Have I blown up my Solar Controller?

[Stemar]

I recently ungraded my domestic bank from 100AH to 330 AH, and had to disconnect the solar controller to do it. Unfortunately, I didn't follow the order of disconnection/reconnection when doing it, and now, I'm not getting the rate of charge I expect, and used to get. It's an Epever Duoracer twin battery MPPT controller connected to 2 x 100w panels.

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

 

[Alex_Blackwood]

I recently ungraded my domestic bank from 100AH to 330 AH, and had to disconnect the solar controller to do it. Unfortunately, I didn't follow the order of disconnection/reconnection when doing it, and now, I'm not getting the rate of charge I expect, and used to get. It's an Epever Duoracer twin battery MPPT controller connected to 2 x 100w panels.

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

Perhaps tripling your battery capacity and the fact that Gosport hasn't exactly been bathed in wall to wall sunshine recently may have something to do with it?
Maybe worth checking. Can you disconnect some of the bank and see what happens?

 

[B27]

I recently ungraded my domestic bank from 100AH to 330 AH, and had to disconnect the solar controller to do it. Unfortunately, I didn't follow the order of disconnection/reconnection when doing it, and now, I'm not getting the rate of charge I expect, and used to get. It's an Epever Duoracer twin battery MPPT controller connected to 2 x 100w panels.

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

If there's decent sun and the panels are pointing the right way, you should get more than 'a couple of amps' from 200W of panels,

If the controller is not drawing the available power from the panels, then the panel voltage will be above the MPP voltage.

For example, my panel has a n open circuit voltage of 22V IIRC. It's max power voltage is about 18V.
These voltages don't seem to change much from dim cloudy sun to full sun, it just changes the current. (mostly)

So if I see 20+V on the panel, I know the regulator is throttling the power, because it thinks the battery is fully charged. If I see 18 or so, the controller is drawing what's available.

Another test you can do is measure the short circuit current of the panel, with nothing else connected. The short circuit current for a given light level is typically 20 to 50% more than the max power current. It's a useful reality check because the power available on overcast days is not always easy to guess.

Check all the voltages, panel, controller output, battery.
Look for unwanted voltage drops.

I suspect the batteries just need charging and you haven't had enough sun.
The batteries might arrive 80% charged so that's over 60Ah to find.

Charging a 110Ah battery at around one amp per battery is a weak trickle charge and 13.0V is quite consistent with the battery being about 90% charged. The battery is barely more than 'resting'.

 

[PaulRainbow]

I recently ungraded my domestic bank from 100AH to 330 AH, and had to disconnect the solar controller to do it. Unfortunately, I didn't follow the order of disconnection/reconnection when doing it, and now, I'm not getting the rate of charge I expect, and used to get. It's an Epever Duoracer twin battery MPPT controller connected to 2 x 100w panels.

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

With 3 x the batteries they won't be depleted as much over night, so won't want as much charging in the morning. What charging is required will be at the upper end of the charge cycle, so battery resistance will mean they can only accept a smaller current.

You can only harvest as much solar energy as has somewhere to go. That's either charging batteries or powering consumers, fully (or thereabouts) batteries and not much turned on equals a very low solar yield.

With the Sun shining, disconnect all but one battery and turn everything on that you can. You'll get the best yield that's available at that time, assuming that you can turn a decent amount of consumers on.

In my experience, MPPT controllers aren't usually harmed by disconnecting the batteries first.

 

[GHA]

With 3 x the batteries they won't be depleted as much over night, so won't want as much charging in the morning. What charging is required will be at the upper end of the charge cycle, so battery resistance will mean they can only accept a smaller current.

though if that was the case voltage would likely be well up above 13v.
" but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, "
That sounds like what you would expect with not enough current available to push the voltage up.

Could be a good excuse to buy the boat a nice dc clamp meter, attach the panels direct to the batteries & see what goes in.

 

[rotrax]

I recently ungraded my domestic bank from 100AH to 330 AH, and had to disconnect the solar controller to do it. Unfortunately, I didn't follow the order of disconnection/reconnection when doing it, and now, I'm not getting the rate of charge I expect, and used to get. It's an Epever Duoracer twin battery MPPT controller connected to 2 x 100w panels.

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

Sounds like it.

 

[Sandy]

I don't recall the current I used to get, but the domestic voltage used to go down to around 12.2v overnight running a fridge, but build up to 14-odd volts during the day, while now, it rarely goes over 13v, with just a couple of amps going in. Have I wrecked it?

How many watt hours have your panels been producing lately?

I'm on the Tamar, with 200 watts of solar panel, 390 Ah of battery and have been running the fridge 24/7 for the last two weeks, for some geeky testing, and here is what Victron say that the panels are doing.

Where are you getting the max of 13v? Do you have a state of charge figure from your system?

Date​	Yield(Wh)​	Consumption(Wh)​	Max. PV power(W)​	Max. PV voltage(V)​	Min. battery voltage(V)​	Max. battery voltage(V)​	Time in bulk(m)​	Time in absorption(m)​	Time in float(m)​
01/07/2024​	460​	10​	166​	21.06​	12.32​	14.94​	781​	135​	0​
02/07/2024​	500​	0​	102​	21.44​	12.29​	14.93​	563​	120​	253​
03/07/2024​	340​	0​	86​	21.54​	12.41​	14.95​	717​	96​	84​
04/07/2024​	370​	0​	96​	21.97​	12.37​	14.97​	420​	107​	363​
05/07/2024​	290​	10​	58​	21.41​	12.33​	14.94​	794​	35​	50​
06/07/2024​	120​	0​	110​	21.01​	12.32​	14.50​	226​	0​	0​

 

[William_H]

It would be surprising the MPPT died to a degree with some charge but less than you expect. One might expect a compete death. What you need is an amp meter. As said you can connect via amp meter panels directly to battery. Expect a current of 10 amps under best conditions to 5 or less not best conditions. Hopefully your MPPt should give some similar charge current if batteries are not fully charged.
If it has all changed with additional batteries. Then try disconnecting new batteries. (one could be bad)
As said perhaps a bit of patience for ideal conditions before you worry too much. ol'will