Lithium & 2nd Alternators Verses Onan Generators - Mike Mas

[IdleUp]

Originally Posted by SteveJ

Citation?



extra spaces to get over the ten character minimum

What am I missing here? . . . . .

[booster]

Originally Posted by IdleUp

What am I missing here? . . . . .

Any post has to be 10 characters or it won't post by the software.

[bwolfsohn]

Originally Posted by SteveJ

Citation?

I raced miniature cars in 2013/2014.. There were many stories of LI batteries bursting into flames.. At the time, there was heavy price competition of the chinese battery end.

[jon]

Another idea:
https://www.wattfuelcell.com/uses/rv/

[avanti]

Originally Posted by jon

Another idea:
https://www.wattfuelcell.com/uses/rv/

Yes, definitely. However, as mentioned above, they were deeply in bed with Hymer/RT as their rollout customer. Their collapse has got to be an existential issue for a startup. Maybe the new buyer of RT will pick up the pieces.
Fingers crossed.

[booster]

Originally Posted by avanti

Yes, definitely. However, as mentioned above, they were deeply in bed with Hymer/RT as their rollout customer. Their collapse has got to be an existential issue for a startup. Maybe the new buyer of RT will pick up the pieces.
Fingers crossed.

Times two, or the future will get delayed, I think.

[jharrell]

Originally Posted by avanti

[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.

Hi Guys, I don't have a Class B but I follow them as one day when the kids are grown I would like to downsize into one. Its very interesting to see the advancements in lithium and alternator based charging. The I saw this article posted over on IRV2 and was trying to make sense of it, you can see the discussion here:

Lithium & 2nd Alternators Verses Onan Generators - Mike Mas - Page 3 - iRV2 Forums

I am happy to find I am not the only one questioning the accuracy of the claims, I tried to get answers from the author noting how many of the claims just don't make sense in terms of physics and math only to be met with appeals to authority. The fuel burn claims seemed immediately off as my V10 gas RV has those kind of idle numbers, it seems odd that a diesel with half the displacement would consume the same.

I too think its very important that there is accurate information out there for people to make there own decisions. So on the idle/high idle fuel burn numbers does anyone here have a scangauge or OBD monitor and high idle to shed some more light on the situation? Does the sprinter report the OBD PID 5E (Fuel Rate) accurately or do the scanner base it on something else like MAF / load?

Advanced RV seems to have a pretty nice system and I believe they claim .5 gph for high idle which would be more inline with a diesel that size and about 1/4 what the author claims.

Also the ammonia smell from the exhaust claim... does anyone know ammonia slip numbers on the sprinter at high idle? Normally there should be very little NH3 left in the exhaust if the SCR system is working properly. Also anyone know if the sprinter has secondary ammonia slip catalyst, I know some of the cars do?

[booster]

Good point about the Scangauge for checking consumption of a Sprinter at high idle, but it also will need to be running the alternator at full output to get a true comparison to Onan loaded specs.


I know the gas Scangauges give fuel use in #/hr and maybe gallons also depending on the settings, so it would be very easy to see if the diesels have the same.

[jharrell]

Originally Posted by booster

Good point about the Scangauge for checking consumption of a Sprinter at high idle, but it also will need to be running the alternator at full output to get a true comparison to Onan loaded specs.

After reading the article I went out and high idled my Ford 6.8 L V10 gas RV engine with the alternator running my roof A/C through my Magnum 3000 hybrid at about 140 amps plus I had the dash A/C on full blast which should easily doubled that load and measured 1.7 gph. Normally it idles at .8 gph and can provide about 130 amps with its 175 amp alternator.

So basically the article is claiming a 3.0L V6 diesel has the same fuel burn rate as a 6.8L V10 gas engine at high idle. I know enough about engines to know this is a big red flag. Claims are also made that 2 GPH is conservative due to "forced regeneration".

I also posted scholarly articles that show a 12-15 liter diesel semi high idles at 1.1 GPH, but according to the author that is just "Googling" assumptions.

