ALERT - Alarm on Temperature, MPPT stopped charging with heavy battery loads

Q&A and troubleshooting
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1

The MPPT stopped charging “to protect the battery” (according to the alarm notification), but the battery was discharging and could have benefitted from the MPPT in that moment.

We received a high temp alarm notification yesterday. Thankfully we were able to shut it down before anything overheated. And we understand the cause. Here is the scenario…

The camper was heat-soaked, probably close to 100F. We started the rooftop air conditioner with no shore power. The invertor pulled upwards of 150A from our Epoch 12V 460Ah battery. While it is rated to handle up to 200A continuous, temperatures began to rise and my cabinet has inadequate ventilation. The battery quickly reached 170F by the time we got it shut down and it began cooling back down.

I expected the Epoch’s internal BMS to cut off discharging to protect the battery from overheating but that didn’t happen. (What is the cutoff temp? On the current spec sheet I see “Discharge Temp Range: -20°C (-4°F) / 60°C (140°F)”.)

Back to the MPPT. I don’t see any user-configurable settings for high temp limit. I understand why it would stop charging when the battery temp is too high, but why should that occur when the battery is discharging?

2

How does the MPPT know the battery is discharging. These things are not complex logic, they are simple is the temp too high, if yes then stop charging. This is less likely to go wrong than a more complex shutdown logic involving 2 inputs.

3

Just a thought - That might be the recommended range - not the internal safety limits. In other words, don’t use it outside this range or bad things can happen (shortened lifespan, electronic failure, cell damage, melting plastic,…) Perhaps contact support@epochbatteries.com or the dealer to find out what the BMS will do and when.