Replacement for old type battery

[Topgearskin]

So - I've got the standard battery tray on my series 2, and would rather replace the old style acid battery with a more modern equivalent, Ideally one that is spill proof and actually holds a charge longer than 2 minutes.

Has anyone found a modern battery to fit the old tray? It would be perfect if it looked vaguely like an old battery.....

[Fast n Furious]

Unless the battery is absolutely knackered, it should retain its charge for weeks. Unless, there is an underlying problem elswhere that is causing it to discharge. In which case, any another battery fitted is just gonna suffer the same fate.
Try using an ammeter (10A scale on a digital multimeter) connected between a disconnected battery earth lead and chassis. If you are pulling current with the scoot at rest, then further inveatigation is needed. (A reading of a few microamps is normal due to leakage current in the Zener diode inside your regulator.)
If you haven't got a multimeter to hand, I would suggest charging the battery up, and then either disconnect the earth lead or remove the fuse and leave it like that for a few days before connecting it back up and checking to see if it has held its charge.
The shunt type regulators on our Lammies are rather primitive and have a propensity to overcharge batteries. Not so much an issue if you only tootle around town, but causes the battery to overheat, dry out and distort on high mileage touring steeds. This severely shortens their working life if they are a not regularly topped up with distilled water, which you can't do with a sealed lead acid "Gell cell" battery. However, running your scoot with the lights on all the time, reduces this overcharging affect on your battery to negligible levels!
Sealed batteries can be made to work very well offering life spans exceeding 10+years, but ideally, they need a better, more controlled, "series type" regulator.
A GB5L-B Gel-cell battery will fit in the standard battery tray but only has about 60% the A/H capacity of a comparable wet cell battery, which is sufficient on most applications.

[Topgearskin]

thank you.
I'll do some more digging with the standard battery to understand whats going on. Thanks for the advice

[vegansydney]

Is the battery tray on your Series 2 the early type or the later type that is same as the Series 3? Is it 6v or 12v? If yes to the latter on both, than I'm a fan of the 12v sealed SIP batteries (Part no.: 85045000). I've tried multiple batteries over the years across my DC Lambrettas and the SIP ones are the best fitting of the modern ones (though not perfect!) and importantly, for me at least, close-ish to period aesthetics. I'd love sealed 12v gel battery in a period-correct case (black Safa or RAE style or similar), but until someone makes one, the SIP ones are my favorite.

[Fast n Furious]

Hmm, I hadn't spotted that it was a series 2.
If it is the standard 6V system here and all original, then it is highly likley that the selenium rectifier in the regulator box has seen its day. These old rectifiers were barely good enough when new and do suffer badly from age related leakage causing the battery to discharge quite rapidly.
Series 1 & 2's had narrower battery trays to series 3's. Typically 47mm wide compared to the later 60mm wide ones. Some spanish Li's and Jet200's used the narrower tray also.
Suitable 12v batteries for these narrow trays I've never found.
To retain original looks, the selenium recifier inside the regulator box can be removed and replaced with silicon diodes to do the same job.