{"id":475,"date":"2023-04-09T11:09:37","date_gmt":"2023-04-09T19:09:37","guid":{"rendered":"https:\/\/denco.ad6dm.net\/batts\/?p=475"},"modified":"2023-04-09T13:12:02","modified_gmt":"2023-04-09T21:12:02","slug":"denco-jag35-headway-beast","status":"publish","type":"post","link":"https:\/\/denco.ad6dm.net\/batts\/denco-jag35-headway-beast\/","title":{"rendered":"DenCo JAG35 Headway Beast"},"content":{"rendered":"\n

This started off looking for LiFePO4 cells on BatteryHookup.com. There was kit for building a 24Ah Headway 38120 battery pack, and so we started searching YouTube to find more information on such a Headway build. Later it led to Jehu Garcia’s PCB Board Bus Kit<\/strong><\/a> and PCB BMS Board Kit<\/strong><\/a> using the same cells. <\/p>\n\n\n\n

Since BatteryHookup.com was selling cells for $5.00 per cell (at the time) we decided to try this out.<\/p>\n\n\n\n

This build proved to be a lot more difficult than anticipated. Other than waiting for China shipments for the 2 Daly 100A BMS<\/strong><\/a>‘s and Hi rise M8 180A terminals<\/strong><\/a>, it turns out that soldering the small connections for the BMS leads meant very fine motor skills and very close through-holes that can very easily be bridged or covered over with errant solder. This might seem like a convenient build, but it is not for the inexperienced solderer.<\/p>\n\n\n\n

This battery allows for 200 amp draw, though the optimum 64Ah would not sustain that for very long. It has a 250A ANL fuse. <\/p>\n\n\n\n

General Specs:<\/strong>
Created: April 1, 2023.
Cells: Used Battery Hookup<\/strong><\/a> Headway 38120 8Ah 3.2V LiFePO4 cells, 4 cells in series, 8 in parallel.
BMS: 2x parallel Daly 100A 4S LiFePO4 12V common port BMS.
PCB Bus Board and PCB BMS Board designed and sold by jag35<\/a><\/strong>.
Configuration: 4S8P.
Nominal Voltage: 12.8V.
Overall weight: 26.2 lbs (11.88 kg).
Current owner: AD6DM Dennis<\/p>\n\n\n\n

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The completed battery only produced 37Ah after initial test (57.8% of rated\/desired capacity). After swapping out a parallel group of older used cells for less old used cells, 44.43Ah was achieved (69.4% of rated capacity). <\/p>\n\n\n\n

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This led to the addition of a 5A Active Balancer<\/strong><\/a>, a newer device that has made it into the DIY battery building scene. It uses capacitors and switched parallel and series relays to redistribute and equalize the voltage differences between series groups for a better overall total performance. <\/p>\n\n\n\n

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Upon installation and testing of the Active Balancer, the full 64Ah was achieved.<\/p>\n\n\n\n

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This goes to show that battery building with passive BMS balancing is best for new and closely-matched cells. Passive BMS balance current only amounts to a few tens of milliamps of balancing current, and this is typically resistive balancing, meaning the higher voltage cells have energy burned off (power is dissipated in the resistors) while other cells continue to charge and catch up in voltage. This amount of balance current is nothing compared to large charging currents, and only helps series cells that are minimally mismatched.<\/p>\n\n\n\n

A significantly weaker series cell (or parallel group in a 4S pack) will be the limiting factor for the whole battery pack. When dealing with “second life” used cells where the degradation level of each of the series members is difficult to determine or remedy, an active balancer is almost a necessity in addition to a BMS.<\/p>\n\n\n\n

All in all, this 824Wh 64Ah battery cost about $375 to build, including the addition of an active balancer, but not including the “good cells” swapped in from a different 12V 24Ah BatteryHookup Headway kit. Also, as of this writing, BatteryHookup raised the price per cell to $5.50. Assume you will get more than the minimum 32 to arrive at a “good set” of 32 cells.<\/p>\n\n\n\n

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Just finished building this thing and it's a beast. 64Ah of 12V #LiFePO4<\/a> power. 819 watt-hours! #Headway<\/a> 38120 4S8P 32-cell @jag35<\/a> PCB Bus Board kit. https:\/\/t.co\/KN2iAzw2cJ<\/a> 2x100A Daly BMS's & 250A fuse. Charging right now with a 25A 14.6V charger. #DenCo<\/a> #PowerAllTheThings<\/a> pic.twitter.com\/d1sjqZVqr6<\/a><\/p>— AD6DM Dennis (@AD6DM) April 1, 2023<\/a><\/blockquote>