w0ss semi DIY powerwall V2

Sojourner

New member
Joined
May 7, 2020
Messages
15
w0ss said:
I never measured the wire so I can't say for sure. 2amp might be ok but I don't want to say yes and have it break something.

Maybe I should isolate the Lifepo4 and do another test.

I see the balance leads on the module are 24 AWG.Your resettable fuses are what amperage,and how did you select that?

That would be very interesting if you can isolate the LG for capacity test :)

Thanks
 

w0ss

Member
Joined
Oct 15, 2019
Messages
56
According to wikipedia 24awg can handle 2.1amps. I picked fuses that trip @ 1.5Amps. I just made a guess... sounds like my guess was close enough :)
 

HydroGeo

New member
Joined
May 7, 2020
Messages
9
w0ss said:
I never measured the wire so I can't say for sure. 2amp might be ok but I don't want to say yes and have it break something.

Here are a few closeups with a penny for scale.

image_aoarrn.jpg

image_dewvto.jpg



My test earlier in the thread showed the following.

Discharge test of the bank from 4.08(3.57) to 3.40(2.98) volts per cell was ~425AH. Nominal is 550ah(378 LiPo/172ah LifePO4).

So I had ~78% capacity from 4.08 to 3.40. Since I had the LifePO4 pack in as well not sure how mush capacity it really has. I was also discharging it at probably .05c. Maybe I should isolate the Lifepo4 and do another test.
Thanks,
Will




Awesome! thanks for the photos. That helps. Keep us posted if you try another capacity test.
 

Sojourner

New member
Joined
May 7, 2020
Messages
15
w0ss said:
I did a capacity test on just the 2 LG batteries I have. Went from 4.15v to 3.22v and had 91.5%(173AH)

91.5%...sounds promising for the unit I got. Although one of my cells may potentially be problematic (not dead, but giving a low voltage reading). Still studying it...awaiting sometesting/charge/discharge devices.

Is your capacity result for one of your 2 batteries? an average?
 

w0ss

Member
Joined
Oct 15, 2019
Messages
56
Both batteries were in parallel. I pulled out 345.338AH from the pair. Here is the Batrium screen showing the cells. They were still pretty even.
Keep in mind the 189AH rating is from 4.2 to 3.0 since I only went from 4.15 to 3.22 I left some capacity unused.


image_bjjlnb.jpg
 

Sojourner

New member
Joined
May 7, 2020
Messages
15
w0ss said:
Keep in mind the 189AH rating is from 4.2 to 3.0 since I only went from 4.15 to 3.22 I left some capacity unused.

You're probablyclose to full rated capacity. Nice:)
 

HydroGeo

New member
Joined
May 7, 2020
Messages
9
w0ss said:
Both batteries were in parallel. I pulled out 345.338AH from the pair. Here is the Batrium screen showing the cells. They were still pretty even.
Keep in mind the 189AH rating is from 4.2 to 3.0 since I only went from 4.15 to 3.22 I left some capacity unused.


Wow, that's great news. Thanks for sharing.
 

HydroGeo

New member
Joined
May 7, 2020
Messages
9
I'm curious what kind of fuses folks are using in their systems. I am planning to use a class T HRC fuse (200 or 225 amp) as a main fuse from my main positive buss bar to to the inverter; however, I would also like to place lower amperage fuses (100amp) coming off each of my batteries. I've read that HRC type fuses are preferable for lithium batteries to prevent arcing, but I'm not really finding HRC fuses in the 100amp range for DC. Ideally, I'd like to install these fuses as close to the battery terminals as possible. Therefore, I am considering these terminal fuses: https://www.amazon.com/Blue-Sea-Sys...&keywords=5191+blue+sea&qid=1591819986&sr=8-1

That's assuming that they fit the module terminals properly. I still need to check. I've used these terminal fuses on lead-acid batteries on boats, but am not sure if if they are appropriate for lithium batteries. Just wondering what other folks are doing to fuse these modules.

Thanks!
 

vegburner

New member
Joined
Mar 24, 2020
Messages
10
THANK YOU!!!! ---> @wOss - for your time in designing and working out the connector. really appreciate you sharing your pcb design as well. i didn't know designing and printing a pcb as a hobbiest was an option. i just received my JLCPCB printed boards and connectors, etc. soldered everything up last night and installed this morning.

Do we know if the existing bms that came with the battery actively balances? I bought from the original batch 6 months ago and was under the impression at the time of purchase that the bms was working.

BH sold the next batch with the language changed saying the bms isn't working and we need to actively balance....just wondering

[size=small][size=small]All of my cells [/size][size=small]stay [/size][size=small]balanced[/size][size=small] through cycling[/size][size=small]. After sitting for a few months, zero change. [/size][size=small]capacity avgs around 8kw.[/size][size=small]
[/size]
[/size]

(BTW, I have 2 extra sets of board and connectors if anyone has interest)

thanks again @wOss


HydroGeo said:
I'm curious what kind of fuses folks are using in their systems. I am planning to use a class T HRC fuse (200 or 225 amp) as a main fuse from my main positive buss bar to to the inverter; however, I would also like to place lower amperage fuses (100amp) coming off each of my batteries. I've read that HRC type fuses are preferable for lithium batteries to prevent arcing, but I'm not really finding HRC fuses in the 100amp range for DC. Ideally, I'd like to install these fuses as close to the battery terminals as possible. Therefore, I am considering these terminal fuses: https://www.amazon.com/Blue-Sea-Sys...&keywords=5191+blue+sea&qid=1591819986&sr=8-1

That's assuming that they fit the module terminals properly. I still need to check. I've used these terminal fuses on lead-acid batteries on boats, but am not sure if if they are appropriate for lithium batteries. Just wondering what other folks are doing to fuse these modules.

