Series controller sizing help

[Turnofftheradio]

Hi!
I have a 77 citicar. I'd like to convert it to a modern controller. I have no clue how to size a controller for it. To guess I'd say I might need 400-600 amp?

Here's the skinny on it
48v (8x 6v)
6.5 hp ge motor
5.17 ratio Dana axle
125/80r12 tires
1300 lbs empty with batteries.

Currently it can go just over 30mph which is fine.

It uses a contactor arrangement that switches between series and parrallel and another for f/r. They are big contacts probably ok for 7-900a as a guess. Like dime size contacts.








Any idea what would be a near equal swap? Think 500a would do it? I don't deal with big hills often. But occasionally might.

What I don't want is to oversize the controller and kill my motor, or so small I can't get anywhere.

This car shares a lot in common with Cushman and ezgo carts of the 70's era.

[KarTek]

I'm interested in this just for curiosity sake. I'm not sure how controllers are rated, whether a 500A controller will limit current to 500A or be overloaded by a current draw of over 500A.

In other words, will a 400A controller only allow 400A to a 500A motor or will the 500A motor overload the 400A controller?

[scottyb]

Controllers limit flow. There are different ratings by peak, 5 min, and continuous. I would assume this cat motor has full access to the battery pack at WOT? If yes I would use 500 min and 600 max

[Turnofftheradio]

Thanks!

As it is I have a 3 position gas pedal. That obviously is not compatible with a modern controller.
1: 24v (parallel) and a resistor for 18v, 5-10mph
2: 24v (parallel) no resistor, 15mph
3: 48v (series) 30mph

As far as I can tell, the only limit to amps are the cables. I think I'll try a 500a and see how it goes.

[Mooncarter]

Look up: "Caroche Runabout" a member here is doing something very similar.

[Turnofftheradio]

Thanks mooncarter. That was a great read of 24 pages, and we share many things in common, being like my citicars older brother from the same father.
I actually use the citicar for commuting. It's great and gets me to work so I can make more money to spend on it. I am totally jealous of the removable top though.

[Mooncarter]

Originally Posted by Turnofftheradio

Thanks mooncarter. That was a great read of 24 pages, and we share many things in common, being like my citicars older brother from the same father.
I actually use the citicar for commuting. It's great and gets me to work so I can make more money to spend on it. I am totally jealous of the removable top though.

[ThreeCW]

Originally Posted by Turnofftheradio

This car shares a lot in common with Cushman and ezgo carts of the 70's era.

My 1998 Cushman Hawk 48v Utility Vehicle has some similarities to yours ... both 48 v with GE 6.5 hp series motors ... both heavier vehicles ... your 1300 lbs / mine 1620 lbs ... speeds are a bit different ... your 30 mph vs. mine at 17 mph (mine is designed for a hauling loads).

Mine has a 600 amp Curtis Controller ... if I was going for a new controller for my cart, I would go with the Alltrax SR 48600 which has 690 peak amps, 600 amps (2 minute rating), 500 amps (5 minute rating) and 450 amps continuous rating. The Alltrax controllers are very popular on the BGW forum ... you can read up on them on the Alltrax website, search Alltrax on this forum or check them out at one of the site sponsors such as Carts Unlimited http://www.cartsunlimited.net/alltrax-sr-series--.html

The 600 amp Alltrax controller is only $90 more than the 500 amp Alltrax ... but either one should work for you.

[Turnofftheradio]

Thanks threecw, that's helpful information to know that a 600a will not immediately destroy the motor. I'm considering both Curtis and alltrax at the moment. It's obvious that alltrax is the king of that choice, at a significant price too. Being that I have to change my 48v cables, contactor, and pot box upgrade, the Curtis seems reasonable to my wallet. Especially after I just bought 8 batteries and a delta quiq charger. Looking into the farther future, I could see a alltrax and motor upgrade afterwards, hopefully selling the used Curtis to offset that. I'll decide on one option soon.

[scottyb]

The Curtis 600a 2 minute and 5 minute output tests will closely match the SR48500 controller. Plus the Alltrax has reverse polarity protection and a 2 year no questions asked replacement warranty..... it's waterproof and more. Hardly a fair comparison