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How about a solar car port on a budget?

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  • Author
7 minutes ago, ExpatOilWorker said:

You never achieved 100% batteries charge for the entire month of May?

 

The days with PEA going negative are battery full days, there are a few.

 

It doesn't take many dull days for the charge to gradually drift downwards to a level where I'm uncomfortable. Bright sunny mornings are offset by mega black cloud afternoons 😞 

 

We've also got one 14kWh pack with what appears to be an iffy MCB so it doesn't charge/discharge properly, awaiting the arrival of a replacement MCB.

 

"I don't want to know why you can't. I want to know how you can!"

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39 minutes ago, Crossy said:

 

The days with PEA going negative are battery full days, there are a few.

 

It doesn't take many dull days for the charge to gradually drift downwards to a level where I'm uncomfortable. Bright sunny mornings are offset by mega black cloud afternoons 😞 

 

We've also got one 14kWh pack with what appears to be an iffy MCB so it doesn't charge/discharge properly, awaiting the arrival of a replacement MCB.

 

Have you got your grandchildren staying too?

  • Author
9 minutes ago, Muhendis said:

Have you got your grandchildren staying too?

 

Ah.

The mega-consumers are indeed here!

 

"I don't want to know why you can't. I want to know how you can!"

  • 4 weeks later...
  • Author

The chickens have been electrified!!

 

That's 3 panels that were in the garage plus one moved from the tool shed which was a bit shaded.

 

We are now truly full (no panels left over).

 

image.jpeg.4226dbbf35f702fe34462e44e707f352.jpeg

 

Also, the latest Beta of Solar Assistant adds live production forecasting. 

 

Of course, we can now see how much energy we are "wasting" by not having an EV to charge!

 

image.png.d5b4294e771f54ebf9676c8eaa55be20.png

"I don't want to know why you can't. I want to know how you can!"

30 minutes ago, Crossy said:

Evidently the SA forecasting is on a par with the UK weather forecast by the great Michael Fish.

He never lived that forecast down!

  • Author

Numbers for June. We are aiming to use nothing from PEA in July (breaker is off).

 

I do notice we are consistently making more than we use.

 

Overall system round-trip efficiency from DC energy input to 220V usage is about 85%.

Obviously the inverters use some energy, they do get pretty warm at times after all. 

Battery efficiency in to out is about 97%.

I suspect some measurement errors too as the data is what is reported by the inverters.

 

Does it really matter? Not really, the input energy is after all, free 🙂 

The most important reading is that of the PEA meter :whistling:

 

image.png.3b59058674a873508eda00c0c602b538.png

"I don't want to know why you can't. I want to know how you can!"

  • 4 weeks later...
  • Author
  • Popular Post

Numbers for July.

The small PEA use is from when I turned on the mains breaker to make the meter move a bit 🙂 

 

image.png.71e3c9c6d83777c85aa93d09dbcdf51b.png

"I don't want to know why you can't. I want to know how you can!"

  • 2 weeks later...
  • Author

These projects are never actually "finished".

 

I spent the weekend re-routing (making shorter) and upgrading (fatter wire) my battery to inverter connections.

 

Net result was my peak charge current increased from just under 300A to around 350A.

 

Right now all that means it the batteries are full sooner, but when we get our EV ...

 

"I don't want to know why you can't. I want to know how you can!"

1 hour ago, Crossy said:

These projects are never actually "finished".

 

I spent the weekend re-routing (making shorter) and upgrading (fatter wire) my battery to inverter connections.

 

Net result was my peak charge current increased from just under 300A to around 350A.

 

Right now all that means it the batteries are full sooner, but when we get our EV ...

 

So the charge current has increased since the original installation?

 

I think that's an upcoming job for my system too even though my cables are only about 300mm or so long.

Between them my new panels are bumping out slightly more than 60A now

 

What will you be using as the replacement heating for the area around the charging cables?........:whistling:

  • Author
40 minutes ago, Muhendis said:

So the charge current has increased since the original installation?

 

Yeah, I suppose replacing 3.5m of 50mm2 with 2.0m of 95mmwithout changing anything else was going to have at least some effect.

 

I really just wanted the wiring to run cooler (so I could actually touch it) :whistling:

 

Every watt is sacred!

 

 

"I don't want to know why you can't. I want to know how you can!"

2 hours ago, Crossy said:

These projects are never actually "finished".

 

I spent the weekend re-routing (making shorter) and upgrading (fatter wire) my battery to inverter connections.

 

Net result was my peak charge current increased from just under 300A to around 350A.

 

Right now all that means it the batteries are full sooner, but when we get our EV ...

