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

[markopolo]

I thought it would be useful to have a new topic that shows the many under-the-hood options available to use to generate power in an RV. I previously posted the four units in the E-Trek topic:

Mobile Electric Power Solution, Inc. (MEPS) - http://www.meps.com/products.html



Aura Systems Inc - http://www.aurasystems.com/pages/prod_intro.html



Raven Technology - http://raventechpower.com/



Fabco Power - http://www.fabcopower.com/generat/bgen.htm



and here are a few more options:

American Power Systems - http://www.americanpowerinc.com/sprinte ... rnator.htm
Alternator 3600 watts rated power. PDF file: http://www.americanpowerinc.com/images/ ... %20amp.pdf



Nations Starter and Alternator - http://www.nationsautoelectric.com/bosch.html



and here's a photo of a second alternator installed in a Sprinter



Mechman Alternators look interesting - http://store.mechmanhighoutputalternato ... ternators/



For my van, it looks like I could get 270+ amps at cruising speed or 165+ amps at actual idle speed for around $500 or 370+ amps at cruising speed and 200+ amps at actual idle speed for around $800.

370 amps x 14 volts = 5,180 watts ! ! !

Couple one of the high output alternators to a suitable sized inverter and you'll have lot of power

[markopolo]

Almost forgot - here's a PDF file from Sprinter Engineering and Compliance Support Team showing how and where to attach an aux alternator on the right side of the engine next to the oil pan. Download link: Sprinter Auxiliary Drive Retrofit (Diesel only)

[Mike]

Anything out there for those of us stuck with GM/Ford/Chrysler gasoline engines?

[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.

[markopolo]

Originally Posted by Mike

Anything out there for those of us stuck with GM/Ford/Chrysler gasoline engines?

I haven't looked for any detailed install docs for GM/Chevy, Dodge and Ford but I think there are products for those vans at the links above. The Mecman alternator I spec'd was for my GMC Savana Van.

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.

Like you, I'm thinking that they could be doing it with two alternators. Maybe combining the output from the two to get to the reported wattage of 3500 at idle and 5500 cruising.

Imagine having two of the Nations high amp alternators. Combined 400 amps at idle and 560 amps on the highway. 400 amps at 14 volts is 5600 watts..... at idle!

For a DIY van or upgrade to a converted van a single $500 Mechman alternator with 165+ amps at idle (in place of the OEM alternator) could be enough to run a Class B sized air conditioner or quickly charge a battery bank. You'd need suitable sized wiring and isolator or separator.

[booster]

It is interesting that the focus seems to be on generating 12volt power from the engine. I think it would be so much more efficient, in so many ways, to generate 120volt AC power. The only downside I could see would be that you would have 120volts under the hood, which is unusual, and could be a hazard.

Just the air conditioning will take about 100 amps at 12volts

Microwave maybe 75?

Fast charge batteries 100 amps

You would need much larger cables than starter cables because the need to carry the load continuously and need to not heat up. Maybe 4-0. A single 8-10 gauge wire could carry that much wattage as 120v AC.

I would just make sense to generate the 120v, use it for the 120volt uses as is, and convert it for battery charging, at the converter, with a much shorter, smaller cable. Alternators make AC power and change it to DC anyway, why keep changing it back and forth? What am I missing here?

The other thing to consider is that the big, big alternators I have seen rarely put out rated power in actual use, especially over longer periods of time. As they heat up from the large output, they lose efficiency quite quickly, so a 250amp alternator may only be 200 when it is running full out and hot. This is especially true on a vehicle that isn't moving, as you have much less cool air through the engine compartment. Things can get really hot while sitting still.

I think I just answered my own question, you would need a frequency converter to generate AC off of a variable rpm source to get anything resembling 60 cycle power.

[pattonsr]

The MEPS system inverts the DC to a pure sine AC that solves the variable rpm source problem. This system seems best for TV vans that do not have a large battery bank nor inverter/charger.

So it may be best to just use a second high amp alternator to feed DC straight to the house batteries. And then use a large inverter to provide pure sine AC to everything including the A/C. Of course, a large battery bank and a large inverter work best. I believe this describes the E-Trek package.

