This article covers three things: which connector to standardise on, how to charge and store 1S LiHV packs, and two Betaflight settings worth checking on every 1S build.
The connectors: weight and sag
In June 2023 Oscar Liang weighed and tested the five common micro connectors. Weights are for a male and female pair:
| Connector | Weight (pair) | Result in the 12 A test |
|---|---|---|
| PH2.0 | 0.4 g | most sag, slightly shorter flight time |
| BT2.0 | 0.6 g | close to the best, marginally ahead of A30 |
| A30 | 0.6 g | almost the same as BT2.0 |
| GNB27 | 0.8 g | similar to BT2.0 and A30 |
| XT30 | 1.6 g | least sag |
The test discharged one 2S 300 mAh LiHV pack at a constant 12 A down to 3.0 V per cell, with the plug swapped for each run. It was 2S only because his battery analyzer needs at least two cells. Oscar notes that a typical tiny whoop draws less than 12 A, so the load was on the heavy side for the class.
What the numbers mean in practice:
- PH2.0 is the lightest but has the highest resistance. More sag means the pack hits your landing voltage earlier with charge still left in it. Fine for old quads and as a charger port, not worth buying new packs for.
- BT2.0 and A30 performed almost identically and are the lightest of the good options. This is the default choice for 65-75 mm 1S whoops.
- GNB27 matched them electrically but weighs more, and Oscar found it hard to pull apart when swapping packs.
- XT30 had the least sag, but the extra gram is about 5% of a typical whoop's weight. Oscar recommends it for larger micros drawing 20 A or more.
BT2.0 and A30: compatible, mostly
A30 is GNB's connector, BT2.0 is BETAFPV's, and the two share nearly identical dimensions. In Oscar's testing, A30 battery plugs fit BT2.0 quads, and he flew that combination for weeks. The other direction is less certain: the A30 plug on the quad has a small raised section inside, so a BT2.0 battery may or may not go in depending on how flexible the plastic is. Forcing it can damage the housing.
Two traps:
- GNB reverses the usual gender naming on A30. Normally the plug with pins is "male"; on A30 it is the other way round. Check pictures, not just the product name, when ordering spare pigtails.
- Manufacturing tolerances vary. Oscar says the BT2.0 ports on the VIFLY WhoopStor V3 charger take A30 packs, while some owners report a loose fit. A loose joint means more resistance and more heat.
The practical rule from quadmath.com's connector guide: pick one connector for the whole fleet and re-solder anything that arrives on something else. Adapters add one more joint and some weight, so keep them for the charger, not the quad.
LiHV: what changes when you charge to 4.35 V
LiHV cells charge to 4.35 V instead of the 4.20 V of a standard LiPo. Oscar notes that LiHV is most common on 1S whoops and 2S micros: the extra voltage gives more RPM, and small packs are cheap enough to replace when they wear out.
The rules from Oscar Liang's LiHV guide:
- Never charge a standard LiPo to 4.35 V. It risks overheating, swelling or fire.
- Charging a LiHV to 4.20 V is safe, but you only use about 90% of its capacity.
- Charge current: the same 1C rule as for LiPo is fine. Oscar charges his 1S packs at around 0.5 A.
- Landing voltage stays the same as for LiPo. Oscar lands LiHV packs at 3.5 V per cell, as he does with LiPo.
- Wear: in his 100-cycle test the LiHV pack lost about 5.4% of its capacity and the LiPo about 3.8%. Voltage sag after 100 cycles was similar for both. LiHV trades some lifespan for performance.
Storage voltage for LiHV is 3.85 V (3.80 V for LiPo). A 1S charger with a storage function such as the WhoopStor V3 lets you choose 3.80 V, 3.85 V, 4.20 V or 4.35 V as the end voltage and charges or discharges each pack to it, at 0.3-1.3 A. The voltage and current apply to all six ports, so do not mix LiPo and LiHV packs in one charging session.
Betaflight: the 4.30 V default and 1S LiHV
Betaflight works out the cell count once, when you plug in a battery and the voltage settles. From the source code (src/main/sensors/battery.c):
cells = (measured voltage / vbat_max_cell_voltage) rounded down + 1
The default vbat_max_cell_voltage is 430 (4.30 V; the setting is in hundredths of a volt). Warning and critical voltages are then the cell count multiplied by vbat_warning_cell_voltage (default 3.50 V) and vbat_min_cell_voltage (default 3.30 V).
A fresh 1S LiHV pack sits above 4.30 V, and that causes two problems:
- Betaflight treats a voltage between
vbat_max_cell_voltageand 6.00 V as possibly coming from USB, not from a battery. A 4.35 V pack can go undetected until it drops. - If detection happens when the pack reads exactly 4.30 V, the formula gives two cells. The critical threshold becomes 6.60 V, which a 1S pack never reaches, and you get a low-voltage warning straight away. UAV Overhead describes the same miscount on a 2S LiHV pack on a Mobula 8.
With vbat_max_cell_voltage at 440, a 4.35 V pack is below the limit and counts as one cell. There are two fixes. Use one:
set vbat_max_cell_voltage = 440
save
or, on a whoop that only ever flies 1S:
set force_battery_cell_count = 1
save
Forcing the cell count is the simpler option on a 1S-only board. Afterwards, plug in a fresh pack and check that the Power & Battery tab and the OSD show one cell.
While you are in the CLI, check the warning voltage. On small packs voltage is a rough fuel gauge, because it sags hard under throttle and recovers when you let go. Land when the warning appears, not when the critical alarm goes off.
Quick checklist for a 1S whoop
- One connector type across the fleet, BT2.0 or A30 for 65-75 mm whoops.
- No adapters between the pack and the quad.
- LiHV packs charged to 4.35 V, LiPo packs never above 4.20 V, storage at 3.85 V or 3.80 V.
vbat_max_cell_voltage = 440orforce_battery_cell_count = 1in Betaflight.- Cell count checked with a fresh pack before the first flight.