Looking For a 48V Inverter.

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  #1  
Old 09-14-13, 01:14 PM
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Looking For a 48V Inverter.

I need to put an inverter on a 48VDC electric train. (basically a fancy golf cart) I've been googling this for the past hour, and I can't find anything from a reputable manufacturer. The best I can think of is using a 48V to 12V converter then using a regular inverter. It needs to be in the 100-250W range.
 
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  #2  
Old 09-14-13, 01:46 PM
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You'd lose a lot of power in stepping 48 volts down to 12.

How is the battery pack configured? It isn't just a 48 volt battery is it? Usually it's a collection of 6 or 12 volt batteries (in a golf cart anyways).

If you could tap off the batteries it may be a better option. Yes, you'll drain those batteries a might quicker but short of adding another it may be your best option.
 
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Old 09-14-13, 02:00 PM
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There are 8 6V batteries in series. The thing I am worried about is if I tap off 2 batteries it will screw them up.
 
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Old 09-14-13, 02:07 PM
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That type of inverter would not be generally found on the open market as it's a specialty unit. I know of a few good commercial models but the cost is prohibitive.

What are you connecting to the inverter ? Sine wave sensitive items.... like electronics.
 
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Old 09-14-13, 02:55 PM
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Could you find space for an additional battery and operate the inverter independently of the main batteries?
You could calculate the load on the inverter then size it's battery to last as long as the train batteries.
 
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Old 09-14-13, 03:16 PM
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Instead of looking for an inverter can you change out what you are connecting up?
 
  #7  
Old 09-14-13, 07:20 PM
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If you have a 12v inverter, try tapping off any two batteries in series. It doesn't have to be the first two or the last two. Just two that are hooked up in series.
 
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Old 09-14-13, 09:15 PM
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When batteries are series connected they must be discharged evenly or they will not charge properly.
 
  #9  
Old 09-14-13, 11:14 PM
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I can find all sorts of inverters with a 48 volt input. How much money do you want to spend?
 
  #10  
Old 09-15-13, 07:47 AM
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What I am running is a powered mixer, wireless microphone, iPod charger, and maybe some lights. The absolute most I can spend on this is $200.
 
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Old 09-15-13, 08:23 AM
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A modified sine inverter and an inexpensive 27 series deep cycle battery should work if you have room for the battery.
Lots of places to buy these so shop around.

If you can figure out the 120 volt current load you would be able to figure out how long that battery would last.
Lights would be the wattage killer unless you go to LED lighting.
 
  #12  
Old 09-15-13, 06:21 PM
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It looks like another battery is what I'll have to do. I'll be able to make room, there's a huge space that's open and unused. I could probably tap off the wiring leading to the charger and run a 12V charger and a relay coil to kill the inverter when the battery is charging.
 
  #13  
Old 09-15-13, 09:00 PM
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Before you make the installation permanent..... try the powered mixer on the inverter first. The switching noise from the inverter may be unacceptable for your application.
 
  #14  
Old 09-18-13, 09:37 PM
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Originally Posted by Justin Smith
There are 8 6V batteries in series. The thing I am worried about is if I tap off 2 batteries it will screw them up.
Yes, it will, and you absolutely cannot do that...
so why not use all of the batteries in 4 paralleled series circuits?
That would just be the same as one pair, but you join the 4 neg and 4 pos wires from each of the 4 pairs... just like bundling the hots and neutrals in a multi-light fixture.
 
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Old 09-18-13, 10:27 PM
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How will that work Nick ?

The batteries need to stay in series to run the cart.
How can you rewire them for the inverter ?
 
  #16  
Old 09-19-13, 05:42 AM
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I know I'm late but have you looked at golf cart voltage reducers? They are sold to reduce a electric cart's 36 or 48 volts down to 12 volts to run common accessories. I've seen them rated up to 25 amps but there could be some with more capacity.

There are also 48 volt inverters which take 48 volts directly and output 120 VAC. They are often used in solar power and other off grid systems. Searching online for "48 volt inverter" should turn up a number of them.
 
