304Ah 16S Battery Build

Castaway Camper

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Sep 15, 2021
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11
Just completed this build for my off grid camp along the James River in Virgina. I checked in with a few recommended prismatic cell vendors that I found on this forum and decided to go with SQO (Shenzhen Qishou Technology) as seen on "Off Grid Garage" videos. The total price delivered including Pay Pal fee came to $2,650. One of the main reasons I selected this supplier is that Amy Peng of SQO stated that these 304Ah EVE cells were only a week away from US warehouse in California, I'm not terribly patient. Ordered on 12-13-21- received on 12-27-22. All cells looked visually in top condition, they were packaged 2 to the box, with the "pool noodle" type foam, 1" around the perimeter 3" thick top and bottom. The cardboard was double thick and very well taped, just a couple dings on the packaging.image1 (41).jpegimage0 (23).jpegimage0 (24).jpeg

The BMS used is the 16S 100amp model from Overkill Solar, I also ordered some 2 gauge wire for the positive and negative leads, along with appropriate lugs to fit over the welded 6MM welded studs that the cells came with.

Wood working is one of my hobbies, so building a plywood box came as the easy option for housing this 215 pound beast. I used 3/4 finished cabinet plywood for the carcass and hardwood for the corners and lid/base trim, painted with aerosol Rust-O-Leum "Hammer finish" gray. It took a couple tries but I got the box perfectly sized to fit the cells snugly into place, having to apply slight pressure to push the last cell into place for each column. I selected this configuration because of specific space constraints, I modified a couple bus bars to join two locations where the cells are attached edge to edge, also made up a jumper with the #2 cable about 14" long to complete the entire series connections
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The BMS from Overkill Solar is mounted to a bridge board using pocket screws on the edge for easy removal if needed, balance leads were cut to length and terminated with 1/4" shrink wrap insulated ring terminals. With this BMS there are three included temperature sensors. I was able to snake them down into the corners where 4 cells come together (just enough space to do so), they are spread out as evenly as possible. Two 1/2" holes were drilled in the box for main positive/negative leads to exit. With shrink insulation on the #2 cable at penetration it provided a very snug fit. The main positive and negative are terminated using 175 amp Anderson connectors hydraulically crimped on.
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I took a chance and skipped the top balancing procedure as some have told me that with better cell suppliers the chances of receiving them balanced is getting better and better. So hooked up my cheap power supply and charging through the BMS with about 5 amps at 54.4 volts. This morning the voltage is 53.82 with a cell delta of 0.004 volts, I programed the BMS to start balancing earlier in the voltage range and with a finer delta of 0.007 volts (this programming will be returned to default once this initial balancing is complete). I'm not saying I'm home free yet as I realize the voltage can spread quickly as I near top SOC. We shall see... Anyway, I wanted to thank this forum for all the information I gained to even make this possible for me to do!
 

Castaway Camper

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Sep 15, 2021
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11
Does any one have suggestion for the an all in one invertor that doesn't have such a high static consumption. That seems to be one of the problems with the all in ones. Looking for about 3-4K watt invertor. Thanks ahead.
 

farnja

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Joined
Apr 15, 2021
Messages
4
Hey Castaway - I just got the exact same set of cells from Amy Peng (arrived on same day) also in a 16s setup. I did a top-balance and then pulled 304ah from them with my lowest cell ending at 2.887v and highest at 3.007v. I'm sure I could have got another dozen ah or so. I think you'll be good!

Your box looks amazing. What did the external dimensions (particularly height) end up at? I need to drop something similar into a sailboat. Wanna make another? :)
 

Castaway Camper

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Sep 15, 2021
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11
I can confirm tonight the finished dimensions. By memory the interior dimensions are 11 3/8" X 32 X 11 Tall
11" the height plus 3/4 for the lid, that includes the cell height with studs, about an additional 3/4" above the studs to the 3/4" thick bridge board, the BMS on top of that board is about 3/4"+ thick. From the top of the BMS to the bottom of the lid is probably close to an inch.

Thanks for the capacity information, I'm not so sophisticated to do that test. Did you pay about what I paid? The pricing is always a little bit of a mystery.
 

farnja

New Member
Joined
Apr 15, 2021
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4
Thanks - that's very helpful.

My Paypal total was $2498, about $500 was shipping. Not sure if there was an additional Paypal fee tacked on.
 

sidpost

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Joined
Mar 27, 2021
Messages
82
Location
Texas, USA
How do these 304Ah batteries compare to the more common 280Ah versions from Amy?

Any recommendations for BMS options to avoid or seek out?
 

Tball

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Joined
Mar 30, 2020
Messages
140
Love the box, only question is I didn't see any support for your handles from the inside of the box, will those handles with wood screws be strong enough to carry the 200+ pounds of weight? Solid build!!
 

richard cabesa

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Mar 16, 2021
Messages
108
Love the box, only question is I didn't see any support for your handles from the inside of the box, will those handles with wood screws be strong enough to carry the 200+ pounds of weight? Solid build!!
Yes, nice box. I think he will probably be OK with the screws. 8 #10 screws properly installed (everything in the pictures indicate so) each screw is responsible for about 25lbs. Easy.
That said, I would have through-bolted
 

Castaway Camper

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Sep 15, 2021
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11
Good question I agree with Richard with a total of 8 screws its probably fine. To be honest however these are not practical handles, they were repurposed from a dehumidifier, problem is they are on canvas straps and when lifting it compresses your fingers against the box OUCH. In reality I’m going to lift from the bottom with strong friend with new rubber coated gloves when setting at its final resting place. So the handles are for esthetics I suppose.
 

Tball

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Joined
Mar 30, 2020
Messages
140
Good question I agree with Richard with a total of 8 screws its probably fine. To be honest however these are not practical handles, they were repurposed from a dehumidifier, problem is they are on canvas straps and when lifting it compresses your fingers against the box OUCH. In reality I’m going to lift from the bottom with strong friend with new rubber coated gloves when setting at its final resting place. So the handles are for esthetics I suppose.
Either way, killer box and it looks great! I'm going to model something similar to this, just need handles since it will be going in and out of a 5th wheel! Thanks for the inspiration!
 
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