I still do not understand how driving all day feeding DC to AGM batteries does not result in overcharging the AGM batteries. Let's assume that one is on shore power and the batteries are close to being fully charged. What is the second high amp alternator doing to the AGM bank if I leave camp and drive for 10 hours?

[booster]

Originally Posted by pattonsr

The MEPS system inverts the DC to a pure sine AC that solves the variable rpm source problem. This system seems best for TV vans that do not have a large battery bank nor inverter/charger.

So it may be best to just use a second high amp alternator to feed DC straight to the house batteries. And then use a large inverter to provide pure sine AC to everything including the A/C. Of course, a large battery bank and a large inverter work best. I believe this describes the E-Trek package.

I still do not understand how driving all day feeding DC to AGM batteries does not result in overcharging the AGM batteries. Let's assume that one is on shore power and the batteries are close to being fully charged. What is the second high amp alternator doing to the AGM bank if I leave camp and drive for 10 hours?

If the MEPS system is putting out DC, as it appears, they are smart to invert it right away to make it easy to move in smaller wires. I wouldn't be surprised that running it to the batteries as AC and using a good 3 step charger would be a good option to save them. High current availability won't kill the batteries, so the size of the alternator doesn't matter, only the output voltage. We have found long drives on full batteries to be hard on our batteries, as our Chevy ran at 14.4-14.5 volts going down the road. Our wet cells would need water every 2500 miles or so, even if it was only a few days. We changed the regulator in the alternator to get it down to 13.9 volts and have been fine since.

So I guess my revised ideal system would be a very high amperage DC generator with very short wiring to the pure sign wave inverter, and then AC to all the AC stuff and a separate converter to charge the batteries.

In our case, it does get to be kind of an exercise in neat stuff, though, and nothing we would ever buy, I think. Since I would never consider using the van engine as a generator to run the air conditioning, the biggest load goes away. That is probably over 1/2 of the increased output needed if you left it in. An extra 180 amp alternator would supply plenty of 12v power for the other things and could be regulated to charge at the correct voltage. Running the van engine to use the microwave would be fine for me, and you would still get the battery fast fill up when needed.

[markopolo]

Great points mentioned - thanks.

I did some testing today and it looks like a new high amp output alternator would be beneficial in my van. It's not a necessity so I don't know if I'll spend the $$$ to do it though.

My 1997 van has a stock 124 amp alternator. I'm pretty sure it is a CS144 type and is the alternator that came with the van so it's 16 years old.
My 600 watt microwave oven power consumption rating is 900 watts. It draws 90 amps DC when run through my 1000 watt inverter. The inverter display actually shows 970 watts when I run the microwave oven so it is maxed out.

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

Fuel consumption noted on my ScanGauge today:
624 RPM .10 GPH
1,070 RPM .22 GPH
1,360 RPM .31 GPH

The test was to run the microwave with the engine running at the three different idle speeds to see the affect on voltage. I combined the 2 house batteries, the 2 chassis batteries (4 batteries total) and the alternator for the test.

The voltage quickly dropped to 12.9 volts at each RPM setting. Each time I tested I ran the microwave for 20 seconds and I tested it 2 or 3 times at each RPM setting. The voltage recovered right away but was a little lower after each test. From 14.4v at the beginning down to 14v by the end.

I expected the voltage drop to be different at the various RPM setting - anyone know why it was the same each time?
Anyone care to speculate why the voltage didn't recover to 14.4v right away?

When I ran the microwave on only the 2 chassis batteries with the engine running the voltage dropped to 12.3 volts. Again, it was the same result at each RPM setting.

Ideally, I'd like to see much less of a voltage drop with that very large 90 amp load. My guess is that I'd need an alternator that outputs 140 amps or more at idle to maintain 14 volts while running the microwave. What do you think?

[mlts22]

I think I remember Sportsmobile offering one of the above as an option, coupled with a transfer switch. The advantage of this would be that when going down the road, one could have the rooftop A/C and the dash A/C on (which is a must here in Texas). Then, when parked, flip the diesel generator on and one wouldn't have to run the engine for long hours idle.

[booster]

Originally Posted by markopolo

Great points mentioned - thanks.

I did some testing today and it looks like a new high amp output alternator would be beneficial in my van. It's not a necessity so I don't know if I'll spend the $$$ to do it though.

