Modern Vespa

I have read the topics, but not really gotten any cleverer... So maybe someone can help? (Or maybe I'm just too daft)

I am thinking of adding a 12 V outlet to the knee panel on my GTS. I would like to run it directly off the battery, so that I can plug in a battery tender if I need to. But I would also like it to be switched off when the bike is off so that no fool can drain my battery when its parked somewhere.

Now comes the tricky part: is there a relay available that works one way when the scooter is on, and the other way when it is off, sort of like the diodes on the buzzer mod. No use having to switch the scooter on to plug in the tender...

The alternative would be putting one in the knee panel for everyday use and another under the pat carrier for the tender.


Thanks for the help!

I have never seen a 12v outlet with three prongs on the rear (one for ignition switching. I'm not saying they don't exist: I have just never seen one. I installed 12v outlets on both of our GTS' and ran the wiring directly from the battery, up through the little tunnel and behind the knee panel. Of course, it's ON all the time. You could buy a toggle switch and mount it in the pet carrier or in the glove box.................then run the hot lead from battery to the toggle and then up to the knee panel. This would allow you to switch it on or off. If you do this, make sure that you get a toggle switch that is capable of handling the needed amperage or you may possibly have another problem that you don't want to deal with.

Or..............you could just mount it in the glove box and it would be out of sight.
Good luck!

I think a regular 12V relay would accomplish that. You will need to tap into a switched +12V to accomplish it but you should be able to find that at the fuse block. (I have a BV 500 so not exactly sure which wire for your bike.)

Wire the +12V from the battery to the adaptor, through the switched circuit of the relay. For the +12V to activate the relay, connect to the switched +12V referenced above/fuse block and the +12V from the adaptor iteself. [And all ground connections to chassis.]

What happens is

1) When bike is parked, tender plugged in. Relay will close. Charging circuit closed. Keyed circuit open, no impact on other electrical.

2) When bike is parked, accessory plugged in. Relay open. No drain.

3) When bike is running, keyed circuit closed. Relay closed. Accessory plug powered.

What I do not know if if bike is running, and tender plugged in. If any sneak current will come back to the keyed circuit and damage anything. Hard to tell without looking at detailed circuits. Just make sure you disconnect tender before starting bike which is a good safety precaution anyway!

Did I miss anything else?

Wow, thanks for the help!
Now I just got to wrap my head around it... that may take some time!
I think I do understand it thou.... maybe!

I figured as much on the mushroom cloud!

Let me know if you have any other specific questions ... at the very least, I can address it from the theoretical perspective!

Have fun!

Oh, I think I will have fun!
If you see a mushroom cloud in the east (at least from California), it was NOT the Russians!

Disclaimer: JOKE

Ok, I think I got it!

What I need is 2 relays in parallel, one triggered by me plugging in the tender, the other by switching on the bike. If I have something plugged in while the bike is on, both circuits will be closed. But that should not be a problem, except if a tender is plugged in. Then....

Are these assumptions correct?

Preface: I am in no way an electronics engineer.

Wouldn't a diode and a relay work? Connect the relay so the outlet is powered along with the ignition, but also wire in a bypass using a diode so that power is always able to flow to the battery but not from it when the relay is open.

Of course, fuse everything appropriately.

The diode idea will work except I would use one heck of a big diode ...

Not sure about 2 relays ... you still need to verify that the switched circuit is fine.

Just make sure tender is not plugged in when you start the bike ... I don't think it is that difficult. (In any instance, with any form of battery tender connection, you always want to make sure it is disconnected when you turn the bike on anyway.) Too many components means 1 more part to fail ... and I just hate that. Call me a lazy engineer.

I drew it on a piece of paper, seems that could work too.

Unfortunately I have not found a 12V 15A diode yet. Is there such a thing? I have no idea!

Thanks for racking your brains!

Hehehe I guess I just needed to long to figure it out!

I agree with the to many components problem, maybe I will just make a second connection under the pet carrier for the tender.

But then who is going to test this theory???

I guess there may be another problem using diodes: the forward voltage drop may lead to one while using the battery tender. I have no idea how the battery tender works, but a 0.7 V difference might just screw around with the brains...

I'm still trying to figure out who's going to plug in to your accessory outlet and steal your power while you're not watching? And what will they be using it for?

The 12V / 15A diode is solvable. You can always string a couple diodes up in parallel to handle the current. (But at this point, you will need some kind of hobby box to make sure they don't short against something.)

As for the battery tender, who knows ...

Simple is always better ... really ... trust me ... I used to work on old British cars ... remember Uncle Lucas anyone?

(I know this sounds like all theoretical discourse ... but then again, that's what the forum is for right ... an exchange of ideas related to our bikes!)

+1 The Prince of Darkness!


-Fin

I agree, simpler is better. If it were my scooter, I would set up the outlet switched, and attach the tender pigtail separately under the seat.

Thats easy.
Your house electrickery meter will run backwards, the power company will send you a check at the end of the month. Also useful during power cuts.

No seriously the tender should have inbuilt protection from this.

I think it can be simpler.

You don't need a big diode unless your charger is going to put out 15A. If you need that kind of charging, open it up, and connect a real battery charger.

Do the normal relay operated outlet, and put a diode across the normally open terminals. It will charge through the diode, and when the scooter is on, the diode will be shorted (inoperative). The diode will block any drain from the battery when the scooter is off.

I don't think most of these trickle battery tenders will care about the .7V diode drop.

'Intelligent' battery tenders draw current from the battery occasionally, and they measure the voltage very accurately. A diode would only be of use with a bog-standard charger, and I wouldn't recommend using one of those on a bike battery.

Thats what I thought, thanks for the input jimc!

I think I will go with the 2 relay option, just to learn something while I am doing it as well. If I notice that the relays aren't up to the job, which they should be, I will reconsider. I mean it is nothing absolutely vital to the scooter.

Thanks for the help!