I am trying to figure out my run time on FW 71 FB motor guide trolling motor. It's 24volt and the problem I'm having is trying to figure out the AH. I have 2 deka batteries for my Triton and the label seems to be different than my other battery from Walmart  that I use for my minn kota says deka does not spell it out that easy it seems or maybe I don't know how to read it. 

 

Deka marine deep cycle heavy duty  27DC CCA 575 MCA 705 32 AMP AVE  200 Min 

 

Thanks

Group 27, depends on how high you run the trolling motor, wind conditions p, boat weight and how often. Should last about 6 to 8 hrs under normal fishing conditions....who knows without fishing all day? Trying to divide amp hours into actual use is a waste of time. If your boat can hold group 31's, you will be a lot better off.

Tom  

 

Using them as trolling motor batteries, CA, CCA, MCA all mean absolutely nothing.  That's just how many amps the battery can deliver in a short burst to turn a starter.  True deep cycle batteries don't even have those number listed on them.  They do it on these because people use them as cranking batteries, especially on small boats with small motor and a 12V TM.

 

The only number on this battery that means anything for trolling motor use is the RC number, which you transposed, it's 23 amps not 32 & 200 min.  or 25 amps & 175 min.  That tells you how long the battery will run a TM at that amp draw before it's totally discharged.  Totally discharge is also when the prop will almost no longer turn, not when it starts slowing down so don't think you fish with it at 25 amps for 175 minutes.   You should never run a battery below 20% charge, basically 11.98 or 12 volts.  Doing so greatly shortens the life of the battery and totally discharging actually damages the battery. 

 

One other number you will see and usually about the only number you see on true deep cycle batteries is the Amp Hour rating, for instance it will say 105 Ah @20 hours.  Some pure deep cycle will have a 5 hour rating because the 20 hour rating is basically a useless number.  That's only how long it will last with about a 5 amp draw, less than one small light bulb and the higher the amp draw the lower that number goes. 

 

Thanks guys that makes sense.

 

My last question is that I know my TM will draw 34 amps at top speed.

 

Can I figure how long the Battery will run at max speed with those figure I had listed above?

 

It was 23 not 32 typo.

You can make a wag, but to get it exact, probably won't happen. 

For instance, notice how the RC number dropped 200 minutes @ 23 amps to 175 minutes @ 25 amps.  As the load on a battery increases, the batteries efficiency goes down rather quickly. 

You also have to consider, that's to 100% discharge so you if you want to protect your battery and the fact you are not going to have any useful speed out of it by the time it's at 25% you can figure another 25% less time right off the bat.  I would be surprised if you could run for two hours constant at max thrust with both batteries fully charged to start with.  Actually, it would surprise me if it went 1 1/2 hours without stopping.

 

Best way to find out, have the big motor break and use the TM to try getting back to the dock.  As soon as you get within a few hundred yards of the dock, the batteries are gonna die. 

I have two batteries for the TM so I figure figure from there. 

 

Thanks for the info much appreciated.  

 

 

Understand, two batteries in series gives you 24 volts, but you still only have the amp hour capacity of one battery.  So only use the ratings for one battery to figure on.