Dual alternator kit for the Ram Promaster announced

[Boxster1971]

Originally Posted by booster

We are using the same charger, with ARC50, and BMK. Have you read the threads on some of the weirdnesses that we have found in the charger programming and controls during our bench testing?

I scanned them a while back, but now that I've committed to a design with four Lifeline GPL-4CTs and the Magnum MS2000 I'll go back and read them again.

[avanti]

Mechanical installation complete:

IMG_6090.jpg

IMG_6091.jpg

(kind of hard to photograph).

I can now recommend Nations Alternator. The kit was first class. Everything was heavy-duty -- fit the Sprinter like a glove and no surprises.

Now on to the wiring...

[booster]

Can't tell from the pix, what does the new belt power off of?

[avanti]

Originally Posted by booster

Can't tell from the pix, what does the new belt power off of?

They provide a new pulley that bolts onto the front of the existing crankcase pulley, as well as a new tensioner. Very well done.

[Davydd]

Originally Posted by booster

I should have mentioned that our Chevy has internal regulator and the only connection to the PCM is a field voltage signal to modify idle, AFAIK.

I have read several places that the Sprinters have issues with any messing with the charging systems. Davydd may have even said ARV said the same thing. MB really does put the clamps on changes in the field with their systems.

Originally Posted by avanti

Many of those comments imply that it is actually DANGEROUS to connect to the Sprinter system. I have never seen evidence that this is true. (I don't think that is what ARV has said, btw). I think that those claims are overblown. What I AM saying is that on the latest models it is increasingly ineffectual. I suspect that this will not be limited to Sprinters going forward.

All you have to do is look it up. This is what Advanced RV said about dual alternators when they made over one of their rentals taking out the AGM batteries and putting in 400ah lithium ion batteries last year.

Candy Gets a Makeover

Most significantly, we swapped out the AGM battery system and installed a state-of-the-art lithium iron battery system with 400 amp-hour capacity. With the previous system, the Mercedes-Benz alternator was the primary source of power for charging the batteries. The alternator simply applied any power it had into recharging. There was no “specific to the battery” charge controller running the alternator, and we could only monitor voltage, which is not a good indicator of charge capacity with LI batteries. With the new system, we can monitor exact state of charge and real-time current usage.

I suspect this was not much of a concern early on. Rarely did any converter offer anything but two batteries max. Now the game has changed. I do know I wanted to add a second battery to my 2005 Pleasure-way Plateau and contacted Pleasure-way about it. They basically said absolutely no with the excuse that Mercedes Benz Sprinter installed controls and wiring for only one auxiliary battery. They seemed to have taken the guidelines at the time seriously. I suspect others pushed the envelope knowing or maybe not knowing what they were doing. And of course DIYers do what they damn please.

Dual alternators have been ARV's standard since 2013 as has lithium ion batteries. I don't think anyone has gone with anything else since other than one person who had since sold his ARV back when he could no longer travel. Until last December they were putting in Smart Batteries but that ended with their ecoOasis program. They installed a Nations 270 in mine and they claim they can charge at up to 300 amps. That is why I have the 4/0 wire. I've only seen about 240 amps reported but that would almost exceed a 3/0 wire I believe.

Clearly extremely fast battery recharging is the major benefit of dual alternators.

[avanti]

Originally Posted by Davydd

They installed a Nations 270 in mine and they claim they can charge at up to 300 amps. That is why I have the 4/0 wire. I've only seen about 240 amps reported but that would almost exceed a 3/0 wire I believe.

3/0 is correct in this application. I didn't just guess. From an ampacity perspective AWG 0 would have sufficed. The 3/0 was due to voltage drop concerns, and is adequate for a 3% drop, which will of course only happen early in the charging cycle and will be corrected by the Balmar regulator.

[booster]

Originally Posted by avanti

3/0 is correct in this application. I didn't just guess. From an ampacity perspective AWG 0 would have sufficed. The 3/0 was due to voltage drop concerns, and is adequate for a 3% drop, which will of course only happen early in the charging cycle and will be corrected by the Balmar regulator.

I checked the 3/0 on the Blue Sea circuit calculator, as mentioned earlier, and they use derating factors for conduit or sheathing to account for the loss of heat compared to bare cable. Even derated the 3/0 would be good for 290 amps continuous. 2/0 would easily carry the 200 max the you will see derated. So you are way, way, safe and conservative.

Davydd's does not need 4/0 either, as 3/0 would be good for 290 amps and he has a 270 alternator, that realistically gives 240 amps. The 4/0 on the Blue Sea calculator starts at 300 amps with derating, so ARV probably designed at 300 amps just in case someone put in a 300 amp alternator later, or ordered one as an option.

