I wouldnt mind charging a standard 'flooded' battery with caps off, unless you want to weld or grind stuff while charging it. Except for the first charge, the vent hose it's enough for a slow charge to top-up the battery, so no need to open caps. I charge my car batt. with an electronic charger, max output 3.8A and they never bubble.
I'm constantly charging Rv batteries in my shop at high charge rates, multiple at a time. Not a big deal. They don't constantly offgas as you suggest, and such a small battery will charge fairly quickly, it really won't vent a significant amount.
How much battery do you need? Could you use a "stick" of NiCad's instead of a regular battery? Less weight, space and no out-gassing.
What kind of scooter is this? Does the scooter have electric start? If it does, scratch the ni-cads. Does your headlight only run when the engine is running? What is on/working when the key is on/engine off vs. key on/engine on?
Check the specs on your OEM battery cable. Big doesn't mean it has much wire in it. Recently cut into an old one....lots of rubber sheating, not much copper, about 10Ga to my eye. BTW that type of battery you are contemplating with the wires built in, often used in old 6V BMW motorcycles. Like this: http://bmwdean.com/6_Volt_Battery.htm Fuse it to be on the safe side, altough if you think you may blow the fuse troubleshooting, I'd use something like that: http://www.grainger.com/Grainger/COOPER-BUSSMANN-Circuit-Breaker-6AYJ4 Thread worthless without pics....I want to see the old scooter.
Left ooops edit, long day...RIGHT click on any pics if they are online somewhere, open "properties" then copy/paste the URL in the window that opens when you click on the yellow mountain/sun icon above. May have to click delete first to get rid of the Http:// thing in the window. I know what you mean with translating German, often comes out weird with online translations .:eek1 Then I go to my German neighbor, old retired mechanic, good for them technical terms. Nice scooter...! Got to wonder now if they looked at some Buicks for the portholes.
The 6v batteries I get are shipped to me dry and then I add the acid and charge them up. I pull the caps off for the initial charge and after that for maintianance charging I leave the caps on and let it vent through the vent tube. Ive not had any problems doing this, but I also don't have my batteries charging below my welding bench.
When I was just out of High School in the late sixties, my first job was in an auto electric shop. There were still a lot of cars running around with 6 volt systems left over from the 50's. The boss made sure I understood that I had to use heavier gauge battery cable for the six volt systems,as the lower voltage needs more conductor because the amperage is higher for the same power.
http://www.amazon.com/Panasonic-LC-R0611P1-LCR0611P1-12Ah-Battery/dp/images/B009DKCX62 will one of these unit do? I had 12 volt one and there was no issues beyond making up a leads to the battery . seal units.
That is a beautiful old scooter. I don't think I have ever seen one of those before. If it has no electric starter, it should be easy to convert it to 12V and keep the 6V electrics with a step down transformer. It most likely will need to be a motorcycle/scooter battery, the headlight can still draw quite a bit of current. But, you can charge an old style flooded battery without removing the caps, as long as you don't try to charge it to fast, which can damage the battery anyway, they do have a vent. My Genuine Stella is 12V, but it came with an old fashioned flooded battery. It is still holding up, so I have not replaced it. I keep it in my living room with a Deltran battery tender hooked to it, with the battery in the scooter, and all the covers on. I have a pigtail wired to the battery, and just unplug it and plug it back in when I ride it. I have 2 other scooters in the same room hooked up the same way, but with sealed batteries. I would only charge it outside or in the garage, but a battery tender does not have enough power to hurt anything, even if the battery shorts out. They automatically shut off if that happens.
