Replace My Golf-cart's 48V Battery Pack With a Small Engine Generator?

i have taken this up as a college project,actually the aim of my project is to increase the range of the electric golf cart,once the batteries run out of charge,i need the secondary source to power the vehicle.that is the reason why i thought of a engine generator to replace the batteries.

If this is a college project, why are you asking for help with fundamental issues such as this. You should understand batteries and motors much better than you seem to before even beginning. If you think this will work, who are we to stand in your way.

Go ahead and try it. Report the results back here.

http://www.alternatorparts.com/small_starters_generators.htm
http://www.repowerspecialists.com/golf-cart-engines.htm

The odds are your 48 volt drive motor probably has a peak short term amp draw well into the few hundreds of amps and the speed controller requires a fairly stable 40 - 50 volt input to work properly.

48 volts at 300+ amps would require a rather expensive alternator and a good sized engine to keep up with it.

Either buy new battery's or trade it in toward a gas drive. Either way you will money and time ahead.

...which is sort-of-why no-one else is doing it now.

"i have taken this up as a college project,actually the aim of my project is to increase the range of the electric golf cart,once the batteries run out of charge,i need the secondary source to power the vehicle.that is the reason why i thought of a engine generator to replace the batteries."

You need to learn about volts, amps, watts, horsepower, torque, battery amp hour ratings, efficiency of energy conversion, practical applied real world mathematics, and applied economic analisis processs first.

Unless you are a first year student I recommend you don't quit your job at McDonald's any time soon to pursue a career in engineering.

LOL!!

Despite the fairly negative comments you could use a small motor/generator to charge the battery. The motor probably can't provide enough instantaneous power to run the cart but, using a battery, enough energy can be stored to run the system.

I'd suggest you have a go and see what happens. Projects are all about getting real world experience. It doesn't matter where you start out so long as you make a small amount progress with each step.

Who knows, one day you may become smart enough to feel you can mock beginners

thankyou for your reply,i was biginning to think that this cant be done for a while

What's wrong with the present set up? My Company has been in business since 1892 and have been building electric drives for the marine industry to present day. Why not stay with battery operation? We also do hybrid systems, where a genset suplies power to the complete system. This can also be from Wind and solar besides gen or combination of. There are no limits today!

can you provide me with some info about the gensets you use for your hybrid vehicles?

Hey,

Don't listen to mockers.

Yes you can do it. But modify the idea a bit. In the way you want to do it, you need very expensive components,you will not be able to use the electrical motor and it's components as such. A different propulsion system must be used.

So DO NOT discard the Batteries.

A small gas engine to CHARGE the batteries will do it. and if your aim is extending the endurance than you just did it.

Wangito.

If a heavy duty 24 volt car/truck alternator is found on a scrapyard and the rotor windings removed, t6ogether with the slip rings and brushes, then the voltage output will be a product of the RPM. Find the optimal RPM to allow the rectified current to be able to charge the 48Volt battery and there you have it.....

Use V-Belts and pulleys to get the optimal alternator RPM coincidental with the best motor RPM.....

Having some charge control would be nice but not critical as long as you keep an eye on the DC voltage and current direction when the motor is used, with simple voltage and current meters.....do not overcharge the battery too often, it will damage it quickly. Never is best.....use 57.6 volts as an absolute max, ever!! 54 volts would be healthier......

Have fun....

Let us, all, not forget that this is a college project.

AKA homework.

The initial post was also filled with mis-information.

48 volt alternators are found in locomotives. Auxiliary power units of 48volts are found in commercial airplanes. Leese-Neville manufactures alternators with isolated negative terminals. 4 of these could be used to charge each of four 12 volt battery packs. Two 24 volt alternators of this design are also possible, but it is harder to find high output 24 volt alternators.

thanks for replying Bob,

and yes as i came to know,it is hard to find such high output alternators.say i find one but its still hard to make it efficient.

instead iv decided to use a portable engine generator from honda,maybe a 3Hp one,it roughly generates 0.8 Kva,ill use this to charge my batteries on the go....

what do you advice on this idea?

