Custom 2017 Hymer Aktiv on order

[Bud]

Originally Posted by BBQ

.


LOL

SAME back at you and thanks, enjoyed the response. Question:

Why did wgo do the fit folks as they did? Marketing, publicity, show folks what they can't have like the fit folks, .........?

Why?

Bud

[cruising7388]

Originally Posted by booster

I would agree, for the most part.

The idling is an issue, as output is lower than driving, and it drops more, besides, from excess heat. We have heard of the "death spiral" of Roadtreks and even ARVs before they changed to the megabuck alternator related to killing the batteries while trying to run the AC at idle. I think the jury is still out on how all the various vehicles will handle repeated long term cyclic idling runs. This would include the engine and alternator related stuff.

I hear about this "death spiral"? But what dies? The batteries? The alternator? With the AC on at engine idle, once the batteries deplete to a threshold point, Voltstart engages the Nations alternator. It's probably the case that at this point, that the hot Nations output will be directed pretty much toward the inverter to support AC operation with not a lot of headroom to support other coach loads or recharge the batteries. As a practical matter, the primary power source for the AC switches from the batteries to the alternator. True, the battery recharge rate is low or under some circumstances even zero, but what death spiral presumably ensues? Did the batteries or the alternators fail?

That said, I think ARV's adoption of the Delco unit is a great improvement and their success in mitigating the alternator noise levels is signficant. I've heard high power alternators at idle in public service vehicles that were noisier than the engine. However, I wonder if its physical dimensions will permit its employment in Chevy, Dodge or Ford RV platforms.

[booster]

The death spiral is the progressive depletion of the batteries over a period of engine generator charging cycles, usually with an autostart and with the coach AC running. The problem is that the hot alternator, at idle, doesn't have enough output to recharge the engine off battery usage during the engine on time, so you just keep going deader.

You could leave the dog thinking he will be all comfy with the AC on, and come back to dead batteries, and maybe dead dog besides, as the systems don't compensate and run longer.

[BBQ]

Originally Posted by Bud

SAME back at you and thanks, enjoyed the response. Question:

Why did wgo do the fit folks as they did? Marketing, publicity, show folks what they can't have like the fit folks, .........?

Why?

Bud

$$$


Most people are price sensitive.
Most people do not know what they are buying.

You will be surprised to learn how many new WGO owners discovered their RV have no inverters AFTER they have made their purchase.

[Bud]

Originally Posted by BBQ

$$$


Most people are price sensitive.
Most people do not know what they are buying.

You will be surprised to learn how many new WGO owners discovered their RV have no inverters AFTER they have made their purchase.

Hi BBQ, I missed it. Was that an answer to my question concerning a specific application (ething) and the fit folks?

Bud

[BBQ]

Originally Posted by Bud

Hi BBQ, I missed it. Was that an answer to my question concerning a specific application (ething) and the fit folks?

Bud

Cancel that... cross posted.

[cruising7388]

Originally Posted by booster

The death spiral is the progressive depletion of the batteries over a period of engine generator charging cycles, usually with an autostart and with the coach AC running. The problem is that the hot alternator, at idle, doesn't have enough output to recharge the engine off battery usage during the engine on time, so you just keep going deader.

You could leave the dog thinking he will be all comfy with the AC on, and come back to dead batteries, and maybe dead dog besides, as the systems don't compensate and run longer.

IMO, it is irresponsible to leave pets or infants that are unable to extricate themselves from a vehicle if the circumstances necessitate it. The weak link is not the batteries or the alternator - it's the inverter. If if I found myself unavoidably in that situation, I wouldn't run the AC from the batteries and Voltstart in any event. I would start the engine manually, turn on both the engine AC and the roof AC and let the alternator provide power without battery support. Even if the alternator or inverter or the AC quit, the engine AC would at least prevent a terrible disaster. That is certainly less risky than just relying on battery management and auto start operation.

Your scenario regarding battery deterioration is theoretically correct but it doesn't comport with typical real world situations. Sure, never driven, in a brutally high temperature environment requiring a high duty if not continuous AC operation, the batteries could remain in a discharged condition sufficiently long to damage them, but for lithiums isn't this grace period substantially longer than it is for lead acid batteries? Paradoxically, lithiums have a lower rate of ah capacity decay when kept in a partially charged condition then when left fully charged. Further, when the RV is occupied, there are invariably periods where it is driven and if it is even only occasionally driven, it doesn't take much driving at highway speeds to recharge lithium batteries to a reasonable state of charge. So I just don't see the scenario you describe happening with any frequency in the real world.

