Batteries: Difference between revisions

Revision as of 18:46, 19 July 2023

Expect to burn ~6000mAh in a race.
You will have <1hr to recharge between races. Typically 45 mins.
Charging a pair of 6S batteries is typically easier than charging a 12S.
Safe handing and charging processes must always be followed in the pits, including use of lipo bags.

Cells are reclaimed Samsung 21700 30T from NKON.
Spot welded using an eBay China special PCB and handheld electrodes.
- PCB needed some solder reinforcement as pictured where tracks started to cook.
- Instructions called for ~80Ah battery. I ended up needing a 100Ah (1000cca) in parallel with slightly crusty 36Ah (330cca) being constantly topped off by a PSU to >14v for decent welds.
- Electrodes need to be regularly redressed. Not too blunt, not too pointy. Like a small ball point pen seems to work.
- Did try using rewound microwave oven transformer, pulsing a solid state relay. Seemed like not enough current for too much time. Electrodes would melt without welding the nickel at all.
Initially planned to use 0.3mm nickel strip for high current handling but getting pure 0.15mm to weld was tough enough, so that's what I went with. It's in links of 3 parallel rungs which seems to stand up to the task.
BMS - Cheap and supposedly rated for 40A continuous, 70A peak (rules stipulate 30A fuse at 12s). Performance in races is somewhat lacking. Just about keeps up, but runs so hot it melts the battery wrap.
- Plan to try 100A DALY unit

...

Turnigy Accucel / HTRC C150 - Runs directly from mains, only just charges packs between races at 1hr intervals
HOTA D6 Pro - Pro runs directly from mains, little faster than C150, popular in the pits.

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