# QuadDrive 80A: Weight, power distribution, voltage spikes and heatsink requirements **URL:** \ **Category:** BotBlox Hardware\ **Tags:** quaddrive\ **Created:** [September 19, 2026, 12:46pm UTC](https://forum.botblox.org/t/quaddrive-80a-weight-power-distribution-voltage-spikes-and-heatsink-requirements/648 "2026-09-19T12:46:37Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![ElsieMichaelson](https://avatars.discourse-cdn.com/v4/letter/e/b5ac83/32.png) [@ElsieMichaelson](https://forum.botblox.org/u/ElsieMichaelson)\ **Post date:** [September 19, 2026, 12:46pm UTC](https://forum.botblox.org/t/quaddrive-80a-weight-power-distribution-voltage-spikes-and-heatsink-requirements/648/1 "2026-09-19T12:46:37Z")
_This topic was migrated from the BotBlox ticketing system after being summarized and anonymized._ **Question** We’re evaluating QuadDrive 80A for a drone and have a few questions about the Rev B datasheet and system integration. Does the quoted weight include the heatsink? Does J1 provide a voltage-sense output or regulated power for a flight controller and peripherals? If we need a separate power distribution board, how should it connect? We’re also interested in the back-EMF protection. We’ve previously seen voltage spikes from 6S battery levels to nearly 40 V and beyond during rapid motor deceleration. Does QuadDrive suppress these transients, or only detect back-EMF? Finally, our total current draw is approximately 40–50 A on average, with peaks of 70–80 A across four motors. How should we interpret the thermal data, and could we operate without the heatsink if we have a small fan circulating air inside the canopy? **Answer** The Rev B information discussed here distinguishes between the bare-board and heatsink weights, provides raw battery voltage on J1, and includes passive transient suppression. The thermal figures are simulation results, so cooling requirements still need to be assessed for the installation. **Does the weight include the heatsink?** The approximately 30 g figure refers to the board without the heatsink. The Rev B datasheet gives these more precise values: | Configuration | Weight | | --- | --- | | Without heatsink | 31 g | | With heatsink | 70 g | **Does J1 provide a voltage-sense output?** J1 does not provide a separate, conditioned analog voltage-sense output of the type commonly found on flight-controller power modules. **J1 pin 1 is VBAT: the raw battery supply voltage from the XT60 connection.** It should not be treated as a scaled voltage-sense signal. Battery voltage information is available digitally through the AM32 telemetry interface. **Can QuadDrive power a flight controller or other peripherals?** QuadDrive does not include regulated 5 V, 12 V or 24 V outputs. Those supplies need to come from separate regulators or a suitable power distribution board. This is an intentional design choice. ESCs experience substantial electrical stress, and keeping critical system power regulation separate avoids placing that additional function on the ESC. **Should a separate PDB connect before or after QuadDrive?** Electrically, the PDB and QuadDrive would both connect to the battery supply, VBAT. QuadDrive does not provide a separate regulated output that places the PDB “after” the ESC in a power-conversion chain. For physical wiring, distinguish between sharing the same battery supply and routing peripheral power through J1. The support discussion confirms that J1 exposes VBAT, but it does **not establish a maximum current rating for that connector and its board connection**. Confirm that rating with BotBlox before using J1 to supply a PDB or substantial peripheral loads. No specific third-party PDB was recommended in this discussion. **Does back-EMF detection also suppress voltage spikes?** Back-EMF sensing and transient suppression are separate functions. For sensorless motor control, each motor phase is divided down to a safe ADC level so the microcontroller can detect phase crossings. That is the sensing function. Separately, the DC bus has passive transient suppression consisting of: - TVS protection, specified with a maximum clamping voltage of **45.4 V**. - An external **1000 µF capacitor** across VBAT and GND. This provides passive suppression; it is not an active circuit for dumping regenerative energy. **Can we remove an existing external spike suppressor?** That was not confirmed by this discussion. The application described already used an external suppressor that clamped around 27 V. BotBlox indicated that a spike limited to around 27 V should be acceptable, but also noted that transient performance is difficult to predict without examining the actual waveform. The correspondence cites a **40 V absolute maximum input voltage** , while a later reply describes an intention to tolerate 40–50 V spikes. Those statements do not establish a validated allowable transient profile. Likewise, the TVS clamping figure should not be interpreted as an allowable board input voltage. If you are considering removing external suppression, share oscilloscope captures showing the spike amplitude and duration with BotBlox so the behaviour can be assessed for your system. **Are the thermal figures measured results?** No. The thermal results in the Rev B datasheet discussed here are **simulation results, not measured thermal test data**. The correspondence does not specify the operating current behind the referenced Table 10 results or confirm that its 121.2 W heat-removal figure represents a maximum heatsink capacity. It therefore does not establish how much heat the ESC will release inside a particular drone canopy. For the stated load, assuming an even distribution across four motors: | Operating condition | Total current | Approximate current per motor | | --- | --- | --- | | Average | 40–50 A | 10–12.5 A | | Peak | 70–80 A | 17.5–20 A | BotBlox estimated approximately **10–20 W of total MOSFET losses** with 12.5 A average DC current flowing in each of the four motors simultaneously. This is an estimate of MOSFET losses, rather than a measured total-board heat output. **Could this application run without the heatsink?** BotBlox’s preliminary assessment was that the heatsink would probably not be necessary at the stated current draw, with the reported 40 mm fan circulating air inside the drone. That assessment is specific to the described operating conditions. Confirming heatsink-free operation requires thermal testing in the actual installation, including its airflow, enclosure and motor load.