Needing help powering new electronics!

[Hemi6677]

So I pulled the trigger this winter and upgraded the electronics on my boat. Purchased a Lowrance HDS Gen-3 bundle with a HDS-12 and a HDS-9. My boat is a 1997 Triton TR21 with a 3 bank battery system. Standard two batteries for the trolling motor and one for the big motor and electronics. All batteries were Group 27 that are a few years old. Using my previous electronics I never had any power issues. But now that I have upgraded everything I am finding that power is lacking. My cranking battery was a Duralast 27DP-DL with 800CCA. I noticed the battery seemed weak when I fired the boat up on muffs at home a few weeks ago. But it would start the engine so I waited until I had the boat on the water to decide if a new battery was needed. Idling around with the big motor everything worked great. The HDS-12 worked just fine but once I had the big motor off and my HDS-9 on the bow running I soon realized some change was going to be needed. After roughly 45 minutes my supply voltage at the bow was down to 8.5 volts at which point the HDS-9 would start to have issues. So I fished the rest of the day with the unit off and always had enough juice to start the big motor. The HDS-12 at the console even with the big motor off would always read atleast one volt higher or more than the front unit. I had tied into the existing power wires that were ran up front for my old sonar and honestly I'm not sure if they are tied into a fuse block at the console or are ran directly back to the battery. If i'm not mistaken I think they may run to a fuse panel up front which could explain the extra voltage drop. I do plan on running them back directly to the battery before my next outing. 

 

After the initial fishing trip I purchased a new group 27 battery (Everstart...don't burn me at the stake please as I bought cheap just to test my theory) just to see if a new battery would solve my issue on running out of power so fast. Well, it sort of did. I was able to use the front graph for a little over an hour before the voltage finally dropped enough to start having issues.

 

So, my question now becomes, do I need to really upgrade my battery type/size or go ahead and throw another battery into the mix and have two for my big motor/electronics? I've currently priced some Interstate Marine batteries as I get a very nice discount for them through work. I thought about going with two Group 27 Deep Cycle batteries as the current battery holder is made to fit those. Anything bigger and I will have to modify the tray plus add another tray for the extra battery. Or, do I really bite the bullet and add two Group 31 AGM batteries? Here at the specs for them.

 

BCI Group                      CCA         MCA        RC        Hours of Ampere Load at 5 amps and 15 amps

Deep Cycle 27M               600         750        160                              17.2      and     4.8

AGM 31M                        800         1190      190                              100 (does not break down into different amp loads)

 

Obviously the AGM's seem to have the better numbers. But, does an HDS-9 and an HDS-12 require this amount of battery power? Or do I have something else going on. My NEMA network is ran to switchable power like it is supposed to be. Any other suggestions?

 

Thanks,

Jake

[Wayne P.]

Exactly to what are the unit power cords connected to?

[Hemi6677]

I'm going to dig back into it tomorrow night to see exactly where the power wires in the bow run to. The console unit is directly ran to the battery.