Aquasport Mechanicals - things that need a wrench, screwdriver or multimeter > Trolling Motors and Kickers

Battery Location: 175, & Other Questions

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CTsalt12:
Hi All,

I am in the process of mounting a Minn Kota Riptide 70 lb on my 175.  I have a few questions.  You'll see how it's mounted in the picture.  I will be cutting the bow rails in the taped off area and adding a sliding rail sheath like the popular BoatUS article.

I am really on the fence as to where to put the two 60 lb batteries.  My first thought was to put them in the hatch I have the arrow pointing to.  The issue here is that it's not flat in there, and I'll have to build a wedge/brace in that hatch.  It also shifts the weight forward.  The boat still self bails just fine, so I haven't decided if this is a good thing or not.  It's also an area that will be bouncing around a lot in a chop.  Is this bad for my batteries? 

My next options would be to mount them in the stern, below deck, under the storage boxes in the stern corner.  The issue here is more distance between motor and batteries, more weight in the stern which leads to more wet feet.  However, there is no brace needed, and it's a stabile area for the batteries and no loss of storage.    What do you guys think??  The console is not an option for me as I have 2 batteries in there already, and i use the rest of it for precious dry storage.

Additionally, I'm struggling to grapple with the concept of onboard chargers vs portable chargers.  As far as I can tell, the only difference is that onboard chargers stay on your boat, are permanently connected to your batteries.  They both have to be plugged into a power source right?  Any recommendations for good chargers that will recharge 2 12V's overnight??  How much Amperage will I need? 

Appreciate the help as I'm clearly clueless here.

boatnamesue:
Why do you need a 4th battery?  You've got 2 already, i assume 1 for engine and 1 for accessories.  All you need is a 3rd battery to run your 24v trolling motor.  You take the 2 accessory batteries and connect into a series by bridging a wire from the positive terminal of one to the negative terminal of the other.  Its a good idea to have a 50-60 amp fuse on positive nearest battery. 

All other accessories (nav, bilge, baitwell, etc) can still be powered and grounded from either of these 2 batteries. 

On board charger is easiest because you can charge the 2 accessory batteries at the same time.  Otherwise with the standard 12v charger you'll need to disconnect the series bridge and charge each battery separate.  If you're hoping to charge both batteries overnight using a standard 12v charger you'll need 2 chargers. 

Personally I wouldn't keep a battery, let alone 2 batteries, in a bow compartment because the bow takes a lot of pounding.  Unlikely a battery will explode, but it is an explosive energy source. 

Capt. Bob:
A couple of thoughts CT.

Having owned a 170, I realize space is at a premium. That stated,

First, while the bow does take a beating, batteries like AGM type are designed for such use. Think about a battery in an off road vehicle. They can get pounded pretty good too. Anyway, does your style boating take you offshore so as to encounter such pounding? Another thought is the cable size and length in relation to the power supply and the motor.

Second, while I don't own a trolling motor I personally would want a dedicated power source for it. While I would guess under the right conditions, you could get home on the trolling motor should your starting battery die :think1:

Still, running the trolling motor all you want without fear of possible adverse effect on other electrical systems is a "peace of mind" thing to my way of thinking. Since we have a few members who are running trolling motors, I'd be curious how many are using their "house" battery bank to power it. Hopefully, they will chime in.

Lastly, Pro Mariner makes multi bank battery chargers that would fit your need. I like the idea of an on-board charger that you just plug in and forget it. Depending on the state of discharge of your trolling batteries, they charge very quickly (relatively speaking). Of course the downside is that an on-board can't be used to charge say your wife's/girlfriend's car, motorcycle, riding tractor or any additional device due to it's location. That's why I drag my charger out to the boat but if someone died and made me King, I'd have both. :mrgreen:

A lot to think about. Good luck. :thumright:

CTsalt12:
Appreciate the thoughts both.  My confusion about onboard chargers is totally cleared up now.

Unfortunately I did not buy AGM Batteries because of the heavy price tag ($220+!). 

I didn't think I could use my accessory battery for the trolling motor.  I don't think they are the right size either, Minn Kota and most resources recommend 2 group 31's with upwards of 100 AH, and that's way bigger than my starting/accessory batteries under the console, so it would be a mismatch with one 31 and one smaller house battery.  It would also mean routing from the console back to the stern through the rigging tube, then back up to the bow.  That's at least 25 feet of wire and I would need heavier gauge and more resistance.  As opposed to the 5 feet I would need if mounted in a wedge on the bow.

While I don't go offshore, we get a pretty good chop here in the Long Island sound.  2 footers in a rapid succession are not uncommon.  How much abuse can standard (Marine grade) deep cycle batteries stand up to?  I have battery boxes for them.  I am also considering using some kind of foam to mount them in and maybe absorb some shock.

Also-how necessary are the battery boxes anyway?  My thought was that they are used to keep out any moisture.  I do get some water in the far bow, mostly in the keel area from bilge drainage.  Because of shape of the boat, water seems to pool up in the keel in the center of the boat, and I pump it out when I have my bow up around 2200 RPMs.

Capt. Bob:
One thought.
http://classicaquasport.com/smf/index.php?topic=9842.msg129255#msg129255

This is a great compromise but was put in place during the rebuild so....

Still, space is a premium and Group 31's weight about 70+ pounds IIRC.
The deep cycle flooded have larger plates in their construction which may help provide some additional resistance to the pounding. The use of a box(s) could help contain spillage (if it happens). Mounting in the back resolves the pounding and larger conductors reduce the voltage drop but then there's the additional 140 lbs in the stern.

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