Under the hood generators, dual alternators etc.......

[markopolo]

The AGM I bought is up about $30 in 2 years. I just looked at CDN Tire and found a slightly cheaper group 31 at $260 x 2 plus 2 Core charges $30 plus tax = $617

I remember working in the back of my RT near the AC panel ......... It's kind of tight back there I could still be useful though...... passing you tools and stuff

[Mike]

I just bought an SL34MAGM Duracell (East Penn M) deep cycle AGM to use as a starting battery, from Sam's Club last month for $114US - totalled around $121 - and traded in the CTC wet cell starting battery for it (no core charge). I had to stop at AutoZone and pick up a set of top to side mount terminal adapters, for another $5 or so. It's only 55ah at 20 amp hour rating, but it's probably less likely to be completely trashed if it runs below 50% charge a few times, particularly while it sits in the driveway in the Roadtrek.
They had some bigger (GC2AGM, GR31DTMAGM) ones available (strangely, no GR27) for pretty decent prices, each around $179 + 6% tax + core charge if you don't have a trade-in.
http://www.samsclub.com/sams/search/sea ... tid=232335

The trick is getting the more expensive deep cycle or golf cart ones back across the border, but 48 hours away allows $800 per person, so take a weekender and buy a couple. I would try just bringing one back at that price though, and even if they made me pay the extra 13%, it would be worth it.

[markopolo]

That's a savings of about $200 on the batteries - good to know, thanks for the info.

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Here's an article from 1996 about Aura Systems Inc.'s combined starter / generator that can produce 4,000 watts. At the time it was thought all new cars could have such a device under-the-hood by 2006 .................. http://www.nytimes.com/1996/03/03/automobiles/will-cars-ride-to-the-rescue-when-houses-lose-power

[Mike]

Originally Posted by markopolo

That's a savings of about $200 on the batteries - good to know, thanks for the info.

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Here's an article from 1996 about Aura Systems Inc.'s combined starter / generator that can produce 4,000 watts. At the time it was thought all new cars could have such a device under-the-hood by 2006 .................. http://www.nytimes.com/1996/03/03/automobiles/will-cars-ride-to-the-rescue-when-houses-lose-power

Yeah, for a Sam's Club $40/year membership, you'll make that back on your next fill up at their gas station alone. Not everything there is a deal, so knowing your basic prices for a single item is important. It helps dispel the mantra that "if I'm buying it in bulk, it must be cheaper". In fact, the price of much of the stuff they sell in bulk, is the same as the total price if you had bought the same number of single items.
Isn't the auto-alternator/generator becomes house backup generator principle used by some current electric car makers as a selling point?
The down side of using the vehicle as the power source for the home is, you're stuck in your driveway keeping the furnace or fridge/freezer running, and can't use the vehicle to go for supplies and other things it was designed for. Still, as an RV application it makes a huge amount of sense to use something that can produce scads of current at the engine's idle speed. Even if it's slightly less efficient than a portable generator or solar + battery + big inverter system, it's so much easier and more convenient to use for short periods of high energy draw requirement (like coffee in the morning, if your batteries have been drained overnight by some other application, and it's too early to run the generator).

[markopolo]

OK, not exactly on topic but here's an update to this post: http://www.classbforum.com/phpBB2/vi...&t=2668#p15768 about my alternator voltage when running the microwave oven.

I ran the microwave for three 25 second tests. Engine RPM had no noticeable effect. The voltage readings were taken at the isolator posts with a voltmeter.

Before running the microwave oven:
Alternator (isolator center post): 15.3 volts
Chassis battery (isolator post): 14.5 volts
House battery (isolator post): 14.5 volts
Inverter display inside the van: 14.4 volts
Scangauge display: 14.1 volts

After running the microwave oven:
Alternator (isolator center post): 15 volts
Chassis battery (isolator post): 14.2 volts
House battery (isolator post): 14.2 volts
Inverter display inside the van: 14.2 volts
Scangauge display: 13.9 volts

That 90 amp draw on the batteries, even though short duration, does have a observable impact on the batteries. I did not record the voltages when the microwave oven was actually running this time, only before and immediately after. Next test will be to measure the voltages at the isolator posts after driving an hour or so (if I remember). I want those numbers to see what effect heat buildup has on the alternator output.

[markopolo]

Originally Posted by pattonsr

I now believe the E-Trek is using a Nations 280 amp unit which was mentioned previously by markopolo as a possible contender. The use of the word generator is I believe for marketing reasons since people want to know where is the generator. When told it is under the hood they are satisfied.

