22 replies to this topic

[THE TRAILERKING]

I am going to be building a motorhome conversion in a 1993 MCI 102C3. What I would like to know is what is the better generator to go with, Onan or Powertech? Also what brand of inverter/charger and transfer switch to go with.

[Bill B]

Shiny - kinda open there. Need to know what you want to do. One A/C or 2, microwave, refrig - gas or as many are doing residential, batteries and sizes, 12 volt or are you going for larger? Fuel - propane, gas or diesel? How much do you plan on running off the inverter?

Johnny 5 say - "Need more input"

[THE TRAILERKING]

Shiny - kinda open there. Need to know what you want to do. One A/C or 2, microwave, refrig - gas or as many are doing residential, batteries and sizes, 12 volt or are you going for larger? Fuel - propane, gas or diesel? How much do you plan on running off the inverter?

Johnny 5 say - "Need more input"

Sorry for not enough info. I was thinking of a ducted A/C from the basement. Microwave. House size fridge. Some electric heaters(maybe two) 12 volt batteries(10-12). I thought it would be 12 volt inverter, why is there higher voltage and any benefits? Generator would be diesel for sure to run off the coach tank. Fridge for sure off of the inverter, maybe electric heater on occasion, T.V

[Bill B]

OK - that is a bit better. You will need nameplate ratings for the stuff. AC is going to be what size? a rough rule is 12,000 btu = 1 ton = 1 HP = 12 amps at 120v. Microwave - 1.6 kw (pretty standard kitchen size. House size fridge, what is the startup load and how long are you planning on running on batteries before starting the genny. Diesel, good - good economy, heavy though. electric heater on batteries - ouch - Bus heater - hydronic (hot water) off the engine - shower hot water (free) diesel heater for the water and bus heat?? Think Esper or Aquahot.

Is the bus 12 volt now or 24 volt?? inverters come in 12 - 24 - 48 volt flavors. The higher the voltage, the smaller and easier it is to wire and there are less wire losses in the system. 100 amps at 12 volts - 1200 watts is 50 amps at 24 volts and 25 amps at 48 volts. 12 volt has been around since we left 6 volts back in the 50's. Most off grid house systems use 48 volt batteries. (3 sets of 4 - 12 volts or better 8 - 6 volts)

Its a great project but now - before you get started or to deep, got to start thinking of the systems that you want. Another thought - put everything on slide out trays so that you can pull out and work on it.

[THE TRAILERKING]

OK - that is a bit better. You will need nameplate ratings for the stuff. AC is going to be what size? a rough rule is 12,000 btu = 1 ton = 1 HP = 12 amps at 120v. Microwave - 1.6 kw (pretty standard kitchen size. House size fridge, what is the startup load and how long are you planning on running on batteries before starting the genny. Diesel, good - good economy, heavy though. electric heater on batteries - ouch - Bus heater - hydronic (hot water) off the engine - shower hot water (free) diesel heater for the water and bus heat?? Think Esper or Aquahot.

Is the bus 12 volt now or 24 volt?? inverters come in 12 - 24 - 48 volt flavors. The higher the voltage, the smaller and easier it is to wire and there are less wire losses in the system. 100 amps at 12 volts - 1200 watts is 50 amps at 24 volts and 25 amps at 48 volts. 12 volt has been around since we left 6 volts back in the 50's. Most off grid house systems use 48 volt batteries. (3 sets of 4 - 12 volts or better 8 - 6 volts)

Its a great project but now - before you get started or to deep, got to start thinking of the systems that you want. Another thought - put everything on slide out trays so that you can pull out and work on it.

What I'm concerned about right now is which one is better, Onan or Powertech? I was thinking of a 12kw whether I need that large or not. I know the Powertech runs at 1800 rpm which is a lot slower than Onan. I wasn't concerned about the 24v bus voltage because house batteries were going to be seperate. But if it is better to run 24v 0r 48v inverter that's fine but which brands are better to go with?