[booster]

Originally Posted by jharrell

After reading the article I went out and high idled my Ford 6.8 L V10 gas RV engine with the alternator running my roof A/C through my Magnum 3000 hybrid at about 140 amps plus I had the dash A/C on full blast which should easily doubled that load and measured 1.7 gph. Normally it idles at .8 gph and can provide about 130 amps with its 175 amp alternator.

So basically the article is claiming a 3.0L V6 diesel has the same fuel burn rate as a 6.8L V10 gas engine at high idle. I know enough about engines to know this is a big red flag. Claims are also made that 2 GPH is conservative due to "forced regeneration".

I also posted scholarly articles that show a 12-15 liter diesel semi high idles at 1.1 GPH, but according to the author that is just "Googling" assumptions.

Are you checking the amps to the coach with the "hybrid" feature of the charger turned off, or do you have a separate ammeter to the coach?

[jharrell]

Originally Posted by booster

Are you checking the amps to the coach with the "hybrid" feature of the charger turned off, or do you have a separate ammeter to the coach?

I disconnected shore power (which disables the hybrid function) then used the Magnum BMK (Shunt based ammeter) to monitor AH in/out. The inverter was running the A/C showing 140-150 amps which is typical while the BMK hovered around zero on the batteries.

I have 320 watts of solar that was providing about 180 watts but also had some minor house loads (router etc) at the time so around 1500W from the alternator.

High idling the V10 at 1600 rpm is pointless because even at low idle it can provide nearly all the power needed but I did want see how it compared to the claims made on a small diesel.

[markopolo]

Some fuel consumption info:

I have a 2012 email from Sprinter Engineering Support that states fuel consumption is .4 - . 5 gal. per hour of idling. (Edit: that would be single stock alternator not dual, load was not discussed)

With the Scangauge in my 1997 GM 6.5L Turbo diesel (no DPF, no DEF etc.) I've recorded:

0.11 GPH at 634 RPM idling with the 5,200 BTU A/C (less than a 600W load) running off inverter.
0.45 GPH at 651 RPM idling with the 5,200 BTU A/C running off inverter plus van dash air conditioning on "Max Air".

Fuel consumption for the gas engine Onan 2800W typically used in gas engine B vans is listed in the manual as being:

No load 0.16 gph
Half load 0.28 gph
Full load 0.46 gph

[jharrell]

Originally Posted by markopolo

Some fuel consumption info:

I have a 2012 email from Sprinter Engineering Support that states fuel consumption is .4 - . 5 gal. per hour of idling. (Edit: that would be single stock alternator not dual, load was not discussed)

With the Scangauge in my 1997 GM 6.5L Turbo diesel (no DPF, no DEF etc.) I've recorded:

0.11 GPH at 634 RPM idling with the 5,200 BTU A/C (less than a 600W load) running off inverter.
0.45 GPH at 651 RPM idling with the 5,200 BTU A/C running off inverter plus van dash air conditioning on "Max Air".

Fuel consumption for the gas engine Onan 2800W typically used in gas engine B vans is listed in the manual as being:

No load 0.16 gph
Half load 0.28 gph
Full load 0.46 gph

That seems more in line with my experience for diesel idle consumption.

The propane Onan 2500 is the same as the 2800 gasoline and consumes .4 under half load and .6 under full load. Less power and more consumption due to the lower energy density of propane vs gasoline.

Diesels has even more energy density than gasoline and diesel generators like the sprinter engine are direct injected with high compression ratios and lean burn producing higher combustion temps and more complete combustion, so they have a double advantage compared to a standard carbureted spark ignition generator.

The Onan 3200 diesel is .3 half load .4 full load, similar to the 2800 gasoline but more power. As example closer to the sprinters displacement a 3.3L 35 kw 1800 rpm fixed diesel Onan consumes 1 gph at 1/4 load producing nearly 9000 watts.

