Quote:
Originally Posted by JohnVirginia
I am probably still not understanding/misinterpretting, but I thought one (or more) of the 1449 subcodes could cause the DC-DC converter to shut down, perhaps either subcode 72 or 73. So if one could increase the airflow by using a bigger capacity (CFM) battery fan, then perhaps you could prevent say a 1449 (78 ), which does not shut down the DC-DC converter, from turning into a 1449 (72) or 1449 (73) as the pack continues to get worse (as in the descripion of 72 ad 73.
P1449 [72] battery module overheating:
probably looking at excessive overall temp, which is measured by the three thermistors, which could be caused by insufficient air flow, high internal resistance in multiple cells.
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Civics have three, Insights have four thermistors. This is a general overheating of the entire pack due to a large number of cells overheating. While it's possible that increasing fan flow might whisk the heat away, the pack is only going to continue to get hotter as it's used. The fan is already on and the pack has reached 176F. If it was insufficient airflow (if the fan didn't make a dent in the temperature), a P1448 would be thrown instead.
Quote:
Originally Posted by JohnVirginia
P1449 [73] battery cell overheating:
Likely the PTC strip detected a cell or more that exceed the max allowable temp.
likely cause extreme internal resistance, or very low capacity cell that is always in the fully charged condition.
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This is the most common failure that causes a DC-DC converter shutdown. The PTC strips show that one or more cells are extremely hot. Increasing the fan won't help. The cell is actually close to catching fire. That's why the car shuts it down.
If you have a P1449 with a DC-DC converter shutdown and you let the car sit for a few hours to cool down and then clear the codes, and you get a P1449 shortly after restarting with DC-DC converter shutdown, it's a 73.
Quote:
Originally Posted by JohnVirginia
P1449 [74] Battery module individual voltage input deviation:
This is the likely code for an unbalanced pack that should respond well to grid charging.
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Yes, but it will require grid charging on a periodic basis forever. We call this "grid charger life support". It also responds well to swapping out the bad stick for a good one.
Quote:
Originally Posted by JohnVirginia
P1449 [78] Battery module deterioration:
Possibly looks at voltage deviation, and overall capacity.
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These are starting to become more common as the cars age. They're known as a P1433 in Civic or P0A7F in 2005+ cars. There isn't anything anyone can do about it. The cells are shot. They're in balance (right now) or there'd be other codes, but the cells are extremely weak. Any well balanced pack will eventually become a 78 as it wears out.
Repeated from above:
Quote:
Originally Posted by JohnVirginia
So if one could increase the airflow by using a bigger capacity (CFM) battery fan, then perhaps you could prevent say a 1449 (78 ), which does not shut down the DC-DC converter, from turning into a 1449 (72) or 1449 (73) as the pack continues to get worse (as in the descripion of 72 ad 73.
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No, grid charging that 78 would keep it in balance and probably forstall a 72/73. The fan attacks the symptom, not the cause.
