DIY Lithium RV Battery Build - Part 2: Building the battery, Start to Finish
Are you ready to dive in and start building your Lithium battery for your RV, Van, or Trailer? It's easier than you may think, and really rewarding. I guarantee, you'll love doing it.
In Part 2 of this multi-video series, I'll build our first Lithium Iron Phosphate battery pack for our 22 foot trailer. I'll go through all the parts we picked, balance the cells (and talk about WHY you do this), assemble the battery, and even program the BMS using bluetooth and an app on my smart phone. The finished product is one of the cleanest home builds you'll find. If you want to get up and running quickly, you'll be able to follow along step by step and end up with a working battery ready in less than a week.
There's a lot in this video, so, you'll find a list of parts, tools, settings, and equations below.
DISCLAIMER:
Undertake any project at your own risk. I'm being as safe as I can be and making that judgment for myself. I'm sharing my knowledge as I go, but I could be incorrect or miss something, and do not know about every possible unexpected issue that could arise. I try to push myself, but I also know my limits and don't exceed them. Before you embark on a project, you should too.
PARTS:
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Cells:
New CALB CA Series 100 AH LiFePO4 cells (https://www.aliexpress.com/ite....m/4000306076197.html
Bus bar kit (bus bars, terminal caps, bolts, lock washers)
BMS:
120 Amp LiFePO4 4S Smart BMS (https://www.aliexpress.com/item/1005002481368256.html?spm=a2g0o.productlist.0.0.779236f7xwfmGx&algo_pvid=5d455f9f-afc9-4da0-8e57-a4c6a3826b7d&algo_exp_id=5d455f9f-afc9-4da0-8e57-a4c6a3826b7d-22)
Bluetooth module (included with BMS above)
BMS management app:
Xiaoxiang/Jiabaida BMS App
IPhone: https://apps.apple.com/us/app/....xiaoxiang-bms/id1375
Android: https://play.google.com/store/apps/details?id=com.jiabaida.bms&hl=en_US&gl=US
Bracket:
22 gauge plain steel (3" x 35.5") (Lowe's)
(3) #10 x 1 inch stainless socket head cap screws
(3) #10 nylon locking nuts
(3) nylon spacers, 0.188 ID, filed to appropriate thickness
(2) 1/2" wide x 1/8" thick x 3" long steel bar (for reinforcement plates)
TOOLS:
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Constant voltage power supply
5 amp version (https://www.amazon.com/dp/B08DHZ2X2Q/ref=cm_sw_em_r_mt_dp_0B11QGFJ29VHJEN2QY0Q?_encoding=UTF8&psc=1)
Wire strippers
Crimping tool (built into most wire strippers)
Soldering iron (not required, depending)
Heat gun or lighter
OTHER PARTS:
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(Qty 5) 5/16" heat shrink ring connectors
copper battery lugs for 5/16" terminals
(Qty 3) 10 gauge
(Qty 1) 4 gauge
SUPPLIES:
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Gorilla tape
Masking tape/Electrical tape
Paint and primer for bracket
A couple of extra battery cables
small zip ties
ACRONYMS AND TERMINOLOGY:
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SOC: State of Charge
AH: Amp Hours
BMS: Battery Management System
FORMULAS:
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Amp Hours (AH) to Milliamp Hours (mAH):
mAH = AH * 1000
Estimating time to balance cells:
AH left to charge = [ Per cell capacity (AH) ] - [ Per Cell capacity (AH) * Current State of Charge(%) ]
Minimum Time to charge in Hours = [ AH left to charge * Number of Cells in Pack ] / Max Power Supply Output* (Amps)
*Note: power supply will never hit this max, and drops as it charges, so a better value for Max Power Supply Output that approximates the average current over time might be something like 70% of its max.
BMS SETTINGS:
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Coming soon...
