Fried Batteries

[arwebbwind]

We purchased our 2015 30ft Flying Cloud used 1 year ago. Let me start this off with the backstory. When we brought the trailer home we were hanging out enjoying and exploring our new toy. A couple hours later the battery died. We just chalked it up to being in an indoor showroom and not getting charged. We then spent the summer with full hooks up and never dry camped to test the system out. We brought the trailer home after the summer and a week later I went out to put something away and the trailer was dead. Being that it has Solar I knew that this should not happen. Our previous trailer had solar and was parked in the same spot and never a dead battery was found. Well, we discovered that the Gel batteries were fried...dead…bulging even. We believe the batteries were like this when we got the trailer. It’s our fault for not checking…shame on us. Lesson learned.

What I am trying to determine is how this could happen so it doesn’t happen again. The trailer is equipped with the Go Power Solar system (2 panels & controller), Progressive Dynamics PD9200 converter, WF-1500 series 1000 watt power inverter, and the Bogart Engineering TM-2030 Monitor. My husband has not had the time to dig into yet to figure out how it is all wired. Shouldn’t this system stop over charging when left of Shore Power? Or is it only set up to control the Solar charging. The batteries were not original to the coach, the previous owner had them and the whole system added by the dealer when it was new. We found the battery dealer that sold them to Airstream. They were fantastic. I couldn’t believe that they replaced them for us. They had them in the system and knew that they were sold to Airstream. We replaced them with AGMs instead of the Gels.

[sgschwend]

I would ask how does the PD9200 know that it is not overcharging the battery?

I did not find a temperature probe for temperature compensation. You didn't say what model but the largest version is rated at 80amps, which is over 1300 watts of power.

Plenty to overheat a set of batteries, with the right amount of discharge the batteries could soak up all that energy.

Lead acid batteries have very low internal resistance and as they warm up this resistance goes even lower causes them to heat up faster. This effect is what is often called thermal run away. The batteries swell up or worse things can happen. Luckily you only had the batteries go bad.

[alano]

Your converter and solar charger have the necessary features to prevent over-charging, however, nothing in your system can prevent over-discharge. It's possible that the batteries were left in a depleted state for an extended period. At some point the damage is done and your converter and solar charger won't be able to heal the batteries. The chargers will try to raise the battery terminal voltage, but an internal shunt resistance (fault) will dissipate power, causing the batteries to swell. Bottom line, avoid over discharge. Best to only deplete your batteries no more than 50% of capacity.

[arwebbwind]

Thank you for the replies. We have more investigating to do next time we take the trailer out. It's stored off site right now so we don't have access to it. During the summer we currently leave it in a park full time and like to leave the shore power on to keep the fridge going.

[OTRA15]

Ditto to alano's comment. Your used batteries were probably allowed to run down and were damaged. Buy new batteries and enjoy the trailer!

Originally Posted by alano

Your converter and solar charger have the necessary features to prevent over-charging, however, nothing in your system can prevent over-discharge. It's possible that the batteries were left in a depleted state for an extended period. At some point the damage is done and your converter and solar charger won't be able to heal the batteries. The chargers will try to raise the battery terminal voltage, but an internal shunt resistance (fault) will dissipate power, causing the batteries to swell. Bottom line, avoid over discharge. Best to only deplete your batteries no more than 50% of capacity.