  #17  
Old 09-19-13, 09:58 AM
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Originally Posted by PJmax
How will that work Nick ?
The batteries need to stay in series to run the cart.
How can you rewire them for the inverter ?
I'm surprised that this needs to be explained... but it is entirely possible to have batteries in multiple circuits at the same time.

The gray is the 48V for the train
Assume that the colored and gray wires share a terminal (of course)
Each red and each blue go together, thereby giving you 12V from 4 pairs of batteries. It's no different than tying together hots and neutrals in a chandelier.
 
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Old 09-19-13, 11:12 AM
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I don't understand how your drawing shows multiple batteries in different circuits. "colored and gray wires share a terminal"???

Are the black boxes batteries or are the black boxes + and - terminals on a battery? Is each pair of red and blue wires with two black boxes one battery? What is the gray line tying together since it's crossing all the black boxes?
 
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Old 09-19-13, 11:15 AM
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if you connect all the reds and blue all you will get is a big melted pile of metal and plastic
 
  #20  
Old 09-19-13, 02:47 PM
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Originally Posted by Pilot Dane
I don't understand how your drawing shows multiple batteries in different circuits. "colored and gray wires share a terminal"???

Are the black boxes batteries or are the black boxes + and - terminals on a battery? Is each pair of red and blue wires with two black boxes one battery? What is the gray line tying together since it's crossing all the black boxes?
Justin stated that the train has eight 6V batteries in one series to produce 48 volts. There are 8 black boxes in the diagram. The gray line is the 48V circuit. I colored it gray because it is established and will not be modified.


Originally Posted by braether3
if you connect all the reds and blue all you will get is a big melted pile of metal and plastic
I'm not sure what the purpose of this comment is.
 
  #21  
Old 09-19-13, 03:01 PM
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What are you using that you need 48V????

As an RV'er your best bet would be to hook them up series/Parallel.

You hook two 6 volts batt in series. You have eight... That will give you 4-12 volt banks. Hook those 4 banks in parallel and you will have oodles of stand by power.

Then run an inverter off that.




f you connect all the reds and blue all you will get is a big melted pile of metal and plastic
Huh!!! You will have 12 volts with 4 times the amps of the 4 banks if you tap from the red and blue for 12 volts.

If each 6 volt battery is say 230 amp hours you will have a whopping 920 amp hours. @ 20 amp load I believe which is 240 watts.

Cut that 920 amp hours in half since you only want to drain batteries down 50% is 460 amp hours.

So you will be able to run two 100 watt bulbs 24/7 for 20 days plus..

Thats from my calculations. I may be wrong so someone check that for me.
 

Last edited by lawrosa; 09-19-13 at 03:45 PM.
  #22  
Old 09-19-13, 03:34 PM
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Nick's diagram shows how to obtain 12 volts from any two series connected 6 volt batteries. As Braether points out if you were to connect each of the new positive connections and the new negative connections in parallel you will have a huge short circuit and blow the entire battery bank.

Perhaps Nick is suggesting to connect ONE of the derived 12 volt volt supplies to the inverter and merely shows that there are four such derived 12 volt supplies.

The trouble with this is, as has already been pointed out, when you discharge the individual batteries in a bank UN-equally they will also charge unequally. The result will be damaged batteries.

The idea of a separate 12 volt battery supplying ONLY the inverter is the best answer given the financial restraints of not being able to afford the proper 48 volt inverter.

lawrosa

What are you using that you need 48V????
It is a battery-powered golf cart. Requires 48 volts for the main drive motor.
 
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Old 09-19-13, 03:47 PM
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lawrosa

What are you using that you need 48V????
It is a battery-powered golf cart. Requires 48 volts for the main drive motor.
Ohh I missed that somehow with my speed reading...LOL
 
  #24  
Old 09-19-13, 04:00 PM
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Originally Posted by Furd
As Braether points out if you were to connect each of the new positive connections and the new negative connections in parallel you will have a huge short circuit and blow the entire battery bank.
Absolutely not. No way, no how.