My 1997 van has a stock 124 amp alternator. I'm pretty sure it is a CS144 type and is the alternator that came with the van so it's 16 years old.
My 600 watt microwave oven power consumption rating is 900 watts. It draws 90 amps DC when run through my 1000 watt inverter. The inverter display actually shows 970 watts when I run the microwave oven so it is maxed out.

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

Fuel consumption noted on my ScanGauge today:
624 RPM .10 GPH
1,070 RPM .22 GPH
1,360 RPM .31 GPH

The test was to run the microwave with the engine running at the three different idle speeds to see the affect on voltage. I combined the 2 house batteries, the 2 chassis batteries (4 batteries total) and the alternator for the test.

The voltage quickly dropped to 12.9 volts at each RPM setting. Each time I tested I ran the microwave for 20 seconds and I tested it 2 or 3 times at each RPM setting. The voltage recovered right away but was a little lower after each test. From 14.4v at the beginning down to 14v by the end.

I expected the voltage drop to be different at the various RPM setting - anyone know why it was the same each time?
Anyone care to speculate why the voltage didn't recover to 14.4v right away?

When I ran the microwave on only the 2 chassis batteries with the engine running the voltage dropped to 12.3 volts. Again, it was the same result at each RPM setting.

Ideally, I'd like to see much less of a voltage drop with that very large 90 amp load. My guess is that I'd need an alternator that outputs 140 amps or more at idle to maintain 14 volts while running the microwave. What do you think?

You could have some wire size or isolator drop issues, so it would depend on where you are checking your voltage. Knowing what the voltage is at the alternator and at the batteries would be useful to find out where the losses are. As far as recovery goes, if the alternator is getting hot, it will reduce voltage, and it would take a while to cool off. Perhaps that is where your recovery delay is coming from.

[markopolo]

The voltage reading was coming off the inverter display. The house and chassis batteries were combined two ways simultaneously through the isolator and also through a manual battery switch bypassing the isolator. Voltage shown on the inverter was 14.4 as I rolled out of the garage with the isolator bypassed.

I was also trying to get sound level readings with a db meter but it was too windy to get accurate measurements. It was a hot day and I ran the engine with the van stationary for maybe 30 to 45 minutes and the engine did get hot. It made me wonder about idling for long periods of time.

Thanks for the idea re: measuring voltage under the hood. I'll have to do that next.

[pattonsr]

Assuming the E-Trek is really using a hi amp Nations alternator to feed the house bank, then I wondered how it could be shut down if the internal voltage regulator had a problem or the battery bank was being overcharged. Blue Sea makes a nice 12v disconnect but it works only with an external regulator. The problem is that the alternator will think the battery voltage is low and crank the amps up if the battery bank is disconnected resulting in overheating of the alternator. The Blue Sea device will keep the external regulator happy but does not work with alternators that are internally regulated like the 280 amp Nations. I may be wrong but this is what I currently think.

I am now leaning towards the MEPS design to eliminate any of the above problems. The MEPS is just like a pure sine Honda or Yamaha inverter generator (e.g.the 2000 watt models). Let the MEPS connect to the transfer switch and provide pure sine power while driving or stationary. It is just like being on 30 amp shore power. No chance of harming the battery bank since the expensive Magnum or Outback inverter/charger does the charging. The only raw 12v DC amps are from the Sprinter alternator via a Sure Power 1315.

It will be interesting to see what the E-Trek is using and actual long term results from real customers. Until I see some results, I am not sure I would want my large expensive battery bank to be at the mercy of a high power alternator without some ability to disconnect it.

[Mike]

This is getting interesting, but also a bit confusing for me.
So, you would use one of the MEPS alternators to hit the transfer switch like a shore power cable, and let your Magnum or Outback 3 stage/smart inverter/converter charger feed it to the house batteries that way? You would also let the chassis' standard alternator hit the batteries more directly (12VDC) through a Sure Power 1315 separator? You could also add a PV panel and a charge controller if all that isn't enough. Could you feed raw PV panel output through the transfer switch as well, and use the Magnum or Outback charging system to feed it to the batteries as required? I would think you could make the PV current one directional with diodes like an isolator, or something similar. That would amount to 3 separate charging sources, 2 from running the engine, and the third renewable. It would use the existing converter/charger to protect the batteries from overcharge as you suggest.