Thanks!

@hydro
Would this be an option at the battery? https://www.delcity.net/store/Del-City-Manual-Reset-(Switchable),-Surface-Mount/p_811053.h_195738 ----Your terminal fuses look nice and clean.
 

Etn06448

New member
Joined
Apr 21, 2020
Messages
9
Another shoutout to @w0ss for the board. I would likely not take on the project without it.

Finally finished wiring my 8 batteries. These are well balanced packs.

I'm using the Outback Skybox for my charger/inverter. Please share your charging parameter settings. I have tried to Google search but didn't get anywhere with this battery.
Thank you.
 

Sojourner

New member
Joined
May 7, 2020
Messages
15
Etn06448 said:
Another shoutout to @w0ss for the board. I would likely not take on the project without it.

Finally finished wiring my 8 batteries. These are well balanced packs.

I'm using the Outback Skybox for my charger/inverter. Please share your charging parameter settings. I have tried to Google search but didn't get anywhere with this battery.
Thank you.
8 batteries...wow. Any photos? Did you use a BMS? If so, what's your setup?
 

w0ss

Member
Joined
Oct 15, 2019
Messages
56
Right now I am charging to 57.4(4.1 per cell) I was doing 4.08 but changed it based on the limits some of the equipment have.

I never got anything on the included "BMS" working. If someone could figure out how to talk to it then you could probably at least get monitoring and balancing from it.
 

Etn06448

New member
Joined
Apr 21, 2020
Messages
9
I'm using 8 Daly 80A BMS. It's their new version that has bluetooth and UART for PC software. I also have the "light board" connected to it to see the SOC at a glance. The BMS also has it's own temperature sensor, which I placed inside the vent port to measure battery temperature (being covered on the picture with a gap built in just in case the batteries get hot). So far, with my 5KW inverter, the temperature of these batteries did not go up any during charge or discharge. Of course, each only see about 15A max. If the batteries get warm, I will probably create a vent system for the cabinet.

I decided to have them standing up in my garage cabinetas they just fit in perfectly. Hopefully that would not cause it any longterm problem. I could not find a detail picture of how the cells are packed but making a guess that it's probably similar to the LG Resu10 48V which are installed vertically.

Ideally, I would love to get the Batrium for my setup, but spending another $2500 is too much.

It's my first system so any suggestion is greatly appreciated.


image_dwrpvo.jpg
 

Sojourner

New member
Joined
May 7, 2020
Messages
15
@Etn06448
Very cool, thanks for the details. Would be interested in your opinion of the new app/software for the Daly's. Have you had any issues?
 

Etn06448

New member
Joined
Apr 21, 2020
Messages
9
Sojourner said:
@Etn06448
Very cool, thanks for the details. Would be interested in your opinion of the new app/software for the Daly's. Have you had any issues?


The app interface is horrible. Looks like they just use the same app for scooters with GPS/licence plate/etc. Not intuitive at all. However, I was able to see my cell voltages.
The PC software is also not great. It supposed to let me change some of the balancing parameters if I want.

My main reason for going with the bluetooth version is just to check on the cell voltages once in a while. It has not done any balancing yet as the packs are very well balanced (10-20mV spread) for mine.

If doing it over again, I don't know if I would go with these. Out of 8, one came defective giving low voltage on the reading and also heats up without any load. They did send a replacement but the replacement came with wrong wire gauge, not giving great confidence in the product or QC.
 

Sojourner

New member
Joined
May 7, 2020
Messages
15
Hope you don't mind more questions. Way back in this thread atPost #31, this issuewas raised:

HEADS UP!!!! If you have ordered the 10kwh LG Chem modules... be aware that the ENTIRE external case is bonded to the negative terminal of the battery pack..... resulting in an external bms NOT being able to cut power if a cell becomes over voltage! you MUST either break the internal connection to chassis ground or isolate the module from other grounds in your system... lesson learned the hard way today...?--feeling embarrassed.

In your setup, was this a concern?
 

Etn06448

New member
Joined
Apr 21, 2020
Messages
9
Sojourner said:
Hope you don't mind more questions. Way back in this thread atPost #31, this issuewas raised:

HEADS UP!!!! If you have ordered the 10kwh LG Chem modules... be aware that the ENTIRE external case is bonded to the negative terminal of the battery pack..... resulting in an external bms NOT being able to cut power if a cell becomes over voltage! you MUST either break the internal connection to chassis ground or isolate the module from other grounds in your system... lesson learned the hard way today...?--feeling embarrassed.

In your setup, was this a concern?

I was scared when I saw that post. I measured my packs and there's no continuity between the case and negative terminal. Nevertheless, I did insulate my packs from each other and also from the cabinet just in case. I might be totally wrong but if the negative terminal is bonded to the case, then there should be continuity between the two as well as able to measure voltage between the case and positive terminal. Neither one of those were true in all my packs.

I regretted not opening up one to see the packs inside. If anyone opened up theirs, please post some pictures.
 

w0ss

Member
Joined
Oct 15, 2019
Messages
56
I saw connectivity between the negative and the case. I also saw the voltage between the case and the positive terminal. I wonder if there are multiple models? Or perhaps some of them have a defect? I do have some pictures I took of the internals. I will try to dig them up. The case comes off with just a few bolts.


image_miafeq.jpg

image_lknvje.jpg

image_bcxjpj.jpg
 

Etn06448

New member
Joined
Apr 21, 2020
Messages
9
My paranoia sets in. I went tomeasure again and no voltage between my case and positive terminal. Am I doing something wrong?

Thanks for the pictures. They are stacking like I was imagining. Can't tell from your pictures whether there are plastic spacers between the cells similar to the packs for the Chevy Bolt? Hopefully they are stable standing up like I have them now.


image_ymujvk.jpg
 
Top