Boat Battery questions

[BallisticRenegade]

Currently I run two isolated batteries. One for the engine and accessories and one for the Trolling motor. I would like to modernize my systems a little which brings me to a few questions.

I have some dead space under the tip of my bow that I could stash a battery in. If I get a sealed battery can I strap a battery permanently under there? (it would be accessible for replacement if needed) If needed could I do it on its side if it is sealed? Battery recommendations? It is a 12V system.

If the bow does not work I have storage under the front deck of my boat. There is a label that states no fuel storage as it is not vented. Can I strap a battery down in there, it has the potential to be buried under life jackets and ropes.

Can I link the two batteries together to charge off of the motor? How do I go about this? It would be a long trunk (16 foot) I have a 1988 Johnson 90 HP doing the charging.

If it won't handle it or I cannot link them I would like to either put in a on board charger (recommendations?) or have a connection such as the trolling motor plug that goes to the battery that I can hook the charger up to so it can remain below deck or under the bow. would there be any problems with this?

Is there a monitoring system you would recommend to install to keep an eye on the two of them?

If the bow does not work I have storage under the front deck of my boat. There is a label that states no fuel storage as it is not vented. Can I strap a battery down in there, it has the potential to be buried under life jackets and ropes.

 

[KX6D]

Re: Boat Battery questions

You will want a sealed AGM battery if you want to lay it on its side. The BEST battery is made by Odyssey. The Sears Platinum is private labeled by Odyssey for Sears. Don't store anything on top of the battery. Put it in its own box and make sure its tied down!

You can isolate and charge both batteries from eachother using one of THESE. There are many different ones available; I gave you this link only as a reference.

I'm a big fan of using two different batteries! Just make sure you do it right!

BTW, stay away from Optima Batteries! They used to be GREAT...not so much anymore!

 

[Todd4]

Re: Boat Battery questions

I've just about completed a multi-battery set up with on board chargers so I'll share what I've learned - YMMV. Your outboard alternator probably will not fully charge your trolling motor battery, unless you run the outboard for hours at a time, or you don't use your trolling motor that much. It'll help charge it back up a little while you're on the water, but probbably won't top it off like a deep cycle battery likes after a discharge. In my case, I have a 24 V trolling motor (2 batteries) a house and a start battery; and I added a DC charger, but I do not anticipate that it'll keep them charged up. So, I also added an onboard AC charger that plugs into an extension cord ("shore power"). Both chargers have built in battery isolators so the one shown above would not be needed also. If you are going to add just one on-board charger, I'd make it an AC charger, so it'll keep your batteries topped off while on the trailer or in the slip. Also, make sure you use the correct size wire for your long runs (plenty of guides on the internet) and fuse them accordingly.

I have Minn Kota's chargers (no experience with them, yet, so I'm not recommending one way or the other). As for simple monitoring, I like volt meters (in the dash), but you could get Minn Kota's battery boxes that come with circuit breakers and a LED battery charge indicator built in. You have to protect from arcing to meet USCG rules - a common way is by putting them in a battery box (or similar dedicated built-in storage locker) anyways. BTW - don't let the MK battery boxes get rained on - apparently they aren't made for that (go figure - it's for a boat).

I think I commented on your remainig questions. Remember, there are many ways to accomplish your goal - good luck choosing what's right for you.

Todd

 

[BallisticRenegade]

Re: Boat Battery questions

Thanks for all the info guys. Just to clarify I can put the battery below in the storage unit and an AGM battery can be installed on its side correct?

The one remaining question is if I choose to stay away from the on board charger for now (upgrade one step at a time) can I get another trolling motor plug with open wires, hook my charger to it, and charge my battery so I do not have to dig it out from its storage location?

Todd Do the Minn Kota chargers handle two batteries? as well as isolate them?

Thanks again guys.

 

[Silvertip]

Re: Boat Battery questions

You can buy single, dual, triple and quad out on-board chargers for a one battery, two battery, three battery or four battery setup. The charger outputs are totally separate from each other and connect directly to each battery. You then only need to plug the AC power cord into shore power or an extension cord at your private dock. I strongly advise you to avoid ISOLATORS for technical reasons (voltage drop) if you intend to charge batteries from the engine charging system Automatic Charge Relays (ACR) is a far better solution but is limited to just two batteries. A dual battery switch allows manual control over which battery is being used to power things but if you are switch challenged, then that is not a good solution for you. For your installation and number of batteries, I strongly urge you to consider the on-board charger. I also suggest you forget the high cost AGM and apply the savings to the on-board charger. You can buy deep cycle batteries at most farm stores that have higher capacity numbers than most AGMs and are about 1/3 - 1/2 the price.

 

[glenn property of pam]

Re: Boat Battery questions

i still havent bought a on board charger yet but while reading it seems that some now come with the acr already built into the unit so not only is it a charger but its also a switchable acr. the bass pro 555 is one ive been looking at (to be honest the acr wont work on my boat as the alt is only 6amp but i like the idea). i agree with silvertips unless you are mounting the battery sideway and to be honest thats never a good idea its more of a last option then save the money and put that into the charging system. most chargers under $400 do not like to have mixed batteries so consider that before purchasing as the amg will require a diffrent charge setting.

 

[Todd4]

Re: Boat Battery questions

Yes, an AGM battery can be stored and used on its side without any leakage. (However, I've heard they are not recommended to be used upside down.) Another advantage is, no corrosive fumes; so they can be mounted (and charged) inside unvented compartments, including storage comparments with other things (like life jackets) or even a cabin (this may be what you had in mind??). Just be sure to positively protect your connections from accidental arcing across the battery terminals and add fuses/breakers to protect your wiring (USCG rules). So anyways, the advantages of AGM may outweigh the higher cost for you.

Yes, you can easily wire up a little jumper wire adapter that'll plug into your portable battery charger leads and your permanent trolling motor outlet (battery side) to charge your single battery. I'd have to think about how to do a 24V dual battery set up. Just be carefull of the polarity and remember you'll have an exposed 12V hot plug prong sticking out (will short against any ground) of your "trolling motor charging plug" adapter wire - so be careful what order you plug everything together in to charge (adapter wire to charger, adapter wire to battery outlet, charger to wall).

To reiterate what Silvetip explained: I have Minn Kota's 4 battery AC charger which totally isolates itself from all batteries all the time - while charging or underway (so one deeply discharged battery cannot suck down another battery, like a battery switch might allow). I also have Minn Kota's 3 battery DC charger (start battery first charges normally from outboard motor, then DC 'charger' directs excess alternator power to charge the other 3 batteries). Minn Kota (as well as many, many others - I'm not endorsing MK's over anyone else's) make models that charge 1, 2, 3 and 4 batteries. I'm sure there are other, more elaborate, systems to charge even more batteries, but I stopped looking at 4, since that's what met my needs. With as many batteries as I have, the convenience of an onboard charger sure is nice (one plug and done) even though it was a LOT of wires to make up - I'm happy.

Have fun researching and designing what works best for you.

Todd