⚠️ Last edited by addicted on UTC; edited 1 time
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I just hot-wired a BMW branded electrically heated vest to my ET4. The nominal battery terminal voltage, with the engine off and no power drain, is measured at 12.7V. The battery terminal voltage rises to 13V, with the engine running at warm idle, with no added accessories. Connecting the vest at idle draws an additional measured 3A, and the battery terminal voltage drops to 12.4V. This indicates the battery is discharging at idle, with the vest connected. Since I'm using both my hands to secure all the temporary connections to the battery (vest and VOM), I can't currently determine if the battery voltage rises above 12.7 volts at higher RPM. It will rise, as generator output rises with increased RPM, but I don't know if it will rise sufficiently. I'm going to Radio Shack now to get what's needed to wire-up the vest for driving. I'll post more information at a later date.
⚠️ Last edited by addicted on UTC; edited 1 time
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I permanently wired the scooter with a fused accessory outlet (RS 270-1556 $6.99), and swapped-out the vest's proprietary BMW power plug for a generic power plug (RS 270-1509 $3.99).
As previously reported, the vest draws a measured 3A (rated 3.5A). The scooter's generator can't keep up with the added load at idle, but the engine continues to run smooth. At above idle, the battery is charging. Battery terminal voltage rises between 13V and 14V, depending on cruising speed. So, what does this all mean? Basically, the modern Vespas (LEADER engine generator design) can marginally handle an increased measured load of 3A (36W). For completeness, the vest is rated at 3.5A (42W). Tomorrow's forecasted high is only 38F, so it will be a good day to test the vest's thermal performance. ⚠️ Last edited by addicted on UTC; edited 1 time
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Addicted
GTS250 "Atomic Blast", GT200 Blue and White "Alfie", SQREAM Scooter Club
Joined: UTC
Posts: 1004 Location: Denver, CO |
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addicted wrote: So, what does this all mean? Basically, the modern Vespas (LEADER engine alternator design) can marginally handle an increased measured load of 3A (36W). For completeness, the vest is rated at 3.5A (42W). I still say to be safe install an amp meter, and make sure the vest only comes on with engine running. Maybe there is way to do it by engine rpm as well, I'd have to think about it. Seems like a PIC, and IR rpm counter should do the trick. |
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Thanks for the Scooter Science! I've not seen anything this precise to date about what a Vespa can actually handle re: electic gear.
Would love to see comparable figures for electric grips, e.g. these from Aerostich that just draw 1.6 amps>> http://www.aerostich.com/catalog/US/Aerostich-Warm-Wrap-Grips-p-16731.html |
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pdxvespa wrote: Would love to see comparable figures for electric grips, e.g. these from Aerostich that just draw 1.6 amps>> Heated grips? |
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phr3d wrote: pdxvespa wrote: Would love to see comparable figures for electric grips, e.g. these from Aerostich that just draw 1.6 amps>> Heated grips? The velcro model I linked to above has a single-setting 1.6 amp draw, so maybe it would be more workable. |
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A 9AH battery can afford to run the 3A vest for a long time, on it's own. So, knowing the battery is charging above idle, the measured discharge state at idle isn't any concern. Something I didn't do, was to calculate what current the generator supplied, versus what additional current the battery had to contribute, to the 3A vest draw at idle. The difference between the total generator power draw at idle, and the generator's normal current draw at idle, would be the current the generator is supplying to the vest at idle. Subtract that result from the 3A the vest draws, and the final result is the current the battery contributes at idle. If you didn't follow that, it's really not important at this point. Empirically, the scooter's electrical system, as a whole, can handle an addition 3A (36W) load.
My power port is wired directly to the battery (via it's own fuse) by choice. I'll probably find other uses for the power port real soon. One, which I'm probably going to do in a few days, is to make an adapter for my battery trickle charger to plug directly into the power port (for the ultimate in battery charging convenience). I may start carrying a spare cell phone adaptor in the scooter too. Maybe I should get a little radar detector for the scooter (no, what's the point )? If you stay within the 3A (36W) limit, I personally assure you the LEADER engine's electrical system can handle the additional accessory load. That's not to imply there may be some additional headroom, it's only an absolute statement of measured observations at an additional 3A draw. ⚠️ Last edited by addicted on UTC; edited 1 time
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Gary - This is a great set of numbers and a really solid empirical foundation for anyone doing electrical work to their Vespa. Thanks for taking the time to do this experiment.