[pattonsr]

Actually the MEPS system is run to the transfer switch in place of the Onan 3600 propane generator (or the 2500 propane generator). It is just a different type of generator. The Magnum or Outback are not converter chargers. They are inverter/chargers which are much different than the converters found on most Sprinters or trailers.

The use of a Sure Power 1315 is how most Sprinter Conversions are done. The Mercedes 220 amp alternator is fed to the starter battery and then passed on to the house bank via a combiner like the 1315.

Yes one could add in solar which would charge the house bank via 4 stage charging. The solar controller goes straight to the battery bank. The transfer switch is for shore power/on board generator selection. Also there is not much roof space for solar panels to make much of a difference if the battery bank is very large. I would rather take along a Yahama 2000 converted to run on propane for additional backup. It would look like shore power. Besides, my first choice with limited roof space is a RF Mogul satellite dish and then see if any solar panels would fit

A good solar controller takes care of the battery charging just like the Magnum or Outback. Or for that matter a converter like the IOTA which has multiple stage charging. The key feature is multi stage charging which is especially important if AGM batteries are used.

Remember all of this only makes sense if one is trying to produce an all electric Sprinter like the E-Trek. Whether that is a good idea is also up for debate.

[Mike]

I see. Since I have an older 190P with an Onan 2.8KW generator, and 2 AGM coach batteries, I was thinking I could add an under hood PTO generator to charge (while driving or idling) 2 more AGM batteries doubling my battery bank to 4, and add a large capacity inverter to use the battery power to run just about everything except the roof air. As for running your A/C off of an inverter (everyone's dream?), markopolo did the math a few years ago on the size of the battery bank necessary to run the A/C, and the problem wasn't necessarily the number of batteries (although finding space for them and their added weight would be no small feat) required for it, but the time it would take to recharge them after use. The extra high output TPO alternator might help solve that problem, or at least it might cut the recharge time down a bit. If I ever replace the Dometic A/C unit I have now, I think I'd go with a smaller BTU and lower power consumption model like the one markopolo has installed in his rear window. I don't need the van to be frosty inside, just comfortable and perhaps with slightly less humidity.
I would still have the Onan in place as the backup you suggest (Yamaha/Honda 2000W).

[pattonsr]

Mike,

Finding space for more batteries is why it is hard to increase the number beyond what the manufacturer had in mind.

Great West Vans and Advanced RV have put battery compartments under the floor in the rear. Advanced RV has on their extended Sprinter 4 group 31 battery compartments as well as a storage box. They say if the underneath Onan generator is eliminated, they can add two more battery compartments and still keep the storage box.

The E-Trek has 8 200 amp 6v batteries (6 in the rear and 2 in the engine compartment) which is 800 12v amp hours. If the batteries are AGM, then 400 useful amps (50% discharge).

If money is no object, then I can have on the Advanced RV 6 12v 100 amp Lithium. They total 600 12v amp hours which gives one around 500 useful amps (83% discharge) which is comparable to 10 E-Trek batteries. Lithium batteries are roughly 1/3 the weight of AGM. Plus one needs less (6 instead of 8 or 10) so a great weight savings in the rear of the Sprinter. An engine generator also removes the weight of the Onan 3600 generator in the rear.

With that much battery capacity to replace, one has to make sure that a robust charging system is in place. The Magnum or Outback charger sections are 125 amps and do not taper off as most converter chargers do. AGMs have a Bulk phase to about 80% then a much slower Absorb phase which is why most people get solar to finish off the AGMs rather than run the generator forever.

Lithiium batteries have no such restrictions and do not care if they ever get fully charged. So driving for over four hours with an engine generator should replace the 500 useable amps of my Lithium example. Their downside is the initial cost which can be somewhat mitigated by many more charging cycles than AGM assuming they perform as promised. Of course, time will tell. The bright side is that one can easily fall back to AGMs since the rear under compartments are still there.

