[EVmattyP]

Hi all, I'm building an EV project right now and I'm using (6) of the LG Chem A7 battery modules. I was planning on running them in a 3P2S configuration as I was informed that they can't be run in anything more than 2S and even that is "pushing it".

Each module is a 16S pack and I'm unsure what I need to charge them collectively or even individually. Right now they're just sitting on my work bench because I'm wanting to top and bottom balance each pack prior to installing.

Can anyone provide me with some info about what equipment I need and any pertinent information about charging these batteries properly?

Thanks in advance.

 

[EVmattyP]

Travis, thanks for the response. I think I'm just muddying the waters because I'm not 100% sure what I'm doing right now.

My initial plan was to run the biggest/strongest 48v AC motor I could get away with and then run all of these battery modules as just a 6P configuration, so basically 60.5v @ 270Ah. I was told by a few people (who know more than I do) that these modules have issues running in parallel and I should consider going the other way with it and running it as a 320v+ @ 45Ah instead. It was mentioned that they shouldn't be run more than 2P. I'm guessing for logistical reasons.

My initial plan was to run the HPEVS AC-35 as it would be able to provide about 100+tq which is plenty for my build but if I can't run the batteries in a xP configuration then I'd have no usable range.

A tesla motor/gear drive will not work in my application without serious modification and I'm not interested in going that route. Currently the van has a DC motor in it (set up for 72v) but I figured a newer/better AC motor @ 60v would still be a vast improvement.


If I'm mistaken and the harnesses I got with these units aren't used for an internal BMS then I should be ok to run them in either a 6P or 3S2P configuration, right?? At that point it seems it would just come down to which motor I'd want to use. Am i overlooking something else?

 

[EVmattyP]

Sorry, one more thing I need to clarify. The A7 modules are composed of (16) cells in series. When I say "3S2P" I'm talking about how I would connect the modules together once they're in the van

 

[EVmattyP]

That's very helpful insight. I'm located in the Alabama Gulf Coast and I'm really struggling to find local experts I can bounce ideas off here. I am worried I'm going to need to just ship everything to EVwest and wait several months and write them a giant check to finish this project.

I really jumped in before knowing exactly what I was doing. I saw the batteries as a great deal and jumped on it and now I'm trying to design a system around them and it may be better to cut my losses now and start over OR temper my expectations and work with what I have.

If you would be willing to chat on the phone sometime you could PM me your contact info and we could probably come up with a solution fairly quickly.

Thanks for your help

 

[EVmattyP]

You can certainly run them more than 2 in series. What matters is what they are connected to. Those batteries have a peak voltage of ~65 volts (4.2 x 16). Of course, you can set your BMS to have a lower max voltage to extend your battery life. So say you charge them to a max of 60 volts, you can put 3 in series as long as your motor/controller can handle 180 volts, etc.

By any chance, do you know what the rated peak discharge of those batteries is? Thanks and have fun. gw

I may have misspoken earlier. I was told the LG modules could ONLY be connected in series, not parallel. I could easily run them as 360v+ but not 60v @ 270Ah.

I believe the way I'm going to try to wire this up will be (2) groups of 3 modules in series (48cells)

 

[EVmattyP]

That's great info. Just for clarification, it wasn't EV west who told me they couldn't be run parallel, only that's how they recommend it. That email is from another installer/builder.

I think I understand what you're saying now. I'm perfectly fine with buying a second BMS if it means I'm able to ensure the cells will stay in top shape and I can use all 17kwh I've purchased.

If each module contains 16cells and I'd have (3) modules connected in series I would need a BMS capable of charging 48cells at a time. Is that correct? Then I'd need two of those and I'd need a charger that could power both BMS' at the same time (ideally).

Can you suggest the appropriate BMS and Charger I would need to pull this off? My goal is to have a system I can just plug in like my regular Cmax and have it charge the batteries fully, appropriately and quickly. I'm trying to avoid charging one bank and then going out and charging up the second bank after the first is finished.

 

[EVmattyP]

Thanks again for the prompt replies. Admittedly I'm in a bit over my head so I appreciate the constructive feedback. I will work on a simple drawing tonight that lays out what I'm attempting to do and how I have it planned in my head.

To comment on your last topic about the controller needing to handle 200V+ : https://www.evwest.com/catalog/product_info.php?products_id=482&osCsid=0td1go2hqvsm45hr94ue5t33c0 This is what I was planning to purchase. I may be mistaken but I was under the impression the controller could see more volts than it's rated for but not use them all. This way I could feed 200v+ to the controller but it would only output the 180v the motor can use.

I was also told by the owner of HPEVS that motors don't "see" voltage, only amperage and that's regulated by the controller...so the controller feeds amps to the motor and the motor is then being "run at a specific voltage".

Is this accurate?

 

[EVmattyP]

Let's back up a step. You have six batteries and are asking which way they should be configured - cart before the horse.