 

Right now all that means it the batteries are full sooner, 

 

Doesn't the EV batteries have a recommended/maximum charging rate? How does that workout when the peak charge current is increased from just under 300A to around 350A?

2 hours ago, Crossy said:

I suppose replacing 3.5m of 50mm2 with 2.0m of 95mmwithout changing anything else was going to have at least some effect.

I would guess you're now poking around with your trusty IR camera to see where the knock on effect is.

I honestly can't make up my mind why my cables are slightly warmer than my hand. I'm beginning to suspect the heat may be conducted from the charge controllers which are convection cooled.

 and get toastily ouch when at max.

  • Author
12 hours ago, ravip said:

Right now all that means it the batteries are full sooner, 

 

Doesn't the EV batteries have a recommended/maximum charging rate? How does that workout when the peak charge current is increased from just under 300A to around 350A?

 

Our LiFePO4 packs total 1,720Ah currently, so 350A is around 0.2C they should be very happy at that charge rate 🙂

 

Discharge rate rarely gets near 200A although it could, theoretically, get near 380A, still no worries there.

"I don't want to know why you can't. I want to know how you can!"

Crossy you bought and assembled your own batteries if I remember. Would you do it again?

  • Author
1 minute ago, carlyai said:

Crossy you bought and assembled your own batteries if I remember. Would you do it again?

 

Yup, I'm debating whether we need more storage as we speak.

 

Pre-built batteries are getting cheaper and cheaper 🙂 

BUT

Do you really know what's in there? New cells, used cells, cells that failed production test, quality BMS? 😞

 

Have a look at some of Will Prowse's teardowns on Youtube, some packs are scary inside!

 

Buying cells and BMS etc. from a known reputable supplier means you know what's in your pack and (assuming you are reasonably competant) you know it's all assembled correctly.

 

I know a number of people who have bought pre-built packs and are very happy with them.

 

As with many things, it's entirely Up2U.

"I don't want to know why you can't. I want to know how you can!"

You bought your batteries from this company, then assembled and installed in a container?

Did the same company supply all the kit?

I've seen some vids when people buy their batteries and kit to self assemble.

 

Batteries are from China, specifically Shenzen Luyuan https://szluyuan.en.alibaba.com/

  • Author
9 minutes ago, carlyai said:

You bought your batteries from this company, then assembled and installed in a container?

Did the same company supply all the kit?

I've seen some vids when people buy their batteries and kit to self assemble.

 

Batteries are from China, specifically Shenzen Luyuan https://szluyuan.en.alibaba.com/

 

Yup, I got cells, BMS, box from them as a kit.

 

I'm not sure if they're the cheapest now but they do seem to have some, er, budget cells on their website, I will have to contact them to get the best bang-per-buck.

 

"I don't want to know why you can't. I want to know how you can!"

  • Author
14 hours ago, Muhendis said:

I would guess you're now poking around with your trusty IR camera to see where the knock on effect is.

 

Of course 🙂 

 

Nothing is showing up as tall-tree at present, the 400A DC MCCB (battery main switch) is certainly warm at 50C but nothing that I'm worried about.

 

"I don't want to know why you can't. I want to know how you can!"

Was charging the EV yesterday arvo and full sun into the garage (garage door coming ...) was only at 25A a mear pittance of what you guy are using (fing scary) but app showed the temp climber to 55 degrees but EVES kept going (just thought I'd see what happened). 

This morning no brown smell or moltent glob. I like this EVSE.

  • Author
18 minutes ago, carlyai said:

Was charging the EV yesterday arvo and full sun into the garage (garage door coming ...) was only at 25A a mear pittance of what you guy are using (fing scary) but app showed the temp climber to 55 degrees but EVES kept going (just thought I'd see what happened). 

This morning no brown smell or moltent glob. I like this EVSE.

 

Don't forget our 350A is at 52V (16S LiFePO4 packs) so only about 18kW.

 

 

To finally tidy things up I needed to enlarge the cable holes in my battery shed (Shera board).

 

Got everything ready and marked up.

 

Then the power switch on the angle-grinder fell apart! 😡

 

New one on 24H priority order from Lazada.

"I don't want to know why you can't. I want to know how you can!"

3 hours ago, Crossy said:

 

Yup, I'm debating whether we need more storage as we speak.

 

Pre-built batteries are getting cheaper and cheaper 🙂 

BUT

Do you really know what's in there? New cells, used cells, cells that failed production test, quality BMS? 😞

 

Have a look at some of Will Prowse's teardowns on Youtube, some packs are scary inside!

 

Buying cells and BMS etc. from a known reputable supplier means you know what's in your pack and (assuming you are reasonably competant) you know it's all assembled correctly.