I am now 99% sure Roadtrek is using a second DC alternator under the hood and not an AC generator. I was fooled by the use of the word generator and the display of an AC generator in the early promo videos that were released. Link showing the generator: http://www.classbforum.com/phpBB2/vi...p=12836#p12835

One good thing is that I sure have learned a lot about other advanced under-the-hood systems that I probably would not have researched if I had thought they were using a 2nd alternator under-the-hood. I had some safety concerns about end users working with 110 volts AC under the hood but now think it is a DC system.

I'm sure the good folks at Roadtrek had a few chuckles about all this. It certainly kept the online discussions going longer than usual for a new Class B model.

[markopolo]

I read through some posts on Facebook that indicate to me that the E-treks or semi E-Trek units are performing as advertised on the battery draw down. One guy has a four battery (I think) unit and ran the air conditioner for 4 hours. That's twice as good as what I think my van could do. I guess-timated I could get maybe 2 hours on 2 batteries but only having less than half the cooling BTU's that a Roadtrek has.

It's a good demonstration of Peukert's Equation in action. More batteries sharing the load is much easier on the batteries.

In time I think we'll see some re-charge times posted but it looks like they're performing well. It would not surprise me at all if dual alternators and large inverters and battery banks become a trend.

[Mike]

Originally Posted by markopolo

I read through some posts on Facebook that indicate to me that the E-treks or semi E-Trek units are performing as advertised on the battery draw down. One guy has a four battery (I think) unit and ran the air conditioner for 4 hours. That's twice as good as what I think my van could do. I guess-timated I could get maybe 2 hours on 2 batteries but only having less than half the cooling BTU's that a Roadtrek has.

It's a good demonstration of Peukert's Equation in action. More batteries sharing the load is much easier on the batteries.

In time I think we'll see some re-charge times posted but it looks like they're performing well. It would not surprise me at all if dual alternators and large inverters and battery banks become a trend.

I wonder how the owners are recharging, by idling in place (sort of the method this was supposed to provide?), or are they recharging by the touring method (which has always worked for me)? Recharge times, and battery durability (after many discharge/charge cycles) may become more important issues. I also wonder what type of batteries provide that amount of amperage to run an air conditioner? We have to assume (or do we?) that A/C units have become more efficient over the years, providing more cooling/drying for less amperage, than their predecessors.

[markopolo]

I've been looking online at higher amp alternators trying to sort through performance claims etc. I found a CS144 type 200 amp unit for $270 that would fit my van. Others cost much more. So I did some more research and it looks like I don't need to spend that much to get the extra amps that I want.

These are the performance curves from an ACDelco CS144:



I currently have the one in the middle (CS144 124 amp) but I think the output has dropped as it gets older.

You can figure out the generator (aka alternator) shaft RPM by first dividing the Crankshaft Pulley Diameter by the Alternator Pulley Diameter to find out the ratio.

It looks like I have a 7.5" crankshaft pulley and a 2" alternator pulley (I measured them). 7.5/2=3.75 ratio

Multiply the engine RPM by the ratio to figure out the alternator shaft RPM.

I previously installed a switch on the dash to allow me to choose from 3 different idle RPM speeds, 624, 1070 or 1360.

624 engine rpm x 3.75 ratio = 2340 alternator shaft rpm
1070 engine rpm x 3.75 ratio = 4012 alternator shaft rpm
1360 engine rpm x 3.75 ratio = 5100 alternator shaft rpm

When you look at the chart above you can see the stock 140 amp CS144 should work well with the first two idle speeds. (I don't use the 1360 rpm at idle as it is kind of loud )

At 624 rpm I would get a very respectable 105 amps and at 1070 rpm I would get an awesome 130 amps

A new Remy 140 amp CS144 alternator is only $99 or a new ACDelco 140 amp CS144 alternator is around $125. Both cost a lot less than a high amp alternator and the fast idle switch didn't cost me anything: viewtopic.php?f=12&t=2295 And I wouldn't have to upgrade my isolator.

All I want is an additional 90 amps or so over whatever the van consumes when idling so a new 140 amp CS144 should do the job (or close enough).

[markopolo]

The new alternator showed up at my door today.



I'm looking forward to this project but won't start it yet. I've been thinking of a dual alternator setup but I haven't been able to source the mounting brackets.

