# Conversion question EZGO 48v cart



## Woodsmith (Jun 5, 2008)

Hi, welcome to the forum!

It depends on the controller as to whether it will work at a higher voltage.

Can you find out what the controller is? There may be technical specs online that will tell you the operating voltage.

also you will need to look at how the control contactors and relays are powered. They could be 12v coils using a separate battery or tapped off the pack, or they could have 48v coils. 

My Tractor's Curtis controller is 36/48v running 48v coils on the contactors but I also have a Curtis 48-72v controller for example.
I couldn't change the controller to run at 60-72v as my contactors will still need 48v to energise them.


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## jrlogan1 (Sep 29, 2012)

I have a pretty good view of the controller under the seat, but I don't see any writing on it to determine the specs. Do I have to remove it from the mount? 

Even if my accessories required 48v, if I put another battery in I could just wire it so the motor is the only thing getting the full 60V. I'd just have the accessories wired to the existing battery bank at 48V. Should work, or am I missing something?

Anyway, I'm pretty sure everything uses 48V. It has 6 8V batteries in it, so 12V isn't possible without a converter.


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## Woodsmith (Jun 5, 2008)

Just adding a battery to the motor wouldn't work.

It looks like, if you don't have ant 12v circuit, that the controller is running on pack voltage for the control and the traction side.

You will need to research the vehicle and see what the brand and model of the controller is to see if it will handle more voltage.

Do you have a manual or specification for the vehicle?
Maybe a photo and a question in the controller forum might lead someone to recognise it.


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## jrlogan1 (Sep 29, 2012)

Nothing in the manual or on internet that I can find. I took some things apart and was surprised to find what I thought was the controller is a dc converter, 36-48V input, 12V output, so I do have 12V. I then removed some guards, etc to find the controller:

Curtis 1206HB-5201, Voltage: 48V, current: 250A, S/W: 14

I'm guessing these would all have to be replaced to up the voltage?

On a different note, how do these controllers work? Do they vary the voltage to the motor? Or do they limit the amperage?


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## Woodsmith (Jun 5, 2008)

Looks like all of that will need to be changed to change the pack voltage. I can't find any info on that controller either. Curtis seems to not be listing a number of controllers. Maybe because they are not current models. I did find a suggestion that it could be a SepEx controller rather then a series controller.

Replacing all that could be costly.


The controller basically takes the pack voltage and very rapidly switches it on and off, this is pulse width modulation (PWM). The variation in 'on' time compared to 'off' time creates a variable 'average voltage' as 'seen' by the motor.
The PWM is generally in the region of 15khz.


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## jrlogan1 (Sep 29, 2012)

So I don't want to replace the controller and converter. Too much expense. But, I notice a big difference in power between the machine when fully charged and even just a bar or two down on the charge meter. I haven't tested, but I imagine this difference is no more than a few volts. 

So what would be a relatively easy way to keep it running at full voltage (power) longer. For example, if I added a 6 volt battery to the system, at full charge it would be 54 volts, probably not going to be a problem for the controller or converter, correct? Then my voltage would have to drop much more, and therefore I would have a longer period of full power. Would that work?

So if the controller is just modulating the voltage on/off, when I have it at full throttle wouldn't it send the motor the full voltage of the pack (54V)? Could adding a 6V battery actually up my max power as well, leaving the components the same?


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## Woodsmith (Jun 5, 2008)

The controller will have a maximum voltage. Lets assume that is 48v for now based on four 12v batteries. The controller will be intended to be used with the fully charged voltage of the four batteries, about 13.5v each so already it will be at 54v. That will drop rapidly back down to nearer the 48-50v range, and when current is being drawn it will fall lower, that is the voltage sag.

What you propose is to add another 6v battery to make up the shortfall when the voltage sags. Unfortunately, when the batteries are not sagging then the voltage will be too high for the controller.

Are your batteries new or old. Older batteries start to get 'weak' and so the voltages could be a little low to begin with.

It would be worth checking the individual batteries to see if you might also have one that is failing faster then the rest.


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## jrlogan1 (Sep 29, 2012)

The vehicle is new including the batteries.
I can't imagine that 6 extra volts would fry my controller. I know it isn't designed for that, but would it really hurt it?


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## PStechPaul (May 1, 2012)

You will run a risk of causing damage by going to 54 volt nominal, but it might be OK. Another idea might be a switch to add the extra 6V battery in series when the main pack runs low. But then you will be discharging the pack further, causing reduced life, and a 250A SPDT switch is not easily available, and is likely to be expensive.

Before trying anything I would check the actual voltages when fully charged and when the meter reads one bar low. A cheap electric fuel gauge might not be very accurate.

You might be happier with Lithium batteries, but that's a major and expensive change.


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## mizlplix (May 1, 2011)

Go here and ask.
http://www.buggiesgonewild.com/electric-ezgo/


Or more to the point, here:
http://www.buggiesgonewild.com/extreme-dc/

Miz


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