC Power Engineering units that Nations and others use. The DC Power alternators are not 100% hot duty rated like marine or the Delco units are, and on the the DC Engineering website they even say they are not designed to be battery charging units. The testing I have done to this point, and from the charging trace Avanti posted a while ago, would indicate you can get about 65% of rated output from a DC Power alternator over time, when controlled by a temp sensing Balmar regulator.

The big question that needs to be asked is why aren't the customers being told that they will not get the rated output, and even mislead by being shown "calculations" that use full alternator output over long charging times? Even ARV made the same initial error, but have since corrected their statements and alternator offerings, but they seem to be the only ones to do so.

Bottom line, I think, is that Roadtrek knows that their units will not perform as well as they claim. If they don't know, they could never have tested the system, as it is pretty basic. For those with pets to take care of, like the OP, the accuracy of the information is a very, very, critical point, up to and including whether the unit is suitable for what they need. It could easily be the yes/no decider on a $100K+ purchase, so very real. Roadtrek is targeting that customer area quite heavily, it appears, so they really should be more upfront on expectations.

For those without the pet and air conditioning plans, the disappointment of the system capabilities is not as catastrophic, I think. Basically, just longer battery recharging times due to the lower output of the alternator than expected (2/3 longer though).

IIRC, davydd has stated in the past that his all electric ARV uses around 100ah per day when not actively camping and up into the 300ah per day when in use, without using the air conditioning. When you need to get 300ah per day, the difference from getting it in just over an hour or closer to 1.7 hours is significant, but not huge.

Roadtrek also has the parasitic drain issue that in the past has been stated at over 100ah per day, per active lithium module. We don't know if the newer units are significantly better or not at this point. Assuming you are really good about using only one module at a time, you still have an automatic need for an extra .5 hours of engine charging just to cover the parasitic losses.

I hope we will see all of this shake out over time, especially as more information gets out about how the systems are actually performing in the real world. IMO, the air conditioning for pets is still best done with a generator with auto start based on temperature in the van, even though I really don't care for generators and their associated issues (we removed ours-no pets). Second best would be the cop car setup with autostart off temp and running the dash air.

 

[BBQ-ClassB]

The "death spiral" is pretty much what the name implies. The state of charge range of the batteries "spirals" downward with each subsequent recharge cycle, until the batteries are "dead", be it from low voltage cutout or totally out of energy.

::

Bottom line, I think, is that Roadtrek knows that their units will not perform as well as they claim. If they don't know, they could never have tested the system, as it is pretty basic.

::

What RT doing is borderline fraud, if not outright lying.

 

[Davydd]

My batteries will never go "dead" as in totally out of energy. They will shut down and disconnect at 20% SOC or at a programmable higher SOC to one's desires. I'm not sure what I have it set at right now but I think around 30%. It doesn't happen because it is nearly impossible to get that low in a day no matter what our use if not running the air conditioner off grid.

Overnight camping stays use about 200ah on the average but that includes cooking with induction cooktop and brewing several cups of coffee, watching TV, etc., and not having any propane functions. We have luxuries like internal wifi always on, the 5" screen Silverleaf monitor, tuners, speakers, at least 4 devices plugged in and recharging, Trik-L-Start, lights of course and who knows what else. 24 hours sitting unused will with inverter always on will drain about 100ah but then you can sit for four days that way or three days with the refrigerator plugged in. In reality we've stretched a week once in May driveway sitting that way with the 420 watts of solar and could turn off our inverter. But then didn't I say I enjoyed the transparency of no difference off grid or on? Also we rarely do we sit more than a day without driving and 1/2 to 1 hours of driving recharges 100% all our uses for a day.

I'm pretty sure we can account for all amp hours used with a detailed analysis and don't have those mysterious high vampire drains attributed to Roadtreks.

 

[Beanbug]

In an earlier post I stated that RT sales people "implied" that the Lithium/VS/UG was the solution for our desire to be able to run our a/c "worry free" for well over the 4 to 5 hr. max that we would ever leave our dog in the coach. I was actually being diplomatic given that reputations and ethics are at issue. Truth be told, I would say that sales phraseology would have been construed by most novices to the EcoTrek concept to lead the buyer to believe what he wanted to believe. It did to us. We had a Chinook with a 4kw Onan for 20 years and could run our a/c indefinitely as well as running our microwave together with our a/c. We were "allowed" to believe we could do the same with the EcoTrek without the "noisy, stinky" generator. So, here is another question for the forum: Given that our primary concern was the worry-free a/c for our pet, would we have been better of with the AGM / conventional generator option than the (2) EcoTrek modules our Versatile could accomodate?