It looks like I may have to remove the pulley from my old alternator and put it on the new one. The new pulley is close to 2.25" diameter and I think the old pulley is 2".

New pulley 2.25"
624 engine rpm x 3.33 ratio = 2078 alternator shaft rpm
1070 engine rpm x 3.33 ratio = 3563 alternator shaft rpm
1360 engine rpm x 3.33 ratio = 4528 alternator shaft rpm

Old pulley 2"
624 engine rpm x 3.75 ratio = 2340 alternator shaft rpm
1070 engine rpm x 3.75 ratio = 4012 alternator shaft rpm
1360 engine rpm x 3.75 ratio = 5100 alternator shaft rpm

With old pulley at 624 rpm idle I would get 105 amps and at 1070 rpm I would get 130 amps.
With new pulley at 624 rpm idle I would get 100 amps and at 1070 rpm I would get 125 amps.

I haven't put my calipers on the old pulley to measure it yet as it is hard to get to. I plan on upgrading the wiring as necessary for the new alternator.

[markopolo]

Just bumping up this topic

Looking back at older posts, I can see that I was quite interested in this. Interested enough to install the fast idle switch and interested enough to purchase an alternator with an output at idle that could provide (or come close to) satisfying what the microwave oven needs.

I think I lost interest when I realized it would would be very unlikely for me to ever idle the engine for long term load like air conditioning while parked at a campsite. Come to think of it, I probably wouldn't want to do that with a generator either!

So I'm going to try to get excited by this concept again and move that new alternator off the bench and install it in the van. I wish batteries cost less Locally, 2 x 100Ah AGM's would set me back $500 if I factor in core charges and taxes etc. Then more for the wiring.....

But I'm getting ahead of myself again. After the bike rack project I really should install that alternator.

I was thinking of paralleling a relay type isolator (across the terminals) with my existing diode type isolator that I saw in a store near here. It cuts in at 13.3v and cuts out at 12.8v and is rated 140A continuous / 170A intermittent. $70. No specs on whether there's any parasitic load

I'd parallel it for ease of installation and redundancy. The new isolator is not a known brand - "Aopec".
New alternator is 140A
Existing isolator is 120A
I think the new relay type isolator would eliminate the voltage drop that occurs with the diode type isolator.

Any thoughts on the parallel installation?

[booster]

The only thing on the parallel that comes to mind is that the diode isolator has some resistance to it, so in a pure parallel setup (both ends of the circuits tied together), you will have more current going through the relay separator than the isolator. You might get over the rated on the separator depending on how it worked out.

If you are running parallel systems without the alternator ends tied together, just the battery ends, you wouldn't have that issue.

The alternator working through the lower resistance will be doing more of the work, but that shouldn't matter, I think.

[markopolo]

Oops, maybe I bumped the wrong topic.

I'd go with one alternator. Just replacing the older 120A that is under the hood now with the brand new 140A unit.

[Davydd]

The second alternator under the hood means a major thing to me - get rid of the Onan generator. But it means little unless you have a large inverter and large battery bank because I also don't see it as a substitute for an Onan generator under the idea of running it while camping. It would mean faster charging while driving and an emergency backup but not an expected use feature. The other thing I desire to achieve is full use of the B in the same way whether boondocked or on shore power. In other words, appliances work and no half-dozen dead 120VAC outlets without running an Onan generator or idling.

I could probably get as much air conditioning as I want or historically need with my set up but it has never been a primary consideration. The most I have run an air conditioner in all our travels at one time was maybe the three hours we ran it in South Padre Island because the B needed to be dried out from the excessive humidity that was overwhelming us. I most likely try not to camp anywhere and when air conditioning is needed and if I do get caught up in that situation by circumstances not under my control or by miscalculation then I would simply head for an electrical hookup campground. We end up at them more times than not anyway.

This may be Sprinter specific as I don't know about Chevy or Ford, but Mercedes Benz with all their electronic and computer circuitry doesn't like that being messed with. The second alternator is an independent work around to power the house systems with full control in how to do so.

[gerrym51]

Originally Posted by Davydd

The second alternator under the hood means a major thing to me - get rid of the Onan generator. But it means little unless you have a large inverter and large battery bank because I also don't see it as a substitute for an Onan generator under the idea of running it while camping. It would mean faster charging while driving and an emergency backup but not an expected use feature. The other thing I desire to achieve is full use of the B in the same way whether boondocked or on shore power. In other words, appliances work and no half-dozen dead 120VAC outlets without running an Onan generator or idling.

