RE: Batteries, what the?
On the upside there is probably a lot less variation with the electrical demands of an ignition than say your servo set up. So this shouldn't be too hard to figure out.
I know you stated that there is a change from your personal experience and history with this battery. But as an additional check, I would find out about what the DLE ignition uses in mah per 10 minutes or whatever...that should be pretty standard and someone here probably knows that answer from experience. It wouldn't matter what airplane the engine was in and it would be a good reference because everyone using that engine would have a similar experience (not much variation).
Also, regarding your specific battery, I would record and verify capacity by putting it through 3 charge/discharge routines. It is either a capable little chemical engine or it isn't! What you are seeing with it now may simply be telling you that the battery isn't good anymore!
Very good that you are aware of what is going on with your equipment and you may have caught an issue with your power system!
Let me know should you get additional information, and don't "try" additional flights...it isn't worth the risk.
Tom