Adding a deep cycle battery for graphs

So I am adding another deep cycle battery for my 2 live 12s and 1 carbon 9. If I were to make a jumper to my starting battery as well, would this hurt my starting battery? I don't have the funds to get a lithium right now and I plan on getting lithiums within a year so I don't want to spend the money on a duralast AGM 31 series. I was just gonna get a 31 series lead deep cycle from O'Reilly's. Only reason I ask is, I have a AGM 31 interstate starting battery right now for my motor and I have been running 2 gen3 hds 7s and all the other electronics off that battery like bilge etc.... I want to be able to use both battery's to have the power last longer.

I don’t think it would be good to mix a lead acid to an AGM, they have different voltages and I believe the lead acid would try to pull from the AGM. 2 of the same kind of batteries would be fine, but obviously AGM’s are more expensive.

Just run the lead acid by itself and charge her up after every trip.

How long would a lead acid 31 group last with 3 graphs?

I honestly can’t answer that, because don’t know the actual amp hour time of a lead acid. I know lithiums are true to their AH.


Best thing to do is pull the specs from the lowrance page. I think the 12’s pull about 3 amps each and the 9 is probably around 1.5. If you add active target, that’s another 1.5 amps or so. In standby my carbon 12 only pulls 1 amp. So, figure out what you’re going to run exactly and then you’ll know your total amp hour draw. I would think you could make a new lead acid last all day. The Walmart everstarts group 27 were 122ah, but let’s say you only get a true 80ah from them (just a guess).


I know you don’t want to spend it, but the Wieze, Chins, AmpereTime 100ah lithiums are about $320. (These are non-cranking) of course a proper charger is needed. But you’re gonna spend $100+ on a lead acid.


Edit: if you are only going to connect the AGM to the lead acid while AT the lake, it would probably be OK. I wouldn’t leave them hooked up while resting though.

The one I got is the O'Reilly's 31 group lead deep cycle. It's 105AH. I don't have AT right now. I will get lithiums when I do.

I run the Impulse Lithium 12v-100ah All Purpose. running (5) 12's, mega 360 and livescope. Havent come close to killing it in a day