Originally Posted by lawrosa
You hook two 6 volts batt in series. You have eight... That will give you 4-12 volt banks. Hook those 4 banks in parallel and you will have oodles of stand by power.

Originally Posted by lawrosa
Originally Posted by braether3
if you connect all the reds and blue all you will get is a big melted pile of metal and plastic
Huh!!! You will have 12 volts with 4 times the amps of the 4 banks if you tap from the red and blue for 12 volts.
 
  #25  
Old 09-19-13, 04:09 PM
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Nick, re-draw your circuit but this time use the intertie between batteries as a single +/- connection point, which it is. Then you can easily see that what you have is one big fat short circuit.
 
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Old 09-19-13, 04:10 PM
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Nick are you saying this does not work? Its every RV's dream to run 6 volts batterys like this..

But in my reply I was not aware he needed 48v. But I see no reason not to tap off anywhere for the desired 12 volts.


 
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Old 09-19-13, 04:12 PM
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What I ended up doing is I found a 12V system (like on a bus). Wireless mic already runs on 12VDC, and for the ipod, I used a 12V to 5V regulator. This is all being powered through 12V sockets I installed on the dash with a 12V 10A regulator.


Now you all ought to see what's going on the tractors next year.
 
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Old 09-19-13, 04:15 PM
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Now you all ought to see what's going on the tractors next year.
I just want to come to the party...Im ready...


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  #29  
Old 09-19-13, 04:18 PM
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Originally Posted by Furd
Nick, re-draw your circuit but this time use the intertie between batteries as a single +/- connection point, which it is. Then you can easily see that what you have is one big fat short circuit.
Please discuss this with Mike, not me. I have nothing left to explain or clarify.
 
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Old 09-19-13, 04:27 PM
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But in my reply I was not aware he needed 48v. But I see no reason not to tap off anywhere for the desired 12 volts.
Carefully re-read the entire thread. I think it was Greg that first pointed out that tapping a lower voltage from the entire battery bank would cause that portion to discharge unequally and THAT will eventually ruin those cells of the bank, if not the entire bank.
 
  #31  
Old 09-19-13, 04:34 PM
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Nick D.
Quote Originally Posted by Furd
Nick, re-draw your circuit but this time use the intertie between batteries as a single +/- connection point, which it is. Then you can easily see that what you have is one big fat short circuit.
Please discuss this with Mike, not me. I have nothing left to explain or clarify.
I suggest that you check your attitude at the door, kid. Mike drew a circuit with eight 6-volt batteries with two each of the batteries in a series circuit with each such series then connected in parallel making a 12 volt bank.

YOU have taken a series of eight 6 volt batteries, totaling 48 volts and then attempting to tap off four 12 volt supplys and THEN paralleling these four supplys. Doing it according to YOUR drawing is a short circuit, no way around it. As I suggested, if you draw out the complete circuit you will easily see the error in your thinking.
 
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Old 09-19-13, 04:48 PM
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Yes mine are separate 12v banks hooked in parallel.

Nick if they were all connected in series, as in the blue line I drew then tapping from x/- would produce a short.


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  #33  
Old 09-20-13, 01:28 PM
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Okay, time for an apology from me...
I had some doubt about the design and I wished I could test it out myself to be sure, but I showed it to an EE friend and he casually checked it off, so I became (falsely) reassured. I asked him again later when he was free and admitted that it did not work.

Sorry guys!
 
  #34  
Old 09-20-13, 01:49 PM
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Thank you, Nick. Everyone makes mistakes, even old farts like me. At first glance your idea did look sound but once you realize that the tie points in the midst of the entire bank are both plus and minus you can see how it ends up being a short circuit.
 
  #35  
Old 09-21-13, 04:33 AM
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Nick, pay another visit to your EE friend and ask him where he would insert the diodes into the circuit.
 
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