Using 1 RTS for 2 Charge Controllers on 1 battery bank

charlie hepler

I have 2 seperate solar panel arays that use 2 seperate Morningstar CCs charging 1 battery bank.

1 CC is the 30amp Morningstar Prostar (not MPPT) CC and the other is a 15amp Morningstar Sunsaver (MPPT) Cc.

My question is about the Remote Temp Sensor that is suggested you use on the Morningstar CCs.

Since my battery is only 5 feet away from the CCs I was wondering if I can use 1 RTS and splice it to both of the CCs?

Will this work?

Will it cause any issues?

Should I splurge for a 2nd RTS?

I am on a budget and don't want to purchase a 2nd RTS if I don't need to!

Cariboocoot

Re: Using 1 RTS for 2 Charge Controllers on 1 battery bank

No it will not work.
The RTS is a resistance that varies with the temperature. Each charge controller is expecting to see a range of so many Ohms from it. If you parallel it to two controllers they will be "looking at each other" as well as the value of the RTS. No telling what value they'll come up with as a result, but it will be wrong.

Whether or not you spend the $ for a second would be a question of how necessary the temp compensation is for your particular installation. That depends on quite number of details, and chiefly on how long you want to make the batteries last.

You don't have meters on those, so you can't even get a reading of the Voltage difference with/without the RTS.

charlie hepler

Re: Using 1 RTS for 2 Charge Controllers on 1 battery bank

Actually the prostar has the meter and I have several watt meters installed on the system as well just for my curiosity.

I guess I may need to invest in another Morningstar RTS.

Are there big differences in RTS for these vs battery chargers as I have several of those already.

If I buy another Morningstar RTS and connect it to the battery along with the 1st RTS will it also effect the other CC like sharing the same RTS? I am confused!



Thanks for the info Cariboocoot!

Cariboocoot

Re: Using 1 RTS for 2 Charge Controllers on 1 battery bank

An RTS is pretty much specific to what it was designed for. You really don't know what the resistance/change per degree is so you should always get the right one for the controller.

Two of them on the same battery will just allow each controller to read the battery temp and adjust its output accordingly. This may not be a 100% agreement between the two, however. But it will probably be closer than only one controller or none at all.

Muskoka

Re: Using 1 RTS for 2 Charge Controllers on 1 battery bank

I have RTS's connected to each of my Morningstar controllers, connected to a single battery bank (taped to the side and covered with insulation), and they are always within 1 degree Celsius of each other. My battery room can get quite cool / cold, and the batteries are always 5-10 degrees above ambient temperature of the room. Right now the room is 8 degrees Celsius, the RTS temperatures are 14 and 15 degrees Celsius. Charge voltages would be way off if not using the sensors for temperature compensation.

Glen

charlie hepler

Re: Using 1 RTS for 2 Charge Controllers on 1 battery bank

Thanks for the info guys!

I will get another RTS cause the batteries are just too expensive to not take good care of them!