DC motor voltages.

[simple man]

I have a " simple " question this time, I hope! I currently have an Advanced CH7-4001 48V motor in my cart. Can this safely run on 72V? I'm not looking for speed, I need pulling power ( torque ) and longer run time. I want to upgrade from 36V, but I'd only like to do it once! I know I will need the controller and solenoid for 72V. My cart was originally 48V, but I have a 36V controller in it so I can at least use it until an upgrade. What's your thinking on this? As always, I appreciate you guys help!

[JohnnieB]

If you got the room to carry them in your industrial cart, connect two sets of 8 x 6V battery packs in parallel and install the highest ampacity 48V controller and solenoid available.
Also look into bridging controllers.

A set up like that would give new meaning to the term "Lead Sled"

Might want to look into 4-wheel disk brakes also.

[72volt_ezgo]

Unless it happens to be a special motor,I don't see a reason that it would not run good on 72V.

I've been running my stock ez-go motor on 72V for a few years now and in the past year I'm running it on 84V with no problem what so ever.

People doing budget EV car conversions have been running 48V forklift motors on 120V-144V however they advance the timing about 10 degrees for those higher voltages. (brush timing)

Just make sure what ever you are pulling with it,still allows the motor to turn at a decent RPM and it will be fine!

Barna

[simple man]

Ha ha, I love " JohnnieB's " answer! No, I'm not using it for tractor pulls, just moving boats around and stuff like that. I figured since the motor runs on wattage, the more voltage I use, the less current I'll use. Like I said before the speed part is no issue. Believe me, you can't drive this fast unless you're on pavement, which the cart hardly ever sees. Less current should also be better for the motor and should give longer run time to boot! Since " 72volt_ezgo " has been running his motor for a good while on 72V, I don't think I'd have a problem with mine at all! The only problem I know I'll have, is in the wallet area!

[arcitech]

Originally Posted by simple man

I have a " simple " question this time, I hope! I currently have an Advanced CH7-4001 48V motor in my cart. Can this safely run on 72V? I'm not looking for speed, I need pulling power ( torque ) and longer run time. I want to upgrade from 36V, but I'd only like to do it once! I know I will need the controller and solenoid for 72V. My cart was originally 48V, but I have a 36V controller in it so I can at least use it until an upgrade. What's your thinking on this? As always, I appreciate you guys help!

Electricity has 2 major forces voltage and amperage which are affected and controlled by the resistance in a curcuit. If the resistance stays the same (48v motor) then more voltage will give more amperage by default (I=E/R) in simple math terms. It is a lot more complex when you figure in a motor controller and cables and then the impedence caused when a electric motor runs at lower than designed speed. If you look at voltage as the ability to go fast (Horse Power) and amperage as the ability to do work (Torque) then you get less than simple answers. So 72v will want to run fast, and you will get more torque by default, but it might not be in the speed range that you want it. I would start with a few phone calls to some of the vendors here on BGW and get a recommendation on the upgrades you will need for your use, and then plan your purchases (i.e. Controller and solenoid, cables, motor or more batteries) around a recommended design.

[arcitech]

Just got to thinking about 24v fork lifts, they are a prime example of doing heavy work with less voltage. It all comes back to how much do you have to tow, and how fast do you need to tow it? A 200amp surge for 20 seconds to get up to speed, or a 400amp surge for 10 seconds to get up to speed still equals the same amount of energy spent for the same amount of weight moved. We haven't even started to talk about changing the rearend gears for some better towing capacity!

[72volt_ezgo]

I don't want to sound like I am arguing but I do not understand why as soon as people start talking about going up with the voltage, the general consensus is oh now we need some heavy gauge cables and everything else.
( I admit I see that mostly associated with 48V upgrades )

I am not against good thick cables by all means, I love efficiency and oversized cables will reduce heat losses and it's nothing but good! Also if one wants new solenoid and F&R switch,go for it! However my point is that when someone goes from 36V to 72V all you really need is a controller that can handle the 72volts and the battery pack that can provide it! The controls like solenoid activation etc.can be left on the original 36V spot if you want to go that rout for budget reasons or what ever. You can make a separate charging lead too for the second 36V pack and charge them one after another.

As far as NEEDING to upgrade to heavy duty components due to a VOLTAGE UPGRADE , ( how did he say it in the movie office space?) "I'm gonna go ahead and sorta disagree with you on that"

I attached a picture of my actual final battery connection that I have been using for years on my cart. (sorry for quality! Just snapped it with the netbook I'm typing on.) It's an automotive battery charger replacement clip,I believe they are 50A rated attached to 4 strands of some houshold appliance cord that I originally made up for testing. (and never had to change it out with a real battery cable).