Barry

[booster]

You can get more battery capacity into a Chevy 190. Folks have done it a couple of different ways. Campskunk duplicated the existing tray design, behind the passenger rear wheel setup, on the driver side. Dick Tillinger did similar, but did both sides, because he has the two 6 volt batteries in front of the passenger rear wheel. He used two more 6 volts batteries. On ours, we left the battery behind the passenger rear wheel, but modified the battery location in front of that wheel to take two 6v batteries, similarly to Roadtrek's setup, but able to take the taller GC batteries that are 260AH. We also made it so the starter battery can run the compressor frig if we want. That allows the 12v switch to be off in the van when we are gone, eliminating the parasitic losses. We now have a 115AH deep cycle as our starter battery that we can use about 60AH of for the frig, running it for about 48 hours. Currently, we have 260 + 115 + 60 = 435AH of coach batteries, which is pretty good compared to the 180AH it came with (and it had the optional second battery). We do also have the Onan and 200 watts of solar. Hopefully, we will good for quite a while off grid, even with the compressor frig.

[markopolo]

Originally Posted by Mike

I see. Since I have an older 190P with an Onan 2.8KW generator, and 2 AGM coach batteries, I was thinking I could add an under hood PTO generator to charge (while driving or idling) 2 more AGM batteries doubling my battery bank to 4, and add a large capacity inverter to use the battery power to run just about everything except the roof air. As for running your A/C off of an inverter (everyone's dream?), markopolo did the math a few years ago on the size of the battery bank necessary to run the A/C, and the problem wasn't necessarily the number of batteries (although finding space for them and their added weight would be no small feat) required for it, but the time it would take to recharge them after use. The extra high output PTO alternator might help solve that problem, or at least it might cut the recharge time down a bit. If I ever replace the Dometic A/C unit I have now, I think I'd go with a smaller BTU and lower power consumption model like the one markopolo has installed in his rear window. I don't need the van to be frosty inside, just comfortable and perhaps with slightly less humidity.
I would still have the Onan in place as the backup you suggest (Yamaha/Honda 2000W).

You could get by with a new high capacity inverter charger with a transfer switch and some wiring upgrades. In the past you've tended to drive a lot so you recharge the batteries that way. Your two AGM's would provide enough power for early morning coffee and a toaster etc. You have the advantage of being able to run your generator when it is suitable.

If your alternator fails then replace it with a better one. It looks like your 2002 5.7L Chevy RT van was available with either the standard 105 amp Delco AD230 alternator or the optional Delco AD244 130 amp alternator. There should be a Service Parts Identification (SPID) sticker on your van with a list of RPO codes. This post: http://www.classbforum.com/phpBB2/vi...hp?f=17&t=1825 explains how to enter the codes in the decoder. It will list your alternator amps (probably listed as "generator"). My vans sticker was on the passenger door.

This AD-244 165 amp alternator from Nations http://nationsautoelectric.com/165-amp- ... icles.html is advertised as producing 100 amps at idle and is $190. Looks like a nice upgrade but you might have to upgrade your Hehr isolator. You'd have to confirm that the alternator would fit your van.

I think I might buy an alternator with the approximately the same specs as that one (165A/100A idle) if I find a brand new one on sale. It is not unreasonable for me to expect to have to replace my alternator at some point and I'd hate to have to accept one with OEM specs available locally and miss the opportunity for a nice performance upgrade. I'd need a new isolator with the higher output alternator also.

These upgrades add up quickly. $600 (inc. taxes and fees) for two AGM's, $200 alternator, $150 isolator + wiring and taxes and you might be at $1,200 or so Add something like a Xantrex Prosine 2.0 inverter/charger and some labor and you'll have spent $3,000.

[Mike]

I recall talking to a guy at Hehr Power in DFW, TX a few years ago, when I picked up the replacement isolator on a trip that year, and he said they always under stated the capacity of their products by a good margin, so my existing isolator might do the job as it sits. I'll have to dig through my old emails and see if I can find it. I may have posted the numbers on here, back when I was going through that post-purchase fix process. Just another in a long list of repairs. Buying used has it's challenges.
It's the devil I know, though.

Have AGMs gone up that much? Seems like I bought my EPM/Deka AGMs 2 years ago for closer to $450.
btw, what's your hourly labor fee for installing that system you spoke of in your previous post? just in case we're ever in the neighborhood?