Lithium & 2nd Alternators Verses Onan Generators - Mike Mas

[RossWilliams]

I am unaware of "major failure rates" for the underhood generators on major brands of diesel based RV's. Or any other RV's for that matter. They seem to be at least as reliable as the typical alternator in motor vehicles.

"One lithium charging cycle can take 5-6 hours. if you charge for 2 cycles a day for just 2 days, you will use almost 1/2 a tank of fuel"

I am also not aware of anyone who needs to idle their rv for 12 hours a day to charge their batteries. I agree, this is a bad idea regardless of the size of your fuel tank. If you require the kind of off-grid electrical usage that would require a lithium battery bank that takes 6 hours to charge with a 3500 watt generator on a regular basis then you probably need a larger generator that will provide it. I doubt your typical propane RV generator has that capacity.

[Idleup]

Originally Posted by RossWilliams

I am unaware of "major failure rates" for the underhood generators on major brands of diesel based RV's. Or any other RV's for that matter. They seem to be at least as reliable as the typical alternator in motor vehicles.

"One lithium charging cycle can take 5-6 hours. if you charge for 2 cycles a day for just 2 days, you will use almost 1/2 a tank of fuel"

I am also not aware of anyone who needs to idle their rv for 12 hours a day to charge their batteries. I agree, this is a bad idea regardless of the size of your fuel tank. If you require the kind of off-grid electrical usage that would require a lithium battery bank that takes 6 hours to charge with a 3500 watt generator on a regular basis then you probably need a larger generator that will provide it. I doubt your typical propane RV generator has that capacity.

Hello - I'm not sure I was clear in my last post, I was referencing to a 2nd alternator lithium system.


An average "Engine Idling" charging cycle for a lithium pack such as Lithionics is; 2.5-3 hours, so in 2 cycles a day that would be the 5-6 hours I mentioned.

In just two days (10-12 hrs.) it would deplete almost half a tank of fuel from a Sprinter.

I'm just impressing the fact that engine charging is costly in both engine problems and fuel cost. These consumption figures does not take into account added fuel from the engine fan fully engaged on hot days requiring another 5-8 hp nor that you will instantly need a forced DPF regeneration when you get back on the road which uses 1-3 "Gallons" of fuel itself.

Failure rate on 2nd alternators was around 70-80%. Automotive alternators are not designed for continuous full power operation especially at idle when there is no frontal cooling air to help cool the windings and bearings. New generation alternators now have protection from over-work and high temperatures, plus special pulley clutches which help reduce their failures.

I cover this in detail in my article - here's a link:

http://www.rotory.com/sprinter/lithium/

[jharrell]

Originally Posted by Idleup

Hello - I'm not sure I was clear in my last post, I was referencing to a 2nd alternator lithium system.


An average "Engine Idling" charging cycle for a lithium pack such as Lithionics is; 2.5-3 hours, so in 2 cycles a day that would be the 5-6 hours I mentioned.

In just two days (10-12 hrs.) it would deplete almost half a tank of fuel from a Sprinter.

I'm just impressing the fact that engine charging is costly in both engine problems and fuel cost. These consumption figures does not take into account added fuel from the engine fan fully engaged on hot days requiring another 5-8 hp nor that you will instantly need a forced DPF regeneration when you get back on the road which uses 1-3 "Gallons" of fuel itself.

Failure rate on 2nd alternators was around 70-80%. Automotive alternators are not designed for continuous full power operation especially at idle when there is no frontal cooling air to help cool the windings and bearings. New generation alternators now have protection from over-work and high temperatures, plus special pulley clutches which help reduce their failures.

I cover this in detail in my article - here's a link:

http://www.rotory.com/sprinter/lithium/

Where are you getting these numbers, 2 GPH at high idle??? My gas 6.8 V10 will idle at .8 GPH with A/C and a full load on the alternator all day long. Just a quick search show .3gph normal idle to .5 GPH high idle on the MB small diesel which would be pretty normal for a small diesel under light load, 2 gph would be driving down the road at 45 mph, sprinters run 3 gph at highway speeds...