[gregmchugh]

Originally Posted by cruising7388

IMO, it is irresponsible to leave pets or infants that are unable to extricate themselves from a vehicle if the circumstances necessitate it. The weak link is not the batteries or the alternator - it's the inverter. If if I found myself unavoidably in that situation, I wouldn't run the AC from the batteries and Voltstart in any event. I would start the engine manually, turn on both the engine AC and the roof AC and let the alternator provide power without battery support. Even if the alternator or inverter or the AC quit, the engine AC would at least prevent a terrible disaster. That is certainly less risky than just relying on battery management and auto start operation.

Your scenario regarding battery deterioration is theoretically correct but it doesn't comport with typical real world situations. Sure, never driven, in a brutally high temperature environment requiring a high duty if not continuous AC operation, the batteries could remain in a discharged condition sufficiently long to damage them, but for lithiums isn't this grace period substantially longer than it is for lead acid batteries? Paradoxically, lithiums have a lower rate of ah capacity decay when kept in a partially charged condition then when left fully charged. Further, when the RV is occupied, there are invariably periods where it is driven and if it is even only occasionally driven, it doesn't take much driving at highway speeds to recharge lithium batteries to a reasonable state of charge. So I just don't see the scenario you describe happening with any frequency in the real world.

It happens often enough that Roadtrek is developing a fix for the death spiral that has been happenning in hot weather conditions for some customers...

[cruising7388]

Originally Posted by gregmchugh

It happens often enough that Roadtrek is developing a fix for the death spiral that has been happenning in hot weather conditions for some customers...

What are they fixing? The hot weather?

[gregmchugh]

Originally Posted by cruising7388

What are they fixing? The hot weather?

If I had to guess, I would guess that the fix will be a high idle to provide more output from the underhood generator...

[cruising7388]

Originally Posted by gregmchugh

If I had to guess, I would guess that the fix will be a high idle to provide more output from the underhood generator...

When I was a young Turk, a high idle was easy to implement by getting a small aircraft type throttle cable control and housing from J.C. Whitney. But with modern engines, that's no longer in the cards.

What perplexes me is why the coach builders that use the Sprinter platform don't order the fixed high idle or even preferably the adjustable high idle option. Doing this after production is a PITA that involves both hardware changes and software modifications for the PCM. It's not a cheap fix. Is a similar option available on the Promaster or the Transit?

It might be less expensive to swap out the Nations alternator for the Delco which apparently has a lower hot rating penalty than the Nations and forego a high idle which is more likely to affect the peace and quiet of those nearby. If ARV thought that a high idle would fix the condition, I don't think they would have elected to change out the alternator.

So, if the Nations is in a hot derated condition, I wonder if increasing its rpm sufficiently increases its output to satisfy both AC and battery charging requirements. Perhaps it increases airflow around the unit sufficiently to cool it somewhat.

If you are aware of someone that is currently addressing this with Roadtrek it would be enlightening if they contributed their experience and any resolution proposed by Roadtrek to the forum.

[gregmchugh]

Advanced RV Sprinters are ordered with the high idle option.

[BobB]

Probably can expect more "high idle" solutions in the future.

I don't have an RV with an additional alternator, but often most sailboats, if not all, have an additional alternator for assisting in the re-charging of the battery bank. BUT it is never done at idle. One reason is diesels like to have a load on them, but mostly because that alternator doesn't charge much at idle. Every time we charter, we ask the operator about the battery bank and charging. Answer is always "X hours per day and keep it above 1200rpm". Now if we have to motor part of the way (i.e. no wind) for at least x hours, no issue since standard cruising speed is around 2200-2400 rpm. But if we mostly sail, we will keep the motor on after anchoring, kick it to 1200rpm and then track the time.

Question: Do the instruction manuals for RVs with the underhood/additional alternator say to "run at idle" to recharge OR at a higher RPM?

[booster]

Originally Posted by cruising7388

When I was a young Turk, a high idle was easy to implement by getting a small aircraft type throttle cable control and housing from J.C. Whitney. But with modern engines, that's no longer in the cards.

What perplexes me is why the coach builders that use the Sprinter platform don't order the fixed high idle or even preferably the adjustable high idle option. Doing this after production is a PITA that involves both hardware changes and software modifications for the PCM. It's not a cheap fix. Is a similar option available on the Promaster or the Transit?

It might be less expensive to swap out the Nations alternator for the Delco which apparently has a lower hot rating penalty than the Nations and forego a high idle which is more likely to affect the peace and quiet of those nearby. If ARV thought that a high idle would fix the condition, I don't think they would have elected to change out the alternator.

So, if the Nations is in a hot derated condition, I wonder if increasing its rpm sufficiently increases its output to satisfy both AC and battery charging requirements. Perhaps it increases airflow around the unit sufficiently to cool it somewhat.

