Top speed and acceleration drops dramatically after few miles

[bronsonj]

Originally Posted by Salty821

Do you mind sharing what Lithium setup you have? What top speed do you get now?
I'm wondering if I should make that investment?

I did it DIY style, so my setup is much cheaper but involves more work than others. I took a 12 cell Volt pack and a 6 cell, mated them together and tapped off of the 14th cell. Then for the remaining 4 cells I have that for my accessory power for stereo, lights, horn. So 14 cells for traction, 4 for accessory. Then I doubled that with another pack in parallel. The traction pack can handle 58.8V but I never charge it that high. 57.6V is my personal max and most the time I don't even charge that high. You don't want to store lith batteries at full charge for any real period of time. But they don't self discharge enough to be a meaningful loss, so they'll be perfectly happy sitting at 75% charge for months on end.

I used Chevy Volt cells because they are generally cheaper although harder to work with. Nissan Leaf cells are the preferred cells by most people on this forum, they are absolutely an easier form factor to work with. There are other options too, Fiat and Ford both have lithium powered hybrids with cells that can possibly be used. The OEM BMS code for the Chevy Volt cells protects those cells a little better than Nissan Leaf, so if buying leaf make sure the seller states the capacity. Also the Volt cells are the right width, so they fit in my TXT48 battery tray without modification to the tray. One 18cell Chevy Volt module is about 2 times the length of a single 8V battery and vaguely the same width/height.

I have the Alltrax XCT300-TXT48 from Scotty B.
http://www.cartsunlimited.net/alltrax-xct-sepex--.html

I have it tuned to only allow 5600 rpm (IIRC) and that gets me 32mph. 32mph is uneasy... Next time I get the laptop hooked to it I will lower that to 5500.

You will need to source a BMS and figure out your top or bottom balance method, you will need to source a new charger as well. You will need to verify your methodology for never overcharging and never over discharging your cells. A BMS handles pretty much all of that for you if you go that route.

The charger does not have to be large/high amperage. It will need to talk with your BMS so it doesn't overcharge your pack, but lithium is fine with a slower charge. I use a 5 amp charger.

Your battery capacity (ah) numbers will be vastly different since much more of the capacity of a lithium cell is usable while relatively little of the capacity of a lead acid cell is usable. So don't worry if you put together a 90ah lith pack, it will out perform a 125ah lead acid pack, and weigh 350 to 400 lbs less.

The stock controller turned into a beast on lithium! Since the voltage was much higher and didn't sag and the cart was so much lighter. But, I don't know how long it'd last on the higher V. Going to an Alltrax also let me set the low V cutoff to whatever I wanted, so that's another layer of protection on the lith pack.

If your batteries are shot, then the conversion becomes something to think about. Spend $650 to $750 on new lead acid or jump to lithium.

Best thing you can do is read... Battery University website has a few hours of research to start you off. Google the various hybrids to see what chemistry battery those have. Take time in advance, it's interesting and will save you from wasted money and injury. The tech is safe, if you respect it properly.

[bronsonj]

Oh, the other stuff...

With lith your cart will loose so much weight you will be amazed at what it can do! Even keeping the stock controller, completely night and day.

If you are at the limit for clearance for fitting into your garage you may want to remember losing 400 lbs 'might' make it harder to fit in without hitting the overhead door.

Your ride may be a bit harsher too. I have HD springs and it is a little harder than before. I have a set of 'progressive' springs to put on, but have not done so yet.

You will never check water levels or have to neutralize the acid all over your frame again... No more worries about rusting out from acid boil-over.

Your lead acid pack, fully charged is between 50.8v and 51v, ish. If you go with a lithium settup with 12 cells and only charge to 4.1 volts per cell for longevity, then it'll reach 49.2V and your cart while it will reach top speed faster, will not be as fast as a 50+v cart. If you go 13 cells at 4.1vpc you have 53.3 and a smile... 14 cells at 4.1vpc if 57.4 and a bigger smile... Also on lead acid at 48V you were dead. On lith you can go much lower voltage, generally 3vpc is the lower safe limit. I set mine to 3.25vpc which is a pack voltage of 45.5V.

Your stock lead acid charger WILL overcharge your lith pack. Do not use it unless it is an emergency and you are watching it like a hawk. Seriously. A 48v lead acid charger will reach over 60V and a 14cell pack max safe V is 58.8V, preferrably a little less.

Your controller will love batteries that don't sag much voltage under load. Currently your pack at 51V will get down to 42.7 under load. My pack I charged to 56.6V before the parade where I was pulling a float with 12 people on it. Under parade-load it droped 0.1 to 0.2v... Without pulling the float it will drop 0.1v under load.

So there are some technical and monetary hurdles to the lithium jump but there are also benefits to it as well. Both are viable options, both have benefits. For example, lead acid is very forgiving in regards to overcharging and lithium is absolutely not. Either way, good luck!

[badandyturbo]

Great info Bronsonj. You are an inspiration to us all.

[basshawk84]

Batteries would be the first thing I would change. They are likely original to the cart. Pulling down in the 42 volt range on a fresh charge is too low for my comfort. So start with a good set, then have Bob reprogram your stock controller or upgrade to an Alltrax.

[bronsonj]

Thanks BadAndy!

Salty, if you get a fresh set of batteries and it doesn't do what you need then the next person to talk to would be Bob. The is the Maestro of controller programming.

[Salty821]

Just got a fresh set of batteries today. I'll install them over the weekend and take it from there! thanks everyone for the help!

[Salty821]

New batteries worked out! Speed went up to 19mph (top) and went for a few miles and everything stayed the same. Thanks everyone for your help. I did notice the cables between the batteries are not in great shape. I'm going to swap them out as well as order a new controller/solenoid in the new year.