Battery Hookup new listing “Case 100x 3.3v 2200mah - 200x 18650 Lifepo4” for $100.00 + shipping

[sam_sam_sam]

I have a question about this GTI solar controller

https://www.ebay.com/itm/32631398408...BST1E0VNMMJPT9


It says that it can accept 10.8 to 32 volts DC voltage
or
solar panels

Solar Panels
36cells-Vmp:18-21V:Voc:20-30V

60cells-Vmp:26-30V:Voc:34-38V

72cells-Vmp:35-39V:Voc:42-51V

is this what I am looking for but I am confused about what they are saying about this (36 , 60 72 cells and voltage range

because the solar panels that I have are 30 cells each ( the no load voltage is 20. something ) and if I parallel them to have 60 cells or are they referring to cells in series then I would still have 60 cells in series this is another story but if this is the case then why the difference in battery voltage input is limited to 32 volts

[eccerr0r]

This is a "limited range" mppt "microinverter" (despite it being over 1KW it's still a 'microinverter' since it cannot handle long strings, usually meaning Vmpp of 100V or higher. Expensive mppt inverters have a larger voltage range.)

They have two versions there. You pick the one that your panels match. They have a version for 30(?)/36 cell and 60/72 cell.

In any case the auction you wrote did say "1. The inverter is designed to handle PV panels as input source only and will not work with batteries/wind turbines as input source." so I'm not sure what you mean abut battery voltage limit.

Indeed there is a Voc limit and minimum on the two versions. They will not run if you exceed or go below. If you try to hook up a 30 cell panel to the 36-volt version it will not work (voltage too low, no damage). Also won't work if you hook up a 72-cell panel to the 18-volt version (this case it may leak magic smoke.)

Yes, if you connect two identical 30-cell panels in series you get a 60-cell panel. It's always a tradeoff: more cells in series is less wire but cannot deal with shading as well - parallel connections deal with shading better.

It seems people tend to have 36-cell for offgrid use (because the 18v can readily be used to charge 12V lead acid batteries without a charge controller) and 60-cell for grid tie. However solar panels are solar panels, get the voltage that works.

[sam_sam_sam]

However solar panels are solar panels, get the voltage that works.

That what I figured out that solar are solar panels all I am not sure what voltage


Please read the description of this GTI if what they are talking about the switch for turning off the MPPT controller and using the battery power is this possible or is this hypothetical scenario and might not really work or does it really work the way it is says in the description

https://www.ebay.com/itm/40581058497....c101465.m3507

[eccerr0r]

if it does what it says, then yes this one it's valid to use battery as a source, and you can ebay NAD it if it doesn't work.

[sam_sam_sam]

if it does what it says, then yes this one it's valid to use battery as a source, and you can ebay NAD it if it doesn't work.

Thank you for your reply I going to find out if it will actually work the way it is described in this listing for this device

[eccerr0r]

almost done trying to mod a (good) 24V6Ah to 12V12Ah pack of the same form factor...granted it'll be a gimped 12V12Ah pack that's limited at 15A which is only a little over 1C... need more wire...

The bad one is bad. That one cell's self discharge probably means I have to port out that cell so I can charge it separately in order to get 12V@~4+Ah from the pack.

[eccerr0r]

FFFCCKK the hacked BMS is not working after mod ! Maybe I should use the repaired one on this pack...

oHHH I found my f**kup! bad assumption that B4 is hooked up properly! It's not!

Yup I think I fried one of the balancers due to the connection f**Kup These are the days I wish I had a FLIR camera to pinpoint which one, but my finger temperature sensor seems to point it in that general direction.

[sam_sam_sam]

FFFCCKK the hacked BMS is not working after mod ! Maybe I should use the repaired one on this pack...

oHHH I found my f**kup! bad assumption that B4 is hooked up properly! It's not!

Yup I think I fried one of the balancers due to the connection f**Kup These are the days I wish I had a FLIR camera to pinpoint which one, but my finger temperature sensor seems to point it in that general direction.

I have made the wrong assumption before when trying to modding something that is why I tested the heck out of it to see if it still works as was designed to do with the modding in place but that just me trying to make sure I can not get to fail

I found some inexpensive 12 volt BMS boards that do not have the balancing function on them
I also found a BMS board that the balancing function is on a separate circuit board which will be convenient to use in a project that I need a higher current circuit capacity board and just need the balancing function just for charging the battery pack


https://www.ebay.com/itm/235974682699?var=536446917743

I was not sure if a BMS balancing balancing function would be possible with an ic chip that does multiple battery cells and changing it's configuration
I am not disappointed that it might not be possible to reconfigure because still have a use for the BMS protection boards that I remove from these battery packs and reuse them on low current battery cells and make it much higher current capacity but in a smaller footprint than what the original setup is now

[eccerr0r]

Oh I might have dodged a bullet...
Couldn't figure out what was wrong. I N/C'ed the extra interstitials instead of leaving them and it seems to stop getting hot now.

[eccerr0r]

Hmm... weird... or maybe not so weird.
I charged up my first not-waterlogged 24V6Ah to 12V12Ah hack to 14.4V and then drained it approximately 4 ampere hours, now it's sitting at 13.18V (all cells are around 3.29 or 3.30 volts). Minus age wear I suppose this should still have at least 6Ah left in it... so far this actually seems to be about right. Wonder if I should charge it up again or see what happens if I drain another 4 ampere hours.
Next I need to figure out what I want to do to stop using alligator clip wires to attach to it... mainly because passing more than 3 or 4 amps through these clip wires is starting to cause them to heat up (though wasting a few of these clip wires in parallel helps...)

[sam_sam_sam]

Hmm... weird... or maybe not so weird.
I charged up my first not-waterlogged 24V6Ah to 12V12Ah hack to 14.4V and then drained it approximately 4 ampere hours, now it's sitting at 13.18V (all cells are around 3.29 or 3.30 volts). Minus age wear I suppose this should still have at least 6Ah left in it... so far this actually seems to be about right. Wonder if I should charge it up again or see what happens if I drain another 4 ampere hours.
Next I need to figure out what I want to do to stop using alligator clip wires to attach to it... mainly because passing more than 3 or 4 amps through these clip wires is starting to cause them to heat up (though wasting a few of these clip wires in parallel helps...)

I just soldered to the tabbing and be done with it that is what I have done with the one I split into two separate battery packs

[eccerr0r]

Will need to solder something to the pads on the BMS. However I have to admit I did a poor job on resoldering the tabbing back to the BMS. I suspect it won't be an issue until I draw 15A from the pack...

[sam_sam_sam]

Will need to solder something to the pads on the BMS. However I have to admit I did a poor job on resoldering the tabbing back to the BMS. I suspect it won't be an issue until I draw 15A from the pack...

Drill a small hole in the center of the tabbing to make it easier to solder but when you do this run the drill very slowly and put a piece of wood on the bottom of the tabbing so that it lays flat on the top use a paint stick and make it like a sandwich maker sure to use a very sharp drill bit you do not need a very big hole either

Using a drill press would make this process easier to do if you have one