Hi guys,
Has anyone tried using two 24v 160 amp alternators instead of the 50 dn. I took the old alt. in to be checked and looks as if everything needs replacing. So what do you think?
Richard
Hello.
Why not? All the new coaches are running twin alternators instead of one.
By new coaches, I mean MCI and Prevost....
happy coaching!
buswarrior
Check this thread, some wher it was mentioned about a controller that keeps the 2 from effecting each other.
http://www.busconversions.com/bbs/index.php?topic=3163.0 (http://www.busconversions.com/bbs/index.php?topic=3163.0)
I put a 70amp 24 volt on my MCI and then added a 12 volt alt. along side of that for charging the house battries. I just completed it in July but everything seems to be working very well so far.
why do you think you need two alternators???
Our setups for a motor home style would probably not ever use the full capabilites of the 160 amp alt. unless your running something very unusual we don't have the light load a typical passenger buss does.
Running two air conditioners each pulling 25 amps for a total of 50 amps still leaves you 110 amps to use for your lights etc. Maybe something I don't understand plus a 160 amp alt can be had at almost any truck/auto parts house try that with the standard GMC alt.
just my 2 cents
LarryH
I have two 12V 140 amp alternators on my RTS. One for house the other for chassis. When running one roof air on the inverter one alternator dosn't quite keep up with the load. Flipping a switch to tie them both togeather, they easily handle the load. There have been no issues with the two regulators disagreeing, the setup works just fine. My next step will be to replace the manual switch with a continuos duty solinoid so I can control them from the driver's seat. Donn
Quote from: larryh on September 19, 2007, 04:25:33 AM
why do you think you need two alternators???
Our setups for a motor home style would probably not ever use the full capabilites of the 160 amp alt. unless your running something very unusual we don't have the light load a typical passenger buss does.
Running two air conditioners each pulling 25 amps for a total of 50 amps still leaves you 110 amps to use for your lights etc. Maybe something I don't understand plus a 160 amp alt can be had at almost any truck/auto parts house try that with the standard GMC alt.
just my 2 cents
LarryH
I think you are comparing amps at different voltages. ACs using 25 amps @ 120 volts=3000 watts. Alternator output of 160 amps @ 12 volts=1920 watts. Jack
Quote from: buswarrior on September 18, 2007, 05:47:38 PM
Hello.
Why not? All the new coaches are running twin alternators instead of one.
By new coaches, I mean MCI and Prevost....
happy coaching!
buswarrior
My 45' SETRA does too!
QuoteACs using 25 amps @ 120 volts=3000 watts.
WOW. My A/C's only uses 12 amps @ 120 volts (1440 watts) at the most while running, ignoring compressor starts.
Given that, a 140 amp, 12 volt alternator (1680) watts would be undersized for this load. I do not believe it is possible, or desirable to run an alternator at its peak output rating continously.
Richard
OK,
My old alt. put out 225 amps. How about two 140 amp 24v?
Richard
Quote from: rdbishop on September 19, 2007, 06:54:42 AM
OK,
My old alt. put out 225 amps. How about two 140 amp 24v?
Richard
Fine if you have a 24 volt inverter. You would have 3360 watts per unit maximum and should be in great shape.
Richard
Quote from: rdbishop on September 19, 2007, 06:54:42 AM
OK,
My old alt. put out 225 amps. How about two 140 amp 24v?
Richard
P(W) = V x A
so 225A @ 24V would be 5400W or 5.4Kw
140A @ 24V equals 3360W or 3.36Kw
X 2 would equal 6720W or 6.72Kw
Thanks Richard,
All my systems are 24v. I don't mind a little over kill. Richard
OK, so 140amps X 2 would be just about right?
Richard
Hello Remember the watt story with respect to voltage... AT 24v and 100 amps 2400 watts are available. AT 12V and 100 amps 1200 watts are available. SO the bottom line is more volts equals more available watts at the same amperage draw .
WHen you think about an inverter for example at 120 volts AC with one amp how many amps does it take at 24V and 12V to provide that 1 amp of 120V .. as a rule of thumb you can divide the voltages for a rough approximation .... 120V/ 24V = 5 120V/12V = 10
SO can you see that it takes 2X the amps at 12V as it does 24V to make one amp of AC @ 120 V I have neglected the efficiency of the machines which in the real world means that it takes a little more than 5 or 10 to do the job.. the inverters need power and the conversion is not 100% efficient. I also did not mention the fact that at 12V : 2 times the amps means bigger heavier wiring to handle the amp draw.
In the real world there are more 12V gadgets available than 24V so that needs to be factored in. ( you can use an equalizer for that chore across your 24V bank) . but the bottom line is if you want to run high amperage units on the road like ACs you can do it with less amp draw at 24V than with 12.. a 2500W 24V inverter will run one rooftop if you utilize the bus alternator with 200 amps to charge the inverter batts at the same time because the alternator is effectively running the AC using the batteries and inverter as a conduit for the power... When you do this you must be sure your battery bank is adequate for the task. SO in my humble opinion and mine alone if at all possible stay with the higher voltages because more power (WATTS ) are available for your use.....
Of course an 8KW generator running whilst going down the road will power 2 rooftops also
Choices choices choices whats a busnut to do?
FWIW. happy bussin mike
QuoteOf course an 8KW generator running whilst going down the road will power 2 rooftops also
And to me, this is the best suggestion of all. You can also run the microwave and coffee pot and anything else including the TV if desired. Personally I would have hated having to rely on the bus alternators and an inverter for all my travels. How many times did I stop at a rest area or a Flying J for an hour or so? With the genset, I just left everything running, and when stopping overnight at a WalMart or rest area or wherever, I
always had A/C. If I had to choose between a genset and the inverter/alternator setup, the genset would win, hands down.
Richard
Richard,
I've been running about 4 yrs now without an alt. I've been using either the gen. or the invert. I still have my OTR air and it works great. So now with the truck 24v alt i'll get back to normal?? I now need to know... 140a or 160a?
Richard
Quote from: rdbishop on September 19, 2007, 08:41:22 AM
Richard,
I've been running about 4 yrs now without an alt. I've been using either the gen. or the invert. I still have my OTR air and it works great. So now with the truck 24v alt i'll get back to normal?? I now need to know... 140a or 160a?
Richard
Sorry but I can not advise on that. I think either one would be sufficient to operate your OTR air and I believe that should be the main consideration.
Richard