Battery life on electric motor

[abhunt]

I am looking for some info on how long my electric trolling motor should last with 2 fully charged batteries.
i have a new Motor Guide 75lb thrust motor with 2 new 12v deep cycle batteries.I am only able to get about 2.5 hrs trolling before the batteries die out.Seems to me I should get more life than that out of these batteries.
I bought it at Alberta Marine and the mechanic that installed it said I should be able to go all day on 2 fully charged batteries.When I realized this was not the case I took it back to them and they checked it out and said the batteries test good and the motor is working fine.If the batteries are good and the motor is working fine why do I get 2-3 hrs out of it beetween charges?
Any advice would be appreciated!!
thanks,Doug M.

[FishinFreak]

something is wrong; I get approx 7 hrs of trolling time out of my 24 volt MinnKota 70lb thrust system and its pulling a Lund ProSport 1700
did they test the system for parasitic power drains ?? also do you have the ability to confirm the batterys are fully charged before setting out ?? it is possible to have one battery get fully recharged and the other not be charged if recharging is done improperly and this will shorten battery life considerably

[Kingfisher]

Deep cycle batteries are rated in group sizes. Check and see what your group size is. Yours if probably a group 27. I just bought a group 31 for running my 46# thrust Minn Kota Maxxum. The Endura's are not as efficient as the Maxxum line. Not sure what make or modle yours is. But some are more efficient than others. Mine should last all day on one group 31 battery. But yours is a 70lb thrust and a lot matters on how you use it (full out, just slow trolling, or moving from one location to another). But you have to know some facts. Temperature can affect your battery life more than you can imagine. Here is a few paragraphs from a website on everything you'd ever want to know about batteries and more. http://www.magnacharge.com/mchg_all.htm#Battery Size Codes

Battery Size Codes
Batteries come in all different sizes. Many have "group" sizes, which is based upon the physical size and terminal placement. It is NOT a measure of battery capacity. Typical BCI codes are group U1,24, 27, and 31. Industrial batteries are usually designated by a part number such as "FS" for floor sweeper, or"GC" for golf cart. Many batteries follow no particular code, and are just manufacturers part numbers. Other standard size codes are 4D & 8D, large industrial batteries, commonly used in solar electric systems.

Temperature
Battery capacity is reduced as temperatures go down. This is why your car battery dies on a cold winter morning. Capacity is increased at temperatures over 25 C (77 F), but battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F. Battery life is reduced at higher temperatures - for every 15 degrees F over 75, battery life is cut in half, for ANY type of Lead-Acid battery, whether sealed, gelled, etc.

Cycles vs. Life
A battery "cycle" is one complete discharge and recharge cycle. It is usually considered to be discharging from 100% to 20%, and then back to 100%. Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50% - but to do so, you would need a very large battery capacity in most cases.

Hope this helps.

Rob

[hardabaft]

As well on this subject as a for instance Canadian Tire or Wallyworld will sell you a ' deep cycle' battery off their shelf for 119.00 give or take, however these are typically hybrids. Cranking an engine over amps as well as a longer reserve. Not a true deep cycle battery. Thicker plates yes but not meant to be drawn down past 50% as opposed to a stricktly purpose built battery as seen in forklift or even wheelchair and such applications. I've run an 8 inch Lectric ice auger with one of these and it's good for 25 to 35 feet worth of holes if the battery is warm-(in your truck 'till you pull onto the lake and eyeball or GPS a likely spot then way you go). Better batteries cost more. I have an old 12 foot aluminum and a 55 lb thrust Maxima (overkill to be sure) and i'ts great for a 5-7 hour 2-3 kilometer tour around trolling and drifting and anchoring up when my equally ancient fihin' buddy shows some fish or weed edge but thats all she wrote so we plan a route that ends up back at the launch site. Your motor will show what it draws. Trolling motors usually max out at 5 or so miles an hour no matter how many pounds thrust and this puts max draw on your battery. I think for me I will step up in quality(and$$) for a true deep cycle -31- as previously posted.
Anybody know any battery guys?
-oh and my buddies 12 lb Sevalor motor that came with a 2 man dingy he bought will troll all day clamped on to Hardabaft

[bobalong]

I have a 70 lb 24 volt minn-kota (with maximizer) on an 18.5 ft boat and I usually get at least a day of normal fishing out of two 180 minutes reserve batteries. If you are only getting about 2-3 hours something is definetly wrong IMO. Do you have a maximizer on your motor and how many minute reserve are your batteries? Reserve time is usually based on about 25 amp draw per hour and although your motor probably draws in the 30+ amp range you should still get about 3 hours at full power, and at least a day of normal fishing, as long as the chop is less than 3 ft.

[eys8830]

To start I did not read all the other thread before me cuz I am a bit lazy today...

But I was having the same problem with my Minn Kota 55 lbs! I changed on thing to maximize my battery life, and it's easy. SLOW DOWN! If I keep it under half the speed and over one quarter speed I fish 4hrs on one battery and running the fish finder.

The boat is a 12 foot aluminum I am 225lbs my fishing partner is about 175lbs plus all the gear... my battery is a marine deep cycle with 130 min whatever... one other thing I built and little stand to keep the battery out of the water too so maybe two thing to do...

good luck