Sonic's Powerwall (London, UK)

Just by using a multimeter on the cells themselves and not the bus bar. it may test differently or not its just that, a test. I have found it useful in finding bad cells or bad soldering
 
A "cold" or bad solder connectionis hard to messure... avisual check would be one of the things to do, a good solder connection leaves a shinyfinish, with well flowed solder.
A good electrical connection is also a good mechanical connection, so a check with some mechanical force applied might be a good test.

or.... post some high quality close up pics of your packs, and i am sure they wil be thoroughly studied ... ;)
 
Korishan said:
Sonic01 said:
but how do youtest the cells individually if they are all soldered to the bus bar?
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Under a heavy load, you test the voltage on the bus bar, then you test each cell voltage. If there is a difference, there's an issue. The reason there'd be a difference is due to resistance. When there is no load, there's no resistance, and all cells will have the same voltage. That's why you test while under load and before any resistance spots. So you measure the voltages on the cell themselves, not the solder or fuse wire portion.
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ah i get it now, thanks :) this was actually going to be another question of mine, are there any recommendations on devices for testing whole packs? charge/discharge/capacity test etc?

wim said:
A "cold" or bad solder connectionis hard to messure... avisual check would be one of the things to do, a good solder connection leaves a shinyfinish, with well flowed solder.
A good electrical connection is also a good mechanical connection, so a check with some mechanical force applied might be a good test.

or.... post some high quality close up pics of your packs, and i am sure they wil be thoroughly studied ... ;)
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yeah i think im actually too embarrassed to post that mess of solder and melted plastic.... :D

ok so unless anyone has any objections im going to go for that cheap 7s bms i linked before :)
 
JasonMorris said:
Also theese ones:
7S 150A Li-ion LiPo BMS/PCM/PCB battery protection board for 7 Packs 18650 Battery electric car w/balance w/APP
http://s.aliexpress.com/q2YBFBvi?fromSns=Copy to Clipboard
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thanks again, ill have a review later :D

but new project update!! :D I now have my solar panels thanks to memberDaveyboyhe has a thread here selling a bunch of second hand panels in essex:

https://secondlifestorage.com/t-SELLING-UK-Essex-250w-Solar-panels-for-sale

and here's my 4:


image_wravku.jpg
 
Daveyboy said:
Hahaha! That hashtag!
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its a banner from the rally to mongolia i was telling you about, all the teams signed it and i hung it in my dinning room wall :D
 
Nice setup. However, all your lugs are facing with the flats to the inside of the pack. How are you connecting them together? Wouldn't it be better to have the flats facing out so they can bolted together?
 
Korishan said:
Nice setup. However, all your lugs are facing with the flats to the inside of the pack. How are you connecting them together? Wouldn't it be better to have the flats facing out so they can bolted together?
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I wasn't planning on bolting the packs directly together, I will chain them together using short cables like shown below.

This way if i want to expand i can easily add new packs in parallel.

I didn't really realise the lugs had a "correct side" because it seems like another lug would connect on either side, but yes it would have made sense to have the larger side outward facing :D

It doesn't matter though, i have enough space on either side of the lug to mount stuff.

That actually brings my next question, what bolts should i use to secure my lugs together? i know my holes are 8mm so M8 bolts should be used, but does any specific kind need to be used? Can i just use steel M8 nuts and bolts or do i need something else? should there be washers in the mix too?



image_fatekf.jpg
 
The bolts don't matter as much as long as they make the lugs have solid contact with each other. In theory, there shouldn't be any current flowing through the bolts. Pete showed in one of thie FLIR videos that a connection was noticeably warmer than others. Upon closer inspection it wasn't as tight as the others. So you'll want a lock nut and a couple washers to make sure everything stays tight. They will loosen over time due to charge/discharge cycles if they aren't locked down tight enough.
 
Korishan said:
The bolts don't matter as much as long as they make the lugs have solid contact with each other. In theory, there shouldn't be any current flowing through the bolts. Pete showed in one of thie FLIR videos that a connection was noticeably warmer than others. Upon closer inspection it wasn't as tight as the others. So you'll want a lock nut and a couple washers to make sure everything stays tight. They will loosen over time due to charge/discharge cycles if they aren't locked down tight enough.
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Thank you very much once again :)

I'm hoping to have the system live this weekend.
 
Sonic01 said:
pack power connectors and BMS leads done :D


image_ecqjti.jpg
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Looking good bud, excited for you for the next update once its live! Your thread ahs really given me a kick to get my powerwall adventure started

Can I just ask is this for off grid purposes or will you be using it for your house?
 
chris330 said:
Looking good bud, excited for you for the next update once its live! Your thread ahs really given me a kick to get my powerwall adventure started

Can I just ask is this for off grid purposes or will you be using it for your house?
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it wont feed into the grid but it will be chained off my houses AC for bypass/backup etc :)

the pack wires are now done so i have a 24v battery now, I'm going to see if i can wire in the BMS now :)
 
And now i finally have a major update :D

My powerwall is online :D

BMS and PIP are both working and both are connected via USB to my server, I can view and manage them :D


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image_qrqwhm.jpgimage_jhsoig.jpg
 
jesusangel said:
Hi, recently I've setup Raspiv8 from Daniel and working to include MPI not fully supported (I think PIP is) and having the same BMS as you I hadto code my own nodejs script to inject BMS voltage to the grafana server.

If you need some info let me know.

Regards
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very pretty... im just getting off the ground here and still learning how to configure my bms and pip, so you have a script that pulls data from the BMS and injects it into grafana? thats cool...
 
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