deep cycle batteries

[walligator]

Looking for opinions on deep cycle batteries please. Need one for my 55 lb thrust Minn kota powerdrive v2  but I want something that will last n go for yrs. And something thats a true deep cycle battery.

[oldccm]

How many batteries do you run? On what kind of boat?

[walligator]

Well I just bought boat  so dunno my plan  I'm gonna have one battery at back for my 60 mercury n trolling mtr 55 lb minn kota on back n also have bow mount 55 Min. Kota up front with ipilot. On a 16 ft sylvan aluminum. But I want something that will last n hold good charge

[redneckrmsy]

no matter what one you end up buying make you use a battery maintainer during the off season, and inbetween trips, it will last alot longer, i have a everstart marine from wal-mart going on 5 years old, only used to move a 14' deep v around the lake

[oldccm]

Do you have both transom mount and bow mount minn kota's or did you mean 1 battery for the Merc and 1 for the minn Kota?

[walligator]

I have both. One up front bow n one transom. There was one battery that came with boat for starting the 60 mercury  but dunno should I get separate batteries for each trolling mtr? Cuz the battery thats for the 60 mercury charges the battery when ur driving.

[oldccm]

You need to keep 1 battery for the Merc. That battery can run your starter, nav lights, bilge and any other electronics that are NOT your trolling motor. Trolling motors can drain batteries fast and also cause interference with electronics. Your Merc battery is also probably a starting/deep cycle battery not a true deep cycle. As for the trolling motors in my head you have 3 options
1. You can run both trolling motors off 1 deep cell battery
2. You can buy 2 deep cell batteries with 1 dedicated to each battery
3. You can buy 2 deep cell batteries and connect them in parrallel. (My 1st choice)

As for batteries to buy you need to be deep cell/agm. Most are starting/deep cycle, true deep cells are hard to find and very expensive. What you are looking for is the AH (amp hour) rating. You want to make sure you buy 2 matching batteries that are the same size and AH rating (you can mix battery sizes and rating when connecting in parallel but not when making different voltages.) By matching the batteries you're just going to make it easier on yourself.  A decent deep cycle is 100ah, a 55 minn kota on its highest speed can draw upwards of 50 amps which is only 2 hours run time. By connecting 2 x 100ah batteries in parallel you increase to 200ah (there is some ah lost in wiring and resistance, but it is minimal and for calculations this is easier). You now have 200ah/50amp draw on highest setting. (I run 2 batteries for a 55 & can get 12+ hours of continuous use). Now for sizing and prices. Deep cycles come in 3 main sizes called group, there's 27, 29, 31. 27 is about the size of a car battery where a 31 is a few inches longer and rectangle. The larger the battery the more ah. As for prices you could pick up a group 27 100ah Trojan at Battery Man and its going to run you upwards of $300+. You could get the same ah battery at Canadian tire for $150 all the way to $400. Depending on how much you use them and if you maintain them you should get 5+ years of service. (I got 6 on my last Trojan group 27, 4 on a cheaper brand). It's up to you whether the extra $ is worth it. If you're just a weekend warrior I would find something in the mid budget, maybe $400ish for both batteries. One thing you do need is a decent charger, over the last few years I fried 2 Canadian tire portable chargers. I have since upgraded to MK220D for the boat. It is a permenant mounted on board charger from minn kota. Simply hook each lead up to the batteries and anytime you're at a dock with power you can plug it in straight from the boat or as soon as you get home (deep cycles need to be recharged quickly or over time they won't go back to full charge). The MK220D is not cheap $300 but is a heavy duty charger meant for deep cycles. The advantages of it are worthy of another long winded write up. I hope that helps. If you got any more questions just ask or shoot me a pm.

[budwinslow]

oldcm, you are right on with getting a good charger like the MK220D.  The 3 stage charge cycle makes all the difference in the world.  Even the non-AGM deep cycle batteries can give you 8 years of service if you put the battery on a good charger immediately after use.  Leaving a battery discharged after use drastically shortens its life.  I run 2 group 29 series batteries made by everstart in series since my trolling motor is a 24 volt.  My motor and electronics run off a standard car battery in the back.  I have had this setup for three years now and have not noticed any drop in performance from the batteries yet, even when trolling at 2.5 MPH for salmon off the trolling motor. Make sure you keep the batteries on the charger during the winter.  A good charger has a lower voltage maintenance charge level that will not overcharge the battery like a standard charger.

[walligator]

Wow! Thanx alot oldccm. That sounds like very good advice  I'm willing to spend the money for good batteries  I fish alot n want em to last  n also thanx for explaining how those onboard chargers work  wasnt sure how they get there power to charge batteries. N ya the battery I have for my mercury n bilge n livewell n CD player is off a bigger more rectangular look battery. But I dnt have it on charge a moment. So u recommend keeping them on charge all thru winter r how do u go bout that? I also carry a Minn kota batt tester in my tackle box to check em as your fishing. I will be goin to wpg this Friday for the weekend.

