Using 9v Battery for Boost

[mrmarc]

Hi, just bought my first e-bike. Motor is 200w so 1/4 HP. Can I just get a 9v battery (like the standard 9v battery from the Dollar Store) and put it in series with the regular battery to boost the output? From what I've read a regular 9v battery has 0.5 AH so 30 minutes of boost for $1? I'm sure I am missing some important concepts here, or others would have tried this before. Thanks in advance for your replies!

 

[major]

In theory, yes, I guess so. Let's look at it. For that half hour boost it would be 1 Amp at 9 Volts or 9 Watts. 9 Watts is like 1/100th of a horsepower. Doesn't seem like much, does it? Think you'll even feel it? All that was in the perfect world. In the real world, you'd have the full current from the 200W running through the 9V battery (like 10 or 20 Amps), so it would fall on its face due to the internal resistance in the 9V battery and likely smoke the 9 Volter in short order. But, WTH, give it a try and report back It's only a buck.

 

[dogman dan]

Stack enough of them together and you have something. But not just one. You'd need enough of them connected in parallel to amount to something.

Mabye look at something else, like a 6v lead acid battery intended to run a kids toy electric car. Or two batteries for a drill connected parallel, that sort of thing. The battery does need to be able to dispense 10 amps of current.

 

[amberwolf]

I'd like to see the video of the experiment, camera focused on the 9V.

In my experience most of those 9V are only intended to supply about 100mA. A few times that load and they warm up noticeably in a cool room. I expect that attempting to pull ebike-level currents (perhaps 100 times that) would be similar results to the time (when I was younger and dumber and more interested in dramatic results) I plugged two new Duracell 9V into each other. Too bad digicams and Youtube weren't around then. :lol: