Electric Bikes with power source
September 3, 2019 6:19 AM   Subscribe

Say I'm crazy. Imagine that I want to make a mobile propaganda bike with loudspeakers and a small projector. Are there electric bikes with large rechargeable batteries that have power outlets on them that could power said PA systems and projector? Is there another option I should consider? In NYC, if that matters.
posted by history is a weapon to Technology (9 answers total) 1 user marked this as a favorite
I would personally create two electrical systems -- one for the e-bike, and the other one for the speaker/projector system. That way, you can fix one without affecting the other -- I suspect that in the long run, this will be simpler and cheaper.

A bicycle-speaker-system is actually done often at Burning Man, so searching that way might lead you a lot of results. Here's a particularly useful thread.
posted by many more sunsets at 7:21 AM on September 3, 2019 [6 favorites]

Since many electric scooters and bikes use 48VDC or 24VDC battery packs instead of higher voltage packs like electric cars, you can take advantage of wiring an inverter directly to the propulsion battery.

Then, you can power a projector and loudspeakers within the limits of your inverter.

It may get you a few extra miles, or more time for the projector and speakers, but if you can find either that run at the native DC voltage of the propulsion battery, you'll save in inverter inefficiency.

I know that doesn't provide you with any specific models, but if you can suggest a budget, I may be able to hone in on some items.
posted by tomierna at 7:22 AM on September 3, 2019

While there is all kinds of tech that can likely be wired into the bike itself, you might be better off (since bikes are easily damaged/removed from your possession) using an entirely separate power source. These lithium battery generators (they can be recharged using solar, house power, or 12v on a running vehicle) are popular with the campervan/car-camping crowd for basic power needs. They get bigger than the size I linked, with more wattage, so you'll want to decide on your power needs first and then determine how much battery you want/need.
posted by Lyn Never at 7:44 AM on September 3, 2019 [1 favorite]

I don't know about the projector side of this, but there are so many affordable bluetooth PA systems that come with their own batteries right now, and they are LOUD.
posted by advicepig at 8:18 AM on September 3, 2019

How much DIY are you comfortable doing? A lot of the Burning Man style art-bike stuff is going to require at least some moderate reading-of-specs-and-assembling-bits.

It may be worth looking into Vivitek mini projectors. I've used these in indoor installations and if I remember correctly they run on 18.5V 3A power bricks, which is within the range of "could be sourced from the scale of battery pack you could mount on a bike, with a well-designed buck/boost converter (exact topology depends on expected range of pack voltages)." Then again, that particular unit maxes out at 800 lumen, which is pretty dim. Fine in a dark room onto a white wall. Might be visible at short range on a street at night. Definitely not usable to, say, project onto the wall of a building from across the street.
posted by Alterscape at 8:26 AM on September 3, 2019

I think I am going to see if one of my students can do this for an engineering project. The separate power source option.
posted by biffa at 8:34 AM on September 3, 2019

Agree with Alterscape-- the projector will likely be your sticking point-- you'll likely need a really really hefty one (therefore a hefty ass power supply) for it to use useful in a city.

I'd be tempted to get a super-quiet gas generator (The Honda 2200i is top of the line for that, small enough to wrangle onto a e-fatbike with racks) which should give you plenty of power for projectors in a normal-humans price range (look for 'high lumen projectors') Epson do a 4200 lumen one for $1250 which needs ~500w to run, but again, 4200lumens in a lit city, probably against darkish walls-- I wouldn't get too excited.
posted by Static Vagabond at 8:37 AM on September 3, 2019

Are you determined to fit everything on the bike? If not, you could attach a small bike trailer, which would give you plenty of carrying capacity
posted by Faint of Butt at 1:07 PM on September 3, 2019

A bike with a couple of Bosch's largest PowerTubes would run a 500w projector for a couple of hours. Or one hour if you wanted to power large speakers and the bike itself. Does seem like a separate power source would make this a much simpler project though.
posted by rhamphorhynchus at 9:14 AM on September 4, 2019

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