V5 Power Expander?

Hey guys, first post on forums here, so sorry if I got the wrong discussion.

Does anyone know if V5 has a power expander like the current cortex and batterieis have? I know we can’t use the ones from this year, since the battery connection to the cortex will be different, or am I wrong?

There is no power expander available for the V5. Due to the design, you won’t need one for V5 smart motors.

As @kypyro said, you will not need a power expander. The batteries for the v5 are much more powerful from what I heard, so it will certainly be possible to get by with just 1.

Powerful by what metric? Yes, the V5 batteries have a higher nominal voltage than the current NiMH batteries but that isn’t the reason for a power expander in the first place. The power expander adds another battery in paralel to the system in order to increase capacity and thus duration of play.

It seems to me (although I’m no expert on batteries) that the relevant metric here would be the mAh rating. The current NiMH batteries have 3000 mAh meaning that the battery can deliver 3 amperes for 1 hour of use. If the new batteries have the same or similar mAh rating that means that regardless of the higher voltage, they will likely only last as long as one of the current batteries because the new electronics also operate at higher voltages and draw more current.

I remember reading somewhere that the new batteries definitely have higher capacity. And the correct metric to look at would be Watt-hours instead of milliamp-hours because the new batteries are 13V instead of 7V and no public information exists yet regarding the new system’s current draw (though, assuming similar efficiency and load, current should theoretically be less due to the higher voltage).

I believe the point of the power expander for most teams was to reduce the likelihood of tripping PTCs by adding a third, separately fused circuit for powering motors.

What @kypyro was alluding to is the V5 design feature of firmware-based current limiting, which would merely limit motors to a certain current draw instead of the PTC consequence of a complete open-circuit.

The motors are 2 - 2.5 as powerful as 393s. We can deduce most of that is just the different voltage and that they also run at a little higher current.

Fair point.

The main difference is the battery technology and the discharge curve. The Cortex NiMH batteries might have had 3000mAh, but you never use the full capacity for a host of reasons. Voltage sag both due to discharge and load limits you to <20% of the nominal capacity of the NiMH cells (with charge state <80%, your consistency is gone and you risk the Cortex reset under load).

The V5 battery has flatter discharge curve and much better load handling (think of “jumpstarting a car” load), limiting the voltage variations under low charge and/or high load. Also, with smart motors, you could rely on much better consistency accross different charge states, allowing you to run with less-than-full batteries with no worries.

Exactly what @nenik said is why there is no need for a new PE. Lithium batteries have a much higher and longer usable capacity than an equal size NiMH battery.

a lot of already answered questions about V5 are being asked again, I’m not blaming the people who are asking, it can be hard to find stuff on here, perhaps someone should compile everything Paul has said about V5 into one, easy to reference post.

You are a nicer man than I. I am blaming people who are asking.


If you go to youtube and search for V5 there are videos from multiple conventions. I would recommend looking at those. I am pretty sure I saw two batteries on one of the more recent videos.

There is only one brain port for a battery, and since there is no v5 power expander the only way this is possible is for a robot to have two brains, which is not likely and definitely not competition legal

I believe the blocks on both sides of V5 are batteries
Screen Shot 2018-03-26 at 3.49.10 PM.png

Each of these robots has one battery. The larger bot has its battery on the left as you look at it from the front. What you may think is a battery on the right is the new V5 radio (replaces VEXnet keys).

Is that screenshot from the video? In the video I can tell that

VEX 02

only has one battery, but in the picture you attached it’s hard to tell.
Edit: Tried to delete duplicate post but it deleted both duplicate posts. This is the repost. I also agree with @Rick TYler

If that’s the radio, that’s going to be a pain! That’s huge!

It is not that big. It can be connected with any length wire to any smart port on the brain.