70-80% failure rate on 2nd alternators??? If your are going to put a second alternator in for continuous duty there are many high quality options designed for this at far lower cost than a generator, why would you put a cheap non continuous rated alternator in for this use?

[Idleup]

Originally Posted by jharrell

Where are you getting these numbers, 2 GPH at high idle??? My gas 6.8 V10 will idle at .8 GPH with A/C and a full load on the alternator all day long. Just a quick search show .3gph normal idle to .5 GPH high idle on the MB small diesel which would be pretty normal for a small diesel under light load, 2 gph would be driving down the road at 45 mph, sprinters run 3 gph at highway speeds...

70-80% failure rate on 2nd alternators??? If your are going to put a second alternator in for continuous duty there are many high quality options designed for this at far lower cost than a generator, why would you put a cheap non continuous rated alternator in for this use?

Thanks for the reply - But your idling example is not the least comparable to the workload of a lithium alternator system.

In addition, it has less to do with the quality of the alternator as it does the fact these units are "not designed" for continuous high output, which is only worsened by the fact the van is sitting still with no frontal air to cool them.

Alternators are designed for convection cooling of the case, openings, and internal fans to maintain proper operating temperature to prevent the windings and bearings from over-heating. This requires frontal air to move heated air from the compartment.

This is why companies like Nations now protects their alternators for over-current and temperature. They didn't incorporate those features for just something to do, they did it because they were pulling back off most all the alternators they installed.

Concerning the math for fuel used for charging, the fact your V-10 burns .8 gph, just confirms my findings. First of all, your just idling and not running at 1600 rpm which makes a major difference. Secondly you're not pulling 7-12 hp to turn the alternator nor accounting for the engine fan which can draw 5-15 hp when fully engaged.

I suggest you re-read the article as it covers in detail how my findings were achieved.

http://www.rotory.com/sprinter/lithium/

Regards - Mike

[jharrell]

Originally Posted by Idleup

Thanks for the reply - But your idling example is not the least comparable to the workload of a lithium alternator system.

In addition, it has less to do with the quality of the alternator as it does the fact these units are "not designed" for continuous high output, which is only worsened by the fact the van is sitting still with no frontal air to cool them.

Alternators are designed for convection cooling of the case, openings, and internal fans to maintain proper operating temperature to prevent the windings and bearings from over-heating. This requires frontal air to move heated air from the compartment.

This is why companies like Nations now protects their alternators for over-current and temperature. They didn't incorporate those features for just something to do, they did it because they were pulling back off most all the alternators they installed.

Concerning the math for fuel used for charging, the fact your V-10 burns .8 gph, just confirms my findings. First of all, your just idling and not running at 1600 rpm which makes a major difference. Secondly you're not pulling 7-12 hp to turn the alternator nor accounting for the engine fan which can draw 5-15 hp when fully engaged.

I suggest you re-read the article as it covers in detail how my findings were achieved.

http://www.rotory.com/sprinter/lithium/

Regards - Mike

Well I went out and measured my V10 GPH at 1600 rpm running the dash air at full blast and my roof air off inverter pulling 1500 watts pulling about 140 amps from my alternator, 1.7 GPH. To suggest a diesel with half the displacement that gets more than twice the mpg of my V10 uses more fuel at the same rpm is highly suspect. Diesel scale much better than port injected gasoline engines, they are high pressure direct injection and run extremely lean burn especially under light load, they idle very efficiently. Every report I can find shows .3 to .5 gph on the sprinter, how did you measure 2 gph?

I can't find any reference in the article to how fuel consumption was measured, I may have missed as the article is extremely hard to read and impossible to search since it is a image rather than real text with a strange font.

An alternator pulling 12hp would be putting out at least 7000 watts. Diesel fuel has 139,000 btu's per gallon of heat energy. Assuming only 30% engine efficiency (diesels in cars can be over 40%) would make 24 kilowatts at the driveshaft for 2 gph that's 32hp. The cooling fan is not going to draw 15hp at 1600 rpm, here is a graph showing fan HP demand from large 7+ liter diesel engines, they show maybe 12hp at 1600 rpm for an engine twice the size:



A 3.4l 35 kilowatt diesel generator running at 50% load (17,000 watts) uses 1.7 gph of fuel and 1 gph at 25% load (8000 watts), this is at a fixed 1800 rpm: https://www.generac.com/Industrial/p...esel-generator

Again where are you getting these numbers?

