How best to handle motors with different voltage needs ie drive and weapons?

We are running our 18v gimson drive motors off a 6s currently (22v) and I've got a scooter motor that I'm wanting to run at a higher voltage. What ways are there to handle this sort of situation (as I assume its quite common). Multiple batter packs? That would need multiple removable links which I think are within the rules as long as they are together. Or are people using something to step the voltage down or similar? If so my knowledge in that area is lacking hence the question :)

If multiple batteries how do you balance weight and charge time, how many spares to get (currently I've just the one 6s battery for testing)?

Hi Pete, welcome back to the scene.

Most people will either use multiple packs or perhaps two packs in series, running the higher voltage components off the two packs but taking a feed from just one pack to power the lower voltage components. This has a downside in that one battery will be under more load than the other; if you're using lithium polymer packs, you'd need to make sure it doesn't lead to over-discharging. No-one really uses step-down electronics to get different voltages but that's not to say it wouldn't be worth exploring.

If going the multiple packs route, to get through a 3-minute fight with a standard drill motor drive setup, you don't need a large capacity pack. Perhaps 1Ah to see you comfortably through. Upshot of this is that the pack will be physically quite small so it won't take up too much room in your internal layout.

As for spares, I'd always go for a minimum of one spare pack for each voltage arrangement, but if you have the budget for more, go for it, as it takes a bit of pressure off in the pits if you've got several charged packs just ready to drop in.

P.S. I believe Martin Dawson is meeting with you soon to collect parts from Milly-Ann Bug. It's myself that's got the Milly chassis now, so hi and thanks for passing the bits on :)
P.P.S. I'm not sure if you'll be aware or not, but there are featherweight events that take place in Sherburn-In-Elmet throughout the year (full combat and 'sportsman', aka no spinners) so if you're looking for events to compete in, they'll be reasonably local for you. Nice relaxed atmosphere at them. Next one is March 22nd if you wanted to pop along and get a feel for the current field.

Hi Jamie,

Thanks for the warm welcome. Yes I had a chat with Martin the other week. I hear you are getting a lathe you lucky so and so, if it won't fit give me a call ;)

Plan was to try to have something running for the March 22nd event but I fear I'm getting carried away with myself and what I want to do. Got enough bits I think to put something together but I would really like to make something "well" but time...cursed time! And money.

Like the sound of a sportsman class, that might save some tears from the boy, will take a look.

Pete

Haha, I don't actually have space for it at the moment (plan is for it to live in work until I get my own house) but I likely won't be able to give it a berth until the end of the year at the earliest so if it's something you have space for and could make use of, I'd be happy to say to Martin to let you have it. It's a ye olde belt-driven number so would be something a bit different for sure!
Plus I started a new job at a college recently so got plenty of lathes there that I can use if I need stuff turned.

Nice one with the March 22nd target. Might be a bit of a stretch to get something finished depending on what free time and budget you have, but even if you don't get it done or maybe only have the drive working, bring it along anyway for a look. The organisers have an electric axe bot and linear actuator crusher/gripper bot that they're happy to loan out to people who don't have a robot for the event, so you and your boy would be able to get involved :)