Battery voltage spike while battery is fully charged and disconnecting high load

[mr-solar]

Hello everyone,

I am using a 370W solar panel and a Epever 3210N solar charge controller charging a 12V 70Ah AGM battery. The system runs perfectly fine, but I recently noticed the following problem:

When the battery is fully charged and I connect a load of for example 100W, the charge controller immediately starts supplying that power from solar, so that the battery stays fully charged. If I then disconnect the load, the battery voltage spikes to ~15-16V for a very short period of ~1-2s.

Because the over voltage disconnect is set to 14.6V, the charge controller immediately caps off solar from the battery. But it seems to me, that the charge controller is not able to react fast enough to prevent that battery voltage spike, because I can still see it in statistics.

How problematic is this voltage spike for an AGM battery? Can it take it, because it is only for ~1-2s or will it decrease its lifespan dramatically? I am thinking of getting a new and bigger capacity battery, but first want to clear this problem.

Is there a solution to prevent this battery voltage spike?

 

[Bobert]

I don’t think that will hurt your battery at all. I would be more concerned about low draw sensitive electronics if they are connected to that battery.

 

[timselectric]

Agree

 

[Bobert]

Is there a solution to prevent this battery voltage spike?

A larger battery bank will help. Unlike Lifepo4 with extremely low internal resistance the resistance of lead based batteries gets higher and higher as the state of charge rises. So if the charge controller takes 2 seconds to respond to the reduction of load you will have a voltage spike since the battery can only absorb a small portion of the energy being given to it. The more battery you have the less of an issue this will be.

 

[ozjado]

Hello all, im running a 200ah lifpo4 12v battery and see voltage spikes at 100% soc when the controller cuts pv input I've seen it peak to 18v it appears to happen over a 1-2 second window but it's hard to say as the controller only samples every 2 seconds it freaked me out at 1st but it seems to function as normal when the load pulls some juice out of the battery the controller fire's back up and starts charging. Does the same thing with 2 different controllers of different models but same brand epever tracer bp 7810 and 3906