If you are aware of someone that is currently addressing this with Roadtrek it would be enlightening if they contributed their experience and any resolution proposed by Roadtrek to the forum.

I can't say much about the Sprinter setups, as we don't have one, but we have two Nations alternators in our Chevy (250XP and 280XP), and I have been watching for others results for a long time.

First, you have to understand that the Nations alternator is not doing the derating in almost all of these systems. It is being done by the Balmar remote regulator and the amount is 50%, triggered by hitting 225*F at the alternator output post. By then the alternator is also going to losing some output efficiency by then due to the higher temperature, but it isn't an auto turndown, just efficiency change.

More rpm means more alternator output, more airflow for cooling, and also more airflow from the engine it it has a mechanical fan (not if it has an electric). If you are driving over 30mph, you will get lots more airflow through the engine compartment. Because of all the variables, raising the rpm will help you to very variable amounts dependent on conditions. Probably the biggest help is if the outside air is fairly cool, so that the air coming through the radiator into the engine compartment cooler. The location of the alternator can also be a big deal. Our Chevy ones are both higher than the bottom of the radiator, one by a small amount, and on fairly high up on top of the engine. Almost all the air they will see appears to have to come through the radiator. The Sprinter and Promaster setups look to be low mounting, so the air when driving may actually be fairly ambient. It is up for grabs what air they will get when sitting, though, as many cooling systems send a lot of the radiator air down toward the ground (low pressure area when driving). The alternators take in air at the rear, so they might be right in the hot air path when not moving.

From what we have heard, even the best designed ARV systems did the "death spiral" in hot weather, meaning that their 280 amp alternator could not provide enough power to keep up with the coach AC, when limited by the legal run times and total number of cycles. IIRC the AC takes about 100 amps, and ARVs use a lot of other power, so probably 125+amps continuous would be needed. I think the ARVs also had the fast idle, so it isn't the cure all.

DC Power (Nations) alternators are rated at 2400 rpm alternator speed for idle, so a 3 to 1 ratio would require a 800 rpm engine speed. Our Chevy gasser idles at 545 rpm and we have a 3.1 ratio, so we get 1700 rpm at the alternator. If you look at the output chart, you drop a whole bunch at 1700 to rated. Ratio counts big on idle output, but also on life, so it is a tradeoff.

From what our testing has shown so far, I think that the DC Power alternators are probably good for 55-65% of their rated output at any given temperature. The hotter it gets, the lower you go, and if on a Balmar, it will thermal cycle you to that average output. At idle you will be in the 100 amp range on a 200 idle rated amp alternator spinning a bit slower than 2400 rpm alternator and hot. Higher rpm at idle will probably help some, but I think it will be quite variable by conditions and vehicle. At idle, even wind conditions can make a huge difference. We had a hotrod the would overheat if there was a small tailwind when sitting, but not if it was a headwind (hot air looping back into the radiator).

Of course when you start idling at higher speeds, you immediately become pretty obvious to everyone around you, and probably as irritating as having a generator running, but that is a side issue.

The only "cure", that we were able to think of, was to massively oversize the alternator capacity so they could run at lower output % and stay cooler. We have 530 amps of DC Power alternator running parallel. Although the testing is still early (no hot weather yet here), the preliminary results show that even running the alternators with limited output (by reducing field %) they will get to above 220*F at idle of 545 engine rpm and 180 amp output. Our second turndown setting of about 115 amps will run at about 195* in most cases at the same 545. Going down the road, we can get an easy 280 amps at the high output, but both the alternators and batteries will start to get hotter than we like (need more testing for this as it is hard to use that much power). With a lower setting of 180 amps, both the alternators and batteries are very happy, it appears. We are also running the engine and chassis, so add 15 maps to the get actual alternator outputs. By comparison, the limited data I have seen from 280 amp Nations setups is they thermal cycle between about 130 and 180 amps going down the road, and net about 165 amps average over time (60%). Bottom line is that we are running at about 53% of rated alternator output at the high setting and 37% at the lower one, so it pretty much confirms that you need to pretty severely limit the output of the DC Power alternators if you want to keep the within reasonable temp levels.

All of this would point to the idea that ARV going to the Delco is a good idea, but heavy and and very expensive. We will see how it holds up over time in the heavy cycling load that the AC and lithium batteries can give. They do well in ambulances and such. Many applications probably don't have room for one, though.

Of interest, maybe, is that the DC Power alternators with Balmar regulators are essentially both going against both manufacturers recommendations. DC Power states on their website that their alternators are not designed to be battery chargers and shouldn't be used for that application. Balmar states that their regulator should not be used for thermal cycling hot alternators, as the feature is only a safety item in case of some kind of problem that should be fixed so there is no cycling. I think davydd did have a Balmar thermal sensor failure on his Balmar. My guess is that any engine generator system out there with 400ah of AGM or lithium batteries is thermal cycling the engine generator alternator.

