Dave's Build Thread


MASSIVE restock of EV Batteries at www.batteryhookup.com 5% coupon "POWERWALLS"

Daveyboy

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Aug 6, 2017
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91
hbpowerwall said:
Black inverter looks good!

Yeah, I like it too.I ordered black cable trunking to match

I charged the batteries via solar only yesterday while powering the garage. Didn't get to fully charged. Thought i'd get through the night though as battery was at 55v but alas. Nope. Went flat at 3am :/
Need a higher panel to cell ratio!
 

Daveyboy

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Not that I needed to see proof of concept, but yes, the thing works. With just the 2.5kwh of battery and 4 panels temporarily strewn across the lawn, I was able to keep the garage off grid and I could see a clear reduction in the total house energy use. Sweet. So now to get it properly up and running.
It took me two days to install the rails on the garage roof. I'm sure a more capable person could do it in just a few hours, but a) i'm really bad with heights and I was doing this on ladders (yes its only one story up and yes I still cacked myself about it!)and b) I had to learn how to use an angle grinder as the tiles needed cutting so the brackets would fit. But finally today I got the rails finished. had some help from father in law too, which was nice.

image_dzskdt.jpg

Panels need a good scrub, then i'm going to lay them out on the lawn and make sure all cabling is long enough etc before mounting them on the roof.
2kw of panels will charge 2.5kwh of battery pretty quickly wouldn't you say! So next task is to weld/solderup the rest of them.
 
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I can see space to fit another panel :D
 

Korishan

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completelycharged said:
I can see space to fit another panel :D

Or 2! once on each end
 
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I was not going to point that out.... I figured the two ends of the rails shouting for another solar panel would be enough...


I did think, the other option would have been a cover with supports up from the side of the path with the panel cover going up to the apex. Enough of a slope to wash the dust off (bird residue still needs a brush, especially seagulls or a well fed crow) and then put twice the numper of panels up. Rain cover for the path...


End of the day the most important aspect is making a difference.... we all need to do it.
 

Daveyboy

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completelycharged said:
I did think, the other option would have been a cover with supports up from the side of the path with the panel cover going up to the apex. Enough of a slope to wash the dust off (bird residue still needs a brush, especially seagulls or a well fed crow) and then put twice the numper of panels up. Rain cover for the path...

Actually, I plan something like this. A pergola over the path with 12 more panels on it. The inverter is rated 4000w, so I'm presuming ill be good to load it with 1.3x panels, so 5.2kw of them. So 12 more panels at about 260w would be about right.
But this would be an upgrade to come in maybe a year of two due to time and budget constraints lol

completelycharged said:
End of the day the most important aspect is making a difference.... we all need to do it.
I'll drink to that!
 

Daveyboy

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Aug 6, 2017
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I got the wiring for the panels sorted today. It charged up my 280 cells in about 1.5 hours. But as it neared 4.1v per cell WatchPower reported that solar generation dropped (from about 1kw to 150w) when the sun was still out. I presume this is just the inverter throttling power from solar so as to not overcharge the batteries?
 

Katarn_89

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Jun 10, 2018
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Power output will be throttled back as the cells near capacity. An easy way to test if this is happening is to put a load on the system. The power generation should increase by the size of the load.
 

Daveyboy

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Aug 6, 2017
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brwainer said:
It looks like youve gone for the bare minimum with no shunt?

Hahahahahahaha! With import duty and shipping I ended up paying 520 for this. Damn right I'm not having the shunt or the expansion board!
I did buy a spare longmon just in case I broke one...so it's not quite the bare minimum!
 

Daveyboy

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Aug 6, 2017
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Small update. I went away on vacation for a week, and I thought it was a great opportunity to test the system out, unmanaged for a week. In preparation, I wired up the next row of cells. So i'm now at 14S40P. I installed the Batrium and got that working. Then Sonic walked me through setting up RDP on my android phone, so I could see Watchpower and Watchmon on my phone. It all worked flawlessly for 5 days. On the 6th day I lost communications with my garage pc. When I returned home, all that had happened is the laptop i'm using had just locked up and near non responsive. Powerwall, inverter, solar and batrium were all still functioning perfectly. I had no power interruptions at all and thats even with 2 days of heavy rain and thunderstorms.
I couldn't be happier with it!
Now I need to crack on with wiring up the rest of the packs and getting this connected to my house.
 

Daveyboy

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A few days ago my Sunkko 709A Spot welder packed up. I had no response from the seller on Ebay, So I thought i'd might as well take it apart to see if there were any obvious blown components. unfortunately, there is nothing visibly wrong with it. I'm not skilled enough to be able to test the pcb, plus that fact I can't power it up. It just trips the 16A breaker in m garage. I also tried it on my cooker power supply in the house, which is 50A it turns out. but this just blew the Sunkko fuse in the back.
So all work on the powerwall has stopped for now as I don't have the money to just go buy another welder.
 

Redpacket

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Feb 28, 2018
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Daveyboy said:
A few days ago my Sunkko 709A Spot welder packed up. .... I also tried it on my cooker power supply in the house, which is 50A it turns out. but this just blew the Sunkko fuse in the back.
Sounds like there's a serious short in there, maybe the transformer?

