Lead acid battery conversion

CCDSWizard

I am converting a 2000.5 Club Car DS from lead acid (LA) to LiCO02 batteries (same batteries used in VOLT). I need a little help understanding how to treat the OBC.

New batteries consist of two parallel 48V 50Ah packs. Each pack has its own BMS. Each BMS is wired as follows:
o -Battery to BMS B+,
o BMS P- to -Charger Receptacle (this I know for sure, per BMS instructions) and Controller B- (the latter is an assumption based on, 1) OEM schematic showing -Battery "thru" OBC to Controller B-, and 2) BMS schematic).

Here's my interpretation of OBC function using lead acid batteties:
1. during charge, OBC monitors charge voltage till full charge met, then signals charger to stop charging, and
2. during operation, OBC monitors voltage drop (battery drain) till a low-voltage condition is met then, signals controller to stop? The last part is a deduction.
I've witnessed #1, never yet #2.

With the new battery packs each having a BMS,
1. it seems the OBC is not necessary to monitor charging since BMSs manage charge balance (to each pack cell), and
2. it seems the OBC is not necessary to monitor voltage drop during operation because BMSs will "disconnect" battery pack individually when 36V low-voltage is met.

If my understanding is correct, then the only piece missing is how to address charger shut-off during the charge phase.

Please comment on any or all of my post. My goal is to rewire the cart so it actually works . What a thought... sarcasm included.
Walt

BGW

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Volt_Ampere

You can't use the OBC or the charger that goes with your FLA batteries. You need a charger designed for the Lithium batteries at the voltage you are running them at. I am not an expert on Club Cars but I think the OBC is only used to manage the charger function.

CCDSWizard

Yep Volt_Amp, a different charger is required. Workin' on it...

Background: I replaced 6 8v Trojan T-875 wet cell batteries with 2 48v 50Ah LiCoO2 Chevy VOLT battery packs in parallel, yielding 48v 100Ah.

The procedure and answer to my questions in my original post:
1. Remove OBC. This includes disconnecting 3-pin triangle connector nearby the CONTROLLER (black, yellow and red wires), removing 10 AWG black wire connected to CHARGE RECEPTACLE- to OBC, fuse at CHARGING RECEPTACLE, and disconnecting black 12 AWG wire from OBC to the ring terminal on CONTROLLER B-.
2. Add 10 AWG black wire from CHARGE RECEPTACLE- to CONTROLLER B-, or, cut wire at OBC and add 5/16" ring terminal.
3. Add 10 AWG yellow wire from TRIANGLE CONNECTOR YELLOW wire to CONTROLLER B-.
4. BATTERY- or, in my case, BATTERIES- to CONTROLLER B-.
5. Each BMS P- to CONTROLLER B-.
6. BATTERY+ or in my case, BATTERIES+ to SOLENOID+.

Since battery packs are of a different material (LiCoO2) and do not fall within lead acid deep cycle category, the Lester OBC and Lester PowerDrive charger are no longer needed and wouldn't work anyway. So both become obsolete.

As you can read, the CONTROLLER B- terminal gets a little crowded. I replaced the bolt/nut combination for a slightly longer bolt.

Losing 700 lbs of wet cells for roughly 40 lbs of new batteries really makes a difference in acceleration and handling. I can chirp the rear wheels on launch now!

The complete conversion, including trips to Home Depot, fabricating mounting brackets, installing batteries and anchoring hardware, fabricating new wires and installing, soldering, tie-wrapping, etc, took about 20 hours. Not too bad. That also includes researching how to bypass OBC, and calling the battery supplier to be sure I was clear about how to connect the BMSs, which is part of the answer to my own question in the original post.

Hope this helps to get away from those pesky wet cell boat anchors.

270Handiman

700#'s? Were you running 12 batteries? New project is cool, keep us updated as you get further along.

crash test dummy

6 (t875s) x 63 lbs = 378 - 40 = 338 lbs still a good reduction

what is the cost of this conversion , including charger(s) ?

CCDSWizard

Hi Crash.

It's not cheap...
- Batteries can be found on eBay for around $550 each. There are 2 suppliers listing LiCoO2 (Lithium Cobalt Oxide) battery packs in various voltages and Ah ratings.
- BMSs, $200 each (includes "testing to be sure they work") - from the seller from whom I bought batteries.
- Charger, $375 drop ship from Asia. Same seller.
- Miscellaneous, maybe $150 for all hardware and wires.

Probably $2000 out the door, tax 'n' license...

...trying to recover costs by selling OBC, Trojan battery hold down parts, and deep cycle battery charger. If I get what I'm asking, - hopefully - will offset costs by $500.

To give another idea what other batteries might run, I contacted an EV expert offering LiFePO4 batteries out of Los Angeles. For 16 cells, $2000 - about $125 per cell - charger cost on top of that. Assume same cost for charger, $2300.

I asked for quotes from Alibaba.com from at least 6 lithium ion battery vendors. Samples ranged in cost from $1350 USD for one 48v 100Ah battery including shipping, to over $3500 for the 3.2v LiFePO4 equivalent batteries with shipping.

There are other options. In each case, one would need time to "shoe in" the chosen option. No snap, click, done.

Hope that gives an idea of cost ranges, battery choices and relative effort. Nonetheless, learming experience... and fun.

Yes, I over calculated battery weight. Sorry about that!

crash test dummy

good to know, what is the life expectations of the LiCoO2 ?

any photos of the set up ?

vadum

$2000 is not terrible. About the same cost to convert 4 12v's to a 6 8v setup, which I was about to do. Not sure I have the technical knowledge to complete what you did though, which is just an assumption due to not understand about half of the words you used. Pics would be super if you had the chance.

crash test dummy

he took 2 batteries from an electric car
red necked them in
it works

kgsc

$2000? To convert from 4 12s to 6 8s should be less than a grand.