You will still need 4, 115 volt to 12 volt battery chargers to maintain the 4 battery packs. Battery chargers above 20 amp start to get expensive.

You need to think of an efficient way to convert gasoline, or kerosene to electrical energy.

I have a 48v cart and i am in the process of doing something very similar. I have a 2000 watt compact honda generator and i have found a 1000 watt 48v power supply that i am gonna buy and use it to power my golf cart and charge my batterys on the fly like a hybrid. The power supply has a input range of 180~264vac so it converts ac to dc. Im still gonna charge my golf cart over night with the regular charger like i always have but im gonna use the generator to extend my range and also give a stable power source so it doesnt bogg down pulling hills going down the road. They make the 48v power supplys all the way up to 3000 watts and thats about what it would take to soley power the golf cart without any assistance from the batterys but it is about $600 and the 1000 watt power supply is $200.

How does my view of this sound?? If i can get other people to agree that this is possible i am going to start on it within the next week of so

That should work.

It probably won't help you with hill climbing. Sluggish hill climbing is due to either, small motor(s), small conductors, loose connections, high battery internal resistance or any combination of these. If it (the low torque) is a battery internal resistance artefact then your rolling charger will help here. Bigger conductors will ameliorate the voltage drop under loading (and improve torque) if that is a deficiency and good, clean and tight connections (another place where voltage can drop due to series resistance) are just good to have anyway.

Before committing to any expense, perform some measurements.... battery voltage, motor voltage and motor current under different driving conditions. That will tell you what is going on now. The poor hill climbing needs to be sorted first if that is something you want to improve on.

Check the battery voltage and and charge current with your present charging arrangement.

Sketch the arrangement and plan your augmentation.

your reply gave some good solutions for the hill climbing problem of the cart,but can you give me some advice on how i can charge my batteries when i am running the cart?
the problem is i donot have a running cart to perform experiments on,by experiance can u just tell me how much power is consumed on an average by the motor when its running(its a 3.5Kw motor,with a 48V batt-pack)???from that i can estimate how much KVA generator i need to charge the batteries constantly

Your full motor load is 3.5kW, therefore to run the motor flay out constantly via a generator/rectifier you will need a 3.5kW generator (assuming no losses)

But a vehicle spends time stationary and an electric vehicle doesn't demand power when it is sationary and you aren't always demanding full power so the better way to calculate this is with an energy {power x time) budget and not a loaded power budget.

A generator with a peak output that is less than the peak demand is buffered with batteries. The batteries will discharge during peak demand and recharge during low (motor) demand.

Does that help?

yes,kinda answered half of my doubt.. ie that i must look for a generator that provides just more than the average consumption.

i had put forward a question in this forum asking for the current drawn from the batteries on average by the golf cart,one person said its usually 90Amp on an average in a 36V golf cart,but since mine is a 48V cart the draw should be less....maybe 70Amp.

so if my basic formula is right the power consumed is 48V*70Amp=3360VA that is 3.3Kva

so i need a generator that can provide me 3.3Kva

is the peak current draw suggested by the person right?my math and the conversion from VA to KW??

Its going to be hard to to generate the 3300 watts thats needed to run the cart without any assistance from the batterys because yes they make generators all the way up to 11,000 watts and some even higher but thats ac power and we need dc power for our cars so the problem were going to run into is with the charger or converter we us. my charger is a 25 amp charger so at its peak it puts out 1200 watts(25ampsx48volts) so that is enough to help the cart run about 40% longer under wide open constant throttle and if your only running half throttle or stopping that percentage would be even higher. You can prolly buy a 50 amp charger that would get you to 2400 watts but thats prolly the biggest charger you can buy. and my cart will run with the charger plugged in i tested it earlier today.

also here it a site where they sell ac to dc converters http://www.trcelectronics.com/48-volt-power-supplies-high-all-2.shtml

Power is power, whether AC or DC......talking about watts makes it easy to compare DC and AC sources rather well.....with even different voltages....

Which is why for example that a given AC voltage value, is an AC voltage that will do the same amount of work as an equivalent DC voltage. But if you look on a scope, you will see that the AC peak is far higher than the DC voltage......