DEF should have improved the consumption as it allowed increased combustion temps (reduced egr) and leaner mixtures while still keeping NOx under control. Most reports I have seen are better fuel economy vs pre def engines unless you go back much further where they didn't care about NOx emissions at all and ran hot and lean regardless like perhaps your 1997.

[IdleUp]

Originally Posted by Bud

"Since this thread is dedicated to Midwest Automotive Designs beautiful 4x4 diesel conversion, let’s please keep the focus on this coach.

Regards - Mike"

Mike you've made some it about You, so that may or may not stop.

You may have missed it earlier:

"Mike, you seem to confirm what I've thought since the word etrek was first used. It was and mostly still is about ac although lithium will rule down the road. It is about how much, how often the van's engine will be used for charging.

- No ac use, no big amount of amp hours needed

- ac with shore power, no big amount of amp hours needed

- ac with batteries with recharge from van's engine 3 times a year, 12 volt lithium system

- ac with batteries with recharge from van's engine 75 times a year, Volta

Have I got that about right?

Bud

Thanks for the reply - It seems few RV owners do need "off the grid" power for camping. For this reason, most owners can fully charge the lithium set before they depart and have the freedom of pulling over for lunch or a nap and flipping on the AC to run off lithium with the generator off. As they continue their trip, the stock alternator can top the battery back off, so if they decide to spend the night at a Wal-Mart camping lodge, they can use the AC for comfortable conditions, without bothering other campers.

As my article outlined, extended idle "stationary" charging has many issues, from possible engine problems, consuming considerably more fuel, plus insane heat day or night. Mercedes no longer allows Up fitters from using the engine in any manner for lithium charging, in fact they don't want up fitters to pull no more than 40 amps from the stock alternator.

In any case, lithium is definitely the future of RV's. It's already taken over in the marine industry. Even an owner changes out his two house batteries for two 100 ah lithium cells, he has many advantages over flooded cells. While be won't be able to use the AC, it does provide plenty of power for electric ranges, lights and the refrigerator which is a big advantage.

Mike

[dw8928]

What about the Firefly Carbon Foam batteries used in the marine industry? Seem to have the lithium advantages.

[markopolo]

Midwest's approach has some similarities to mojoman's Mojovan.

mojo had 50% more lithium battery capacity though so much longer A/C runtime. It likely had more solar as well. mojo also chose a Onan mounting that reduced noise and skipped the second alternator.

It seems as though commercial B builders have been stuck at the powering the van phase for a long time now - we're overdue for some innovation in this area. In the B van users world there seems to be almost universal dislike for the smaller Onan generators if you read through forum postings. Noise, monthly maintenance, difficulty of access, failures, costly repairs, smell .......

The much discussed DC fuel cell would be a leap forward.

Hybrid inverters like the one Mobilecabin just installed could be an interim push forward. Couple it with a super quiet 1,000W remote start generator on a motorized, automated slide-out tray could be one fresh approach using what's currently available.

For vast majority of RV's lithium batteries are not needed IMO. 400Ah or so of lead acid batteries easily permits use of an electric kettle, toaster oven, coffee maker, microwave oven, running the fuel supplied furnace through the coldest nights etc.

[jharrell]

Originally Posted by IdleUp

As my article outlined, extended idle "stationary" charging has many issues, from possible engine problems, consuming considerably more fuel, plus insane heat day or night. Mercedes no longer allows Up fitters from using the engine in any manner for lithium charging, in fact they don't want up fitters to pull no more than 40 amps from the stock alternator.

Do you have any proof Mercedes does not allow lithium charging? I think that would be of interest to a lots of people here. Why would they care how power is used? Can I charge lead acid but not lithium? Makes no sense. There still seems to be upfitters doing lithium main engine charging such as Advanced RV, Sportsmobile, etc.

