Apexium DIY Battery Kit Build - Seplos BMS V2 (10E)

Building the perfect battery... almost! In this video we begin building big battery #1. This will be using a Seplos BMS with 150ma passive balancer. Challenge Accepted! We will be using the matched cells from the previous video to give the BMS the best chance at balancing the cells. I have a theory where if I arrange the cells from largest to smallest capacity this might help to create a naturally balanced pack.
Topics covered in this video include: Prepping the box, installing the bus bars and installing the cells and pressure plate.
• Cycle Testing and Matc...
• Balancing Matched VS. ...
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RC3563 Lithium Battery Internal Resistance Tester with 4-wire Probes
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Where to Buy Cells:
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Key topics included in this video:
00:00
01:00 - What's In The Box?
02:00 - Breaking It Down
02:35 - Insulate It
03:36 - Install Cells
04:32 - Arrange The Cells
07:36 - The Theory
08:49 - Compression
09:43 - Pressure Plate
14:00 - Bus Bars
15:12 - The Abys
19:32 - Top Brackets
21:57 - The PCBs
23:27 - What The Wire!
27:47 - Tourque Time
29:00 - To Be Continued
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[@tiborchren]

I'd have one tip for you to consider. The rear battery cells only support the square beams in the centre, top and bottom of the rear wall. The battery cells will expand over time and it would be better if they had full support for their complete surface on the back wall. It would be good to fill the rear section with precision cut wood in the gap between the rear beams or put aluminium plates in the back on the rear wall. I know it requires disassembling the whole battery, but it's worth considering. I saw on another KZbin video that they filled it in so that the rear battery cells also have back wall support across their full surfaces.

[@natesdiysolar]

Good point. I may just do that then. Where did you see that.. off grid garage?

[@tiborchren]

@@natesdiysolar I saw it first time on kirkdis channel where he used wood filler to solve it, then I posted it in the comments to Andy from Off-Grid Garage when he was making a Frankenstein DIY battery box and based on that comment he made a video where he used an aluminum plate in the back of the box.

[@MatthewYBarbo]

Very clean setup that is easy on the eyes. Another great video, Nate! Awesome job as always!

[@natesdiysolar]

Thanks

[@daviebaggins]

Thats quite a setup🎉🎉🎉

[@dustanltye]

Awesome build! You are hired! Sending you plane tickets to ky!

[@natesdiysolar]

Lol

[@TechNTorque]

Very nice! I've been looking for the last month for your next video! I'm selling all my lead acid batteries and buying 280ah cells if I find a deal on 16. I'm going to wait to see how this enclosure turns out instead of building my own. Can't wait for part 2!

[@natesdiysolar]

I'll be testing a couple of different ones. What really matters is what bms you get. All the enclosures are pretty standard now. In the 2nd build, I'll list the cost of everything as well.

[@TechNTorque]

@natesdiysolar I didn't buy anything yet, but overkill solar is at the top of my list for programming and features right now. The 16s 100A bms looks like it checks all the boxes and decent reviews. I live in the northeast so I'll need low temp protection here. I'm not buying anything until I see your videos 😄

[@natesdiysolar]

@TechNTorque cool. Keep in mind unless you are going to have more than one battery you will be able to get about 5kw of power out of that bms before hitting 100a.

[@TechNTorque]

@natesdiysolar one battery to start, going to scale up in the future. Just looking to take a few light load circuits off grid such as my refrigerator and some lights to run off solar/battery at all times. Hoping to keep a few things running all the time so I don't have to worry about power outages. When I scale up I'd like to have everything off grid, but still grid connected if needed. How do you feel about the 6000xp inverter?

[@offgriddreaming5403]

How do you like the seplos bms please?

[@natesdiysolar]

Well . The v2 bms is slow to balance initially but once you get to using it it's really not that bad.. it functions lol. The display is lacking compared to the jk Touch screen. I'll be doing a video about balancing with this bms. But it was frustratingly slow. If you want quick and easy just use the JK inverter bms or an externalbalancer. Videos coming out soon on both of these bms. I can't really say I'd recommend it over the jk bms... that said I haven't gotten into the comm/inverter functions yet... the v3 does have a 2 or 3A balancer so if they had a better screen AND balancer I would be ok with it...

[@offgriddreaming5403]

@@natesdiysolar Thanks for the quick reply. Yes I have 12v jk bms and really like it. I've ordered a box similar to yours with the seplos. I wish it had the jk but am willing to give it a try 👍🏼

[@natesdiysolar]

@offgriddreaming5403 just be sure to pre balance by putting Cells in parallel or just use an external balancer for the initial balance. You will be fine. What Box did you go with..

[@offgriddreaming5403]

@@natesdiysolar I only have 105ah cells so I went with a box by battery queen lol. I believe it's a rebranded seplos. I'll probably do a video once the box arrives. I'm just testing the cells now

[@christalbert722]

Uhhhhh....... they're in series, they should all see the same amount of current. Voltage cell to cell may differ, and when the BMS is running balancing things you've got multiple current paths so that's a different critter, but initially when you've just got 16 cells in series.... I can't see how the current would vary.

[@natesdiysolar]

That's what I was thinking especially in parallel but in series u also have internal resistance of each cell adding up ... I was surprised to see more current on the meter when probing the 2 ends of the pack

[@natesdiysolar]

That's what I was thinking especially in parallel but in series u also have internal resistance of each cell adding up ... I was surprised to see more current on the meter when probing the 2 ends of the pack.

[@nottelling41]

No, you missed an obvious difference: you're measuring the current direction positively and then negatively. It is a bias flaw of your meter

[@natesdiysolar]

​@nottelling41 is there a way to measure it accurately..

[@nottelling41]

@@natesdiysolar you would need a few especially accurate alternative current measurements and then average them and then compare to your positive and negative direction currents to see which is most accurate or you could time average to see if forward or reverse was closer to the total charge eventually. I'd just guess that forward is more accurate and then there is a50% chance you're correct with no work required :-)

[@daviebaggins]

Weee