Lithium RXV - Talk me out of it

[Chad McCan]

I bought a used fleet 2011 RXV. My first cart. Read everything I could find here, on the subject of lithium batteries before the purchase. Sportcoupe and Toplsvette made me feel inferior if I don't get Leaf modules. They ship on the 14th :)

The local dealer came by today and gave me my speed upgrade (19.5mph programming). Tire and wheels will be here tomorrow, along with dc to dc converters (30 amp and 10 amp) and led light kit (LGT311L).

Needless to say, I'm in over my head. The dealer told me I was crazy and the lithiums wouldn't work because "it's a different charging system". I told him I'm going to have a new charger built, with a lithium charging profile. Then he said the solenoid would need to be changed, but wasn't sure why, just needed a "different one". Then he hit me with the hard sell - "Just use Trojans, or you'll be on your own when you cart has a problem, because I'll always blame your batteries first". He's got a good point there...

Anyways, I'm going ahead with my battery swap, unless someone here tells me I'll blow up the controller just hooking up the new batts. This is just a neighborhood cruiser and an occasional trip around my golf course.

Any advice now that I'm locked in?

[DIRTPIT HC]

I know your looking for some very specific information. My advice is grab sportcoupe a beverage out of the fridge on the back porch and become his best friend for a while. Good luck with what sounds like its going to be a great cart.
Keep us updated.

[cgtech]

I have built some RXV with lithiums, the pack voltage ends up being just slightly higher (around 54v full charge instead of 51v). The pack voltage does not sag as much when under load. The lighter batteries actually reduces stress on the controller. The guys running my lithium setups love 'em, never had a complaint yet. Your original fuel gauge will not work accurately with lithiums, i suggest a system from "mini bms" for a fuel gauge, fits in the original gauge hole. Everyone loves Scotty B's digital voltage meters but, voltage is a poor indicator of state of charge on a lithium battery, voltage stays pretty flat until the very end then drops very quickly. Wont see me trying to convince you to not go lithium, it works great, and its the way of the future. 80ah lithiums are about equvilent to T-1275 lead batt pack, 100ah lithiums are the same as T-875 lead pack. The 80ah compairason is based on customer feedback who started with lead batts, the 100ah compairason was done by me with discharge tests to 20% SOC and math.

Here is a couple i built,

The black ones are 100ah cells.
The blue ones are series/parallel 40ah cells, totaling 80ah.

[scottyb]

Go for it and give us a full report - somebody has to be the pioneers

[Chad McCan]

cgtech, I've read all your posts too. You're obviously doing this on a daily basis and have some great info. Is there anything else you need to change, beside the battery pack (and charger)?

I ordered the ev display. Looks awesome.

[cgtech]

Originally Posted by Chad McCan

cgtech, I've read all your posts too. You're obviously doing this on a daily basis and have some great info. Is there anything else you need to change, beside the battery pack (and charger)?

I ordered the ev display. Looks awesome.

Thats the beauty of it, not much work involved in the conversion. A fuse must be added to the pack for safety. Even fits in the stock battery tray (you will need to fashion a system to secure them in the tray). I actually build one every month or two, not every day, that would be sweet.

[sportcoupe]

I don't remember making anyone bust out their credit card for leaf modules.

How many did you buy and what was your intended voltage? What charging system you going with? There are several options out there.

Talk you out of it? OK, sell me your leaf modules and you won't be able to do the conversion. They are so unsafe.

[dougs_huntingcart]

very interesting! keep us posted!

[Chad McCan]

sportcoupe, I'm ordering 7 modules initially, but I'm sure I'll end up with 14. I'd like to test 7 around the golf course. 48(ish) volt system. I'd love to get a description, parts list and/or photos of your bottom balancing rig. I assume I need a voltmeter, maybe with a trigger to a load? And this takes about 3 days???

cgtech - What size fuse/breaker? Just put it inline from the battery to the solenoid?

[benjylafond]

Originally Posted by Chad McCan

sportcoupe, I'm ordering 7 modules initially, but I'm sure I'll end up with 14. I'd like to test 7 around the golf course. 48(ish) volt system. I'd love to get a description, parts list and/or photos of your bottom balancing rig. I assume I need a voltmeter, maybe with a trigger to a load? And this takes about 3 days???

cgtech - What size fuse/breaker? Just put it inline from the battery to the solenoid?

Chad: I went with 5 modules (36V) system. Gets me to golf course and back (3 miles round trip) plus at least 18 holes. Acceleration increase due to drop in weight (400 pounds or so) is incredible, surprisingly there was very little increase in top speed (2mph). I bought the miniBMS system but still can't get it working right, but to be safe I bottom balanced my cells like Sportcoupe and have a 40volt relay to cut off charger when it hits that point.