24v alt.

[rdbishop]

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

[buswarrior]

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

[NewbeeMC9]

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

[bobsw]

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.

[larryh]

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

[donnreeves]

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

[JackConrad]

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

[Busted Knuckle]

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!

[DrivingMissLazy]

ACs 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

[rdbishop]

OK,

My old alt. put out 225 amps. How about two 140 amp 24v?

Richard

[DrivingMissLazy]

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

[Dallas]

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

[rdbishop]

Thanks Richard,

All my systems are 24v. I don't mind a little over kill.                                                                                                                                                                                                                                                               Richard

[rdbishop]

OK, so 140amps X 2 would be just about right?

Richard

[mikelutestanski]

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