Re the Batrium shunt, the point of having the shunt is to know the battery SoC by tracking current in & out.
 

hermitdave

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Aug 12, 2018
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Daveyboy said:
Go for it!
I paid a local print shop to do mine. I've got too much on right now to spare time setting up a 3d printer. :rolleyes:
The only thing i'd say is make sure you print them on their side such that the grain is from top to bottom when they are on the wall and not grain left to right. I learned this the hard way as it isn't strong and WILL break along the grain of the print if sufficient force is applied. Mine snapped when taking a pack out, as the holder needs to flex a little.
I had mine printed in PLAat 25% infill. Plenty strong now. Would def hold your 40p packs.
And if I was to print them again, I would recess the screw holes a little deeper to allow screws with a thicker head to sit further into the holder.

I was debating starting with 20P pack and then adding more as needed. I only have about 125 cells so far and only started capacity testing last night. With only one Opus at hand you can imagine its a slow process. Prior to this phase was mostly charge and leave it to settle. Prior to capacity test I checked voltage of each cell. Got rid of few that were below 4.1V. Some are on the border and will need to be monitored.

The thing I like about 20P pack is that its small enough to be isolated and unplugged. Thinking of crimp or XT60 connector to simplify this process. A circuit breaker per pack or a removeable fuse should simplify TLC work.

Not adding any fuse to the packs ?
 

Daveyboy

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Aug 6, 2017
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Redpacket said:
Daveyboy said:
A few days ago my Sunkko 709A Spot welder packed up. .... I also tried it on my cooker power supply in the house, which is 50A it turns out. but this just blew the Sunkko fuse in the back.
Sounds like there's a serious short in there, maybe the transformer?

Re the Batrium shunt, the point of having the shunt is to know the battery SoC by tracking current in & out.
I've tested the transformer for short. No short. Definitely something up with the PCB. I've seen some continuity between live in and live out when the power switch is on, but foot pedal not engaged and that's not right at all. I don't know whats causing that though.

Yeah, the Shunt will give me SoC. I get that. I just don't need it. I know when the battery is going flat based on voltage under load and current draw. My aim is to oversize the battery by quite a large margin, so as to only use half the capacity anyway.


Hi Hermit, yes, the 20P design allows the powerwall to go into service sooner than waiting until you have enough cells for 80P for example. It will also be easier to fix problems. I intend to leave the battery online when removing a 20 cell pack for replacement / repair. It would be great to not have to shut it all down for maintenance.

I wouldn't be discarding cells that are <4.1V. My cutoff was 0.5V, which worked well as Opus tends not to register them below 0.5V anyway. Some of my best cells were as low as 2V, but recovered well. I stick them all in the charger and those that don't take a charge well, will top out at about 2V then say they are fully charged. I also remove any heaters. Then let the cells sit for a good month and remove any that are below 4.05V after resting. I don't want that level of self discharge in my wall.
I considered using XT60 or XT90 connectors, but finally settled on ring terminals. Easier to install with just a crimper, plus you don't put much strain on the cables when trying to disconnect the pack.

I haven't fused the packs, no. I'm thinking about it. I have cell level fuses, but yes, additional fuses are a good idea as Fullycharged pointed out to me recently.

My offer to lend you spot welder is subject to me fixing the thing first too. I need to finish my packs, and I can't get the welder working. Its going to be either a new (same) PCB, or for around the same money, go with an arduino controller. Offer still stands to borrow my 5x Opus chargers though if you want to speed up testing. I'm not processing any more laptop packs for a few months now.
 

hermitdave

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Aug 12, 2018
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254
Daveyboy said:
Hi Hermit, yes, the 20P design allows the powerwall to go into service sooner than waiting until you have enough cells for 80P for example. It will also be easier to fix problems. I intend to leave the battery online when removing a 20 cell pack for replacement / repair. It would be great to not have to shut it all down for maintenance.

I wouldn't be discarding cells that are <4.1V. My cutoff was 0.5V, which worked well as Opus tends not to register them below 0.5V anyway. Some of my best cells were as low as 2V, but recovered well. I stick them all in the charger and those that don't take a charge well, will top out at about 2V then say they are fully charged. I also remove any heaters. Then let the cells sit for a good month and remove any that are below 4.05V after resting. I don't want that level of self discharge in my wall.
I considered using XT60 or XT90 connectors, but finally settled on ring terminals. Easier to install with just a crimper, plus you don't put much strain on the cables when trying to disconnect the pack.

I haven't fused the packs, no. I'm thinking about it. I have cell level fuses, but yes, additional fuses are a good idea as Fullycharged pointed out to me recently.

My offer to lend you spot welder is subject to me fixing the thing first too. I need to finish my packs, and I can't get the welder working. Its going to be either a new (same) PCB, or for around the same money, go with an arduino controller. Offer still stands to borrow my 5x Opus chargers though if you want to speed up testing. I'm not processing any more laptop packs for a few months now.

I meant that those that were charged and then discharged... discarded a few below 4.1V.. will retest them.
I will ping you w.r.t Opus.. Might pop around in a week or two. I might make myself a MOT spot welder now that my soldering effort (dyson 30A 6P) failed last night.

Looking to recycle a microwave :)
 
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