Quote:
Originally Posted by Ecky
1) There's an intermittent parasitic draw which happened this weekend.
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Quote:
Originally Posted by Ecky
4) The battery is gradually losing charge over time due to the resistor.
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I see 1 & 4 as two sides of the same coin.
Well .. LEDs and diodes don't truly go to zero .. they just go to high resistance .. thus to very low parasitic draw .. but it is always there if they are always connected.
If you have the part number and such you used .. you should be able to look up what amount of that effect would be reasonable to expect in your setup over __Hours.
Quote:
Originally Posted by Ecky
2) The caps are draining the battery.
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Unless you have something to prevent them from doing so .. it's only a question how fast is the self discharge rate for the caps .. If you have their part #s you should be able to look up and see what would be reasonable to expect over __ Hours.
Quote:
Originally Posted by Ecky
3) The battery is draining the caps.
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If there is a small internal short in a cell , they could be self discharging faster than the caps .. thus your #3 .. but .. generally speaking caps usually have much much higher rates of self discharge than batteries do .. especially Li Family batteries without small internal shorts.
Quote:
Originally Posted by Ecky
5) Temperature change is causing voltage changes.
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Yes , we would expect this to happen .. but it's kind of indirect.
a temperature change .. can effect the values of components like the resistors .. and the SoC of the sitting battery .. etc .. so , yes a change in voltage can cause effects that , will in turn cause changes in voltage / current levels.
Quote:
Originally Posted by Ecky
I'm quite surprised a 20Ah battery emptied out over a 36 hour period.
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20ah / 36 hours = ~555 mA rate.
But .. keep in mind a 20Ah battery isn't a 20Ah battery when it gets very cold .. if .. because of how cold it was .. it was effectively only a ~15Ah battery .. than 15/36 = ~416mA rate .. and if cold enough maybe it was only effectively a ~10Ah battery / 36 hours = ~277mA rate.
For example .. even brand new Grade A strong A123 LiFePO4 pouch cells that test as a true 20Ah at +25C temps , can drop to being effectively only an ~11Ah cell by the time they are -20C temps , and at the same time it's internal resistance can go up 6-7 times higher than it was at +25C temps.