it actually sounds like they are holding just fine under the 'STORE' provision, with very little loss overnight
when you are in 'USE' mode, you have things that are obviously drawing power, even if you don't think there is...as exhibited by your own numbers you provided.
Charging the batteries for 'several hours' may not be enough time to fully charge them, when you expect closer to 12.8volts at rest.... but 12.69 is not bad.
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