Dual Purpose or Deep Cycle

[drJ]

I just installed a 55 # thrust trolling motor on my boat and I used a dual purpose battery with 120 min. reserve that i had laying around. Should i invest in the deep cycle. my motor seemed sluggish with the dual purpose or is it just how it is going to be.
Thanks

 

[Boatist]

Re: Dual Purpose or Deep Cycle

Deep cycle normally has less starting current than the same size dual purpose battery. From what I seen the deep cycle in most boat has enough current to easily start most motors. If you have a big motor and small battery then it may not be enough current. Your motor manual will tell you the starting current and many deep cycle batteries will tell you there starting amps and reserve current.

The battery you had laying around could have a dead cell or something that would make it sluggish. Check your old battery voltage while trying to start and also right after. if it dropps below 10 volts while cranking or if it does not come right back to 12.4 after you stop cranking then battery likely bad. Take it in for a free load test.

 

[Silvertip]

Re: Dual Purpose or Deep Cycle

He's not using it as a starting battery -- its for the troller. Regardless, the battery is probably due for replacement. Have it tested.

 

[drewpster]

Re: Dual Purpose or Deep Cycle

Dual purpose batteries are supposed to be able to serve both functions. Its basically a start battery made to handle deeper discharging like a deep cycle. We started installing them in our trucks (3300 units +) a couple of years ago to help combat a serious bad battery problem we were having. The result has been promising however I cannot attribute it to the batteries alone as that was not the only change we made. They seem to handle abuse a little better. At least that is what the supplier says. And I know we are changing out fewer of them.
If you are having a slow starter problem it is most likely a wiring, or a bad battery. (assuming it is properly sized) I doubt it has anything to do with whether it is dual purpose or deep cycle. My deep cycle starts my big V8 with no problem. Make sure it is charged up before testing it and it should work if the battery is good. In fact I am considering a dual purpose battery to replace my start battery when it goes bad.

 

[jtexas]

Re: Dual Purpose or Deep Cycle

He's not using it as a starting battery -- its for the troller. Regardless, the battery is probably due for replacement. Have it tested.

yup, deep cycle or dual purpose, should have the same performance especially with a fresh charge. Whether it'll be sluggish or not depends on the boat, the load & the wind.

 

[ZmOz]

Re: Dual Purpose or Deep Cycle

Dual purpose batteries are supposed to be able to serve both functions.

Yes, but in the real world, it's only a compromise and it doesn't really do either of those things as well as a dedicated battery. A dual purpose battery won't last as long as a deep cycle in cycling applications, and it won't put out as many amps as a starting battery. For a trolling motor, there is no question, get a deep cycle.

 

[drewpster]

Re: Dual Purpose or Deep Cycle

I agree with ZmOz on this one. Dedicated functions need dedicated power sources. However I have directly observed real world use of dual purpose batteries over a wide range and concluded that they lasted longer in the application I mentioned. I would be using a dual purpose as a start battery only. And take advantage of the design of needs dictate. They have shown to hold up better to deeper discharge and abuse compared to standard start batteries based on my observation. ($10k per qtr/ down 40% in batterys after starting use of dual purpose design) 40%!