[Davydd]

It depends on what chart you look at. One I checked said 239 amps for 3/0. ARV also said up to 300 amps. Is it possible both alternators can simultaneously charge? I know I can charge at over 300 amps combining shore power, solar and engine idling at the same time.

[avanti]

First light!

Alternator came up without issues. Battery was full so I couldn't look at charging behavior yet. But, I did do one test: Turned on the inverter and the Air Conditioner. The Trimetric showed -132 amps. Started the engine. Trimetric immediately went to +1 amp (on idle). I'm liking this.

I am now running the A/C to get the battery down. Then we can get a look at charging.

[booster]

Originally Posted by avanti

First light!

Alternator came up without issues. Battery was full so I couldn't look at charging behavior yet. But, I did do one test: Turned on the inverter and the Air Conditioner. The Trimetric showed -132 amps. Started the engine. Trimetric immediately went to +1 amp (on idle). I'm liking this.

I am now running the A/C to get the battery down. Then we can get a look at charging.

Sounds nice!

132 amps at idle is really good for 200 amp alternator. Was the engine still on fast idle at the time? The probably also spin the alternator a bit faster than usual when they use it as an add on, besides. Do you have a tach so you can measure alternator speed?

[booster]

I have a really dumb question. The original discussion mentioned an XP270 alternator in the kit. Nations lists that alternator at 200 amps at idle.

Do you really have a 270 amp alternator? maybe? The pictures look like the XP270.

[avanti]

Originally Posted by booster

I have a really dumb question. The original discussion mentioned an XP270 alternator in the kit. Nations lists that alternator at 200 amps at idle.

Do you really have a 270 amp alternator? maybe? The pictures look like the XP270.

Uh, Yeah. Sorry for the confusion. The "200" number is indeed the spec at idle--it got stuck in my head and I kept typing it. Max amps is 270. Sorry.

[booster]

That would probably make it the same one that Davydd has, so you probably will see similar amounts of max output, nearing 240 amps, maybe a bit less with the 3/0 vs 4/0 cable.

[avanti]

Yes, I am pretty sure it is the same alternator. DavyDD mentions the Nations 270 above. Does ARV use the Balmar MC-614?

[booster]

Davydd had posted something with a pic that showed a built in add on regulator, but I don't recall if it had a brand on it. With lithium, his may be set for a fixed voltage and the lithium controls shut it off, but who knows.

[avanti]

Evening update:

1) It took exactly 2 hours running the A/C to get down to 50% SOC. Temperature was between 75 and 80, A/C was set to 66. I left the windows open.

2) Turned on the engine. At idle, the Nations/Balmar ramped up to 207 amps, as advertised.

3) Rev'd the engine to 3000rpm. Charge rate peaked at 248 amps and then drifted down slightly. Same ballpark as DavyDD has reported. I hand't expected my AGM bank to do this well. My ~5 minute test added 3% to the SOC.

I'm liking this.

[booster]

That is what I would expect from your system, and points out what I have been saying for a long time. If you have a 400+ah bank it doesn't matter if it is lithium, AGM, TPPL, as all of them are going to accept everything you can send to them with any kind of normal setup

I would guess you will lose something close to 20 amps when the alternator gets hot, which isn't a bad thing. The DC Power alternators do much better at high temps than the stock stuff and I think they list that one at 240 amps hot at speed.

Is you main 3/0 cable in sleeving, or bare? Fused on both ends?

[avanti]

Originally Posted by booster

Is you main 3/0 cable in sleeving, or bare? Fused on both ends?

It is in black plastic split loom. Only fused on the battery end. I researched this and that appears to be considered best practice.

[booster]

I only ask because the loom reduces the ampicity a whole bunch, just like conduit. I think your current will drop fast enough to take care of it, though. The charts list a 10 minute heat up window, and that is very conservative, I think.

The "rules" that I have seen recommended that cables be fused on any end that has a potential current feed, so with the alternator on one end and the batteries on the other, you could feed from both ends. If the wire shorts, there will be no protection from the alternator current. Our Roadtrek was even fused on both ends of the only 80 amps each way OEM setup.

[Boxster1971]

Nice job avanti!

Now I'm worried that the measly 4 gauge wire Airstream installed to charge the house batteries form the Sprinter won't be adequate for my planned 400 Ah AGMs.

Several folks on the Airstream forum have made the same battery upgrade I plan. I'll have to ask them some questions.