[Bill B]

At 1800 rpm, the life is 3 - 4 times longer and usually much quieter. (quiet is good). 12 KW is alot. I can run our entire S and B off of that (10KW actually) including electric hot water tank, well pump, and everything else. As a kinda reference, look at your all day / every day pipeline welders. 1800 rpm diesel for most of them. You should get like 15000 hours out of that.

I would only look at the pure sine wave inverters. Just too many issues with the MSW's. I would look at:
Magnum - http://www.magnumene...terChargers.htm
Outback - http://www.outbackpo...erter/off_grid/
Sunnyboy - http://www.sma-ameri...-inverters.html

These are all good units - many of them are designed for grid connections and such. A good magazine, if you can find it, Home Power can do a lot to educate you on this stuff. http://homepower.com/home/

They get into a lot of this stuff and things like battery differences, inverters etc.

Fun stuff Shiny.

Also check out Jack Mayers web page - http://www.jackdanma...l_and_solar.htm - He has put a ton of work into it and is a real good reference.

[THE TRAILERKING]

Good stuff..........Also what about using 10 or 12 bateries? AGM or Acid? I hear there may be a lot of risk of corosion problems with venting of acid batteries.

[bobsallyh]

Although I haven't looked for a couple of years, but when working on race teams, all transport haulers used Kubota diesel gennys. Could not be beat. Run all day/night in the garage areas, a week at a time, couldn't hear them etc. Onan requires so much TLC in my opinion.

[Ann N Gene]

I have been told by my trusted truck mechanic that my onan diesel genny is actually a Kubota diesel and a great little engine. Not much to go wrong if it is serviced regularly. Don't know much, just my experience for what it is worth.

[Liberty]

http://www.wricointernational.com/
You might contact Dick here at WRICO as that is what he does for a living and is very good at it.

[Larry V]

I have been told by my trusted truck mechanic that my onan diesel genny is actually a Kubota diesel and a great little engine. Not much to go wrong if it is serviced regularly. Don't know much, just my experience for what it is worth.

My 7500wt Onan is an older non encapsulated model in my 1995 rig and also runs the 3cyl diesel Kubota engine. Been trouble free and works great, but only have around 900 hrs on it. Actually pretty quiet and seems economical on fuel. Runs dual airs and anything else we need all at once. The badge riveted to side says it runs at 1900 rpm.

[StarDreamers.us]

Looking for the parts to convert an LP-6500 Oren generator to burn vapor LP not liquid LP. Oren made a kit to convert the system, that they no longer sell. Any suggestions or leads to find the kit would be appreciated.

Safe Travels!

[THE TRAILERKING]

Looking for the parts to convert an LP-6500 Oren generator to burn vapor LP not liquid LP. Oren made a kit to convert the system, that they no longer sell. Any suggestions or leads to find the kit would be appreciated.

Safe Travels!

Edited by shinyblackpaint, 25 February 2011 - 08:41 PM.

[Butch & Fonda]

Hello Shiny,

I have never heard anything bad about PowerTech, period.

Mine has a 3 cylinder Cat engine, I understand that they have since changed to Kubota engines.

You might check with John Palmer in Lake City FL, he on occasion has "take outs" for sale, mine came out of a Marathon conversion, the owners "upgraded" form my 8KW to a 12 KW. Mine only has 7 hour on it, looks and runs like new. John also handles Magnum Energy, LifeLine and a lot of Solar stuff too.

Butch and Fonda Williams, 1987 MCI MC9

[Roadwarrior]

I am going to be building a motorhome conversion in a 1993 MCI 102C3. What I would like to know is what is the better generator to go with, Onan or Powertech? Also what brand of inverter/charger and transfer switch to go with.

if by onan your are speaking of the new hybrid
http://www.cumminsonan.com/rv/products/dieselandhybrid
then this wins hands down.
The key here is that power plant does not run at a constant speed.
The Power comes from the Inverter/batteries, with the power plant used to charge the batteries.
The power plant only comes on and only ramps up in speed (fuel use) based on the power being demanded by the inverter.

as a side note if you are in a place where wind is available, and stationary then a wind generator is a good source for charging up to 400 watts.

