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w0ss semi DIY powerwall V2
#31
Today, a purchaser of the lg battery posted this. Were you aware. If you are how are you dealing with this issue?

He wrote the following:

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.

Ido not knowwhther his pack was damaged etc.
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#32
I am going to be using an external shunt trip breaker that will cut negative and positive so for me not an issue.

I think in most cases the external portion of the cell is bonded or just straight up the negative terminal. That is why people put heat shrink on 18650's. So while it sucks, it is the risk we all take when we do this DIY work. Make sure you understand how it all works Smile In this case you could heatshrink the case or put some wood/rubber mat in between them if you are just stacking them on top of each other.
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#33
got my batrium multimon8 in so cleaned up my wiring. Expanded the existing hole and covered my wiring with a cloth loam




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#34
Nice..
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#35
(04-29-2020, 02:52 PM)w0ss Wrote: I am going to be using an external shunt trip breaker that will cut negative and positive so for me not an issue.

I think in most cases the external portion of the cell is bonded or just straight up the negative terminal. That is why people put heat shrink on 18650's. So while it sucks, it is the risk we all take when we do this DIY work. Make sure you understand how it all works Smile In this case you could heatshrink the case or put some wood/rubber mat in between them if you are just stacking them on top of each other.
Batrium , in the help  files , describes a shunt trip breaker installation, with photos. i believe off the shunt that comes with then watchman.. they use a Schneider breaker. Is this what you are describing, above?
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#36
(04-30-2020, 05:24 AM)w0ss Wrote: got my batrium multimon8 in so cleaned up my wiring. Expanded the existing hole and covered my wiring with a cloth loam




Hello again:

I assembled the breakout board you designed and have your photo of he leads in to thboard. I just received my watchmon 5.

There are a total of 15 leads going into the breakout board. You skipped number 8 and proceed to use 4 of the connectors on the rear connector for a total of 15 leads going in. If you wire this to the  Watchmon 5  as a 14s, you are instructed to insert a single jumper at position jc1. 


Some questions I hope you can answer before i attempt to wire this guy.


1. Is this actually being wired as a 15s - meaning all of the 15 of the leads you have on the breakout board connect to the 15 positions on the high and low boards (thereby requiring no jumper)?

2. When I measured the voltage of each of the leads after connecting the board to the LG yoke, the first lead on teh left of the lower jumper was high (+52.5V)  and it progressed downward with voltage at about 3.7v per jumper - except for 4 and 5 which read the same and 8 and 9 which read the same... this continued onto the 4 leads on the back connector. IS there something I am supposed to do different with the positions 4 and  which read the same voltage? I am skipping 8 as you have done.
   

Thanks in advance for clarification.



Evan
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#37
This is setup as a 14s(15 cables), looks like it's good except 4 and 5. There should be different voltage between them. Check your solder joints I guess but if it was bridged I think that would be pretty apparent.

It's a pretty basic board so I doubt is was made wrong at the factory but it's always possible. Are you seeing the same on all the boards?

On your shunt question I used ABB S3N 225A breaker off ebay they can be had pretty cheap. Just make sure you get one with the correct control voltage you are running.
evangarber likes this post
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#38
Hello. A few weeks ago, I picked up 3 of the LG Chem modules from that batch of 60 that BH was selling. I'm pretty new to all this so I'm glad to have found other knowledgeable folks who are using these batteries and sharing their designs/experiences. Thanks! It has been very helpful. I will likely be asking a lot of (potentially dumb) questions... so I apologize in advance.

Here is what I am planning:

I am looking to set up residential application as a 48v system using an MPP Solar LV5048 to power a critical load panel that was originally set up as a 10 circuit generator transfer switch.

As I mentioned, the battery bank will be 3 of these 189 ah LG chem modules.

For now, the goal will be to use the LV5048 and batteries as a UPS/peak shaving system. Where I live the off-peak power rate is 1/5 of the on-peak rate, so if I can power my critical loads from battery during on-peak and charge during off-peak, it will be a good start.

