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Teardown & Rebuild of a MuscleGrid LiFePO4 Server Rack Battery
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<blockquote data-quote="rsaeon" data-source="post: 2506076" data-attributes="member: 76792"><p>As it turns out, it wasn't that bad! That was a nice surprise. As shipped/received, lowest measured voltage was 3.28V and highest was 3.31V for a delta of 30mV. It's not great but it's way better than what I was dreading. Ideal would have been under 10mV.</p><p></p><p>Update time! I put together a rudimentary high-amp charger to top off these cells to 3.65V:</p><p></p><p>[ATTACH]188292[/ATTACH]</p><p></p><p>I've always wanted to use these instrument cases for something and now I finally get a chance! They're from: <a href="https://vkenterprises.tech/product/medico-plastic-table-top-enclosure-for-medical-equipment-4/" target="_blank">https://vkenterprises.tech/product/medico-plastic-table-top-enclosure-for-medical-equipment-4/</a></p><p></p><p>Also here is a PZEM-015 DC Battery Capacity tester, a panel mount IEC socket+fuse+switch from Sharvi Electronics, 2 meters of 12AWG silicone wire from Quartz Components cut into thirds, and PG11 cable glands from Sunrom Electronics.</p><p></p><p>First was to crimp the wires into a 10mm sq uninsulated terminal lug, these were only available in 8mm hole sizes at Quartz Components:</p><p></p><p>[ATTACH]188293[/ATTACH]</p><p></p><p>I'm using 24AWG silicone wire for voltage sense of the PZEM module.</p><p></p><p>Gratuitous bokeh:</p><p></p><p>[ATTACH]188294[/ATTACH]</p><p></p><p>Front panel layout:</p><p></p><p>[ATTACH]188295[/ATTACH]</p><p></p><p>I wanted everything to be accessible in the front, including the power socket and switch. It's not conventional but way more usable, in my opinion. Switches are outward facing for the same reason: usability.</p><p></p><p>After some quality time with a rotary tool, I got the first revision of the panel ready (already found ways to improve it — but that'll be in another update):</p><p></p><p>[ATTACH]188296[/ATTACH]</p><p></p><p>That's a mockup of the exhaust/venting in the background. Funny, I wanted something angular and futuristic and ended up with something organic instead. The design evolved to rounded edges with no sharp corners so as to facilitate easy dust cleaning.</p><p></p><p>Then a week a later this showed up — 40A at 3.3V! It's adjustable so I'll have it set at 3.65V:</p><p></p><p>[ATTACH]188297[/ATTACH]</p><p></p><p>oops:</p><p></p><p>[ATTACH]188298[/ATTACH]</p><p></p><p>Some hours of sanding later, it's a snug fit.</p><p></p><p>[ATTACH]188299[/ATTACH]</p><p></p><p>A couple of evenings of were spent wiring everything up:</p><p></p><p>[ATTACH]188300[/ATTACH]</p><p></p><p>Eventually the PZEM module will be powered from the same power socket to make this all self contained.</p><p></p><p>I'm also considering adding a ESP8266+INA219+Relay to cut off power automatically at 3.66V volts.</p><p></p><p>With the power supply adjusted and powered on, everything looks good:</p><p></p><p>[ATTACH]188301[/ATTACH]</p><p></p><p>And here it is in use, charging up these cells, one by one:</p><p></p><p>[ATTACH]188302[/ATTACH]</p><p></p><p>It's taking about 45mins to add about 11.8Ah per cell to bring it up to 3.65V, that would mean these cells were shipped at 89% State of Charge, if they really are 105Ah.</p><p></p><p>Next up is to charge up all the other cells and do a capacity test of each cell down to 2.5V.</p></blockquote><p></p>
[QUOTE="rsaeon, post: 2506076, member: 76792"] As it turns out, it wasn't that bad! That was a nice surprise. As shipped/received, lowest measured voltage was 3.28V and highest was 3.31V for a delta of 30mV. It's not great but it's way better than what I was dreading. Ideal would have been under 10mV. Update time! I put together a rudimentary high-amp charger to top off these cells to 3.65V: [ATTACH]188292[/ATTACH] I've always wanted to use these instrument cases for something and now I finally get a chance! They're from: [URL]https://vkenterprises.tech/product/medico-plastic-table-top-enclosure-for-medical-equipment-4/[/URL] Also here is a PZEM-015 DC Battery Capacity tester, a panel mount IEC socket+fuse+switch from Sharvi Electronics, 2 meters of 12AWG silicone wire from Quartz Components cut into thirds, and PG11 cable glands from Sunrom Electronics. First was to crimp the wires into a 10mm sq uninsulated terminal lug, these were only available in 8mm hole sizes at Quartz Components: [ATTACH]188293[/ATTACH] I'm using 24AWG silicone wire for voltage sense of the PZEM module. Gratuitous bokeh: [ATTACH]188294[/ATTACH] Front panel layout: [ATTACH]188295[/ATTACH] I wanted everything to be accessible in the front, including the power socket and switch. It's not conventional but way more usable, in my opinion. Switches are outward facing for the same reason: usability. After some quality time with a rotary tool, I got the first revision of the panel ready (already found ways to improve it — but that'll be in another update): [ATTACH]188296[/ATTACH] That's a mockup of the exhaust/venting in the background. Funny, I wanted something angular and futuristic and ended up with something organic instead. The design evolved to rounded edges with no sharp corners so as to facilitate easy dust cleaning. Then a week a later this showed up — 40A at 3.3V! It's adjustable so I'll have it set at 3.65V: [ATTACH]188297[/ATTACH] oops: [ATTACH]188298[/ATTACH] Some hours of sanding later, it's a snug fit. [ATTACH]188299[/ATTACH] A couple of evenings of were spent wiring everything up: [ATTACH]188300[/ATTACH] Eventually the PZEM module will be powered from the same power socket to make this all self contained. I'm also considering adding a ESP8266+INA219+Relay to cut off power automatically at 3.66V volts. With the power supply adjusted and powered on, everything looks good: [ATTACH]188301[/ATTACH] And here it is in use, charging up these cells, one by one: [ATTACH]188302[/ATTACH] It's taking about 45mins to add about 11.8Ah per cell to bring it up to 3.65V, that would mean these cells were shipped at 89% State of Charge, if they really are 105Ah. Next up is to charge up all the other cells and do a capacity test of each cell down to 2.5V. [/QUOTE]
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Teardown & Rebuild of a MuscleGrid LiFePO4 Server Rack Battery
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