Limiting stock alternator pull is reasonable and I wouldn't doubt that is Mercedes recommendation, disallowing lithium charging from engine, regardless of alternator makes absolutely no sense. I can charge Lithium through a 40A DC-DC charger and be within their stock alternator pull recommendations, 40A is 40A regardless of battery chemistry or you can add a secondary alternator and just pull whatever wattage from the engine directly again regardless of battery chemistry.

You seem to be conflating stock alternator issues with stationary idle issues. If your going to add an entire secondary properly designed propane system and generator to the vehicle then the equivalent would a properly designed and sized secondary alternator. Using the stock alternator would never be recommended for any kind of high power idle charging.

"Insane heat" seems like more hyperbole, producing the same power from an ICE with similar efficiency will produce similar heat. A diesel engine is more efficient than a propane otto at converting heat to mechanical energy it would normally produce less heat for the same power. You seem to be confusing temperature with heat. Diesels run at higher temps which make them more efficient which means they produce less waste heat per unit of energy converted.

Biggest problem is the fuel numbers again, by all accounts the sprinter consumes around .5 GPH at high idle, yet you claim 3-4x times the fuel consumption conservatively (1.5 - 2 GPH!), in fact you claim a sprinter high idle charging consumes as much fuel as its does pushing itself down the road at 45 mph or a similarly sized diesel generator producing ~20kw! That would be what 30-35hp or ~25kw of driveshaft power, which is going where exactly? Completely preposterous.

[booster]

Originally Posted by markopolo

Midwest's approach has some similarities to mojoman's Mojovan.

mojo had 50% more lithium battery capacity though so much longer A/C runtime. It likely had more solar as well. mojo also chose a Onan mounting that reduced noise and skipped the second alternator.

It seems as though commercial B builders have been stuck at the powering the van phase for a long time now - we're overdue for some innovation in this area. In the B van users world there seems to be almost universal dislike for the smaller Onan generators if you read through forum postings. Noise, monthly maintenance, difficulty of access, failures, costly repairs, smell .......

The much discussed DC fuel cell would be a leap forward.

Hybrid inverters like the one Mobilecabin just installed could be an interim push forward. Couple it with a super quiet 1,000W remote start generator on a motorized, automated slide-out tray could be one fresh approach using what's currently available.

For vast majority of RV's lithium batteries are not needed IMO. 400Ah or so of lead acid batteries easily permits use of an electric kettle, toaster oven, coffee maker, microwave oven, heating through the coldest nights etc.

Well stated.


I particularly agree with fuel cell hopes, or some other technology we don't even know about yet.


The sideout generator tray has been discussed and would be very nice so the much better than Onan portable generators could be used. Even better if it included a way to drop it down and roll a ways away from the van to limit exhaust and noise, as long as it didn't bother neighbors.


Second alternators do work fine and have some advantages over generators and even using the factory alternator, but I don't think they are the long term solution for AC off of the batteries recovery because they require the van to be running and new rules will very likely make that unrealistic in many places in the future, and the vehicle manufacturers may also tighten up the allowable power off the factory stuff and/or idling time rules.


The second alternators work very well for those that need to be able to charge a quite high rate while driving after a long offgrid stay or a big power use stretch. One big advantage is their design which is normally substantially more robust that the factory units. The also can run on external regulation for setability of parameters, including charge rate which can also have multiple rates put in. The multiple charge rates allow quicker or shorter charge times based on driving and give the benefit of less stress on the alternator and batteries from heat on longer drives and hot weather. Being separate from the vehicle system makes any failure a non sit on the side of the road waiting for tow one. Being separate also makes them immune to the factory energy saving protocalls that now manage the charging systems and will turn down, off and on, etc charging in some cases.


As Marko stated 400ah of AGM battery and charging systems to match will cover almost everyone's use and recharge needs and speeds, unless they are trying to run the AC on batteries for longer than a couple of hours. He has such a system, as do we and several others here do, and AFAIK they are all working very well. For us, the no need for heaters on the batteries and the no need to do full shutoff charging, plus recovery methods, easily cover the minor shortcomings of such a system.