[oldccm]

As for charging in the winter you have a few options. You can remove the batteries from the boat if you leave outside for the winter. I just bring mine in the garage for the winter and just put the charger on for maintenance once a month. The 'D' Minn Kota chargers have a digital feature that can be used for long term charging. It will automatically turn off and on to do long term storage charging. I still prefer to keep batteries in heated garage, but that's just my preference. As for winter storage charging in boat I would disconnect all electrical devices from the battery terminals. Even off electronics could drain batteries over the winter. If you do want to use the MK220D for winter charging you have a couple options. You can hook 1 bank to the parallel batteries and the. Use the other bank to connect to the starter battery to keep that charged too. There are more options like more bank chargers and what not. Let me know if you need any more info.

[retired railroder]

All good advice above. If you are thinking of 2 batteries, imho, you might want to look at 2 6v batteries hooked in series. You'll find they should last longer than 2 twelves of the same size. You can buy a true deep cycle gc2 6v golf cart battery  for about $200 or less. Although they have the same footprint as 1 size smaller regular 12v  they are a couple of inches taller and a fair amount heavier. In high end RVs they always run banks of 6 volt batteries as they last better. The ones I have are from interstate and are 240 ah each. Last year CT had 6 volts on sale for $160.00, if I remember correctly. Just food for thought.

[oldccm]

I think there is a disconnect here...

There is battery bank voltage (typically 12, 24 or 48 volt--older cars had 6 volt, and some boats at 32 or 36 volt battery banks).

From a simple energy storage point of view--Remember Energy=Volts*Amps*Hours (time).

If you double the voltage and 1/2 the current--you still have the same amount of energy storage...

For example, 2x 6 volt 225 AH "golf cart" batteries... You can connect them for a 6 volt bank (two batteries in parallel) or the two batteries in series (12 volt bank). Parallel connections add Amp*Hour capacity... Series connections add Voltage:

6 volts * 2x225 AH = 2,700 Watt*Hours of storage at 6 volts
2x6 volts * 225 AH = 2,700 Watt*Hours of storage at 12 volts
So--If you have 400 lbs of batteries, and want to reconfigure them from a 6 volt bank to a 12 or 24 volt bank, there is no difference in the amount of raw energy stored/available.

However, there are reasons why larger systems are higher battery bank voltage... And that is simply the amount of current flow to support a load. And if you (for example) double the bank voltage, you have 1/2 the current (smaller switches, wires, fuses, etc.).

Say you have enough room (and money ) for 4 standard sized storage batteries. And you can get either 6 volt or 12 volt batteries in that size.

You have a choice of connecting 4x 12 volt batteries in parallel. Or 4x 6 volt batteries in series parallel (2 in series, then connected into two parallel for a 12 volt battery bank).

Several issues... One is that batteries must be connected in parallel "correctly" with balanced paths (equal resistance). If you don't do this correctly, one battery may carry all of the charging/discharging and the others will do much less work (and one battery will probably wear out before the others). Here is a web page that describes how to make the connections:

Smart Gauge Battery Bank Wiring

Another issue is that paralleling a bunch of batteries makes "current sharing" and balancing more difficult. And a weak/failed battery/cell can drain the rest of the bank (and is very difficult for you to notice the problem). Personally, I don't like to recommend more than two or three parallel connections.

Plus, every parallel battery string should have its own over current fuse/breaker... 200+ amp breaker/fuses/wring is not cheap or easy to do.

Lastly, if you have flooded cell batteries--4x 12 volt batteries in parallel is 24 cells to check water level in.

2x 6 volt cells (next size larger battery, just two 6 volt in series) and you have just 6 cells to check water levels.

And--that does not get into the main bank voltage discussion either... 12 volt is very common (12 volt DC car equipment/cigarette lighter adapters/etc. are everywhere). And there is some 24 volt items too (truck/boating).

But, for an off-grid system, you also need to look at the total power needed... For example, a 1,200 watt inverter, worst case, would need to have branch circuit designed to handle this amount of current:

1,200 watts * 1/10.5 battery cutoff * 1/0.80 efficiency * 1.25 NEC wiring and fuse derating = 179 amp circuit
So, you are looking at fuses/switches/breakers/wiring to support ~200 amps continuous current flow and do it with only ~1.0 volt drop maximum.

Above 1,200-2,000 watt loads, you should be looking at a 24 volt minimum battery bank. And above 2,400-4,000 watts, you should be looking at a 48 volt battery bank.
-if the Boat's electronics/starting motor is 12 volts--you may wish to keep the living space battery bank at 12 volts too--so you can use the generator on the engine to recharge both sets of batteries (use a battery isolator or A+B type switch). Gives you redundant battery banks with the flip of a switch (i.e., starting bank fails, just switch in the house battery bank to get going

This is from a different topic I was discussing batteries on. There are pros and cons to both 6v & 12v systems. As for boats, everything is set up mainly for 12v except for the 24v or 36v trolling motors but in those instances the batteries are isolated from the rest. IMO there's to many cons to running a 6v series system on a boat