 

[gerrym51]

In an earlier post I stated that RT sales people "implied" that the Lithium/VS/UG was the solution for our desire to be able to run our a/c "worry free" for well over the 4 to 5 hr. max that we would ever leave our dog in the coach. I was actually being diplomatic given that reputations and ethics are at issue. Truth be told, I would say that sales phraseology would have been construed by most novices to the EcoTrek concept to lead the buyer to believe what he wanted to believe. It did to us. We had a Chinook with a 4kw Onan for 20 years and could run our a/c indefinitely as well as running our microwave together with our a/c. We were "allowed" to believe we could do the same with the EcoTrek without the "noisy, stinky" generator. So, here is another question for the forum: Given that our primary concern was the worry-free a/c for our pet, would we have been better of with the AGM / conventional generator option than the (2) EcoTrek modules our Versatile could accomodate?

i have the GU on my zion but with the standard tppl AGM battery. I wanted nothing to do with an onan. i love the fact that we can run the inverter for coffee maker- or run the microwave albeit for shorter times or idle the engine for longer. I would not sleep the generator running.

However in the scenario You describe-you would be better with leaving generator running for ac for your pet-

However i also find leaving a noisy generator runnning-for other people to be forced to listen to a 'rudely issue' if used in that situation.

You could trade in fro an ECO800 which is what you probably should have gotten in first place.

 

[booster]

I would agree that with the need to get 4-5 hours being the threshold of use, going up to the 800ah of batteries would get you there, although with a few disclaimers. If you were looking for continuous AC, more battery wouldn't do it, as the death spiral would still be there, and you just gain time before you ran out of power.

I did run some very rough numbers on the 400ah system, and if you were certain that the batteries were totally full when you started, and everything was in good condition, the system likely would make it to 5 hrs of AC time at 100% compressor running. It is close, though.

Assumptions;

400ah, both modules on, 380ah usable due to end "cushions" on use patterns (it could be lower than the 380ah, but we Roadtrek doesn't give that spec)

5 amps per module parasitic loss, so 50ah loss in 5 hours of use (could use 33ah of parasitic if you assume no loss during engine running times)

AC using 100 amps continuous

5 allowable runs of 20 minutes, or 1.7hrs, which I think is what the Voltstart allows before shutting off.

Net average out of the engine generator of 165 amps.

No other power use going on at the time

Batteries would give 3.3 hrs of run time

The engine running would give 1.7 hrs of run time

There would be 65 amps available during engine running to recharge batteries, so probably about 55 amps actually making it to the batteries due to inefficiencies so 94 ah recovered which is just under an hour of running.

That would give just under 6 hours of run time.

The big assumption is that they are spinning the alternator fast enough to get 165 amps at engine idle, hot (and it will be very hot with the van not moving while sitting in a hot parking lot). If the alternator output dropped to 100 amps, which is very possible, I think, the results would be right at 5 hours of AC time, so no margin for anything else happening, or any other loads.

If you did go to the 800ah of modules, you would be able to run the AC off the batteries for the entire 5 hours if you were at 3/4 full or more when you started.

One of the huge weaknesses of the Roadtrek setup is that you don't know what state of charge you have when you start, or any other time, as no monitor is included. Lithium batteries hold voltage very consistently over discharge so not a good reference, either.

The other thing to be aware of is if you had your 800ah bank pulled way down from running the AC, it would take 4-5 hours of driving to recharge it at 165 amps of alternator output, so your AC runs would have to be at least a few hours apart with driving in between.

As many have mentioned here, generators are still the kings of long period AC use when no shore power is available, with the big battery systems being somewhat useful in the short term pet in the van issues like the OP has (but you need the 800ah of battery). That doesn't change the fact generators are a PITA for most folks (we got rid of ours), or that they likely are more irritating to other people than a van engine running, though. The other unknown at this time is if there are going to be more and more rules about leaving vehicle engines running for long periods. Some cities and campgrounds already have such rules, and it will be interesting to see if the van idling gets to be more or less restricted than generator running rules.

 

[gerrym51]

I would agree that with the need to get 4-5 hours being the threshold of use, going up to the 800ah of batteries would get you there, although with a few disclaimers. If you were looking for continuous AC, more battery wouldn't do it, as the death spiral would still be there, and you just gain time before you ran out of power.