Eventually, I will be adding PV. Right now, I only have a few panels totaling 1kW. So I’m looking to obtain some more panels before setting up that side of the system.

Anyway, now I’m trying to figure out how to wire and manage these batteries. The info w0ss shared on here gave me a lot to think about. I like the breakout board and how clean it makes connecting to a BMS. I will likely be joining you folks in obtaining a few for my setup.

As for a BMS, I want to be able to see all the cell voltages in each module, so I ruled out the Daly units. I was looking into those cheaper bluetooth BMS units but although the price seems favorable, I worry about the quality and don’t want to risk my investment in these batteries (and my safety). So I shifted to looking at the Chargery BMS, but I wasn’t totally sold on those either. Kept seeing mixed reviews.

I wasn’t considering the Batrium system until I came upon this thread. After looking into it more, I like what I see. It’s pricier, but seems like you get what you pay for.. a very functional, quality system.

Based on what I learned so far, I think I’d need a Watchmon5 and probably 2 additional Multimon units to monitor all 42 cells of the 3 modules. I’d consider getting the Shuntmon as well to complete the setup. The cost hurts a little to think about but the capability of that setup is enticing. The one thing I’m not clear on is if I would need the Watchmon with the expansion board. Seems like the expansion board is needed if you want to have the ability to remote trip the breaker or control a fan, both of which I would like to do. Is that the case?

One last, dumb question… I’m looking for some confirmation about what the max current draw could be from my battery bank in order to assist with properly sizing my DC components… breakers, wires, fuses. The LV5048 is a 5kW inverter at peak for AC output. I don’t expect to be putting anywhere near that demand on the inverter from my normal loads. Based on what I’ve seen, the LV5048 taps out pretty quick with very heavy loads/surges. According to the manual, typical amperage is 220A with a recommended minimum battery capacity of 200AH. Recommended wire size from the inverter to the battery is 1/0 awg. I’d likely have a wire distance of <5ft for my main DC cables from the inverter to the distribution bar. I was thinking of going with 2/0 wire to be safe and minimize loss. I’m not sure what size wire to use from each of the 3 modules to the distribution bar. Wire length would be <3ft. I was thinking 2 AWG and could always double it to be safe. any thoughts on breaker/fuse rating would be helpful as well.

Any input on this is appreciated, thanks!
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#39
I did 100amp fuses on each pack going to a bussbar. I then have a 250amp fuse going to the pair of inverters.

For watchmon you would need the WM5 to control the MM8 boards. I do recommend the shuntmon as well to get the full picture. Honestly I would just buy it. I went through Daly then Chargery until I got the WM5. I was never happy and would have saved a bunch if I just went direct to Batrium WM5.
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#40
(05-07-2020, 04:10 PM)w0ss Wrote: This is setup as a 14s(15 cables), looks like it's good except 4 and 5. There should be different voltage between them. Check your solder joints I guess but if it was bridged I think that would be pretty apparent.

It's a pretty basic board so I doubt is was made wrong at the factory but it's always possible. Are you seeing the same on all the boards?

On your shunt question I used ABB S3N 225A breaker off ebay they can be had pretty cheap. Just make sure you get one with the correct control voltage you are running.
The boards are fine. I did continuity testing on two of them.  Just made up another board and it seems OK now. Do not know why I got the joinder of 4 and 5. Lousy soldering technique may be the culprit.

I found a cheap abb S3H 24vdc shunt breaker on ebay - there are many - you just have to make sure you have the model with shunt trip. They seem to have 2 variations on trigger voltage - 24 vdc and 125vdc. Somehow I will have to convert the 48vdc on the watchmon 5  to 24. I believe you can just wire in a resistor to do this. not sure the size - although I could calculate it.

How did you handle this? where goeth the resistor - on the relay?
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