[Sipester]

Originally Posted by Idleup

Thanks for your reply - since some owners like you are using diesel fuel for driving, charging and for water and coach heating, they might want to investigate switching out the fuel tank for a larger one. There are a few companies offering stainless tanks to increase your range, the tank below is 47 gal! Again this is a hassle to be modifying a Sprinter when a simple propane generator is the answer.

Okay, so if someone wants to boondock in a Sprinter and they get both a propane generator and large amount of Lithium (say 600+ah), would you recommend that any of the following also run on propane?

1. Furnace
2. Hot water heater
3. Fridge
4. Cooktop

It looks like Midwest designs forgoes propane on all the above except #2. If you don't go with Propane for any of those, then too bad there isn't a small diesel generator, as it seems a waste to have a whole separate type of fuel for just one need.

[Idleup]

Originally Posted by jharrell

Well I went out and measured my V10 GPH at 1600 rpm running the dash air at full blast and my roof air off inverter pulling 1500 watts pulling about 140 amps from my alternator, 1.7 GPH. To suggest a diesel with half the displacement that gets more than twice the mpg of my V10 uses more fuel at the same rpm is highly suspect. Diesel scale much better than port injected gasoline engines, they are high pressure direct injection and run extremely lean burn especially under light load, they idle very efficiently. Every report I can find shows .3 to .5 gph on the sprinter, how did you measure 2 gph?

I can't find any reference in the article to how fuel consumption was measured, I may have missed as the article is extremely hard to read and impossible to search since it is a image rather than real text with a strange font.

An alternator pulling 12hp would be putting out at least 7000 watts. Diesel fuel has 139,000 btu's per gallon of heat energy. Assuming only 30% engine efficiency (diesels in cars can be over 40%) would make 24 kilowatts at the driveshaft for 2 gph that's 32hp. The cooling fan is not going to draw 15hp at 1600 rpm, here is a graph showing fan HP demand from large 7+ liter diesel engines, they show maybe 12hp at 1600 rpm for an engine twice the size:

Attachment 243137

A 3.4l 35 kilowatt diesel generator running at 50% load (17,000 watts) uses 1.7 gph of fuel and 1 gph at 25% load (8000 watts), this is at a fixed 1800 rpm: https://www.generac.com/Industrial/p...esel-generator

Again where are you getting these numbers?

Thanks for the reply - Regretfully, most of the information you found is “Googled” which is just for reference and not accurate. Also, flow meters are one step above an “Idiot Light” and designed for average reference, they won’t give you accurate readings.

Your comments on comparing the “Fuel Mileage” of a V10 gas to a Sprinter diesel, is like comparing bananas to oranges, and has “Zero” to do with my article on lithium charging. Aside from comparing two totally different engines, fuel mileage has more to do with gear ratios, transmission, aerodynamic drag, weight, load, etc. so don’t let that mis-lead you. We all know the Sprinter diesel has almost twice the mileage of a V-10 pulling the same load.

Your Googled fan data chart which 12 hp does prove the fan can draw more than the alternator but does not represent by any means every engine fan. The average fan draw for most RV’s varies from 5-40 hp. Also keep in mind that fan design and clutch engagement protocol varies as well. It’s not uncommon to find a fan which draws more hp on a smaller engine, because of the fact the radiator may be down sized to accommodate grille design, which means the fan works much harder.

The consumption figures I used of 1.5 - 2.0 gph. is conservative, since actual fuel consumption varies considerably during high temperatures, the alternator, battery and engine fan. As I just mentioned, the engine fan will consume at times more power than the alternator. In addition, these figures does not include the forced regen which will occur after high idle charging when the vehicle hits the road again which will consume 1-3 gallons.

My published results is complied from my own findings, actual lithium RV users, Lithium battery/alternator engineers, real field up-fitters, Mercedes technical staff, and some the best engineers in the business.

Bottom line its not just an engine spinning freely at idle, There’s six “high compression” pistons, 24 valves w/ springs, drag of the transmission torque converter, transmission pump, water pump, engine oil pump, high pressure fuel pump, stock alternator and drag from belt tension. There’s a bit more happening than you realize.

