SeaVolt 800 Starter battery...add AGM..?

[marinesniper]

I have read the other threads but wanted to post my setup...

I have a 30ft cruiser, it has 2 SeaVolt 800 starter battery's and that is it. I installed a stereo and Garmin Nav system.

So right now I run the stereo and Nav off of one of the starter battery's (BAD), I know...

I want to replace one of the SeaVolt 800 starter batteries with a AGM Group31 105AH battery. They are connected to a battery switch device (a and b or both). The removed second SeaVolt 800 will be stored for emergency power needs.

I will start the engine with the SeaVolt 800 and then switch to the AGM for stereo, Nav, etc...

Would this work ok...?
My engine is a stock Yanmar 2GM 15hp, stock alternator///

If more information is needed please let me know...!

thank you,

[camaraderie]

Don't do it. Read the battery threads here. Different types of batteries accept charges at different rates and charge differently.

[Cruisingdad]

Ditto what Cam said. Either replace them all with AGM or keep your wets. If your charger does not have a AGM/gell setting, you are stuck replacing that too are sticking with wets. Expensive mistake.

[marinesniper]

Thank you for the help, I think due to cost I might consider replacing with a bigger AH battery...after I thoroughly read the other threads again...

[camaraderie]

Sniper...if you are building a bigger bank...no matter what type of battery you use, you should consider going to an external smart regulator for your alternator to get proper 3 stage charging. Depending on the size of your new bank you may also need to upgrade the alternator to a higher output model. If your charging is mostly from the dock and you just want the extra capacity for the weekend, don't worry about it.
The idea of storing your "spare" seavolt for emergencies probably won't work due to loss of charge over time. Suggest instead one of those automotive "jump start" packs that you can leave plugged in while at the dock and fully charged while you are out sailing.