(for work read power)

You appear to misunderstand the concept......please correct me if you intended to write something more accurate than you did.....but what you first wrote was most misleading.....

Your right in what your saying but what I was saying was you can't us alternating current on a direct curent system. There is no way that you can just hook ac power to batterys directly with out some sort of converter so I don't think I am misunderstanding anything

You don't need to post as there are relatively cheap chargers around that have all the magic inside to convert from mains AC to the required DC needed AND with the intelligence to control and stop the charging if the battery is full.

The wonderful thing here is that the OP could buy 4 x 12 volt mains battery chargers, and put one to charge each battery........it will probably be cheaper than buying a 48 volt charger (though I haven't actually checked that out!!).....

Run the generator (big enough to supply all 4 devices at maximum charge of course!) and supply each battery via a charger.

This is actually better for each battery (healthier) than the 48 v charger will ever be.....as each battery is an "individual" and should be treated as such.....whenever possible. This will prevent unequal charge levels in different batteries......as one can age faster or slower than another....or they may even be of different ages or manufacturer, which would mean that a 48 v charger might actually damage some of the batteries......

well instead of talking about it i have done it. I put a 2000 watt honda suitcase inverter generator on my golfcart. I plugged my factory charger into the generator and plugged it into the golf cart and it ran perfect. I rode it for about 5 hours with the generator running pretty much the whole time. I have a charge gauge and it never came off of full charge the whole time so my charger was able to put out enough power to run my golf car. It is a 25 amp charger and my cart is 48 volts. My cart seemed to have a higher top speed and it was able to get to top speed faster and also my hill climbing improved 100%

You have proved another one of my theories. When the results do not agree with the theory, invent a new theory.

Good for you. Enjoy your new toy, and thumb your nose to all of the people that said it would not work.

Have fun my friend - but just because the generator is rated at 2000 watts doesn't mean that's what it is putting in to your battery pack. I assure you; your batteries are not electrolysing at 2KW.

Welcome to the world of hybrid power processes.

Gavilan

Please improve my knowledge, what the hell do you mean with that word "electrolysing"?

Thanks in advance.

I found this:-

e·lec·tro·lyze  [ih-lek-truh-lahyz]

verb (used with object), -lyzed, -lyz·ing. Physical Chemistry .

to decompose by electrolysis.

But somehow I cannot resolve it in the situation you used it in, sorry.....did you mean "charging"?

Sorry about that. Ya - charging would have been a better term.

Gav

And I was under the impression that the golf cart is 36Volt.

Wangito

Some are 36 volt. Some are 48 volt. I think the harder working ones (faster) are 48.

There is no way the batteries can accept charge at the high rate they can discharge - right?

If you try to dump 3000 watts into the battery pack whats going to happen?

Gav

I am interested in this as well.

I have a 48v electric vehicle with 220 Ah batteries, I would like to double the drive time, and thought about hooking up a generator, so it charges while it drives.

Is this possible?

Welcome. Read all the posts. It is workable, depending on how far you want to extend the drive time, and what work you are willing to do. Good luck.

It is very posuble I have done it recently and it works great. The only problem I have is the noise, I have been thinking about getting a quieter muffler. But the generator I'm using is a honda 2000i suietcase inverter generator that uses pure sinewave and the chager I use is my factory 25 amp 48v charger which puts out 1200. Watts and that is plenty of power. Most people say you need over 3000 watts to make it work but that wasn't the case for me. The furtherest I have go using the generator is 25 miles and I done it over about 5 hours but we were just road ridin and trail ridin and have a good time but I can go 20 miles in 1 hours if I don't stop. Also I have a 400 amp curtis speed controler

that is really nice to hear that the setup is working for you... any idea how many KMs or miles you do pel/liter of fuel.....?

Shortly before I retired my employer gave me a brand new Ford Fusion Hybrid to drive. It had a range of about 400 miles would go well in excess of 100mph, had very high acceleration, and had a kinetic recovery system (regenerative braking) . So its quite possible to build hybrid power systems.

;0)

Gavilan