I recently purchased a boat.  This weekend I will be installing a 24v trolling motor and an on-board charger.

The guy I bought the boat from bought a brand new wet cell cranking battery (Everstart Marine).  I have an almost brand new Optima Blue Top (AGM) that I have been using in my other boat the I would like to transfer over.  Of course I would have to buy another Optima Blue Top.

My question is .... Can I install 2 different types of batteries (1 wet cell & 2 AGM) for the on-board charger?

Mix and match?

Use the two AGM for the trolling motor, and the wet cell for starting and electronics.

Regarding the on board charger, how many banks does it have.  If it's two, hook a bank up to each of the trolling motor batteries.  The motor's charger should keep the wet cell charged.

If it's a three bank, one to each battery.

Yes you can. I run a wet cell conventional starting battery with two AGM batteries fro my trolling motor.

Good to know.  I am a bit of a novice at this and I couldn't find any info out there about mixing.  Thanks.

It is a 3 bank charger.

I would strongly suggest you check with the charger manufactor. Some DO NOT like for you to mix battery types. AGM's and flooded cell batteries have different charging characteristics.

If your charger has adjustable charging characteristics all you need to do is select the AGM or Sealed battery setting. That is the most conservative setting to protect sealed batteries but it will still charge all batteries OK. The only difference is it may take 10 minutes longer since it will limit how high the voltage can go to push current in.

Although you can mix size, age, chemistry etc., for batteries used in parallel, it becomes important to match the batteries in series for 24 or 36 volt motors as closely as possible.  Not only is the chain as weak as the weakest link when in series, the stronger links can damage the weaker ones and reduce battery life considerably.