New Off Grid Inverter Charger

[Sunshine]

I would like to remind everyone that we will be conducting a very important test on the B17 today. It is vital to it's release. If you are in North America, you will experience partial to full obstruction of the sun over an approximately 2 hour period. Please do not be alarmed. The sun will return to normal as soon as our tests are concluded. Thanks!

We hope the thing doesn't burn out !

ClassicCrazy You are an extremely valued member on this forum. Because of your longstanding efforts, we would like to offer you a lifetime warranty on your sun. Should it ever burn out, simply box it up and ship it back to Midnite and we will replace it, free of charge.

[ClassicCrazy]

I would like to remind everyone that we will be conducting a very important test on the B17 today. It is vital to it's release. If you are in North America, you will experience partial to full obstruction of the sun over an approximately 2 hour period. Please do not be alarmed. The sun will return to normal as soon as our tests are concluded. Thanks!

We hope the thing doesn't burn out !

ClassicCrazy You are an extremely valued member on this forum. Because of your longstanding efforts, we would like to offer you a lifetime warranty on your sun. Should it ever burn out, simply box it up and ship it back to Midnite and we will replace it, free of charge.

Thank you ! I am happy to report the watts are flowing upward again so no warranty will be needed at this time .
Larry

[Vic]

All went smoothly here,   thanks for the heads-up Sue.

That B17 sure does have a lot of capability.   This was  a fun test.

Can hardly wait to get a B17.   Thanks!   Vic

[Robin]

For our first prototypes, we will be using regular Lithium Ion. Take a look at the picture attached. The standard sized module for the B17 allows for up to 104 of the 18650 sized batteries. That really fills the module up. This would result in 2 strings of 13 series groups of 4 in parallel.
The 3.7V nominal batteries give you a 48.1V nominal battery.
Lithium Iron is only 3.2V, so requires more in series. The numbers don't work out for this size of plug in module. I am also dissapointed that the Lithium Iron batteries are only 1.5 amp hours instead of 2.2. The good thing about the Lithium Iron is that cycle life is much higher and they don't catch fire like Lion. We will be making a totally separate B17 enclosure for the batteries so it is possible to get the right mix for Lithium Iron. These modules will not be light weight if we end up with an 8 or 9" wide module instead of the 4.4" wide inverter and charge controller versions.
There is another reason to make a separate cabinet for the batteries that has the same theme as the inverter enclosure. Lithium batteries are not fond of heat, so do we really want a battery module right next to an inverter or Charge controller module? Our airflow seems to work well, but........
I will keep you all informed as to the progress. We are 3D printing all the custom plastic parts now. My job is to make it all fit in a package that looks good and that makes sense. Some of the smart guys (EE's) will have to make the BMS and such actually work. This is a very fun project. Most of you have by now seen the quad stack of B17's on the Alt-E video. A B17 and three battery enclosures would look almost just like that quad stack. Imagine a cool and powerful system like that and no battery cables!

[bailey]

Looks like a very clever packing job!

While we are on the subject of unfortunate tradeoff's (from an energy density point of view), another thing to consider would be to ensure that you can route heat away from individual cells.  As Robin noted, these things don't do well if they get too hot, and many of the new high power packs I've looked at seem to put a lot of effort towards keeping all the cells cool, either by designing a good individual airflow path, or some sort of hybrid arrangement with heat pipes/phase change materials/etc.  You can always instrument the cells for temperature and throttle back when those in the middle start heating up, but...

Like usual, no free lunch!

Kirk Bailey
Abundant Solar, LLC.

