Modern Vespa

Ok, my battery keeps dying and can't start the bike.

So far I have replaced the CDI and the battery.

I've checked the battery voltage at revs and its defo charging and been checking it after short journeys to make sure it's not the short journeys not creating enough charge and its not that and that the regulator is doing its job.

The culprit seems to be something in the system draining, as I checked it when I parked up at night and it had dropped almost a whole volt about 12 hours or so later.

So what can I do to check what is draining in the system ? Can it be a bad earth or something ?

You'll have to use a multimeter and a bit of logic to narrow it down, using the wiring diagram as the main clue. Do check the ignition switch does in fact turn off completely (they can go faulty) and that any relay coils aren't in circuit with the ignition off (I've seen a couple of DIY power outlet relays that were wired so that happened).

First, disconnect the battery, and make sure it's not dead in the same time frame as with it connected. The battery could be bad, all you did was make sure the charging system worked. Will the battery take and hold a charge?

did you made any mods to the electrical wiring on your et4?

i have read in a different thread that you are into modifying your headlamp into a euro light or the other way around.

you must have messed up something.

Yes, this should be your first step. Then reconnect the ground side of the battery and put an ohm meter between the + cable and the + pole and see if there is current flow with the ignition off and the key out. If you see current turn the kill switch off to see if the problem is in the ignition switch.

I don't know if the immobilizer draws significant current, but I would guess not. Most of the clocks are on small internal batteries so its not the clock. If you have substantial current draw there is a parasite somewhere.

Fixed that for you. NEVER use an ohm-meter in a live circuit.

Thanks. You are absolutely right.

Yeah it's Brand new, I just replaced it, it holds a charge when out the bike over night, but not in the bike.

Yeah I want to, but haven't as of yet, due to all the battery issues I'm having, i not wanting to add to the issue

I've replaced the CDI, so no immobiliser now to draw any current and the clock does run on a little 386 cell but that is dead just now as well, and murder to get to, so I left it.

I don't have a kill switch on my model as far as I know.

[quote="Willmcgphoto"]Ok, my battery keeps dying and can't start the bike.

I've checked the battery voltage at revs and its defo charging and been checking it after short journeys to make sure it's not the short journeys not creating enough charge and its not that and that the regulator is doing its job.





it's been more than a month since i've change my battery....and i'm sorry to say that the short trip/journey not creating enough charge is a myth to me....because it still starts fine.

i usually park my et4 on my moms garage because it safer there, it is about 300 meters away from my house and i do that every day...getting it at about 9 in the morning and parking it in my house afterwards. i use this as my daily commute mostly on short trips to the grocery, market and just riding around our community.

Thanks for all of your inputs - I am having the same problem and I had no idea about how to diagnose it. Now I have somewhere to start after having replaced my battery twice.

I eventually replaced the 2 terminal bolts on the battery with charging croc clips (20 amp rated) I disconnect the battery as soon as I've ridden it and connect it back up when I need to start it.

Not had a dead battery/ need to charge it on months (ever since I did the croc clip method)

Obviously there is a short somewhere.

Also I've found if you don't have the cover on the battery, one of the screws on the under side of the seat can short out the battery

Thanks for updating me with your solution - really helpful

How do you know about the screw as I took out the bottom casing underneath for a gel battery - do you think that could be it?

Sounds exactly like the problem I have although after a full charge the battery would originally last 2 weeks, then 1 week and now 3 days. The only change to the bike is that it was knocked over and a rear lens is smashed.

I park on the street so I currently have to disconnect the battery and take it in to the house.

Had to take the tube to work this morning after I lost a full charge in 2.5 days... it is so frustrating - I need to fix it then sell it.

When i went to start the bike, the oil light etc would come on, then when i hit the start button all electrics would die but only sometimes, so i knew there was a short somewhere and the only thing that would change was when i put the seat up and down, so i checked and on the lock barrel on the underside there is a few screws, so i electrical taped up the terminals and the screw and it never happened again (the top batt cover cant go on because i use the croc clips.

I'll take a pic today and post it.

If the seat lock screws are the culprit you could very well be a genius!!!

ha ha thank you sir