Lastly, you’re miles off on your generator numbers, my article only references an Onan 2500-2800 watt propane generator in a Sprinter which only burns about a 1/2 gph.

Regards - Mike

[jharrell]

Originally Posted by Idleup

Thanks for the reply - Regretfully, most of the information you found is “Googled” which is just for reference and not accurate. Also, flow meters are one step above an “Idiot Light” and designed for average reference, they won’t give you accurate readings.

So somehow your sources are more accurate yet you still don't answer the question, how was 2 gph measured and by what source, you or someone else? I get my my readings from the OBD2 PID 5E - fuel rate, this is reported by the engine ECU and uses injector pulse width and fuel pressure to calculate the fuel flow to two decimal places, its very accurate the engine needs this information to get the correct A/F ratio, what information do you have to suggest otherwise?

Originally Posted by Idleup

Your comments on comparing the “Fuel Mileage” of a V10 gas to a Sprinter diesel, is like comparing bananas to oranges, and has “Zero” to do with my article on lithium charging. Aside from comparing two totally different engines, fuel mileage has more to do with gear ratios, transmission, aerodynamic drag, weight, load, etc. so don’t let that mis-lead you. We all know the Sprinter diesel has almost twice the mileage of a V-10 pulling the same load. .

Your article is about the drawbacks of charging an RV house battery bank from the vehicles main engine. My RV's main engine is gas. Battery chemistry does not effect the the ability of a generator to output power. I compared mileage as a starting point since its most obvious, are you suggesting my 6.8L V10 is more efficient than your 3.0 diesel? According to your numbers you seem to be claiming such.

Have you really thought about what you are claiming. 2 gph represents 20 mpg at 40 mph, this is a pretty normal mileage number for a sprinter:



https://windinmyface.com/Sprinter-ma...elEconomy.html

You are claiming that at high idle of 1600 rpm that the 3.0L Mercedes sprinter consumes as much fuel as it does going down the road at 40 mph. Yet everyone else on the internet claims much less, and even my much larger much less efficient gas engine consumes less, yet you claim some authority without revealing your methods.

Originally Posted by Idleup

Your Googled fan data chart which 12 hp does prove the fan can draw more than the alternator but does not represent by any means every engine fan. The average fan draw for most RV’s varies from 5-40 hp. Also keep in mind that fan design and clutch engagement protocol varies as well. It’s not uncommon to find a fan which draws more hp on a smaller engine, because of the fact the radiator may be down sized to accommodate grille design, which means the fan works much harder.

Your un-cited info contradicts Caterpillar. Sorry a small 3 liter diesel does not require as much cooling as a 7 liter diesel, its pretty laughable to suggest the sprinter fan is pulling more HP than the CAT, do you have anything to back this up? Do you have the CFM rate on the sprinter fan, we can calculate the HP rather easily. It looks pretty small like an automobile fan and direct drive unlike a side radiator diesel that has even more losses.

Originally Posted by Idleup

The consumption figures I used of 1.5 - 2.0 gph. is conservative, since actual fuel consumption varies considerably during high temperatures, the alternator, battery and engine fan. As I just mentioned, the engine fan will consume at times more power than the alternator. In addition, these figures does not include the forced regen which will occur after high idle charging when the vehicle hits the road again which will consume 1-3 gallons.

Wow so 2 gph is conservative, what is it actually 3 gph? Now idling to recharging your batteries will consume as much fuel as driving down the highway at 60 mph???

Originally Posted by Idleup

My published results is complied from my own findings, actual lithium RV users, Lithium battery/alternator engineers, real field up-fitters, Mercedes technical staff, and some the best engineers in the business.

Again how was 2 gph measured?

Originally Posted by Idleup

Bottom line its not just an engine spinning freely at idle, There’s six “high compression” pistons, 24 valves w/ springs, drag of the transmission torque converter, transmission pump, water pump, engine oil pump, high pressure fuel pump, stock alternator and drag from belt tension. There’s a bit more happening than you realize.

