what trolling batts.do i need

[oldblue]

i have a 24v 82lbs thrust great white and i am using two 700cca flooded batts. they seem to loose charge after only an hour or so of use the dont go dead but there is a noticeable diff. kind like it running on 12v im pretty sure the batts r good do i need larger batts. any sugestions i have 10gauge wire if that means anything

 

[Barnacle_Bill]

Re: what trolling batts.do i need

Are the batteries deep cycle? Have them load tested and replace that 10 gauge wire with 6 gauge. Also pull the prop and make sure you don't have a lot of line wrapped around it.

 

[Silvertip]

Re: what trolling batts.do i need

Not enough information regarding your current setup but BOTH batteries need to be up to snuff to provide proper performance. They both need to have proper connections (connected in series -- not parallel) and the terminations on each wire need to be clean and corrosion free. If you've not had the batteries load tested you need to do so to see if they are both actually serviceable. And as was mentioned, anything other than DEEP CYCLE batteries are not intended for trolling motor use. Depending on the length of the wiring 10 gauge may not be big enough wire. As for replacements, you need two group 27 deep cycles with the highest "reserve minutes" you can find.

 

[sschefer]

Re: what trolling batts.do i need

The battery question is well answered so your remaining question about wiring is if 10ga is adequate: No. 10ga is only rated for 30amps.
On a 24V system I run 6ga but 8ga is common if the distance is short. Resistance in wire is directly proportional to the cross sectional diameter and the length. The longer the run the fatter the wire you need. You want to make sure you have a 50amp breaker in that circuit also.

 

[pvanv]

Re: what trolling batts.do i need

If you run a 50a breaker, you'd better be using 6ga wire. The 10ga will get bloody hot -- unless it's a very short run, as it's only rated 30a.

If there's room, go with group 31 DEEP CYCLE batteries, as they have about 30% more amp-hours than group 27, and usually cost only 20% more. More amps for the dollar.

 

[oldblue]

Re: what trolling batts.do i need

what exactly is a group 27 or 31 batt. are they like the blue tops theres room for what ever batts i choose but i would like to keep the weight down some one told me to use golf cart batts??? and they would never go dead. i dont want all that weight and i guess i ether need to move my batteries under the front deck or change my cable because its over 20ft long but all soldered in and conected right i dont think the batts i have r deep cycle they dont say but they r pretty big

 

[pvanv]

Re: what trolling batts.do i need

You need deep cycle batteries for trolling. If they don't say that they are, they likely are not. Do not use automotive starting batteries. One or two deep discharges and they will be scrap. You might squeak by with "dual purpose" marine batteries, but they definitely will not survive the deep discharging of trolling like a deep cycle will.

As for size, the Group numbers are physical battery size (think AA, C, D, etc in flashlight batteries). For starting a small electric-start outboard, a 24 marine starting battery will suffice. For trolling, you will want at least 27's, if you expect any decent run time between charges. 31's will definitely weigh more, but likewise hold more amp-hours. They may or may not fit in your existing battery boxes, as they are BIG. Go and look at them at the store, or check size and amp-hour specs online to decide what weight and size will be appropriate. Weight is always a trade-off against amp-hours.

The color of the battery housing makes no difference, except for marketing.

Golf cart batteries are 6v deep cycle batteries, and are used a lot in blue-water cruisers. They are definitely the best amp-hours for the dollar, but you need two, wired in series, to make 12v. And the pair may or may not fit in your battery box. For your 24v setup, you would need 4 golf cart batteries in series. And you DO need a battery box (or boxes), secured with a strap, ventilated, and splashproof.

One nice thing about a 24v trolling motor is that it uses half the amps (but twice the volts), and that means your 10-ga wire may well be adequate. Remember, 10-ga is intended for 30 amps max... 30 amps at 24v is equivalent watts to 60 amps at 12v, but the 60 amp system would require at least 6 ga (or better yet, 4 ga) wire.

If this discussion has your head spinning, you may want to consult with a competent marine electrician before doing any changes, aside from switching to deep cycle batteries.

 

[oldblue]

Re: what trolling batts.do i need

ahh its all making sense now i was confused about the wiring because the trolling motor has 10 gauge leads coming out of it and it has only two wires so i thought going with the same diameter wire was enuff. about blue top batts i was meaning optima's i looked at some to day but did not notice the 27 or 31 numbers any were but they were the biggest ones they had deep cycle and something like 1150 cca i know to look for marine amps now so i might go look again i like to red fish and troll around alot so i really want something to get me around all day not wide open but at a reasonable speed and dont want to spend 250 apiece on something that isnt much better again im not looking for a miracle batt. unless ya know were i can get 2 of them lol.. just something to get me in to the spots and back out again with out the worries of them leaving me wading

 

[oldblue]

Re: what trolling batts.do i need

ok i looked on the optima website and the ones i was looking at are the d31m with 1125 ca with a reserve capacity of `155 and a c/20 rate of 75. isnt the c/20 rate the rate at witch a certian amp draw is pulled over 20 hours till batt drops down to 10.5v so does this mean i can pull 75amps for 20 hours???? before its at a full discharge?