05-13-2020, 02:15 PM | #1 |
Not Yet Wild
Join Date: May 2020
Location: dango town
Posts: 6
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80's EZGO refurbishing
Hello Golf carters,
I'm currently rebuilding an 80's ezgo into a UTV. This entails rebuilding the frame since the one I got was rusted to the point of scrap. I want to install a Li-ion battery system for cost and weight savings. Also I have seen that Li-ion batteries have longer lifespans. I have minimal experience engineering electrical systems and am asking for some advice in regards to max amp draw from the motor. I realize this is dependent on the internal resistances of the battery, and I am aware that Li-ion batteries have low internal resistances. I was advised to put a capacitor in parallel with the motor to reduce draw through the speed controller. The engine I'm working with is a series wound induction type with a 2hp rating. Will this motor exceed 500 amps during a stall scenario? Edit: I've also heard some horror stories about BMS and charger setups. I'm on a pretty tight budget so I'm looking for cost efficiency over most other things. Thank you for your time, Chris |
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05-13-2020, 03:49 PM | #2 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,167
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Re: 80's EZGO refurbishing
IMO Lithium and "Tight Budget" don't go together.
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05-13-2020, 05:33 PM | #3 |
Not Yet Wild
Join Date: May 2020
Location: dango town
Posts: 6
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Re: 80's EZGO refurbishing
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05-13-2020, 09:03 PM | #4 |
Gone Wild
Join Date: Jan 2013
Location: Saint Petersburg, FL
Posts: 2,089
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Re: 80's EZGO refurbishing
The series motor you have will pull a lot of amps at or near a stall condition. If you are planning on using it as a UTV (bigger tires, pulling stuff, hills, harder environment in general) then expect that it can require 400 amps near stall. I'm guessing on the amp draw, but you get the idea. You can put in different gears to reduce the load on the motor as well. That'll drop your top speed, but if you are using it for hauling it may be necessary.
As for cost, 600 is not much for a lithium setup... I have one of the cheaper settups and I spent about a grand or 1200. But I did run a 47ah pack for a bit before going to 94ah. So a cheaper pack is possible... I had a good deal on my pack as well. There are many lithium options out there and if you are creative you can find some good deals out there. But 600 is the exception, not the norm. I would forgo the capacitor. I used caps when I had idiotic car stereo systems, but the length of the cable in a golf cart is much shorter and at a higher V. The voltage sag is pretty minimal with a lithium settup, the cables are fat and short, so the cap isn't going to do much for you. Keep it simple and spend the $ for caps on the lithium pack. Besides, a 12V cap will have to be connected in series with other 12v caps and when you put them in series it reduces the capacitance (IIRC). So a 6 farad 12vdc cap put in series with two other identical caps would only give you 2 farads at 36vdc. Again, it's been a while so I may have confused that. But that's what I remember. Also keep in mind that lithium is NOT forgiving if you overcharge it or overdischarge it. You need a system in place to prevent overdischarge and overcharge. You also need to ensure the cells are balanced, so if you identify that the safe discharge for your pack is XX.X volts then you need to see what your individual cells will be. Different Lithium chemistries have different voltage limits. So whatever lithium you go with you need to be careful in how you treat the pack. Now, there are some emerging systems out there for lithium packs that are pre-made. The industry is pretty young right now, but new products keep coming out so in a year or more there may be something viable in a pre-made format. |
05-14-2020, 08:54 AM | #5 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,167
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Re: 80's EZGO refurbishing
Any reasonable sized cap will make zero difference when connected to a DC motor. Only place you see caps on motors is AC motors - for Power Factor correction and starting. It sounds like your requirements are for fairly high torque - which means high currents. You will need a high current controller and a battery pack that can handle high currents. It's getting hard to find good used Leaf batteries but that is your best bet - and I would go with a 14 module pack for the added current capability. You are not going to find that for $600.
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08-10-2020, 02:14 PM | #6 |
Not Yet Wild
Join Date: May 2020
Location: dango town
Posts: 6
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Re: 80's EZGO refurbishing
Hello all,
Thank you for responding to my questions, I appreciate all y'alls advice. I'm picking up 2x4 steel tubes in a couple days to start welding up the new frame. I have the steering, suspension, brakes and motor from the old BUGGIE. Besides the new frame I have to: Get batteries. Get BMS for batteries. (does this take the place of a charger??) Get speed controller and throttle for 48V (hopefully I can get a 500A controller). I've been looking at wiring diagrams, but I'm no electrician... The batteries I've settled on are as follows: https://batteryhookup.com/products/l...ium-ion-module I plan on buying two. For a BMS, I plan on getting a 48V, 100 amp, 14s system from aliexpress. I'm not sure if I'll need one for each battery though. Honestly I have very little prior electrical experience and no role models, if any of this seems dumb, wrong or plain ignorant please smite me. I'm not sure what other bips and bobs i'll need to get. |
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bms, lithium, peak amp draw |
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