Trolling Motor Battery power depletion

[Murdock]

Hey guys, I need your opinions. I have a 12volt 55# Minkota PD. I have two 12 volt batteries wired positive to positive and then negative to negative for extended battery power. These batteries are maybe 2 yrs old.(Give or take a few months). They haven't seen hard use at all. I recently had about 8 hours of usage with the Minkota. I began noticing the Minkota would not guide my 17' Alumacraft. Once on the trailer, I hooked up the 10 amp charger and it read 4 on each battery.(Meaning 4 volts needed to be charged into the battery to become fully charged). Now wouldn't that mean I had 8 more volts to go before draining each battery. I had the charger on each battery for up to 3 hours a piece and it never went below 3.5-4.0. The easy answer would be "replace the batteries", but is that true? I didn't get a chance to try it in the water after recharging the batteries unfortunately. Let me know if you think this is due to a battery issue or something else.

[Fishin4Life]

I thought volts were always constant, and amps changed. I always wondered which was which...

[Master Guide]

My guess is your abtteriers are worn out. You wouldnt think it, cause the little use they get, but it does happen. Where do you store them in the off season? If you keep them in a cold place it will speed up the aging. Keep them in a basement or at least a heated space in the off season, this will help.

One thing I always thought too, is that wiring the batteries together, wears them out faster. Dont know why, but when I did this, it was a two year deal, then new batteries. It is better to have the boat wired with two seperate leads, one for each battery.

[Giant_Jackpot]

Murdock,

Not sure what kind of charger you are using but the indication is probably for amps. A 12 volt battery is basically dead when it hits about 10.8 volts and at 8 volts would not spin your motor at all. The batteries could be shot but take them to Batteries Plus and have them tested, as they do it for free. If you can swing it, I would pick up an on board charger for the batteries. Cabela’s ProSport 12 (6amps per bank) does a great job for the light user and they are about $100. You can leave them plugged in all winter without fear of overcharging the battery.

Fishin,

Both volts and amps will change over time at the same power setting on the trolling motor. Hard to get into all the why’s and how to’s on all this but that is the basics.

[Fishin4Life]

Quote:

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Fishin,

Both volts and amps will change over time at the same power setting on the trolling motor. Hard to get into all the why’s and how to’s on all this but that is the basics.

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Thanks for the info, My finder has a volt meter and I did notice that it is constantly changing. I just ignore it and charge the battery after each use. I just have a small 30lb troller anyhow. Lasts forever. I have looked at those battery gauges but never got around to getting one.

[castmaster]

another thing to consider is if the batteries have sat dormant for an extended period they wont take a full charge the first couple recharges. everything will say they are fully charged but they arent. sometimes it takes 4 or 5 recharges before they regain full capacity.

but if your arent taking a charge at all its either the batteries or a bad charger.

[Giant_Jackpot]

Master,

Not sure why you have had that experience with the batteries in parallel. As long as the batteries are matched you should be good to go.

[BobT]

There are questions that come to mind. What type of batteries are they? Deep-cycle, Starting, or combination? This can make a difference. I do know that the thought on this varies from battery to battery but some deep-cycle batteries can have a tendency to aclimate to the charge-discharge cycle (check with your battery mfr). In other words, if you start with a fully charged battery and typically use about half its capacity then recharge, the battery may begin to develop a memory to that level of charge. Full capacity can be restored by putting a load, such as a light, on the battery until it completely discharges then recharge it again to full. DO NOT do this to a starting battery as this will diminish its life considerably. Starting batteries are not very receptive to total discharge. Combination batteries may not particularly like it either.

Another thing to keep in mind. If you have two batteries connected in parallel as you describe, if one battery begins to deteriorate and go bad, it will add a load to the other battery and discharge it as well. So, if one of the batteries is bad and actually partially shorted, it will become a load on the other battery instead of helping.

Connecting two batteries in parallel adds the capacity of the batteries together but maintains the same 12-volts. They become as one very large battery and can maintain a high current supply for a longer period of time. Hence two 105 amp-hour batteries = roughly 210 amp-hour capacity less losses.

Connecting two batteries in series adds the voltage but does not increase capacity. Hence, two 12-volt batteries in series = 24-volts.

Bob

[BobT]

Some more things to consider.

Batteries, even maintenance-free batteries, can and do lose fluid due to evaporation or overcharging. If your batteries have removable cell covers, check the fluid levels. The level should be just over the plates. You can add water however distilled water is best. Tap water contains contaminants that can deteriorate your batteries prematurely. In a case where it’s either fill them or throw them away, what have you got to lose? I have used tap water from our well which is filtered, softened, and chlorine free. This worked okay but battery manufacturers don’t recommend using anything other than distilled water.

As mentioned earlier, it is best not to store the batteries where they can be subjected to below freezing temperatures. Batteries will lose charge if they sit for extended periods and a battery that is low on charge is subject to freezing. This will destroy a battery in a heart-beat. Store your batteries in a warm place and put a charger on them about once a month to restore their charge. It is usually not recommended to leave a charger on all the time, even automatic chargers. My battery is now about 8 years old and still going strong.

I can’t say for sure whether this is fact or fiction but I have also heard that a battery placed directly in contact with a cement floor will be damaged. Sounds far-fetched to me but I can’t afford to pay for the experiment. If someone has some facts about this, please speak up. I wonder if it depends more on how firmly you place it onto the floor.

The bottom line is, the better you care for your batteries the longer they will serve you. Treat them gently, keep them warm, and recharge them as soon as practical following mfr recommendations. That last statement refers to the fact that some batteries are best if trickle-charged while others respond best when recharged more rapidly. It does seem to vary by manufacturer and battery type.

Hope this helps,

Bob

[Green&Gold]

I've heard the cement floor rule as well. I have no idea if its true either. Nevertheless, like you BobT, I choose not to risk it and set my batteries on a shelf in the garage.

[TiredOfWorking]

When battery casings were made of rubber, they would discharge sitting on concrete. This does not apply anymore.

[LoonASea]

Many years ago I was givin a tip from am old time about deep cycle batteries ...he suggested putting a non buffered asprin in each cell 2 times a year typicaly before charging ..the theory is that it coats the plates so they dont flake off and short together

Many of You may remember the GNB action pak 105 deep cycle batteries ..well back in 1984 I got one and it lasted me till 2001 ( 17 years) using this old times tip and the only reason I dont still have it is because it hit the ground and cracked ..of course proper maintenence/storage along with the asprin has extended my batteries life... not just my deep cycle batteries but the batteries in my Harleys and other lawn equip tooo

sure you could ask batteries plus or a mfgr about this but they exist to sell batteries

hope this helps

Randoid

[Fishin4Life]

So asprin does really cure everything!

[BIG DIESEL]

Don't want to sound dumb but can you explain to me what the specific difference is in hooking 2 12 volt batteries in series v. hooking them parrallel? THanks!

[LoonASea]

2 12 volt in series = 24 volts with the same current rating

2 12 volt in parallel = 12 volt with current rating x 2