charging system odyssey starts with simple battery question

[zack]

Hi all, thanks for all the helpful answers you've given me on my various other questions so far. I have a 1981 cb650c and the charging system seems to not be working. If I charge overnight with a battery tender, I can start right up and drive off. After about 20 min of spirited driving, keeping it in the 5k to 7k rpm range, if I stop the engine, it will not re-start. At that point, I can typically roll-start it and that is how I got home the first time it happened. So, I will now go through a charging system troubleshoot (using a PDF I got from myhondacb650.com). However, I have a first question and I can't figure it out, about the battery.

Various sources say to make sure your battery has enough electrolyte in it. When I take the side cover off of the motorcycle, there are high and low marks printed at the sides of the battery to show the intended fluid level. Apparently, you should see the fluid level between these two marks.

However, I can not see a thing "in" the battery because the sides are opaque white plastic. I had the same problem with my cm450c. How is one supposed to see the electrolyte level through the plastic sides of the battery? I've tried shining a flashlight, thinking maybe different lighting levels or angles would result in different sights. I've tried rocking the bike, thinking maybe if the fluid sloshed, I could then pick up on the motion.

But nothing works. Am I missing something? I am just too old with my vision failing? did they change battery construction between 1981 and now? How does one see electrolyte level through the side of the battery?

[TOOLS1]

I suffer from the same problem. I take the batterys out to check them, you can see them better. I have to slowly tilt the batter, and watch for the fluid level to move to see it. However they do make AGM battery's now, and they never need maintenance. They also last a LOT longer.
TOOLS

[Re-run]

Question, do you have caps on your battery that you can take off? Or is it a maintenance free battery? Manufacturers use the same cases sometimes and so you may have a maint free or you may not.

If it is not, open the caps and shine a light into the holes and you should see the level through the case.

Do you know the age of it?

Aside from that, have you checked the voltage while running above 2000 rpm? Good chance the battery is not getting charged by the bike.