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Old 02-21-2016, 06:42 PM   #1
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3L V6 fuel consumption at high idle?

I have ordered MB Sprinter 2500 w/3L V6 TD engine with expectation that SMB will fit a 2nd alternator on this instead of a generator approach. I am trying to do the math on range and cost to run A/C unit off this 2nd alternator (the 'all electric' approach). Anyone have guesses as to fuel consumption while parked and idling with idle high enough to support continuous use of the Danhard A/C unit? My use case for this is typically just weekend trips (1 or 2 nights at a time) in the summer, but am I looking at burning 2G an hour or 1/2G an hour? I am just trying to get ballpark numbers here since I have no frame of reference for this engine with the 2nd alternator and idling high.

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Snowy
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Old 02-21-2016, 09:20 PM   #2
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The last thread I saw estimated between .3 and .7 gallons an hour on high idle. But there are several other concerns about idling the engine all night just to run the A/C. A lot of owners say the emissions control system (DPF) does not do well with extended idling.

Also, the engine and exhaust system put out a lot of heat. You can feel it rising up through the floor in hot weather, especially if you're parked in one spot. So the A/C will be fighting that all night too. Not to mention the noise of 1500 rpm plus the Danhard.

For summer travel, I think you would be better off finding campgrounds with shore power, or running a Honda generator a few yards away from the van.

http://www.sportsmobileforum.com/for...l-10426-2.html
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Old 02-21-2016, 10:52 PM   #3
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The last thread I saw estimated between .3 and .7 gallons an hour on high idle. But there are several other concerns about idling the engine all night just to run the A/C. A lot of owners say the emissions control system (DPF) does not do well with extended idling.

Also, the engine and exhaust system put out a lot of heat. You can feel it rising up through the floor in hot weather, especially if you're parked in one spot. So the A/C will be fighting that all night too. Not to mention the noise of 1500 rpm plus the Danhard.

For summer travel, I think you would be better off finding campgrounds with shore power, or running a Honda generator a few yards away from the van.

http://www.sportsmobileforum.com/for...l-10426-2.html
Thanks Ned. Shore power not an option in this scenario. .5 G +/- is good enough for my calculations at this point. I'll research the impact of extended idle on emission. As for heat build-up, I hadn't really thought about it. Would be curious to hear from others doing this 'all electric' route to see if it actually works in practice with regard to A/C on 2nd alternator vs. generator. It sure sounded good on paper (quieter, less maintenance, etc.), but if it simply isn't feasible for one of the reasons you listed, that is what matters most. This scenario is only for one or two night trips a few times a year, not weeks at a time in the Sahara..

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Old 02-26-2016, 08:43 AM   #4
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I can confirm the +/- 0.5 GPH as we have that setup on our SMB Sprinter. The only difference is that our A/C is a rooftop unit. The auxiliary alternator works great and we've had no problems with the emissions system using the high idle function. But,we don't idle as long as you've described.

The only suggestion I have is to add the Balmar external voltage regulator to the setup. This optimizes the charging for AGM batteries and holds the charging in bulk mode longer. I didn't specify this with SMB but added it myself after taking delivery.
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Old 02-26-2016, 05:54 PM   #5
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I can confirm the +/- 0.5 GPH as we have that setup on our SMB Sprinter. The only difference is that our A/C is a rooftop unit. The auxiliary alternator works great and we've had no problems with the emissions system using the high idle function. But,we don't idle as long as you've described.

The only suggestion I have is to add the Balmar external voltage regulator to the setup. This optimizes the charging for AGM batteries and holds the charging in bulk mode longer. I didn't specify this with SMB but added it myself after taking delivery.
Perfect. Worst case scenario of weekend trips in TX summer (night time low still in 90's sometimes) still sounds feasible, which is what I was trying to confirm. Will be checking into voltage regulator options at SMB or after-market. Thanks!

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Old 03-06-2016, 03:26 PM   #6
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Idling all night does not sound like a good idea to me. We have the same engine with the high idle and it is not as quiet as a Honda generator. It is not good for the engine. You would be far better off with a portable generator that would be cheaper to repair and operate. Also, if you do not have the penthouse, a rooftop AC is better that the Danhard from what I understand and a lot cheaper. 12V fans are what we use and find them ok in nearly all conditions and we have spent over 200 nights in our penthouse SMB in all temperatures. The Danhard and second alternator is a lot of stuff for a few nights a year.
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Old 07-22-2016, 02:39 PM   #7
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Idling all night does not sound like a good idea to me. We have the same engine with the high idle and it is not as quiet as a Honda generator. It is not good for the engine. You would be far better off with a portable generator that would be cheaper to repair and operate. Also, if you do not have the penthouse, a rooftop AC is better that the Danhard from what I understand and a lot cheaper. 12V fans are what we use and find them ok in nearly all conditions and we have spent over 200 nights in our penthouse SMB in all temperatures. The Danhard and second alternator is a lot of stuff for a few nights a year.
Thanks for the input. Will pay attention to wear on engine from this. Do you have more details on the impact of this? engine overheat? cat converter die early? I had assumed these vehicles are designed to idle forever. Already committed to try at this point though (2nd alternator and high-idle option). Rooftop AC doesn't make sense with Penthouse/bed option. It will be more than a few nights a year, including all-day hang-outs at certain events here in TX. I had forgotten about these, which are a dozen Saturdays per summer (parked all day serving as refuge from heat). Will definitely be using AC for many hours at a time while parked and need AC above and beyond what fans would offer.
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Old 07-22-2016, 04:52 PM   #8
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I had assumed these vehicles are designed to idle forever.
Not really. It's not good for any of the newer diesels. From the 2016 manual:
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If the vehicle is predominantly used for short-distance driving or is stationary for long periods, this could lead to a malfunction in the automatic cleaning function for the diesel par- ticle filter. This can lead to blockage of the diesel particle filter. This can also result in fuel collecting in the engine oil and cause engine failure
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