Thanks for letting me know what is inside an engine, my gas engine is twice the size has 10 pistons, 30 valves and most of the rest and high idles at 1.7 gph. BTW "high compression" and a high pressure fuel pump is what make a diesel more efficient not less.

Originally Posted by Idleup

Lastly, you’re miles off on your generator numbers, my article only references an Onan 2500-2800 watt propane generator in a Sprinter which only burns about a 1/2 gph.

So I can't compare gas to diesel since its one is banana and the other is an orange but propane genset to diesel??? This is where there is more going on than you seem realize. Propane is only 91,000 btu per gallon, diesel is 139,000. This is before considering engine efficiency which direct injection diesel are far ahead of carbureted propane. If you had bothered to read the specs on the generator you would not have made that statement:



Is Generac putting out false information, how about Cummins:

3.3L diesel 35 KW


8000 quiet diesel used in many RV's puts out 4000w at .5 gph while the little LP takes .5 gph for maybe 1500w:

This is why diesel generators are preferred, they are much more efficient than LP.

Perhaps if you "Googled" some more you could improve the accuracy of your article, also if you publish it as html rather than a series of images it can be "Googled" by others looking for the information.

[RossWilliams]

I agree. If you are making very heavy off-grid use of electricity , like running AC 24/7 in 100 degree heat, then you need a separate generator. You certainly can't do that relying on a standard automobile alternator and a battery bank.



If you are driving a diesel, then a separate diesel generator would likely be a better choice than propane. Diesel fuel is energy denser and you won't have to be refilling as often as you will with propane. Here is a comparison of the two.


I don't need either one. I have a 3400 watt under hood generator that fully charges my batteries while driving and 9600 watt hours of storage. That meets my needs. I have idled briefly only once when the batteries started getting low in extreme (-10F) cold and that was probably unnecessary.

[Idleup]

Jharrell thanks for all the replies, however you’re just confusing yourself trying to establish any valid facts in a few hours of Google searching. In retrospect, all the data in my article is backed up from over a year of extensive research regarding lithium / 2nd alternator RV’s .

The information I compiled is from experts in the lithium battery industry who install numerous systems for companies such as Winnebago, Coachman, Midwest to name a few, plus Up-fitters who install countless 2nd alternators.

In addition, my conclusions on engine data and loads from charging is from actual users and further confirmed by a team of experts I’ve worked with for decades on military aircraft.

Again, it’s important that you understand using your V-10 gas RV engine or the specs from a Cat diesel which are now legally banned from all RV use, is not going to give you anything you can sink your teeth in, they are different animals and have nothing to do with this project.

My article focused on the “many” negatives of using a 6 cyl. diesel or gas engine for extended idling charging, verses the positives of a conventional B RV with a 8D AGM battery and a simple 1cyl Onan generator. The advantages are numerous, since the propane coach avoids damage to the engine and turbo, does not force unneeded regens, consumes less fuel, develops less ambient heat, surely far less agonizing ammonia fumes when idling for 3 hours at 1600 rpm. In addition, the propane coach provides more “off the grid" time than a lithium coach with no generator.

Your assumptions on this matter of a few hours are just that, assumptions, your not dealing with "real world" people in the industry as I have to reach conclusions of fact.

Regards- Mike

[jharrell]

Originally Posted by Idleup

Jharrell thanks for all the replies, however you’re just confusing yourself trying to establish any valid facts in a few hours of Google searching. In retrospect, all the data in my article is backed up from over a year of extensive research regarding lithium / 2nd alternator RV’s .

The information I compiled is from experts in the lithium battery industry who install numerous systems for companies such as Winnebago, Coachman, Midwest to name a few, plus Up-fitters who install countless 2nd alternators.

In addition, my conclusions on engine data and loads from charging is from actual users and further confirmed by a team of experts I’ve worked with for decades on military aircraft.

Again, it’s important that you understand using your V-10 gas RV engine or the specs from a Cat diesel which are now legally banned from all RV use, is not going to give you anything you can sink your teeth in, they are different animals and have nothing to do with this project.