I've been dragging downed trees across the yard,snapping dead trees out,towing/moving dead car etc.with my cart on 72V with this whimpy wire and clip for a battery connection! Never had a problem. I wouldn't try the same on 36V though. I'm sure it would glow red and throw a spark shower then!

Point is: Even though looking at Ohms law, the potential is there to pull serious amps with a voltage upgrade , in real life with a moderately tortured golf cart you will end up running roughly half the amps you did on 36V!

Not to advertise but the most torture I gave my cart,has to be when I made a GPS video of acceleration on 84V with 26" dia. tire. I floored it from a 2-3 MPH rolling start. My 100 pound dog was with me on board and I weigh 230 pounds. That video is in the videos section of the forum titled ez-go acceleration and 37MPH (something close to that) that was done with all the power going through this clip in the picture!

Sorry for the rant! Just trying to prove a point with the upgrade/cable sizes stuff. I see it all the time and I don't understand the trend

Barna

[simple man]

I agree with you whole heartedly! Thats the exact reason auto makers went from 6V to 12V! They could use less material in all the wiring. I'm debating on 72V because of the batteries needed, but 48V is obtainable fairly soon. My cart was 48V and the controller went bad, so I'm using a Curtis 1206 ( E-Z-GO moulded on it ) and running 36V. The cart is a 881 industrial and actually performs Ok on 36V, but the torque it used to have is down a bit. The main thing is it is useable for now. I have a lot of mulling over to do about an upgrade, but I do at least have the time to do it now!

[arcitech]

72volt, I agree with you, and the math works. So, now the question is, how many boats can he tow with a 72volt pack and a 48v motor? Run time and towing capacity are what Simple man is looking for, what has been your experience? (i'm interested in doing someting similar for my wife's cart so she won't have to worry about trips back and forth to our favorite spot)

[72volt_ezgo]

Originally Posted by arcitech

72volt, I agree with you, and the math works. So, now the question is, how many boats can he tow with a 72volt pack and a 48v motor? Run time and towing capacity are what Simple man is looking for, what has been your experience? (i'm interested in doing someting similar for my wife's cart so she won't have to worry about trips back and forth to our favorite spot)

He will be able to tow just as many boats as before and then some!

If he tows the boats at the same speed/motor RPM as before,he will be doing it for roughly half the amps and that would reflect nicely on the runtime by itself alone! Now if he had the room to simply double the amount of batteries he is using now, his total available energy would be twice the KW/h in the pack as well so under those conditions in theory he would quadruple the runtime. But he will probably have some fun with the extra torque and speed and possibly go with smaller A/h and higher voltage batteries so there it goes that quadruple theory

Runtime difference really comes down to the total KW/h available in the old pack vs new pack, (example: 36V X 220 A/h = 7920 W/h or 7.92KW/h) AND how much performance we are asking from the vehicle above what we got from it before! Because the performance will be there but can we behave with that right foot?

I can not give you a direct comparison with my cart because it has never seen a deep cycle battery since I've owned it! I can still give you an idea of my runtime/mileage but my circumstances are different because I run regular automotive car/truck batteries!
For 72V I use a total of 12 individual batteries connected in 6s 2p configuration.( 2 in parallel to make one "bigger" 12V battery and 6 of these pairs connected in series to get 72V).

The individual batteries (all used/murdered once or twice before I got them from the junk pile) range in capacity from 53A/h to 70A/h! So connected in parallel they average out around 120-ish A/h but since they were stone dead at least once in their life that I know about,I like to think they can't be more than around 110A/h combined.
Now if you want to compare this to 6V golf cart batteries they are at least twice the capacity (220+A/h).
If I go for an 11 mile roundtrip ride with the dog and I check the individual battery voltages immidiately upon arrival, (not allowing them time to recover)the highest battery(pair) will be at 12.4V and the lowest pair will be around 12.1V. Now this trip will include at least 1.5 miles of 30+MPH sprint (section on the highway) and the rest is cruising slower.
If I stayed at normal golf cart speeds I could go for a lot longer before reaching this average voltage 60% SOC but I cruise at 20-ish MPH if I'm not in a hurry.
Just to give you an idea of my cart but remember I'm running odball automotive batteries. The furthest thing from what supposed to be powering a golfcart but it works for me and the batteries been lasting at least 3 years now despite they are used/failed testing dealership junk pile batteries.

Barna