Normally you (overly simplified):
i) pick the car you wish to convert conscious of its weight, drag, etc.
ii) pick the motor(s) and controller(s) you wish to use to provide the desired performance using one of the available performance models;
iii) choose a series of modules and cells necessary to produce the input voltage required to drive the controller
iv) choose the number of modules or cells necessary to produce the driving range (kWh) and/or the performance (peak current) you want.

gw

1. I already have the vehicle.

2. It was already an electric vehicle with a 72v DC motor. My plan was to replace the 72v DC motor with a stronger, "48v AC motor" (HPEVS AC-35)

3. The 60v LG batteries I purchased were just going to be run all in parallel for a 60v 270Ah pack which would've been far more powerful, provided double the range and increased the top speed.

4. I didn't do this. I only looked at the voltage of each module and the overall capacity to determine range. Although I should say I was GOING to purchase Smart fortwo modules from EVwest but they had a much lower rated continuous output. Michael from EVW told me that these LG modules would be capable of 800Ah where-as the Smart modules were only good for 100Ah (200Ah peak). At this point I decided that the LG modules were the ones I wanted to use. Admittedly I may not have had all of the information or wiring knowledge prior to buying them.


This vehicle I'm building is just a play thing. I'd like to take it to shows, do some burnouts and maybe tool around to the shops in it with my son. I'd really like to be able to make a profit on it when I decide to sell it on but that's not paramount. I'd just like to have some fun and turn some heads.

I'm confident that no matter what motor/controller I end up being forced to use I'm going to make a ton more power and range than I would if I just restored it to stock. If I'm able to run a 168tq Hyper9 or a 110tq AC-35, it's going to be a lot more fun than the standard 12hp DC motor I'm taking out.

also, this vehicle has a manual transmission and a Dana 44 rear end so I'm able to add limited slip and any rear end size I want to adjust for either top speed or acceleration.

 

[EVmattyP]

If you use the standard voltage Hyper 9, you can put 2 LG Chem modules in series. The High Voltage version won't do you much good since 2 modules in series gives you about 130 volts which is too low for the HV version. 3 modules in series gives you over 180 volts which is too high for the HV version. Good luck with your project. gw

You're suggesting I order the 120v Hyper9 kit and just run (3) sets of 2S modules? It would require me to buy 3 BMS' and the power is slightly less but if this reduces complexity in the system then I'm all for it.

I have a feeling,. from what we've been discussing here, that I'm going to have to take apart the LG modules and have the BMS' wired directly to each cell. One of the most attractive things about these modules was how tidy the packs were and easy to package. I hope the addition of the BMS' doesn't impact this too much.


Also, of the 6 modules I have (4) are at 60v+ and (2) are at 55v+. I was hoping to somehow condition them (bottom/top balancing) prior to using them. I've heard others mention they need to be used in the vehicle first and THEN balanced. Any opinions on this or what I would need to accomplish it?

 

[EVmattyP]

Big thanks to all those who have contributed to the discussion. I'm learning a lot just from listening to you guys banter back and forth.

I want to shift the initial topic slightly to see if this resolves my problem.


Each A7 module has 16cells in series, correct? We've been discussing how to balance charge the cells within each module as I understand it. What if I only wish to treat each module (I have 6) as a singular battery and want to configure my final "pack" a 1S6P (modules not cells) so I should have a 60.5V @ 270Ah or approx. 16kwh pack.

Could I somehow buy a BMS that would only monitor those 6 modules? Would that cause problems based on how I want to connect the modules? Would there be a restriction in how many amps a charger could throw at a "pack" in this configuration? Is that based on the BMS used?

On a different topic, EVWest rates each module as being able to discharge 200-400A continuous with a peak rate of 800A for 10s. If I connect all 6 of my modules in a parallel configuration how does that affect the output rating, in terms of amps? Does it stay the same or does it multiply/stack like the Ah rating does? so 6 modules in parallel would be capable of outputting 4800A for 10s?? That seems highly unlikely but I wanted to make sure in case I needed special wiring to handle an increased load.

Thanks again

 

[EVmattyP]

> EVWest rates each module as being able to discharge 200-400A continuous with a peak rate of 800A for 10s. If I connect all 6 of my modules in a parallel configuration how does that affect the output rating, in terms of amps?

6x 200A = 1200A

Series boosts voltage leaves amps as is.

Your motor controller settings let you set a maximum Amps cap.

So if each module is connected + to + and - to - that would be parallel so my voltage would stay the same and total Ah capacity goes up to 270Ah, correct?

Are you saying that I can configure the controller for (hypothetically) 800A of draw from the battery pack and that would be approx. 133A from each pack?

I'm fairly confused about motor voltage as I was under the impression that the controller just passes through the input voltage as it sees it from the battery pack. Now that I think about it more it seems like the controller is determining the output voltage based on how many amps it can pull from the pack. As the amps drop so would the voltage, am I on the right track?

 

[EVmattyP]

Thanks for the input everyone. It's been helpful.