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Old 04-11-2019, 10:54 PM   #11
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Default It all depends

If one's travel pattern precludes the need to idle the drive engine to recharge the batteries, and the use pattern allows sufficient recharging while driving then neither an auxiliary generator (Onan) nor mistreating of the vehicle engine is necessary. To the extent that lithium technology usefully expands the camping capability while maintaining the starting premise above it may well be a good investment.

For my travels a lithium system is far simpler technologically and operationally than an Onan generator and certainly simpler than a combined system of both. I would not consider lithium if it required extensive engine idling, but it doesn't at least in my case.
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Old 04-11-2019, 11:39 PM   #12
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I am a big fan of the genre of Internet material in which an expert in some area brings together important and reliable information designed to serve as a gateway into a field for the novice. I don't mind if such material is used as profit-making click-bait, so long as it is accurate and useful.

But there is a deceptively similar genre which I simply despise. In this genre, somebody self-declares themselves an expert ("xxx has worked in the yyy field for over zzz years..."). He or she then puts together a screed filled with a toxic mix of plausible-sounding platitudes, random controversial unsupported opinions, and many, many "alternative facts". (There are almost never citations). This text is then tricked up with a bunch of over-saturated images and lots and lots of garish Powerpoint font effects. They then scour the net for venues where they can promote and promote--signing up at lists like this one, hoping to build a following. The poster child for this is the infamous "Steven's Service" BlueTec rant. This piece has been referenced so many times on the Web that it is destined to continue dangerously misinforming people for years to come.

In an effort to prevent the article referenced in this thread from following the same trajectory, I took time to write a critical review of the first third of it. (I don't have the energy or stomach to go any further.)

In the following, the text in italics is from the article. My comments follows in plain text. (The article's website has disabled copying text, so I had to retype it all. Apologies for any errors).

-------------------

AGM or flooded cells only allow 50% discharge.
As has been discussed repeatedly here, this is just untrue. Deeper discharges simply somewhat reduce battery lifetime. It is a straightforward tradeoff.

Lithium offers 2000+ cycles compared 100-200 of flooded cells.
True, but misleading: good deep-cycle AGM VRLA batteries are often rated at 1,000 cycles@50%.

Mercedes recently issued a "Stop Notice" to Up-fitters to dis-allow any auto-start systems from being installed on Sprinters for extended idling, as well as limiting their alternators output.
Really? I would very much like to see this documented. Just a few months ago, On Feb 2, over on the iRV2 forum, the author was PREDICTING this, not stating it as a fact:
New to class B, looking at the Coachmen Galleria Li3 - Page 2 - iRV2 Forums
Did his prediction come true since then or is the author simply getting carried away with his own rhetoric?

[underhod charging] takes 3-4 times more fuel than a (sic) Onan generator [and] generates more pollution and green house gasses.
Almost certainly nonsense. A gasoline Onan consumes .4 gallons/hour, A Sprinter on high idle MIGHT be slightly more. A typical claim is .3-.7g/h. More importantly, the Sprinter has vastly-sophisticated emissions systems, whereas the Onan one-banger is spewing raw exhaust. In fairness, the author seems to have propane in mind, not gasoline. But if the above claim is accurate, I would love to see a citation.

The Mercedes Benz Service Manual clearly states: "Avoid" frequent short distance driving and/or large amounts of idling.
This is completely false. What it ACTUALLY says is:
Quote:
If the vehicle is predominantly used for short-distance driving, this could lead to a malfunction in the automatic cleaning function for the diesel particle filter. As a result, fuel may accumulate in the engine oil and cause engine failure. Therefore, if you mainly drive short distances, you should drive on a highway or on rural roads for 20 minutes every 310 miles (500 km). This ensures sufficient regeneration of the diesel particle filter.
Nary a word about idling here, or anywhere else in the manual. Indeed, upon diligent searching, I have been unable to find ANY bona fide MB document that says ANYTHING about too much idling.

3 hours of idling, is equivalent to 60 miles on your engine.
Huh?

After extended idling, when the vehicle is allowed to travel again, the processor will then use a "Forced Regeneration" which uses gallons [!] of diesel fuel to complete the region cycle.
The author is totally confused about what the terms "forced regeneration" and "passive regeneration" mean in the context of the Sprinter engine. His description is totally inaccurate. What really happens in the situation he describes is a plain old normal regeneration, which happens periodically (every 600km IIRC) anyway. The "gallons of diesel fuel" claim is absurd. "Forced regenerations" must be done by a Sprinter dealer, and is only done in the context of a service issue. Similarly, the talk about "passive regeneration" is also hopelessly confused. Sprinters do not employ "passive regeneration".This whole section is gibberish.

[diesel exhaust] mixes with diesel fluid...creates a horrible ammonia odor
Really? Not in my van.

Spriter engine service is calculated by miles instead of hours...
False. The OCI is computed by the vehicle taking a number of variables into account.

I highly recommend that you use an oil which offers an extreme temperature blend, such as Shell Rotella T6..."
This is maybe the most dangerous piece of advice in the whole mess. The oil that this guy recommends DOES NOT meet the MB MB229.51 specification, which is required by DPF-equipped Sprinters. I'm sure some people use it, and maybe it is fine, but IMO it is totally irresponsible for a self-appointed "expert" to EVER make a recommendation that directly contradicts a published OEM requirement.


This review only covers the first third of the piece. He continues at great length with similar nonsense about how "clean", "quiet" and generally pleasant Onan genesets are, and how "expensive", "unreliable", and "dirty" are second engine alternators. Perhaps the above will assist the interested reader in examining these claims with a critical eye.
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Old 04-12-2019, 12:14 AM   #13
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Avanti got further into the article than I did before it was abundantly clear that the author was pretty much what Avanti described.


