I have a Motorguide 12v TM...about 35-40lb thrust...and I have 2 questions...

1) Who makes the best, longest lasting deep cycle battery on the market...but is still within a normal price range. In other words, not a $300 Optima gel battery.

2) How do you maintain a battery? I'm thinking you're supposed to make sure they are full...but full with what? Distilled water? What are good practices to maintain and make it last a long time?

...thanks in advance!!!

Ok, here's a secret.

Most of your conventional batteries are made by the same people. Everstarts, Cont, Interstate, ect.

Trojan's are awesome, but are pricey. In my opinion, for the money, they are the best battery on the market.

Optima's are good, but Trojan's are cheaper, last as long or longer, and have a much better warranty if you have issues.

Your battery is only as good as the charger you put on it. Charge them as soon as you get back from the lake. Otherwise you will loose the battery pretty quickly.

Get a good charger like a Guest, Dual PRo, ect that has a trickle effect. These chargers don't overcharge and you can leave them hooked up. Manual chargers will overcharge and boil the batteries dry.

Most batteries if taken care of will last 18-24 months. If you really get a good battery and take care of it, then you can get 36 months out of them. But that is really watching the battery and it's levels.

Thanks! What are the maintainence procedures? Is there a solution to fill them with, or is it just water? Just want to make sure that I get all the life out of mine as possible...

i run trojans in mine. continental for the starting battery.

if the water gets low, use only distilled water to re-fill.

one trick i used to do in the ARMY, was put in a couple of asprin into each cell. along with distilled water. works great. it increases the acidity level.

p.s. tylenol won't work..

The main causes of premature battery failures are heat, shock & vibration, and lack of maintenance.

Check the water level more often in hot weather. They say the aspirin trick doesn't work anymore - but I won't dispute steve's experience. Minerals in tap water interfere with the plates, so use only distilled.

You're right about keeping 'em charged all the time. Put it on to charge soon as you get home, and top it off every couple weeks if you don't use it.

Better yet, as Michael suggests, an automatic "smart-charger" that switches to "maintain mode" or "float charge", which can be left on all the time. Some portable chargers have a 1- or 2-amp "trickle charge", which is not the same - trickle charging is ok for overnight, but don't leave it hooked up 24/7.

Next best thing is a charger with "auto-shut-off".

If all you have is a manual charger, you have to keep checking it, and turn it off & disconnect when the amp gauge stops decreasing.

Be aware that some (not all) portable chargers will drain a battery if disconnected from the power supply (e.g. a power outage), so disconnect the terminals when you shut the charger off.

In any case, use a setting of up to 10% of the RC (reserve capacity) rating. If there's no RC rating, use 25% of the AH (amp hour) rating as a guideline.

Generally speaking, the bigger and heavier the battery, the more power it can provide. Two parallel batteries will give you more than 2x the run time of a single.

So how often do you need to check them? Every other time out? Once a month? Every couple of months? Do you just fill them all the way to the top, so that water runs out of the fill caps? Can you over fill them?

You should check water level at least once a month. In the summer every week or two depending on how much you use them. I fill mine to the bottom of the fill holes. As long as water is above the lead cells you should be alright.

+1 on what everyone has said!

Keep 'em charged and topped off with distilled water.

I put my charger on an inexpensive appliance timer (Home Depot)

Comes on for four hours, once a week. Keeps me from worrying about my charger catching on fire or over-charging and frying my no-so-inexpensive Trojan batteries.

It's a sulphuric acid solution in there - the water evaporates but the acid doesn't. If water runs out the caps, mop it up with something you don't care about, it's likely to end up with holes in it, and try not to get any on you, it'll burn like crazy. Baking soda will neutralize it, in case of a spill.

I check mine once a month or so during the summer if I remember.

The water level needs to be above the top of the plates, but it needs room to expand during charging.

Save a couple of asprin for yourself. Batteries on boats are nothing but a headache waiting to happen.

So is it best to fill the batteries when they are charged?

do yourself a favor and get the AGM batteries from Cabelas.
125-150 bucks each.never have to add or check anything.more cranking and reserve amperage than any other for that price.
they charge up faster and last longer.