If there is one thing to take away from all this, IMO, is that the DC Power and Nations systems are severely overrated and oversold specwise for how we use them in RVs. Using the output ratings for calculating expected recharge rates is going to leave you very disappointed, I think. The better choice would be to use 55-60% of rated for any predictions of what you will be able get in real use, and under some conditions, that might even be a push. Yes, they will flash up to near the rated output on a cold start, but will quickly start to heat up and drop output, and eventually the Baldor will turn the to 50% output. I have seen lots of reports where folks have tested the output of their new system and got the bigger numbers, but they didn't check again in 15 minutes to see where it was then. Of course, any way you look at it 165amps average isn't bad and will charge you up pretty quickly, but it certainly isn't the 280 amps they imply that you will be able to get.

There are lots of opinions out there as to the benefits and how to use engine generators, so what is good for us isn't necessarily what others would like. Our system is designed to be a high rate battery charger, first and foremost, with a minor secondary of covering occasional high power use like a big hair dryer or longer microwave run if we want to preserve battery capacity. There is no plan to every run the AC off the batteries or engine, and any idle charging would be a very rare occurrence. We want to be invisible to those around us, and a running engine kind of goes against that.

Another member is building an engine generator system currently, and is planning to test programming the Balmar to be able to be run at two reduced output levels, switch settable to limit alternator output. One would be at 50% output and not settable, the other could be set to whatever output % you want. If this works like it appears it should, based on the Balmar manual, he should be able to eliminate the thermal cycling issue while getting about the same average output. Getting rid of the cycling should be much better for the entire system from alternator, to Balmar, to belts and idlers.

[DCHitt]

Originally Posted by booster

There are lots of opinions out there as to the benefits and how to use engine generators, so what is good for us isn't necessarily what others would like. Our system is designed to be a high rate battery charger, first and foremost, with a minor secondary of covering occasional high power use like a big hair dryer or longer microwave run if we want to preserve battery capacity. There is no plan to every run the AC off the batteries or engine, and any idle charging would be a very rare occurrence. We want to be invisible to those around us, and a running engine kind of goes against that.

It seems many are trying to run an electric air conditioner to keep cool. Batteries don't produce electricity they just hold it for a while. So then we put big alternators on the engine to create the electricity.

The end result is that we are running an engine to charge the batteries, discharging the batteries to create AC electricity, The AC runs a compressor to feed an evaporator to keep us cool.

Why don't we just run the compressor from the engine. Oh.. There is already a compressor on the engine so why don't we just tap off of that and put a fan with an evaporator in the rear of the van????

Then when we run the engine to keep cool the standard small alternator will also keep our batteries up?

KISS is good.

[BBQ]

.

KISS is good.


At the other end of the HVAC spectrum,
RT tapped the engine coolant and routes it through a heat-exchanger to harness the heat to circulate to the Alde hydronic underfloor heating system.

Great idea. Mega complications.

[peteco]

Originally Posted by DCHitt

Why don't we just run the compressor from the engine. Oh.. There is already a compressor on the engine so why don't we just tap off of that and put a fan with an evaporator in the rear of the van????

Then when we run the engine to keep cool the standard small alternator will also keep our batteries up?

KISS is good.

Vans typically have an option for a 2nd AC unit in the rear, which is simply another evaporator, expansion valve, and freon lines that tap into the existing vehicle AC system. It worked fine on our minivan years ago, though I did have 2 evaporators leak over 14 years of ownership. I don't know if the compressor and condenser were oversized for this option; don't think so. It would not cool as well as the RV AC but might provide enough to get by.

[booster]

Running the van AC has come up quite a few times in the past, and I always thought it was a pretty good idea.

I think the only good reason that I have heard for not doing was that the van would have to run 100% of the time instead of about 50% with coach AC of the engine alternator.

I think the canine cop cars do exactly what we are talking about, with the starting controlled off the car inside temp. A canine cop died from a failure of some sort of system like that here a while ago, when the car got too hot.

[DCHitt]

Originally Posted by BBQ

.

At the other end of the HVAC spectrum,
RT tapped the engine coolant and routes it through a heat-exchanger to harness the heat to circulate to the Alde hydronic underfloor heating system.

Great idea. Mega complications.

It would seem that RT always does it the hard way. You do have to give them credit for trying.

[BobB]

Originally Posted by DCHitt

It would seem that RT always does it the hard way. You do have to give them credit for trying.

Not so sure about the "credit for trying". Seems from various posts that their customers are often the Beta Testers, who also then have to spend their energy getting it fixed.