Quote:
Originally Posted by Civicsman
The best advice I can give Segwaythedoor is to get a qualified electrical engineer to design and build the system for you.
Although you are getting a lot of advice from this site, you need an engineer to work through the details, to ensure that the system not only functions properly, but is safe for you and your workers. Providing any other advice to a person who is obviously has little electrical background is inappropriate, in my opinion. An on board charging system requires not only high-current DC, and 110 AC. There are a lot of people who tinker with electricity, but you are running a business, in Wisconsin, with USA liability laws.
Seriously, get a qualified engineer before you either burn your van/trailer to the ground or kill someone.
Perhaps I missed it, but isn't there still the question of whether any charging system can fulfill his requirements? Based on his statement, the worst case is 1 bar remaining, 30 minutes to charge, then a 6 mile tour. We don't know anything about the characteristics of the tour. Hilly uses more power than flat. Fast uses more power than slow. Nor do we know anything about the quality of the batteries.
The rate of charging is dependent on the Segway on-board charger, and, as I recall, the state of the batteries, including temperature. It would be really inconvenient for Segwaythedoor to spend a boatload of money and STILL not be able to meet the need.
Some experimental testing might be in order to determine whether the 30 minute charge is capable of doing what Segwaythedoor wants. Again, get an electrical engineer.
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You really don't need to be an electrical engineer. There's a world of difference between an electrical engineer, and an electrician, and this is well within the realm of an electrician.
In fact, I wouldn't trust a lot of electrical engineers with this. In fact, I recall one exam question in particular, to this day, which I got a zero on, because I was presented with the choice of a solution that would not operate the equipment, or one that would work, but set the building on fire even faster than the non-solution.
The prof obviously had never read the electrical code. I had, and knew exactly how stupid the question was. If he wanted to test my ability to handle an impedance matching problem, he should have just asked a sane impedance matching question, instead of trying to apply impedance matching to power distribution systems, where it is entirely inappropriate.
So that's an example of an MIT electrical engineering professor I would not trust to wire a light switch. (Which reminds me of another story, but...)
But it's really not that hard a design problem, technically, if you're willing to be careful and thorough. You need to figure out how much power you need, for how much time. Wiring sizes you get from tables. That's a matter of established safety standards, not an electrical engineering problem. (The standards are based on the engineering, but you don't repeat that process on your own. Follow the standards).
Alternators have spec sheets. Anybody capable of even contemplating such a project is capable of calculating pulley ratios, and designing a ratio that keeps the alternator within RPM limits when the engine is at its RPM limit.
Battery capacity is amperes * time. Power is voltage * current. If you're following the standards, you don't even need Ohm's law.
While such a system clearly needs some careful design work, and you have to deal with tradeoffs, uncertainties, safety standards that may be difficult to locate, etc....
I firmly believe that basic engineering is within the reach of pretty much anyone willing to put in the time and effort.
You do make some good points, however. In particular, liability exposure (which is one reason I harp on standards rather than what you can make work).
And the importance of ensuring the solution will meet the operational need, before going to all that trouble! Excellent point, that.