[scottorious]

So I just picked up my first Volt battery. I've been a Volt driver for a year now and love the car and now I wanted to tinker with the battery. I'm sure I'm not knowledgeable enough to really dive too far into it yet but it was a good price and I plan on doing my research before getting touching too much of it. I was told the car only had 10,000 miles on it but the battery had been sitting for quite some time. I dragged it home and pulled the fiberglass cover off and noticed that it's missing some of the cables and what I assume are the BMS parts that plug into the top of each module. I got the battery for 1200 dollars which seemed like a good deal but if I want to run a BMS in the future am I going to have a hard time locating those plugs? I have the 4 from the back section of the battery but not the front. I measured each 48v module at 45.5 on the nose and all the cells measured 3.801-3.803 volts. Without knowing everything there is to know I think that's in the acceptable range without being over discharged I hope. I realize I'm behind the curve to grab such a powerful battery but I've got a decent background in DC electronics but never with lithium and never anything this powerful. Should I call and complain about not getting the entire assembly or was my deal good enough that I should just be thankful for what I got?

 

[Solarsail]

New 18650 cells are going for $0.95 /Ah. Used prismatics from EVs are about 2/3 that price.

Assuming you got the complete Volt Gen I pack, which is a 7s12s3p+2s6s3p, with 288 cells, each at 15.4Ah, that would be $0.27 /Ah, which is a terrific price - assuming they all work and you got the full 288 cells.

Depending what your application is, it may not need the BMS. You can also purchase off-the-shelf non-Volt BMS if necessary. Some folks here use this pack without a BMS, and rarely need to re-balance the cells. Besides, the Volt BMS may force you to carry a huge 35% unused buffer, which drops the capacity from nominal 16kWh to 10.4kWh usable. if this is the case, then the Volt BMS is useless.

Looks like a good balanced charge you have there. If they had lost charge and re-charged by the dealer, I would think there would be a greater variance in the 288 voltages.

This appears to be a good deal, and if the BMS has the -35% issue, then you don't need it, and if you really need a BMS, then get 8x 12s BMS (as low as $15 each, depending on amperage).

 

[scottorious]

Thanks! I have been gorging on info since picking that pack up. Safely broken down and into my workshop for further review now. As they warmed up(it was 20 degrees this morning) they showed a little higher voltage. I plan on configuring some of them(the 24 volt modules) for an electric bicycle and the others for a house battery in my RV.

 

[scottorious]

Not to over simplify this whole thing as it's incredibly dangerous but the way this whole battery is built is pretty awesome. I already got it broken down into the smaller packs. Can't wait to tinker more with this! I'm already looking for my next battery! Now that batteries are becoming affordable I can't wait to build my dream electric motorcycle! A perfect dinghy for my motorhome.

 

[piotrsko]

Keep the top caps on. Dont want metallic junk dropping down there between the cells.

Im a no bms person for almost 5 years now. YMMV.....no major imbalance, no smoking holes. Chemistry is fairly benign for lipo. At 600 amps discharge they tend to imbalance. They like being 80 degrees Fahrenheit. If you leave the modules alone, except for the battery posts, chevy put a lot of effort into safety.

 

[scottorious]

I don't think I'll ever draw too much off of them in my motorhome. Just some LED lights, small water pump, a few amps for a DC refrigerator and maybe a couple other random things. I really just want to minimize the need for a generator and solar. Since I'm not worried about leaving these batteries in a partial state of charge it doesn't matter as much if they aren't replenished every day. Or at least that's my theory, if I'm wrong hopefully someone will tell me. What do you do to maintain that 80 degrees in the winter? I suppose if I built a box to store them and had an inverter running inside it might keep them warm. I would like to set up the liquid cooling/warming option but I haven't seen any good setups for that.

 

[piotrsko]

I run a home made spa pipe heater. They work at 32 degrees they just have lower currents and charge longevity. For you an insulated box should work just fine.

 

[Ocean]

I don't think I'll ever draw too much off of them in my motorhome. Just some LED lights, small water pump, a few amps for a DC refrigerator and maybe a couple other random things. I really just want to minimize the need for a generator and solar. Since I'm not worried about leaving these batteries in a partial state of charge it doesn't matter as much if they aren't replenished every day. Or at least that's my theory, if I'm wrong hopefully someone will tell me. What do you do to maintain that 80 degrees in the winter? I suppose if I built a box to store them and had an inverter running inside it might keep them warm. I would like to set up the liquid cooling/warming option but I haven't seen any good setups for that.

I have three of those Volt Packs. 1.5 (24kWh) I put in my EV, and the other 1.5 waiting for ??? maybe integration into my home off-grid solar system.

One thing about those batteries with regards to solar: the modules being blocks of 12s (except two of them 6s) and with a high voltage of 4.2 per cell and a low of 3.0 per cell (as I understand it).... with the 12s modules you have a max voltage of 50.4 and a low of 36. Most 48v (nominal) inverters have a LVDisconnect at 42v. With an inverter like this, you will never realize the whole capacity of your battery. Look for an inverter that can be programmed to have a LVD of 36 volts. I believe the Magnum's can do this. Also the old Trace SW5548's... not sure who else but check the specs before you buy.

Good Luck!!!
-Ocean

 

[Duncan]

Hi Ocean
If you look on this thread
http://www.diyelectriccar.com/forums/showthread.php/2012-chevy-volt-battery-93101.html

there is a voltage v charge graph that somebody did - I think it was Yarbert

I decided to use 4.1v to 3.5v