I did run some very rough numbers on the 400ah system, and if you were certain that the batteries were totally full when you started, and everything was in good condition, the system likely would make it to 5 hrs of AC time at 100% compressor running. It is close, though.

Assumptions;

400ah, both modules on, 380ah usable due to end "cushions" on use patterns (it could be lower than the 380ah, but we Roadtrek doesn't give that spec)

5 amps per module parasitic loss, so 50ah loss in 5 hours of use (could use 33ah of parasitic if you assume no loss during engine running times)

AC using 100 amps continuous

5 allowable runs of 20 minutes, or 1.7hrs, which I think is what the Voltstart allows before shutting off.

Net average out of the engine generator of 165 amps.

No other power use going on at the time

Batteries would give 3.3 hrs of run time

The engine running would give 1.7 hrs of run time

There would be 65 amps available during engine running to recharge batteries, so probably about 55 amps actually making it to the batteries due to inefficiencies so 94 ah recovered which is just under an hour of running.

That would give just under 6 hours of run time.

The big assumption is that they are spinning the alternator fast enough to get 165 amps at engine idle, hot (and it will be very hot with the van not moving while sitting in a hot parking lot). If the alternator output dropped to 100 amps, which is very possible, I think, the results would be right at 5 hours of AC time, so no margin for anything else happening, or any other loads.

If you did go to the 800ah of modules, you would be able to run the AC off the batteries for the entire 5 hours if you were at 3/4 full or more when you started.

One of the huge weaknesses of the Roadtrek setup is that you don't know what state of charge you have when you start, or any other time, as no monitor is included. Lithium batteries hold voltage very consistently over discharge so not a good reference, either.

The other thing to be aware of is if you had your 800ah bank pulled way down from running the AC, it would take 4-5 hours of driving to recharge it at 165 amps of alternator output, so your AC runs would have to be at least a few hours apart with driving in between.

As many have mentioned here, generators are still the kings of long period AC use when no shore power is available, with the big battery systems being somewhat useful in the short term pet in the van issues like the OP has (but you need the 800ah of battery). That doesn't change the fact generators are a PITA for most folks (we got rid of ours), or that they likely are more irritating to other people than a van engine running, though. The other unknown at this time is if there are going to be more and more rules about leaving vehicle engines running for long periods. Some cities and campgrounds already have such rules, and it will be interesting to see if the van idling gets to be more or less restricted than generator running rules.

the OP is making his calculation based on 2 full ecotrek batteries when starting process. Even though long time posters here know these batteries never get fully charged and have full access to the amps in them-70-80 percent at most-i',m not going to try to explain that to him nor convince him of -however he has a 'far better' shot at getting the hour coverage he wants starting with 'full' what ever that might be -of ecotrek800. safer to depend on 800(or whatever amp hours it actually is) than 400(or whatever amp hours it actually is).

 

[gerrym51]

I keep reading stuff basically guessing and throwing figures of how much pwer the air conditioner draws.

so i looked it up and am posting a link -this is the 11,000 btu air conditioner roadtrek uses.

the simplicity uses 9000 but you do not get ecotrek batteries with it.

the 11,000 is at the far left. THESE ARE IN AC AMPS NOT DC

running amps is 10.5. locked rotor amps( which is initial compressor start up and cycling start up is 53. again this is AC amps. DC will be between 10 and 11 dc amps to each ac amp-inverters are not perfect. most here already know this.

depending on how many times it cycles is key

http://dometic3frontend.qbank.se/episerver/437389b63ca307f2500b8b031957a824.pdf

 

[booster]

the OP is making his calculation based on 2 full ecotrek batteries when starting process. Even though long time posters here know these batteries never get fully charged and have full access to the amps in them-70-80 percent at most-i',m not going to try to explain that to him nor convince him of -however he has a 'far better' shot at getting the hour coverage he wants starting with 'full' what ever that might be -of ecotrek800. safer to depend on 800(or whatever amp hours it actually is) than 400(or whatever amp hours it actually is).

Yep, I used 5% total for window on each end of the charge cycle, but as I mentioned, we don't really know how much Roadtrek puts on each end for limit. I think part of the issue of what people may see as not getting all the way full, as in lower than expected return of power from the batteries, could really be the parasitic loss problem. Note that in 12 hours, you would l lose 60ah from your 200ah bank. That is 30% of the bank capacity, and the user has no idea if that is lost due to not getting totally charged, or if it went to the vampire.

