10-21-2022, 06:45 AM
@Richard - based on Joe's schematic, he has the 50DN alternator which should be the oil-cooled unit.
However, being that we're on a forum, it's just as important to provide safe advice for others and the information you've providing is very helpful. I read quite a bit on RV forums as well and I haven't witnessed the same issues with alternators on the larger diesel pushers (DP). On other chassis? Absolutely.
Typically on a DP the belt ratio (from flywheel to alternator) will be somewhere in the range of 1:3 (3 rotations of alternator for every one rotation of crankshaft) keeping the DP alternator running at minimum 2,100 RPM. IMPORTANT NOTE: I am skilled in electronics, NOT mechanics, therefore, I am out of my element in this statement about the ratio; it could be higher/lower in the DD/Cat/Cummins engine/alternator combos in Newells, please let me know if I'm wrong.
At 2100 RPM a high-quality alternator, particularly the DP alternators that run substantially larger-diameter stators (more room to dissipate heat, multiplied by the higher-pressure airflow) should not overheat unless there were some issue with the fan-blades perhaps?
Furthermore, a Newell uses an alternator that is designed to run at 24v, producing half the amperage for the same amount of current (watts). The reason for this is obviously because the gauge of wire and high resistance of running a 12v system which doesn't make as much sense in the context of large diesel engines that require high-current to turn-over, etc. With a 12v line, you're pushing higher amperage for the same number of watts (heat, the offender in this instance) -- and therefore, the resistance of the wire does help mitigate the drain on the alternator in the situation where you mention charging from a low SoC.
Speaking of charging from a very low SoC, this is not typically something that is done. In the event someone runs their house-batteries to a very low SoC, typically this is compensated with a separate generator (not primary engine generator/alternator) if it's not the pedestal responsible for the charge. For that reason, much of this discussion is largely hypothetical or (at least) relatively uncommon in real-world scenarios.
We could go into more detail on the topic, but I think it would be better for me to first understand the issue with people you've witnessed that have suffered from this issue on a large DP with a high-quality alternator. If you have some in-mind, I'll investigate those and that will help me provide better information.
-- To your second point --
I would not draw a substantial conclusion to the anecdotal "almost all Class A manufacturers use some sort of isolator"; it makes perfect sense that a manufacturer would prefer the isolator; this is not because it's the superior solution for an owner/operator.
I'm here to learn, not debate; however, if I were to debate anecdotes without going deeper into the science, I would mention an analog: that "almost all" Motor Yachts use a VSR of some sort (or in modern times with new chemistries, the more pragmatic, microprocessor based DC-DC chargers).
For now -- if you have some posts you can share that will help me investigate the equipment/situations where people with DP's have burnt-out their alternators due to charging battery banks, please share those and I'll investigate further.
However, being that we're on a forum, it's just as important to provide safe advice for others and the information you've providing is very helpful. I read quite a bit on RV forums as well and I haven't witnessed the same issues with alternators on the larger diesel pushers (DP). On other chassis? Absolutely.
Typically on a DP the belt ratio (from flywheel to alternator) will be somewhere in the range of 1:3 (3 rotations of alternator for every one rotation of crankshaft) keeping the DP alternator running at minimum 2,100 RPM. IMPORTANT NOTE: I am skilled in electronics, NOT mechanics, therefore, I am out of my element in this statement about the ratio; it could be higher/lower in the DD/Cat/Cummins engine/alternator combos in Newells, please let me know if I'm wrong.
At 2100 RPM a high-quality alternator, particularly the DP alternators that run substantially larger-diameter stators (more room to dissipate heat, multiplied by the higher-pressure airflow) should not overheat unless there were some issue with the fan-blades perhaps?
Furthermore, a Newell uses an alternator that is designed to run at 24v, producing half the amperage for the same amount of current (watts). The reason for this is obviously because the gauge of wire and high resistance of running a 12v system which doesn't make as much sense in the context of large diesel engines that require high-current to turn-over, etc. With a 12v line, you're pushing higher amperage for the same number of watts (heat, the offender in this instance) -- and therefore, the resistance of the wire does help mitigate the drain on the alternator in the situation where you mention charging from a low SoC.
Speaking of charging from a very low SoC, this is not typically something that is done. In the event someone runs their house-batteries to a very low SoC, typically this is compensated with a separate generator (not primary engine generator/alternator) if it's not the pedestal responsible for the charge. For that reason, much of this discussion is largely hypothetical or (at least) relatively uncommon in real-world scenarios.
We could go into more detail on the topic, but I think it would be better for me to first understand the issue with people you've witnessed that have suffered from this issue on a large DP with a high-quality alternator. If you have some in-mind, I'll investigate those and that will help me provide better information.
-- To your second point --
I would not draw a substantial conclusion to the anecdotal "almost all Class A manufacturers use some sort of isolator"; it makes perfect sense that a manufacturer would prefer the isolator; this is not because it's the superior solution for an owner/operator.
I'm here to learn, not debate; however, if I were to debate anecdotes without going deeper into the science, I would mention an analog: that "almost all" Motor Yachts use a VSR of some sort (or in modern times with new chemistries, the more pragmatic, microprocessor based DC-DC chargers).
For now -- if you have some posts you can share that will help me investigate the equipment/situations where people with DP's have burnt-out their alternators due to charging battery banks, please share those and I'll investigate further.