2s to 3s adapter?

[Glitch]

My sister has a 2s car but I want her to have a 3s battery so it has a chance of being useful for other cars or the same car upgraded in the future. Can I get an adapter that takes the voltage down to 7.4 but still use a 3s battery?

 

[Tunedfrog]

What system are you running @Glitch and what are you trying to achieve ? The first thing I would do is make sure the system will handle 3s.

 

[Rob66]

I don’t know of any voltage changing adapters, adapters are a no go for me. IMO

 

[WickedFog]

My sister has a 2s car but I want her to have a 3s battery so it has a chance of being useful for other cars or the same car upgraded in the future. Can I get an adapter that takes the voltage down to 7.4 but still use a 3s battery?

No, you shouldn't even consider it because there would be no benefit in doing something like this. You'd just be adding more weight to the car without adding any power, thus slowing the car down. And if the batteries are the same mAh, youd also likely reduce the run time. When you have a need for a 3s battery, order a 3s. Until then, run 2s.

 

[tudordewolf]

The adapters you describe exist in theory, they're even used in RC cars to split off power for the servos and receiver, but they can't handle the "main" draw of the motor, most are limited to 2 or 3 amps.

An adapter that could handle the current you need would be nearly as big as the battery, and it would be impractical for other reasons, like losing low-voltage cutoff awareness.

Upgrading voltage isn't the only way to make a car faster; a lower-turn motor might offer a higher top speed, or different gearing could give better acceleration, or a little bit of both, though the battery will drain faster - everything comes with a trade-off.

 

[Doom!]

I know you were hoping to use your existing 3S batteries, but it would probably cost you more to upgrade the car to 3S, than it would to just pick up a couple of 2S batteries. Sometimes shortcuts will get you lost

 

[Tunedfrog]

I missed the 2s part you mentioned your sister has, stay with 2s and just buy the appropriate batteries.

 

[dadvid]

Stepping voltage up or down is complicated and brings a degree of loss in the process, id grab a hobbywing quicrun 120amp esc, drop the pinion size and then run 3s instead - about the same cost as a decent 2s where i live. It’s a cheap and cheerful esc, i run them in my kids cars, braking isn’t the best but it runs up to high volt 3s happily all day.

It will be fine as long as your motor is 10t or roughly 4500kv - any higher kv and you will probably cook the motor over time - please note you should definitely drop pinion size to reduce final drive ratio by about 33% to compensate for the increased voltage.

Sweeping generalisation but higher voltage rather is always better in my opinion: you can run a lower kv motor at a given speed, so cooler and more efficient, and the lower amp draw (power = volts X amps) from running higher voltage reduces the losses in power transmission (part of the reason we have high voltage power lines)

I do empathise, I’ve got a mix of 2s, 3s, and 4s…. Trying to stick to 3s and 4s… I’d go 100% 4s but my kids esc’s have a max of 3s