[IdleUp]

Originally Posted by dw8928

What about the Firefly Carbon Foam batteries used in the marine industry? Seem to have the lithium advantages.

Thanks for the reply - Carbon Foam can be a great option for RV’s since from a price point the battery is about half the cost of lithium. For some RV owners carbon might be a better choice since very few owners will keep their RVs for 15-20 years to reap the benefits of a costly lithium battery investment.

As most know, the advantage of carbon foam is its ”partial charge technology” feature which prevents the plates from sulfating by using special composite carbon materials on the grid. Not worrying about discharging your batteries to 50% is a major advantage over AGM. This means you can discharge the pack to only 10-20% and it will still charge back to 100%. This is a major advantage for our RV’s and boats since most owners store their pride and joys with no power. With a self-discharge rate of only around 3-4% per month, you’ll still have power when you pull your RV rig out of storage.

We have a major problems with batteries today. With the advent of all the electronics they are installing in A models, where the Silverleaf control has 10-15 modules which run continuously, even after you flip the power off as you go out the door, there is still a 5-10 amp draw from all the modules running. If you park any of these new RV’s out in a lot for 3-4 days, the AGM pack is stone dead, yet manufacturers still won’t spend a dime on a battery cut-off to protect your AGM banks. Here’s an article I put up concerning this matter and installing a 3rd level shut-off for coaches.

http://rotory.com/coach/battery/

Other advantages over AGM is charge cycles, most can achieve around 3500 cycles at 50% discharge and less than half of that below 20%. These carbon packs can also be wired in series as well. Regardless of what the manufacture advertise, somewhat like lithium cells, I would refrain from discharging carbon past 20% to preserve the batteries life cycle. In any event, this is a major improvement over an AGM battery.

Carbon’s biggest disadvantage is weight, when compared to lithium, a typical 100 Ah battery carbon battery weighs 75 lbs, where a 100 Ah lithium weighs as little as 25 lbs. If you’re installing four of these batteries in your B RV so you can run the roof air, you’ll lose around 200 lbs of payload compared to lithium, this is major loss for our Type B coaches since most are close to gross weight. Where I can really see an advantage for carbon is type A RV’s, where weight is not a factor and you have large battery compartments to easily install them.

I have a buddy who has a small trawler up in Smith Mountain Lake Va, who replaced his AGM batteries with these carbon batteries and he can’t stop bragging about them. His Cummins engine charges underway, but since he can discharge them to 80+%, (DOD is 100%) he said he hasn’t had to start his generator since he installed them. His one battery bank runs the whole boat, engine starting and even his electric bow thruster.

Here's a link to FireFlyEnergy.

Firefly International Energy

Regards - Mike

[booster]

Idleup said:

As most know, the advantage of carbon foam is its ”partial charge technology” feature which prevents the plates from sulfating by using special composite carbon materials on the grid. Not worrying about discharging your batteries to 50% is a major advantage over AGM. This means you can discharge the pack to only 10-20% and it will still charge back to 100%.

This is not my understanding on what "partial charge technology". From what I have seen is that it refers to the ability of the carbon batteries to run in a mid charge range for quite a while and number of recharge cycles with losing capacity when you do get a full recharge on them. The 50% rule you are stating as gospel is actually pretty much bogus IMO, and there are several discussions on this fourm with data on the subject. Proper recharging parameters on a AGM will bring it back to full after an 80% discharge from all the data I have seen. Single deep discharges are not the major killer of AGMs, it is short charging them. Very few RV chargers are capable of recharging them to full consistently without over or under charging them. The carbon batteries may well get longer cycle life than AGM, as they should do justify the cost, but we really haven't seen any real data from any users yet, so that will be interesting when people have had them a while. Personally, the biggest thing they have to offer would be partial charge cycling without damage if that turns out to be correct and if the time they spend in partial charge area is long enough to do some extended ofgrid camping with partial recoveries.