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Cinergi's 28 kWh / 4 kW Solar / 10 kW inverter RV build

hankcurt said:
Me in second grade - "Can I stay up late cause I heard Tommy say school is going to be cancelled tomorrow."
Mom - "You can't believe everything you hear."
I go to bed and think about that I just HEARD that I can't believe everything I HEAR. A life long struggle begins....

or perhaps more appropriate would be the quote below from Raising Arizona...


In reality, we are most vulnerable to deception when we are being told things that we want to hear. Salesmen count on it. It was questions about the claims of lithium battery vendors that brought me to the forum. So, thanks everyone, for telling me the truth even when its not what I want to hear.
Click to expand...
I try to make it clear when I pass on information that it is what I am being told by the supplier, and for some of it (like a 5 year warranty) that I personally wouldn't count on it.
But, being only human and sometimes trying to fit 20 hours of work into 12 hours, I may at times forget to do that.
 
JoeHam said:
However, a prudent and reasonable person knows you cannot trust everything a sales person half a world away tells you. Especially when the sales culture is known for creative adaptations of the truth in order to make a sale.

What Mom told you is true, you can’t believe everything you hear. If one does there is sure to be a lifetime of disappointment.
Click to expand...
I learned a lesson. The lesson is even when things are put in writing from ANY Chinese supplier they may not be telling the truth. I am old enough to know better. But hey....even with age I learn something new every day.
 
They didn't have to lie to me because I didn't ask any questions. I just ordered them.
Seems like we all got the same cells.
We probably could have got all 280Ah + if we paid extra.
Probably not worth the extra money though.
 
All cells are now charged. Here's where I'm at now (5 cells to be inserted into the "holes" in the bottom row). No fixture until I've decided this is what I want.

IMG_9059.JPG

A preview of the wiring I previously mentioned:

IMG_9060.JPG

The wires in the foreground form a balanced series connection. The posts in the background would have lugs on them for series connection to the adjacent groups of 4 cells. Lugs first, bus bars second.

To cut all those wires to the same length:

IMG_9061.JPG

And you can see the hydraulic crimper on the right. This should make for reasonably similar resistance cables.
The rest of the lugs arrive tomorrow, but the wire doesn't arrive until next week, so I can't assemble the battery until then. But I can work with what I have, plus I can insert the molex connectors (forgot to take picture) into the BMS sense/balance leads.

That's a lot of cutting, stripping, and crimping batman!

BMS, breaker, etc, will be temporarily mounted somewhere on the right. In the final configuration, the first and last cells will have an additional mounting "plate" on the end for that equipment.
 
hrm.. another thread got me thinking ... why not turn the cells around and parallel them with wire (not enough room to create a flexible wire connection if the poles are on the same side) like so?

IMG_9062.JPG

If I do that, then I could do spring-based compression fixture, 8 cells to a fixture, and reduce the number of anderson (and molex) connectors. I think I could still lift the ~95 pound group of 8 cells into the truck and then into the RV when that time comes.

So many things to try! haha. I only wish it didn't mean 64 wires and 128 hydraulic crimps... and what if I don't like it? :)
 
Curious what your calculations were for using that spring.
 
Bob B said:
Curious what your calculations were for using that spring.
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"Rate (lb/inch): 380"
"Load at Solid Height(lb): 182.4"

Measuring displacement probably gives more accurate force than torque wrench. Especially if you calibrate the spring first.
 
Cell face is 53.8 square inches. 4 springs at max compression would be 729.6 pounds or 13.56 PSI. Recommended fixture is 661 pounds or 12.29 PSI. Safe range is 6-17 PSI (from other compression threads here). So I could squash the springs to max while at 100% SoC and achieve what I need. I'll back off the bolt a little as I don't ever want the spring to max out, so say 700 pounds.
According to the spec sheet, each cell can change about 0.5mm from 30% to 100% SoC which is 0.1575 inches for 8 cells. The spring rate is 380 per inch, so at 30% SoC I should be at whatever my value was at 100% SoC minus (380 * .1575 * 4) or 239 pounds. That's 700 - 239 = 461 or 8.57 PSI.
 
Wow, my wire arrived early so I now have all the lugs and wire that I need to get started. I have the neoprene here as well - although that's not useful until I start building the fixture.
This is 64 wires and 128 lugs in the manual hydraulic crimper. That's gonna take a while... :eek:
 
cinergi said:
Wow, my wire arrived early so I now have all the lugs and wire that I need to get started. I have the neoprene here as well - although that's not useful until I start building the fixture.
This is 64 wires and 128 lugs in the manual hydraulic crimper. That's gonna take a while... :eek:
Click to expand...
We're all willing you on mate....great project to follow. (y)
 
cinergi said:
Wow, my wire arrived early so I now have all the lugs and wire that I need to get started. I have the neoprene here as well - although that's not useful until I start building the fixture.
This is 64 wires and 128 lugs in the manual hydraulic crimper. That's gonna take a while... :eek:
Click to expand...
I've been crimping up a storm but I haven't done the big ones yet.

I want to use the crimper that you beat on with a hammer. ?️‍♂️ ?
 
ArthurEld said:
I've been crimping up a storm but I haven't done the big ones yet.

I want to use the crimper that you beat on with a hammer. ?️‍♂️ ?
Click to expand...

I have a hammer crimper, too. The hydraulic produces a much better crimp. But it's a lot slower (and the tool is a lot more expensive).
 
Springs are due to arrive on Monday. Depending on how lazy I am (or whether I get crimp-cramp), I hope to have my battery back up and running (sans a fixture for now) this weekend. That will be the first 2p configuration I've done. It will be interesting to see what differences there are from my previous plain 16s configuration.
 
The most reliable method would be to drive the springs solid, and then back off a full turn at 100% SOC. That doesn't even require a torque wrench, and is much more repeatable than relying on nut torque.

Incidentally I also decided on a similar spring.
 
Dry wiring fit of 4 cell per pack config. Dual 1 gauge serial and 4 gauge parallel.

DB4D070C-4926-4D65-9970-6667422B0097.jpeg
 
cinergi, going off topic briefly, when you were configuring your victron quattro's, and input the low voltage discharge cut off, did your system give a default minimum 2v as the DC input reset value? I only ask, as i was doing a multiplus and it is a bit of a pain. If you run the discharge down till you get kicked off, you are having to almost charge the battery pack back to full before you can discharge again. Either that or you have to set the discharge value that low, that at high discharge amps, the delta on the cells risk the BMS booting you off. Just wondered if you had any tips?
 
Solarfun4jim said:
cinergi, going off topic briefly, when you were configuring your victron quattro's, and input the low voltage discharge cut off, did your system give a default minimum 2v as the DC input reset value? I only ask, as i was doing a multiplus and it is a bit of a pain. If you run the discharge down till you get kicked off, you a having to almost charge the battery pack back to full before you can discharge again. Either that or you have to set the discharge value that low, that at high discharge amps, the delta on the cells risk the BMS booting you off. Just wondered if you had any tips?
Click to expand...

yes. This was fixed in a later version of firmware. I’m surprised how old the firmware I had was.
 
cinergi said:
yes. This was fixed in a later version of firmware. I’m surprised how old the firmware I had was.
Click to expand...
Mine says im on the newest firmware, with no updates available....it is a right bugger not being able to decrease this value down to 1V, which might prove reasonable for the flat curve of lifepo4
When you said yours got fixed, i take it you can lower that value now....what options do you get?
 
I don’t remember what my minimum offset is. It’s easier at 48v since 1v difference at 12 is the same as 4 at 48.
 
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