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You're welcome Jess. I can't post without your forum. It's pretty evident that this forum was needed, based on the volume of posts and rate of membership.
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addicted wrote: If you stay within the 3A (36W) limit, I personally assure you the LEADER engine's electrical system can handle the additional accessory load. That's not to imply there may be some additional headroom, it's only an absolute statement of measured observations at an additional 3A draw. I'm just not comfortable with a 3A load at all. You can have turn signal come on, something that's aged that will draw more than its original load. Inductive loads always drain more at startup. Also an AH rating is cumulative. |
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LOL, I just realized I've been typing (and speaking) alternator, but the LEADER engines actually have a generator (as do most scooters). This really doesn't change anything in terms of the discussion though.
A side-note on fusing: There are two 7.5A fuses housed in the front cowl, and one 7.5A fuse housed under the battery cover. The 7.5A fuses are appropriated between various bulbs in the lighting system. One 7.5A fuse protects the headlight and high beam indicator. Another 7.5A fuse protects the instrument panel illumination bulbs, license plate bulb and tail light bulb. The third 7.5A fuse protects the turn signal, and brake light bulbs. The main circuit, including the generator, is separately fused at 15A. This fuse is located under the battery cover. Vespa did a good job with their multiple fusing. I just got back from a 50 mile, 1 1/2 hour scooter ride at 28F with a 15 MPH wind, and gusts to 25 MPH. I survived. Actually, I was relatively comfortable. Only my ankles were mildly cold at times, and my hands were noticeably cold only while waiting at traffic signals. Neither were bothering me constantly, and I could have continued racking up miles. |
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I was comparing schematics for DIY modulators and noticed this:
http://www.mindspring.com/~wayne.orwig/utils.html#heatctrl |
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Off-Topic discussion on DYI temperature controller
Off-Topic discussion on DYI temperature controller
phr3d wrote: I was comparing schematics for DIY modulators and noticed this: http://www.mindspring.com/~wayne.orwig/utils.html#heatctrl |
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See this post for details on wiring your modern Vespa for a 12V auxiliary power outlet. You don't even have to read the post. Just take a look at the picture.
How To: 12V Accessory Outlet - heated clothes, grips, GPS... (Post 3957) |
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Here is a good site for those of us that may not know exactly what a relay is or how to wire one for our Scooter accessories.
What size fuse should we use on our GT200's? 3 Amp? http://www.r1200gs.info/howto/relay.html This morning's 27°F 70mph commute would have been more comfortable with heated grips. I think they're now on my list for Xmas. |
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NapaCoach wrote: suck it up you wine country yuppie ! |
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Mesmer wrote: What size fuse should be used for the 3amp Heated grips? If the 3 Amps is nominal, then you probably need something a bit more than marginally higher, but without knowing peak current I couldn't really say. You could always start with, say, 4 or 5 Amps and see if you blow it. Worst case scenario is you're out the cost of a fuse. It's empirical engineering, I know... Disclaimer: I am not an electrical engineer! I write software for a living, and electrical engineers often get persnickity when programmers start waving soldering irons around. Proceed at your own risk. Your mileage may vary. Do not attempt to drink and solder at the same time. ⚠️ Last edited by jess on UTC; edited 1 time
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Mesmer wrote: What size fuse should be used for the 3amp Heated grips? |
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Nice. That's probably the way I would go too, based on cost versus performance. From the picture, it appears the throttle element is patterned different than the clutch grip element. The usual feedback is that the throttle element is noticeably hotter, because its insulated from the handlebar. Maybe the different elements take that into account. You might try to insulate the clutch-side element with tape (or a slice of plastic from a soda bottle) before mounting the element. Let us know how it went.
Jess, It appears we both asynchronously posted to the fuse question. |
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I came across the power output chart somewhere online, and it showed that the throttle element puts out less heat for that reason exactly, that the direct contact on the clutch side to the bar acts as a heatsink and pulls heat away from the grip. That way with the differing power outputs, the grips feel about the same temperature.
I'm still psyching myself up to do this mod. |
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addicted wrote: Jess, It appears we both asynchronously posted to the fuse question. |
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jess wrote: addicted wrote: Jess, It appears we both asynchronously posted to the fuse question. |
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