Replacing 15kw diesel Gen with Propane - Recommendation & Important Considerations?

My over 10 year old china diesel genset is knocking horridly and on its way out. Looking for a propane replacement that requires no babysitting. Can you please recommend? And are there any expensive diesel to propane replacement issues? Current generator is in its own shed, large underground propane tank about 20 feet away and basement of house with inverters and batteries about 20 feet away from that. The 15kw was oversized to charge my 16 surrete/48 volt system alternating with 8 panel with PV, so looking for propane 8KW, I think. Any discussions around this would be much appreciated!
Comments
I was having a heavy knock in my lister, and did not have the time to open it up and so I used a hand held spritz bottle and while running at hot temp, sprayed some water in. As it flashes to steam it cleans carbon out.
For converting diesel to propane, you cant. You have to keep some diesel as pilot ignition, and can not go too far past 70% propane. To convert a diesel engine to propane, you have to install a spark plug, adjust timing and reduce combustion ratio to at least 11:1 or lower.
here's a LONG thread about the issues of converting diesel to 100% propane
http://listerengine.com/smf/index.php?topic=7344.0
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A little larger than what you are looking for but a good choice for larger off grid applications. Not sure if they make the lower rpm propane models below 20 kw but try their website.
In my opinion, CumminsOnan manufacture well engineered and reliable gensets.
What is the ah capacity of your battery bank? If I know the ah capacity I can calculate how many generator watts it will take to charge the batteries at a reasonable rate. What other loads will the generator handle while it is charging the batteries? Those loads, plus the charging load will be the generator capacity that you need.
--vtMaps
http://http//www.altendc.com/diesel-battery-charging-dc-generators
http://static1.squarespace.com/static/555b260ee4b07f48c9a7bdac/t/555f8df8e4b08654c670dad3/1432325624979/ALTEN+Duke+Diesel+DC+Generator+eBrochure.pdf
but I have no experience other than admiring it on the internet...
inMichigan
If you are also running loads while charging, you may want a larger generator than 5000 watts.
I believe that your inverters can limit their charging to prevent overloading a generator... i.e. if you have a 5000 watt generator and are charging the battery, and then you switch on the 1500 watt central vac, the inverter will drop the battery charging down to 3500 watts so as to not draw more than 5000 watts from the generator.
By the way, I based the generator size on giving the batteries a 10% charge rate. You don't need that high a rate... it's just a rule of thumb. It is especially useful for solar charging because using higher current (like a 10% charge rate) allows the battery to be charged in less time (and in the winter there is not much time).
If you are using a generator to charge the batteries, you don't have to worry about the sun setting, so you can charge at a slower rate (and the batteries are probably better off being charged at a somewhat lower rate).
--vtMaps
Based on your battery bank description, I'd research 10 - 15 KW units. Personally, I like to have lots of KW headroom when my batteries are being charged by the genset simultaneous with running the house, wells etc.
In addition to Cummins Onan, Kholer makes a very good genset.
Most 1,800 rpm, water cooled propane units are 15 KW or more. My opinion is higher rpm, air cooled units will probably be your best bet. I prefer propane fueled gensets. If you search the forum, you can get a good feel about the back and forth between gas, diesel and propane generators. Everyone has their own opinion based on their set up and fuel availability.
-Bill
The only downside I've discovered is it uses a fair amount of fuel, so take that into consideration when sizing your tank.
Paul
In Georgia
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
http://www.probuilder.com/showvillage/2013/products/pdf/Generac_SizingGuide.pdf
Down to Zero F, it appears that a 500 gallon tank is OK for 15 kWatt load.
Of course, if you run your tank towards empty before refilling it--Then there is less heat transfer from the outside to vaporize the fuel--And you could still lose propane pressure (cold weather, tank less than 1/2 full, heavy load on genset).
As always, get confirmation from your local propane supplier about tank/genset sizing for your area/installation (above/under ground, etc.).
-Bill
Moderators, if I am not supposed add a link please delete post. Sorry in advance.
Off grid in Upper peninsula Michigan
-Bill
From http://www.generatorjoe.net/html/stepxstepgenerator.html :
Here are the specs on my Xantrex units, stacked, 240 volt system, batteries are 16 Rolls Surrette 350 ah, wired series/parallel.
Generator Model Numbers SW4048 and 4048 Plus
Inverter 4000 Watts each Stacked.
Top Inverter S/N 445428 4048 7/2002
Inverter System -
Nominal Battery Bank Voltage 48 Volts
Nominal DC Operating Voltage 59 Volts
Range of Operating Voltage 44-64
Max op DC current 100 Amps
Nominal AC output 120 0 ~
Nominal frequency 60 H
Max continuous output current 33 amps
Max output overcurrent protection 35 amps AC
Max output fault AC current 78 amps AC rms
Battery Charging System -
Nominal AC input voltage 120 Volts
Operating Frequency 60 hz
Max continuous battery charger AC current 30 Amps AC
Max continuous battery charger DC current 60 amps DC
Max continuous battery charger input VA 3600VA
Max AC Transfer switch Input current 60 amps AC
--------
***Also, when I have had down time for repairs to the old china diesel, I have in the past plugged in to an AC outlet, a gas driven Honda generator I think it was 6.5kw. That was backfeeding I know, but Was that going straight to the batteries, bypassing the inverters?
http://www.centralmainediesel.com/order/Honda-5kw-Propane-Generator.asp?page=H04585
Did I miss something about your number of PV panels? Seems you might have inverter/battery capacity for almost double your PV panel count - further possible reduction in generator demands? Would you consider a MPPT CC to further unload the generator - more effective battery charging via solar? I use the SPS of the SMA Sunny Boy as emergency off-grid charging for a 48 volt system, but realize it is not that effective.
On the other hand I use what is called a "secure power supply" (SPS) that comes with the SMA SunnyBoy on-grid inverter to charge the 48 volt battery system with the OEM golf cart battery charger (110 volt AC powered by the SPS). The SPS only works when the grid is down. Not the most efficient by any means, but it is only for emergency - not really "off-grid".
Max continuous battery charger DC current 60 amps DC
Max continuous battery charger input VA 3600VA>>
I have one SW 5548, so I don't have this question, but will each inverter put 60 amps into the bank , boosting the charge rate to a theoretical 120 amps?
It appears that one inverter will only accept 30 amps AC, or 3600 watts. If both inverters were putting out full charge , that would require a maximum input of 7200 watts by my thinking.
To get 7200 watts continuous I would guess that you would need probably something like a 10,000 watt genny.
Propane seems to give trouble starting in very cold temperatures.
That's how I would read those ratings, but I'm a neophyte in these things.
Paul
in Georgia
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k