My article focused on the “many” negatives of using a 6 cyl. diesel or gas engine for extended idling charging, verses the positives of a conventional B RV with a 8D AGM battery and a simple 1cyl Onan generator. The advantages are numerous, since the propane coach avoids damage to the engine and turbo, does not force unneeded regens, consumes less fuel, develops less ambient heat, surely far less agonizing ammonia fumes when idling for 3 hours at 1600 rpm. In addition, the propane coach provides more “off the grid" time than a lithium coach with no generator.

Your assumptions on this matter of a few hours are just that, assumptions, your not dealing with "real world" people in the industry as I have to reach conclusions of fact.

Regards- Mike

Again no mention of how 2 gph hour measurement was attained idling a 3.0L diesel, I have shown multiple +3L diesel gensets that consume 1/2 that amount for 4 times the power output. I have shown that a average sprinter consumes 2 GPH at 40 mph, there are multiple post from multiple sites showing that the high idle loaded consumption of a 3.0 Mercedes diesel is around .5 GPH "real world". Instead the best you can do is an appeal to authority.

My gas RV engine that I use to charge my batteries has nothing to do with RV charging from the main engine? It just shows how ridiculous your fuel consumption claims are, I think everyone knows my gas V10 is not as efficient as the Mercedes 3.0l diesel, yet it consumes less fuel than you claim the small diesel does. CAT didn't get out of the highway market due to their fans being too efficient and what, the Mercedes fan uses 15hp due to being for highway use? What are you arguing, that their fan numbers are wrong because they didn't want to deal with highway emissions?

Your math doesn't add up, a modern diesel engine consuming 2 gph will easily be generating 24 kilowatts at the output shaft and more likely closer to 30 kw, this is just thermodynamics. This is why a 3l diesel genset consuming 2 gph produces 26-27kw after conversion losses . A sprinter with an alternator could be half that efficient and still produce 12kw of power output, are you seriously claiming one will consume 2 gph and only produce 3kw? These are facts based in physics and math not assumptions.

You can argue the well know advantages and disadvantages of using the main engine vs a generator, but making up fuel consumption numbers is was what I take issue with. You have helpful information in your article, that is unfortunately not searchable but you are also seem to be spreading mis-information to make your argument.

Also ammonia fumes? You do know that in a properly working DEF/SCR system the ammonia (NH3) (actually urea) is converted to nitrogen and water (N2 and H2O), if there is any left over ammonia, this is called ammonia slip and should be controlled pretty well. You should not smell ammonia unless there is an issue with the system. I believe Mercedes even does a secondary ammonia slip catalyst to better control any excess ammonia.

Prove me wrong and show a 3.0 sprinter consuming 2 gph at high idle producing only 3kw of power or even 6kw rather than just repeating your credentials and what industry insiders you know that are getting different numbers than everyone else.

[Idleup]

Jharrell thanks again for the reply - I suggest that you first "Study Up" before you begin to question the work of creditable experts in the field.

Certainly your Googled knowledge of Lithium charging and the parameters of fuel usage of a Sprinter diesel are only goofy assumptions. It puzzles me how you feel your knowledge is more advanced or accurate than companies such as; Lithionics, Volta, Xantrex, Nations Battery, Relion, Mercedes, Martin Maretta Aerospace technicians, or myself.

Regretfully, your futile attempt to compare your V-10 gas engine to a Sprinter diesel, revels your inabilities to understanding the article and the principals of lithium engine charging and from enjoying a well written factual article.

Regards - Mike

[gmillerok1]

I think we are missing the point here, which is idling any engine not really designed for long term idling is a bad idea. I wouldn't do it in a Sprinter or any other consumer vehicle.


But what I would do is the lithium upgrade, a DC-DC charger limiting the amp draw on the OEM alternator while I drive, and for many days of boon docking, taking along a small portable generator in case it rains for 3 or 4 days which would be enough to charge the batteries in a worse case situation if the solar can't keep up.



For me, never to say the word "Cummins" or "Onan" again would be worth it.

[Jlo11111]

Sounds like diesels are a poor choice for class B's and smaller class C's. Better to go with a gas Promaster or Transit and skip all the problems. Add in a 6000W 2nd alternator, a big inverter and LifePo4 or EV grade batteries and your good to go. No worries about idling and fully charged after 2 hours.