| Author |
Message |
Tony & Kim Rian (Rianrts)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 01, 2005 - 4:33 pm: | |
Question of the day I have a 24volt starter and 3 24volt blowers for the heaters. I was told thru friends that I can pull the 24 starter and replace with a 12volt starter and leave the blowers alone. Change the batts config into 12 volt and everything should work. Also that all alts in the 8v71 gear driven setups are the same output. I have a 1979 GMC RTS with an 8v71 and the new v730. ps got back from the lake (our frist dragboat race of the season) The rts did great top speed 76mph and pulled the hills at 35mph. What a geart trip no problems. |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 01, 2005 - 5:32 pm: | |
No, You would have to rewire the RTS completely including all logic controls, relays and change the alternator. REALLY BIG JOB.....
The wiring is rated for the lower currents @ 24 volts, Changing to 12 volts might require that you replace all high current 24 volt circuits with wires about double in size.
On the other hand if you rip absolutely every wire and circuit out and start from scratch with 12 volts in mind would be about the only way that it would "technically" be correct. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 01, 2005 - 10:38 pm: | |
Tony & Kim Rian, the blowers might give you a surprise. If they are just motors with switches to turn them on and off, then you might find out how much current they draw on 24 volts and compare that to the current they would draw on 12 volts.
If the current is a bit lower at 12 volts, then try running them to see if you get enough airflow out of them. Since the effort to move the air drops off faster than the volume, you might get enough flow with low enough current.
If the current is equal to or higher than on 24 volts, then the blower motors will run warmer than they did on 24 volts.
When pumping any kind of fluid, the effort and the volume are very non-linear, so testing is required to learn what effects any changes will have.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 03, 2005 - 12:19 am: | |
Unless these motors are different than any other electric motors they have a rated HP, ie, a certain number of amps at 24v.
If you change to 12v the amp rating will double and probably burn out the motors and wiring to them. The motor will always try to produce its rated HP when loaded (Moving air).
If there is no load on it the motor may not do anything different, I'm not sure about that. Can't see any reason to run the motor if there is no load on it. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 03, 2005 - 8:07 am: | |
gusc: DC motors are constant torque motors but not constant HP. They will run happily on any voltage up to the maximum rated voltage, producing constant torque with the speed proportional to the applied voltage. The current goes down with the voltage and the only real problem is if you run the motor too slowly to keep it cool with its own fan. With external cooling, you can run it right down to 0 RPM.
Tom pointed out the non linear air flow from a squirrel cage fan so I have no idea what volume or velocity you would get from these fans at half speed. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 03, 2005 - 8:53 pm: | |
Gusc, if you use a circular saw on a long extension cord and try to do any cutting, the lower voltage reaching the saw will lead to a drop in rpm and and increase in current that may burn out the saw.
The example that I was talking about involved pumping a fluid, in this case, air, so a lowering of supplied voltage might not have that effect. That's all that I was trying to say.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 03, 2005 - 10:00 pm: | |
JUst do not get AC motors anc DC motors mixed up. Their characteristics are different on low voltage.
Richard |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 03, 2005 - 10:41 pm: | |
Tom, Stan and Richard,
Of course I did get the two mixed up!
Conversions do confuse me often, but I did know that the original blowere were DC. I was thinking about AC motors in air conditioners and how they burn out during "Brown Outs"
I'm not sure I will ever get this AC/DC and inverters thing straightened out in my mind but I'm trying. |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 04, 2005 - 10:01 pm: | |
Gusc, starting torque with a fixed voltage on an AC induction motor, like the ones used in a 120 volt air conditioner, is limited. If it is driving a reciprocating (piston) compressor and if the voltage is low, there may not be enough torque to rotate the compressor past top dead center.
In that case, the compressor will stall. There is a protection device on the compressor motor that is supposed to shut off the power if that happens. It is self resetting, so that when it cools off, it turns the power back on.
One way to mess things up is to supply too low of voltage to the air conditioner and then leave it unattended. Then, the compressor could stall, cool off, restart and stall again until it got hot enough to damage the motor.
The only real cooling the motor gets in normal operation is from running, so repeated stalling is going to cause some heat to accumulate.
If the motor protector should fail after repeatedly tripping off by fusing it's contacts, then it would be up to the circuit breaker to save it.
The only way that is going to work is if each air conditioner has its own breaker and that breaker is just the right size to trip on a repeatedly stalled compressor.
