P1) 416 Open Frame Power Pack Kit (It's Time)

Open Frame Power Pack Kit 416 (OFPPk)

for 
18650 batteries – 64P

It’s Time

Having learned from Secondlifestorage forum and DIY Powerwall, Jehu Powerwall fb group and many others, there's many DIYers is building their own Powerwall at home which take advantage of the low cost and free used batteries from laptop or ebike. Once reprocess and reconfigured, they can use for their home Powerwall usage without the need to use the grid supply. Is a alternative solution to have a off-grid or grid-tie system.
Making DIY battery pack is a relatively time consuming process... from searching, breaking, cleaning, charging, discharging, capacity sorting, testing, building and final assembly and connecting until Power ON. It takes many days or months to accomplish all the tasks. If any of the tasks can be simplified, then it will save hours during the final stages for the assembly process. Most process flow is DIY or self-planned. Not everyone has a proper tool or facilities to do it, as such many work are not as planned or in a proper way. As much as possible, this (416 OFPPk) may helps to shorten the time while still maintaining the full functionality of assembled a DIY Powerwall system.
Courtesy of DIY powerwall Fb group 
   
 

Why going for Solderless or No Spot Weld?
A simple answer is, it can be replace anytime without much effort. It doesn’t damage the cell contact surface. Most importantly, no additional heat is applied. For those who wish to use new battery cells, this will be a big plus. 
Most DIYer are using used laptop batteries, medical pack... as such, tendency of failure along the way will be high. Giving the option to replace a single or a few batteries at a specific location can save the DIYers a lot of time during the replacement. 

Solution for solderless or no spot weld method can be easy or difficult, depends on where you look at it. A simplest way is to use a battery holder. Battery holder can provide the function of holding and connecting to the positive and negative terminal during operation.. but when there’s hundreds of batteries needed to connect, it will be a tedious job. 
For building huge stackable power pack, battery holders is not recommended as it trap heat within the holder itself. The ventilation is going to suffers. 
There’s a few solderless or no spot weld solution in the market.. each got is pros and cons… In general, most required to install a cap on each cell, then interconnect to go series or parallel. Lots of interlink connection needed. 
Spot weld on the other hand is better but it does have some issues if not done correctly. Many of spot weld failures generally comes from the setting of spot weld machine and the inconsistency of handling the probe. Need trial and errors to get it right. Many wastage of cells in the process. Spot weld do consume high inrush  power during the process. As such, a good high capacity power supply is unavoidable. Safety is also a Must while performing spot welding.

How Contact works?
In search for a good connection, I look into wire connectors and how they functions. Basically, there’s two important roles is needed. The first is Contact Surface and follow by Pressure Lock. 
For high-powered application, huge contact surface is probably the most important aspect. In-order to reduce the resistance from point A to point B during the high current operations; a bigger or huge contact surface is needed. Secondly, the pressure lock after the contact is mated. This will maintain the connection position when both mating contacts is closed. This is the area where we'll be concentrating.

Measurement & Visual Check.
Be it whether you’re building a small battery pack or huge Powerwall. The very most important is to check electrically whether your voltage is present before the install. Once you have installed you need to check again. One cons about voltage check is you need to have a multimeter or indicator to confirm the voltage… without it you won’t able to tell what’s present.
Visual check is also another simpler way to detect the failure. It is sometime faster and the problem maybe poor contact or misalignment issues. Checking is a Must for all pack assembly.


Next, The Development



By Daniel

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