[Bill Baxter]

Couple of points to consider.
1 Size the generator for the maximum loading. If you have three AC units then figure on a 10 KW unit which will yield about 80 A. Three AC's at 15A ea, plus micro oven at 15A (plus hot water heater maybe) and TV or radio. We have a 6+KW diesel genny powered by a 999 CC Yanmar engine. Will run all day at 45-48 A loading and use less than 0.6 GPH,

2 Oversizing the genny will lead to other problems. Since rarely need to use the full load capability the engine runs cool. Diesels like the required operating temperature usually 180F. Prolonged operation at say 140-160F will lead to carbon buildup and future engine problems.

3 Powertech is good. But they are using a labeled CAT engine which is really a Perkins painted yellow. Parts can be expensive. Dick Wright builds an excellent unit. Last I knew he was using Kubota engines.

4 You have a 24VDC bus with a big alternator. Stay with that system. That means a 24V battery bank. If you take out the bus AC then the starting batteries can be moved to that location. The original supply cable will provide the connection to the house batteries via a relay contactor. Use one of your heating/ventilation contactors, big relay. You can get fancy like normal air pressure or parking brake released etc to control the contactor. I just use a dashboard switch to parallel the batteries when necessary.

5 AGM's preferred. Better charge rate and lower maintenanace. Higher cost by 60%. If you are faithful to maintain the batteries properly then expect 7-8 years for wet cells and 10-12 years for AGM's, Wetcells need level checked monthly until you establish the watering requirements. Equalization maybe quarterly or semi annually depending on specific gravity readings and the spread between cells and batteries. Cleaning monthly. I mean spotless, no dust, no corrosion on the terminals etc. Ventilation is critical. When charging hydrogen gas is produced and must be removed. That requires a ventilation fan that causes fresh air to ventilate the whole battery compartment.

6 Inverters. Pure sine wave, PSV, only stay away from modified, MSW, as they are hard on most electrical equipment. Since you are going to be 24 VDC then you get a 24 VDC inverter/charger. I like the Trace SW4024. No longer produced but available used for $1000-1500. They are repairable. Most of the currently available models are throwaways when they break.

7 I know that roofs without warts are desired but the cost of a roof top AC unit compared to a mini split is a lot less. To fix a broken roof top is about a 30 minute job. Just replace the top unit, 2 plugs and three bolts, and you're done. Repairing a mini split means remove broken part, compressor, evacuate system, add freon and oil and then test for leaks. None of which you can do without the right equipment. And also why lose the bay space when you can put them on the roof.

8 If you are going with a reasonable size house battery bank, more 4 batteries, then invest in a battery monitor. I use the Trimetric. I liked the E Meter better but, alas, no longer produced.

9 Electric heat? That can suck some juice and means power pole to power pole living, And a good bus heat system. Unless you will never be in the cold, less than 60F, ever.

10 Carrying propane? For what? Hot water heater, refrigerator, furnace(s)? If not then go all electric including heat and recalculate your generator sizing.

Bill

[David & Lorna Schinske]

I am going to be building a motorhome conversion in a 1993 MCI 102C3.

You might want to go to www.busnut.com forum and www.busconversions.com

They are better for answering any questions you may have regarding a bus conversion than an RV forum.

As for generators. I have a POS Onan. I dislike Onan, I dislike the lying that was involved with ours. I dealt with an "authorized" dealer/repair shop and will never have another Onan once I get rid of the one that is in pieces.

[Roadwarrior]

both www.busnut.com forum and www.busconversions.com have good printed material about bus conversions.
however I have not seen an active forum on either.
you can find a local Busnuts like the one I belong to, http://www.fmcanw.org/nwb/ attend rallies that you can get a lot of first hand info from.

[Bill Baxter]

both www.busnut.com forum and www.busconversions.com have good printed material about bus conversions.
however I have not seen an active forum on either.
you can find a local Busnuts like the one I belong to, http://www.fmcanw.org/nwb/ attend rallies that you can get a lot of first hand info from.

Try busconversions.com/bbs/ and Bus Nuts online at busnut.com/cgi-bin/bbs both of those will lead to the discussion groups and are active.

Bill