If it tripped on the first stall, then somebody monkeying with the thermostat could cause the breaker to trip, which could cause some people to think that their air conditioner is defective.
I hope some of the above helps.
Tom Caffrey PD4106-2576
Suncatcher |
David Hartley (Drdave)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 05, 2005 - 8:32 am: | |
Wow.. Another one that went out of the ballpark...
The question was converting a 24 volt RTS to 12 volts.
Where did all this other stuff come from? |
Jtng
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 05, 2005 - 8:10 pm: | |
I love it, Dave! It proves that there no simple answers to
simple questions, and there should always be a lesson in
physics to accompany every explanation.
Tony-
David said it all in his first post. And even as a newbie, I
can tell ya' there's mega-benefits keeping it 24v, just as it
was manufactured. It's more than the blower motors to deal
with; it's the rest of the rig's 24v electrical system. Why bother? |
hookairs
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 06, 2005 - 1:23 pm: | |
How many Internet Forum Posters (pick a forum... any forum...) does it take to change a light bulb?
1 to change the light bulb and to post that the light bulb has been changed
14 to share similar experiences of changing light bulbs and how the light bulb could have been changed differently
7 to caution about the dangers of changing light bulbs
27 to point out spelling/grammar errors in posts about changing light bulbs.
53 to flame the spell checkers.
41 to correct spelling/grammar flames.
6 to argue over whether it's "lightbulb" or "light bulb"
6 to condemn those 6 as anal-retentive.
2 industry professionals to inform the group that the proper term is "lamp"
15 know-it-alls who claim they were in the industry, and that "light bulb" is perfectly correct
109 to post that this forum is not about light bulbs and to please take this discussion to a lightbulb forum
111 to defend the posting to this forum saying that we all use light bulbs and therefore the posts are relevant to this forum
306 to debate which method of changing light bulbs is superior, where to buy the best light bulbs, what brand of light bulbs work best for this technique and what brands are faulty
27 to post URL's where one can see examples of different light bulbs.
40 posters who don't believe in light bulbs at all and instead post links to pseudo-scientific sites that claim alternate theories of light production.
12 to point out that there is no right to light in the US Constitution.
4 to post that all the tech support for changing light bulbs is being outsourced to India.
1 post showing a picture of a light bulb and a picture of someone who resembles a light bulb.
14 to post that the URL's were posted incorrectly and then post the corrected URL's
1 poster that has converted all his light bulbs to florescents, so he very rarely has to change them.
12 to post to the group that they will no longer post because they cannot handle the light bulb controversy.
4 to suggest that posters request the light bulb FAQ
44 to ask what is a "FAQ"
13 to tell you candles should be in all well-prepared households in the event of a lightbulb burnout.
5 postings that say they do not use light bulbs...only candles.
1 to mention the "lite" bulb is made of low-fat cheese.
4 to say "didn't we go through this already a short time ago?"
143 to say "do a Google search on light bulbs before posting questions about light bulbs"
1 forum lurker to respond to the original post 6 months from now and start it all over again. |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 06, 2005 - 3:33 pm: | |
GREAT. Definitely applies to the bus nuts boards.
Richard |
gusc
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 06, 2005 - 8:38 pm: | |
And one who has the free time and inspiration to type up a long detailed critical analysis!! |
hookairs
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 08, 2005 - 4:39 pm: | |
Don't worry, when diesel fuel hits $5++ per gallon you'll have plenty of free time to sit in your aluminum box and "type up a long detailed critical analysis!!" |
niles steckbauer (Niles500)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 08, 2005 - 4:54 pm: | |
WASHINGTON (Reuters) - The average retail price for gasoline climbed to within a few pennies of the all-time high, while the cost for diesel fuel hit a new record, the government said Tuesday.
Truckers in the New England states paid the most for diesel at $2.49 a gallon, up almost a penny from last week
** We're half way there! |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, July 09, 2005 - 6:00 am: | |
** We're half way there!
Actually adjusting for inflation were not yet half way to the old 1973 oil prices.
But at these prices (if they stay up) will bring on the huge (3X Saudi) Canadian tar sands oil as well as the huge US supply .
There will be a big sobbing in congress as Bubba closed the best oil sands areas by giving them "National Park" status his last day in office , after passing out hunderds of pardons bought by criminals . Remember Mark Rich?And the Cop Killers turned loose?
FAST FRED |