It is becoming almost the norm for the "impartial" "experts" to make as absurd claims as the less than trustworthy sellers of some of the products.


There are many, many, threads of different power systems on this forum that are far better than this article and many of the recent statements we have seen. The users here have and use engine generators, separate generators both built in and portable, solar, AGM, lithium, lithium AGM hybrid, wet cell, all electric or not, systems and many have built their own so know them inside out. There have even been quite a few discussions that discussed and presented lots of data and reference on questions of how accurate many of the standard RV power system "rules" are or aren't. The 50% rule mentioned by Avanti above is one of them that has had a lot of discussion.



The thing that stands out IMO is that HOW YOU WANT TO USE YOUR SYSTEMS is by far the biggest determiner of what system will be best for you, along with what is an absolute need and what is an absolute deal breaker. No system that is around now is inherently that much better than the others that it is the best choice for everyone or every use pattern.


There are lots of people with lots of opinions here and elsewhere, but none are that much better than any other unless they have data, testing, references, and good basic technical reasoning behind them. Just saying something is useless or wonderful is not enough to support any conclusion.
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Old 04-12-2019, 12:55 AM   #14
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I appreciate your efforts Avanti. Just reading the font was a bit frustrating. I agree there were a lot of assertions from a very narrow viewpoint. To say that one particular system is absolutely best defies belief.
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Old 04-12-2019, 02:13 AM   #15
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Avanti, thank you for a good review, you have patience. After your review I went back and must concur with your points. I still like generators and wish someone would compete with Onan's RV monopoly.

I have no problem with second alternators unless they are hanging too low.

One of my pet peeves, which I missed before, is incorrect units in this case for energy, it is not Amp/hour or kW/hour, it spells lack of basics. Use of incorrect oil was another major flag.
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Old 04-12-2019, 02:26 AM   #16
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Quote:
Originally Posted by GeorgeRa View Post
Avanti, thank you for a good review, you have patience. After your review I went back and must concur with your points. I still like generators and wish someone would compete with Onan's RV monopoly.

I have no problem with second alternators unless they are hanging too low.

One of my pet peeves, which I missed before, is incorrect units in this case for energy, it is not Amp/hour or kW/hour, it spells lack of basics. Use of incorrect oil was another major flag.

I am another with same pet peeve of the incorrect units. Using the wrong ones shows a couple of things. First off is that they don't understand what power is and how it is calculated, which is quite bad if your are trying to explain power systems, and second it points out that they are likely just regurgitating bad information they got somewhere else and never really understood it in the first place. Very typical of flashy, self promoting, internet experts, I fear.
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Old 04-12-2019, 02:52 AM   #17
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I'm not an expert and don't play one on TV.

It doesn't sound like a great idea to use a very expensive vehicle engine(gas or diesel) to charge batteries. Charging while driving is great, but running at idle for extended periods seems like it must add a lot of wear.
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Old 04-12-2019, 03:44 AM   #18
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Quote:
Originally Posted by skiMore View Post
I'm not an expert and don't play one on TV.

It doesn't sound like a great idea to use a very expensive vehicle engine(gas or diesel) to charge batteries. Charging while driving is great, but running at idle for extended periods ems like it must add a lot of wear.
It would depend a lot on the auxiliary alternator used and the batteries.

At one end you could have a Volta system with a 48v lithium battery bank and a 6000 watt 48v alternator which could get you lots of AH into the battery bank pretty quickly (equivalent to 480 amp charging into a 12v battery bank).

At the other end you could have a much lower power alternator running for much longer periods...
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Old 04-12-2019, 02:57 PM   #19
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Quote:
Originally Posted by skiMore View Post
I'm not an expert and don't play one on TV.

It doesn't sound like a great idea to use a very expensive vehicle engine(gas or diesel) to charge batteries. Charging while driving is great, but running at idle for extended periods seems like it must add a lot of wear.
What the author doesn't understand is a second alternator is charging mostly while driving and they are all charging at a much higher rate in a shorter amount of time than running an Onan generator. Driving mostly takes care of charging needs. For most people a second alternator use for idling is very short amount of time well within MB recommendations whether stated or informal, or used for backup just in case the batteries do get too low (the auto start feature.) Idling with a second alternator is not equivalent in need to running an Onan generator.

On the other hand you have to deal with a second expensive internal combustion engine (Onan) that has it's own maintenance problems and a lot of wear.

On the lithium battery side of the discussion, the Hymer/Roadtrek Ecotreks and Advanced RV, the companies that pioneered the second alternator, offered 800ah and more lithium battery banks which is impractical for size and location limits and weight limits to install AGMs in a B van equivalent in power. The engine's alternator could not charge those high amp battery banks in a timely or efficient manner nor could an Onan generator.
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Old 04-12-2019, 03:26 PM   #20
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Default How often will you use it?

Like everything else, the question of a generator is how often will you use it. If you are dry camping in one place for weeks at a time, then having a separate generator may be a necessity. Especially if you want to live in air conditioned comfort.

If you are mostly on the move and don't use the air conditioner, the under-hood generator with a large battery bank will likely serve your needs. Occasionally idling the vehicle to charge the batteries or run the air conditioner in unusual heat is not going to damage it.

If you are doing that regularly, you probably are better off with a separate generator. Whether you want one installed in the RV or a separate portable depends on how consistently you use it. If you don't need propane for heating, cooking or refrigeration carrying it just for a generator seems like a kludge. One of the advantages of the Etrek is that you don't need any other fuel. Fill the fuel tank and off you go.

I have 9600 watts of AGM batteries in my 2015 Etrek and it seems to charge just fine. Of course, we can't run the batteries down as far as lithiums which limits the actual available power which in turn limits the charging demand. I have not tried to run air conditioning off the batteries nor is it likely I will.
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