Chevy Volt Lithium

[Sergio]

Originally Posted by ACCLR8N

Why can't the Volt batteries use the same inexpensive charger we use on the Leaf batteries?

They can and for around $100 they work really well for a single Chevy Volt pack.

[simicrintz]

Originally Posted by Sergio

They can and for around $100 they work really well for a single Chevy Volt pack.

Since I do have a BMS for each pack, could I buy 2 and make it work?

[Will-versed]

Thank you members for the ongoing discussion. My takeaway is that I was in way over my head by buying the two Volt batteries from an eBay seller with little documentation, reviews etc., a no-return and no warranty policy, and just a vague description making me assume they were plug'n'play. It was a sad but typical case of not knowing what I didn't know.

But he was local to me and I was able to pick up the batteries at his home in Livermore. He offered little in the way of caveats or suggestions when I met with him (except to diss LiFeP04 batteries again) which again reinforced my naive view that his Volt batteries were the way to go -- easy to install and maintain, just watch your voltages.

I actually did try the Lester charger on a couple of different profiles, but when the charging voltage got up to 54 volts on an AGM profile their tech recommended I try, I shut it off immediately. I tested the voltage of the system at that point and it showed 42 volts, low, but thought it was Ok for a run up and down my driveway -- it ran great and I left it alone until I received the new Schauer charger and discovered the havoc beneath my seat.

So I had a counterfeit vision of a simple lithium upgrade for an older golf cart, and I need to be grateful that I learned a lot without suffering a fire or explosion like others have documented on BGW.

My goal is to play more golf, using a simple, reliable cart set-up with modern but proven technologies. I need to work on my game, not on my cart. So for now, onward and upward with RoyPow or Allied or ReLion or some-such with a warranty -- the search continues.

[Will-versed]

BTW Simicrintz, your cart is a gorgeous classic and I wish you the best on your LI-Ion conversion!

[simicrintz]

Takeaway-thankfully you are okay and are only out some $$. I ride dirt bikes, and as I told my son and my wife when I taught them to ride; if you get in trouble, get away from the bike. I can buy another bike, but I cannot get another you.

I will forge ahead and find a way to make this work. I plan on taking my time and doing it safely (not that you did not, Will). I will learn along the way. And I appreciate all of the help as I set out down this path.

Thank you, Will. I truly am sorry that this happened to you.

[Sergio]

Originally Posted by simicrintz

Since I do have a BMS for each pack, could I buy 2 (chargers) and make it work?

The issue is not the charger but the fact the packs are in parallel.

Assuming You have pack A and pack B in parallel, if during charge a cell in pack A goes HV and pack A BMS disables the charging, the pack A battery will continue to get charged through pack B charger since the packs are in parallel.

If your BMSs have Bluetooth or other way to change/verify programming, you can make your own LV/HV charge and discharge setup using relays and a solenoid.

I think it would take:

• One SPST solenoid like the one you have for the cart B+ to only parallel the packs when the key switch is ON ($70-$120).
• Two small 48v SPST relays to provide a discharge LV interlock to stop cart ($6 each).
• One small 120v SPDT relay to enable the charger and provide cart lockout ($6).

If you used a more expensive Normally Closed Solenoid or a SPDT (SW201) type Solenoid you could also only power the Solenoid to split the packs when the charger was active, during normal use the solenoid would be OFF (packs in parallel).

I think some folks here that use parallel packs only count on the charger to stop at a safe voltage and hope no cell goes over-voltage.

Perhaps other members can add more ideas on different ways to use and charge two Chevy volts packs in parallel.

[DaveTM]

Is it possible to keep the two packs separate, charge each pack separately, and when pack #1 voltage get's low, switch to pack #2.

Each pack has it's own BMS. One charger could be setup to charge both packs.....but not at the same time.

Ya are gonna need some big switches!!

[Sergio]

DaveTM, You just need a single battery disconnect switch between the pack negatives if you are going to do it manually.

As I mentioned in a previous post that will take care of charging, but on the discharge side there would still be no cell monitoring to disable the cart.

[simicrintz]

Thank you again, Sergio. I thought I had this all figured out before I ordered the packs; guess I was wrong (again!).

I need to sit back and really get a better handle on this before I hook stuff up. I really just need a safe cart and I don't want to "guess" if something is working correctly or not. For some reason I thought that the parallel application would "back balance" from the charger equally, since it is in parallel. I never considered that one particular cell could be affected in the chain (DOH!!).

[Volt_Ampere]

When we connect Leaf modules in parallel each cell has one in parallel with it rather than at the pack level. This balances each cell with it's parallel companion cell and allows the BMS to see the parallel cells as one cell. If you can connect the Volt cells like that then all would be fine. I have never worked with them but from what I have seen that is not easy to do.