Solar Controller overheating

[BHT]

I have a 20 amp solar controller with 200W of solar panels. The system works well, but when the camper van was plugged into the mains, and the 240V battery charger was charging the battery as well, the solar controller overheated and was damaged. When the system is not on 240V charge the voltage gets up to 14.4V, but when being charged by the 240V as well the voltage recorded was 15.5V, at this stage the controller burnt out. Is there any way of preventing this from happening again?

 

[sunshine_eggo]

There is no reason the voltage should have been at 15.5V. You have a problem with your 240VAC charger.

 

[BHT]

Good point, but shouldn't the controller have turned things off so that it was not effected by the higher voltage. The controller should be able to handle 24V.

 

[sunshine_eggo]

I can't comment on that because I'm not familiar with the controller.

What is certain is that you should never charge a 12V battery with a charger that outputs 15.5V unless you are doing it deliberately in an equalization cycle of a flooded lead-acid battery. You will damage your batteries at that voltage level. If your AC charger is outputting 15.5V, it is either defective or improperly configured.

 

[time2roll]

This would be a good time to post the brand and model number of the controller..... and the 240 charger.

 

[Kdkool]

Most would connect the shore power charger as well as the mppt / solar charge controller directly to the battery (assuming they're different units). If your installation is similar, then both chargers would need to be programmed to the same set points. If you only set the solar charge controller side, but didn't set (or buy the the appropriate battery chemistry) shore charger, then that'd be problematic as they're independent from one another.

 

[BHT]

It is a Chinese one with no brand name just Solar Charge Controller, I have used these a number of times before with no problems, not sure about the battery charger. Just seen Kdkool's response, not sure how to set these voltages.

 

[Porch]

It is a Chinese one with no brand name just Solar Charge Controller, I have used these a number of times before with no problems, not sure about the battery charger. Just seen Kdkool's response, not sure how to set these voltages.

It's a no-brand Chinese controller. You got what you paid for.

The built in 120v/240v battery chargers used in most RVs and trailers are cheap, poorly regulated, and make a bunch of noise on the electrical system. They do tend to fry electronics, especially if you happen to disconnect the battery and power the 12v system off the battery charger alone.

 

[mikefitz]

From your terminology you are in the UK. The issue descried should not happen unless there is an error in the way things are connected, or unsuitable units are used, or incorrect settings are in place.
To help identify the problem please indicate the following,
solar controller type, mains charger type, battery type and capacity. If the chargers have user settings for charge voltage or battery type what settings have been used?
An interconnection diagram or sketch and a picture of how things are connected would be helpful.

Mike

 

[740GLE]

Sounds like a good time to upgrade both chargers!