I think most all of us agree that the OP is really not in a comfortable spot with the 400ah setup, but would be OK for his requirements with the 800ah setup, assuming he kept them above 75% charged before starting.

 

[avanti]

I keep reading stuff basically guessing and throwing figures of how much pwer the air conditioner draws.

so i looked it up and am posting a link -this is the 11,000 btu air conditioner roadtrek uses.

the simplicity uses 9000 but you do not get ecotrek batteries with it.

the 11,000 is at the far left. THESE ARE IN AC AMPS NOT DC

running amps is 10.5. locked rotor amps( which is initial compressor start up and cycling start up is 53. again this is AC amps. DC will be between 10 and 11 dc amps to each ac amp-inverters are not perfect. most here already know this.

I have that A/C. While running on high, mine consumes 102A @12VDC, by actual measurement. This includes inverter losses.

 

[booster]

I keep reading stuff basically guessing and throwing figures of how much pwer the air conditioner draws.

so i looked it up and am posting a link -this is the 11,000 btu air conditioner roadtrek uses.

the simplicity uses 9000 but you do not get ecotrek batteries with it.

the 11,000 is at the far left. THESE ARE IN AC AMPS NOT DC

running amps is 10.5. locked rotor amps( which is initial compressor start up and cycling start up is 53. again this is AC amps. DC will be between 10 and 11 dc amps to each ac amp-inverters are not perfect. most here already know this.

depending on how many times it cycles is key

http://dometic3frontend.qbank.se/episerver/437389b63ca307f2500b8b031957a824.pdf

Some of us have actually measured how many amps our AC takes when running on batteries. I have done it a couple of times in the past, and just now did it again. In a 65* garage, the AC pulled 85 amps at 12.1v from the 2000 watt PSW inverter and 440ah of full AGM batteries. We have a Coolcat that is rated 12K btu.

I chose 100 amps to allow some for hot weather efficiency drop. I don't really know if Roadtrek is using a PSW inverter, but if they are not, they will be less efficient as MSW will usually draw more current for the same power when running a motor, from what I have read.

Again we get back to the issue of Roadtrek owners don't have monitors, so they have no clue how much power they are using, or how much they have left. That is where a lot of guessing is required.

 

[gerrym51]

Some of us have actually measured how many amps our AC takes when running on batteries. I have done it a couple of times in the past, and just now did it again. In a 65* garage, the AC pulled 85 amps at 12.1v from the 2000 watt PSW inverter and 440ah of full AGM batteries. We have a Coolcat that is rated 12K btu.

I chose 100 amps to allow some for hot weather efficiency drop. I don't really know if Roadtrek is using a PSW inverter, but if they are not, they will be less efficient as MSW will usually draw more current for the same power when running a motor, from what I have read.

Again we get back to the issue of Roadtrek owners don't have monitors, so they have no clue how much power they are using, or how much they have left. That is where a lot of guessing is required.

booster-don't you have a 2006 190. the Kool cat does pull less amps

 

[gerrym51]

How many amps do your air conditioners pull at each compressor cycle? i would be interested in that

 

[booster]

How many amps do your air conditioners pull at each compressor cycle? i would be interested in that

You are kind of at the mercy of the meter refresh rate, but I watched ours through a few cycles, and it didn't really bump up much over 100 amps.

Ours in a 07 C190P.

 

[avanti]

How many amps do your air conditioners pull at each compressor cycle? i would be interested in that

Don't really know. Mine has soft start--not sure how much that affects it. It starts effortlessly, though. I do know that on a hot day, running 2 hours takes my 440Ah AGM battery down almost exactly to 50% SOC.

 

[gerrym51]

the OP needs to listen to you 2 experts

 

[booster]

Don't really know. Mine has soft start--not sure how much that affects it. It starts effortlessly, though. I do know that on a hot day, running 2 hours takes my 440Ah AGM battery down almost exactly to 50% SOC.

Have you run it down further than 50% SOC on AC? It would be interesting to know how low you can go before the AGMs can't supply enough power and you trip out on the inverter low voltage cutoff.

 

[avanti]

Have you run it down further than 50% SOC on AC? It would be interesting to know how low you can go before the AGMs can't supply enough power and you trip out on the inverter low voltage cutoff.

I'm pretty sure I accidentally got down to 30% once.