 

I know a number of people who have bought pre-built packs and are very happy with them.

 

As with many things, it's entirely Up2U.

While on the subject of batteries, how accurate are your discharge %- numbers?

The top 10%-point of my 42 kWh battery pack evaporate pretty quick after sunset, while the middle 35-65% is the gift that keeps giving.

I haven't been lower than 34%, but the 27 kWh it took to bring it back to 100% match the nameplate capacity, so the batteries are good, the %-numbers are just more of a guideline.

  • Author
35 minutes ago, ExpatOilWorker said:

While on the subject of batteries, how accurate are your discharge %- numbers?

The top 10%-point of my 42 kWh battery pack evaporate pretty quick after sunset, while the middle 35-65% is the gift that keeps giving.

I haven't been lower than 34%, but the 27 kWh it took to bring it back to 100% match the nameplate capacity, so the batteries are good, the %-numbers are just more of a guideline.

 

Pretty carp to be honest.

 

The BMS needs to calibrate itself by being charged to full-full. Just how it does this depends upon the BMS software, all are slightly different. 

 

Once calibrated the BMS "counts coulombs" calculating the %age charge from the Ah value that it's been told.

 

"I don't want to know why you can't. I want to know how you can!"

I have just fitted a coulomb meter to mine mainly because the charge controllers will only tell the total current flow which is, of course, very different from the battery charge current.

It's dead simple to set up if you use the auto feature.

I you feel the need to fit one to your bit of kit then don't forget the inline fuse. The batteries pack a whole world of power and if anything should go wrong in the meter (made in China) your installation could easily go up in smoke.

https://i.ebayimg.com/images/g/4nkAAOSwyJ1k5xLG/s-l1200.jpg

14 minutes ago, Crossy said:

 

Pretty carp to be honest.

 

The BMS needs to calibrate itself by being charged to full-full. Just how it does this depends upon the BMS software, all are slightly different. 

 

Once calibrated the BMS "counts coulombs" calculating the %age charge from the Ah value that it's been told.

 

Ohhh, so percentage is a calculated value, based on power usage from 100%?

I thought it was just using voltage to display a %-value.

My battery is at 52.9 V when it was showing 40%, so pretty healthy. 

 

images (13).png

  • Author
1 minute ago, ExpatOilWorker said:

Ohhh, so percentage is a calculated value, based on power usage from 100%?

I thought it was just using voltage to display a %-value.

My battery is at 52.9 V when it was showing 40%, so pretty healthy. 

 

images (13).png

 

Voltage is a pretty poor indication of charge state in LiFePO4 packs unless you are right at the ends of the curve (sometimes called the "knee"), These packs have a very flat discharge curve for most of their range.

 

Coulomb counting is the way to go, but does tend to get out of sync due to batteries not being 100% efficient, hence it needing to re-calibrate itself periodically.

"I don't want to know why you can't. I want to know how you can!"

22 hours ago, Crossy said:

The BMS needs to calibrate itself by being charged to full-full. Just how it does this depends upon the BMS software, all are slightly different. 

I usually go to 100% for 6 hours from noon to 6 pm, except one day was very different.

The battery stayed at 91% flat for several hours while still charging at 2.5 kW, then suddenly jumped to 100%.

Is this how the BMS calibration and cell balancing looks like?

 

Screenshot_20250815_114511_Deye Cloud.jpg

  • Author

I can't say for certain with your particular BMS, but it certainly looks like it.

 

Has the accuracy of the SOC figure improved??

"I don't want to know why you can't. I want to know how you can!"

19 minutes ago, Crossy said:

I can't say for certain with your particular BMS, but it certainly looks like it.

 

Has the accuracy of the SOC figure improved??

This just happened a few days ago and usage has been low since then. I will let you know the SOC after we have another deep 30% discharge followed by a sunny 🌞 day.

  • Author
On 8/14/2025 at 11:55 AM, Crossy said:

Don't forget our 350A is at 52V (16S LiFePO4 packs) so only about 18kW.

 

To finally tidy things up I needed to enlarge the cable holes in my battery shed (Shera board).

 

Got everything ready and marked up.

 

Then the power switch on the angle-grinder fell apart! 😡

 

New one on 24H priority order from Lazada.

 

The first switch vanished into the Lazada delivery system (the giveaway is that it went from being with Lex to being "in line haul"), Cancel button was still active so I gave it a try.

Error, declined!!!

One does hope that once the system works out that it's lost then I'll get my 70Baht refund.

 

I ordered a second switch on Sunday as soon as it became apparent that the first was lost, it arrived today.

 

It actually took longer to install the switch than it did to do the job! :whistling:

 

 

"I don't want to know why you can't. I want to know how you can!"

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