[ClassicCrazy]

For our first prototypes, we will be using regular Lithium Ion. Take a look at the picture attached. The standard sized module for the B17 allows for up to 104 of the 18650 sized batteries. That really fills the module up. This would result in 2 strings of 13 series groups of 4 in parallel.
The 3.7V nominal batteries give you a 48.1V nominal battery.
Lithium Iron is only 3.2V, so requires more in series. The numbers don't work out for this size of plug in module. I am also dissapointed that the Lithium Iron batteries are only 1.5 amp hours instead of 2.2. The good thing about the Lithium Iron is that cycle life is much higher and they don't catch fire like Lion. We will be making a totally separate B17 enclosure for the batteries so it is possible to get the right mix for Lithium Iron. These modules will not be light weight if we end up with an 8 or 9" wide module instead of the 4.4" wide inverter and charge controller versions.
There is another reason to make a separate cabinet for the batteries that has the same theme as the inverter enclosure. Lithium batteries are not fond of heat, so do we really want a battery module right next to an inverter or Charge controller module? Our airflow seems to work well, but........
I will keep you all informed as to the progress. We are 3D printing all the custom plastic parts now. My job is to make it all fit in a package that looks good and that makes sense. Some of the smart guys (EE's) will have to make the BMS and such actually work. This is a very fun project. Most of you have by now seen the quad stack of B17's on the Alt-E video. A B17 and three battery enclosures would look almost just like that quad stack. Imagine a cool and powerful system like that and no battery cables!

Are these of any use for your project Robin ?
https://www.facebook.com/groups/Endless.Sphere.Sales/permalink/1195185057253128/?sale_post_id=1195185057253128

Larry

[Robin]

We plan on having a fan in the battery system enclosure. With enough sensors, we should be able to control temperature extremes as well as differential temperature from one end to the other. That too is important.
I have attached a picture of one half of the plastic battery cell holders. These pieces of plastic do a lot more than just hold the batteries. They also give us a place to attach the three circuit boards, the front face (with meter) as well as the side covers. These are pretty complicated pieces of plastic.
Notice the protruding piece on the bottom right side of the module. That is what we call the door opener. It moves a spring loaded wishbone up that locks the door closed so the door can move up out of the way when inserting a module.

[Vic]

Hi Robin,

WOW,  that/those side piece/s are complicated.  3-D printing sure is a boon to doing models and prototypes.

Looks like you folks are having FUN.

Thanks for keeping us in the loop.   Vic

[Robin]

Vic, we have five 3D printers. This particular piece was done on our largest printer. It can do 24" by 24" by 24" or something like that. The little Willy was done on many different machines. It took many hundreds of hours to print.
In the old days we had to be much more careful when designing parts like this. The first time you got to see the part was after the tooling had been created. The mistakes were very costly for sure. I remember doing three intricate investment castings for a large power supply that launched nuclear cruise missiles on the B2 bomber. We could not make prototypes and there was no CAD to help in the design, so I was really sweating it during the tooling phase of that project. Tooling was about $100K and it took myself and a drafter three years to get it done. I was afraid I would be fired if it didn't work. It turned out fine. CAD helped a lot, but with 3D printing, I can have a part made that is just a rough concept. No big deal if it isn't perfect. Matt, the engineer who makes the parts may disagree though. We keep him too busy with concepts that change a lot.

[russ_drinkwater]

If you need a tester in australia I will put my hand up!
No snow here in winter and solar production is still 5-7 hours per day depending on rare cloud and fog.

[Robin]

You will want to get signed up for a B17 Beta.
I think you go to www.midnitesolar.com/beta

There should be a sign up sheet.
I do not know when we will have battery modules. I do hope it is right around the time we have the B17 beta units, but maybe shortly after.

[russ_drinkwater]

I have cast my bread upon the water Robin!
Thanks Russ

[Robin]

Russ, you must be either in OZ or NZ? We think the B17 will be able to do 120/240VAC 60Hz or 230VAC 50Hz. Same hardware! Wouldn't that be nice.
Thanks,
Robin

[russ_drinkwater]

Hey Robin,
I am inland from the east coast of Queensland, australia.
Yes we are 240 volt 50Hz here.

[onanparts]

If some day in the near future you discover a Troll going by the name of Margaret, age about 305, with one eyebrow (she shaved the upper one) a height of roughly Less Tall, weight near 300 pounds, works part time as a professional Nanny and has no favorite foods...you will be very close to a 9V NIMH.

If you join the resistance you will be charged and thrown in a dry cell. After a battery of tests the odds of being discharged are very high.