I could probably get as much air conditioning as I want or historically need with my set up but it has never been a primary consideration. The most I have run an air conditioner in all our travels at one time was maybe the three hours we ran it in South Padre Island because the B needed to be dried out from the excessive humidity that was overwhelming us. I most likely try not to camp anywhere and when air conditioning is needed and if I do get caught up in that situation by circumstances not under my control or by miscalculation then I would simply head for an electrical hookup campground. We end up at them more times than not anyway.

This may be Sprinter specific as I don't know about Chevy or Ford, but Mercedes Benz with all their electronic and computer circuitry doesn't like that being messed with. The second alternator is an independent work around to power the house systems with full control in how to do so.

I 100 percent agree with Davydd-never thought i'd say that

[bikerbill]

Lets start off with a VERY important question. Does your Sprinter have the mounting bracket already in place for the 2nd alternator? If not you MAY be looking at a rather complex installation. What I am led to understand that is when the van is ordered with the optional mounting bracket the factory build also changes the radiator lines. If not ordered from the factory it CAN be retrofitted but at a much higher expense due to "plumbing" changes. Just an FYI.

[Davydd]

Originally Posted by bikerbill

Lets start off with a VERY important question. Does your Sprinter have the mounting bracket already in place for the 2nd alternator? If not you MAY be looking at a rather complex installation. What I am led to understand that is when the van is ordered with the optional mounting bracket the factory build also changes the radiator lines. If not ordered from the factory it CAN be retrofitted but at a much higher expense due to "plumbing" changes. Just an FYI.

Bikerbill, Are you addressing this to me? Marko, Booster and Gerry are not into Sprinters. To answer the question, every Advanced RV is ordered with the customer's input and desires and Advanced RV requirements for the conversions. So if the second alternator is part of the deal then the proper Sprinter gets delivered I would assume. The details I don't know. Since Advanced RV made a decision to install second alternators I am aware of only one customer that didn't want one. It's a longer process for sure. I had to wait 5 months for delivery before they could get started with the build. Then a lot of other things had to go into design, research, development, mockup and testing that has caused a 4 month build process and moved at least two Bs ahead of me that I know of. I had anticipated and planned for all this as I did not want delivery until after the first of the year.

I don't know what Roadtrek's practice is in this regard. I kind of understand or think they get Sprinters in as a fleet of one kind they want to offer, put them on the line and build per their options offered. If they did not order Sprinters with brackets in place would that mean they'd have to diddle more than necessary with the installation and pass the cost onto the customer?

[gerrym51]

Originally Posted by bikerbill

Lets start off with a VERY important question. Does your Sprinter have the mounting bracket already in place for the 2nd alternator? If not you MAY be looking at a rather complex installation. What I am led to understand that is when the van is ordered with the optional mounting bracket the factory build also changes the radiator lines. If not ordered from the factory it CAN be retrofitted but at a much higher expense due to "plumbing" changes. Just an FYI.

hey William how are you doing. imiss your posts on the roadterkkers facebook page but do read them on the sprinter roadtrekkers page.

[bobojay]

What DavyDD brought up about messing with the stock Sprinter electrics. Adding a higher output alternator to replace the factory chassis supply unit, the top of the engine one, is not possible as the control of that alternator is in the PCM programming which is only accessible via a dealer. Actually don't know if it can even be changed at all by a dealer.....

Yesterday Jim Hammill the president of Roadtrek, on a Facebook post, stated that RT is one of the largest purchasers of Sprinters . Don't know if he was talking about North America or the world. Anyway, I truly believe in a lot of cases RT buys some leftover fleet units that other buyers don't take that were not originally intended as RV upfits, so in some cases the final RV purchaser may be getting a somewhat cobbled together unit with a non MB factory second alternator setup. I know they used to do that with some Chevy vans, although PleasureWay used to do that also. Our 2007 PW Lexor was an example of this practice.
My point is I very much like the fact that Advanced RV orders their Sprinters in on a per customer want basis, and I know this would be hard to do with a higher volume upfitter

[markopolo]

I've got no idea about most of that.

As far as I can determine from forum posts and Facebook etc. RT has used a good quality aftermarket high amp second alternator from the beginning of the engine as a generator idea. It seems to be a 1-wire type setup and you rev the engine to activate the second alternator. It's not controlled by nor interferes with the Sprinter electronics. I don't remember reading about any variations in that. That's my take on it - I don't know for certain though.