battery question

[nightvision]

Hi all,<br />I just got a minn kota trolling motor (Endura 50). The manufaturer recommend a deep cycle Marine 12 volt battery with atleast 105 ampere hour rating. I do have a deep cycle battery from my tent trailer and I like to use it for this trolling motor when we are not camping. I look at the battery but can not tell if it has 105 ampere hour rating. Here is the info I can see on the the tent trailer battery.<br /><br />Trojan Outdoor, Duel purpose starting/deep cycle 24TM<br /><br />Specs:<br />85 AH at 20 Hr.<br />66 AH at 5 Hr.<br />135 min at 25 amps<br />550 cca at O degree F<br />675 cca at 32 degree F<br />12 volt battery<br /><br />Would this battery be appropriate for the trolling motor? Thanks.

 

[Dunaruna]

Re: battery question

Damn battery manufacturers, could they possible invent ANOTHER way to rate batteries, like there isn't enough already .<br /><br />Usually, deepcycles are rated by how many amps they can deliver in a 10 hour period. Therfore, a 105 AH will deliver 10.5 amps per hour for ten hours, at that point it is close to 50% discharged.<br /><br />Your battery is rated 85 AH at 20 hrs (I haven't seen this before), it will deliver 8.5 amps for 20 hrs OR 17 amps for 10 hours. Then it says 65 AH at 5 hours - now I'm confused.<br /><br />If I've got this right your battery is bigger than the 105 AH, your good to go!!<br /><br />Anyone else want to throw their 2cents in?<br /><br />Aldo

 

[ZmOz]

Re: battery question

Originally posted by Dunaruna:<br />Usually, deepcycles are rated by how many amps they can deliver in a 10 hour period. Therfore, a 105 AH will deliver 10.5 amps per hour for ten hours, at that point it is close to 50% discharged.<br />

A 20 hour discharge is the standard for lead acid batteries. That's the number you see printed on most when they don't specify. Also, the rating is not to 50% discharged, it's 100% discharged. Since you still should only use half the battery, that means you only get 52.5 from a 105ah battery.<br /><br />

Originally posted by Dunaruna:<br />Your battery is rated 85 AH at 20 hrs (I haven't seen this before), it will deliver 8.5 amps for 20 hrs OR 17 amps for 10 hours. Then it says 65 AH at 5 hours - now I'm confused.<br />

No, 85ah at 20 hours would be a 4.25 amp drain. (85/20) The 5 hour rate is smaller because the larger the load on the battery the smaller it's capacity will be.

 

[18rabbit]

Re: battery question

Like Oz said, the slower the discharge, the more amps a battery will cough up. The std spec for a/hr is based on a 5% rate of discharge, or 20-hrs of discharge (20hrs x 5% = 100% discharge). At 5% you get a reasonable amount of energy for the greatest length of time.<br /><br />There is a curve for other rates of discharge. This becomes important when using limited battery resource for high-amp demands, like trolling motors and house banks. Manf of quality bats, like your Trojan, publish the discharge curves for their bats.<br /><br />Aldo is correct, there are more specs for a battery than you can shake a stick at. They go on for pages and pages and pages. A couple of my personal favs are ‘float life’ - how long before a bat dies if left on a float charge, and ‘short circuit potential’ - how many amps would a bat cough up if it had theoretical unlimited capacity and you dropped a wrench across the posts.<br /><br />Nightvision – you said the manf recommended a 105a/hr battery. We talk about a battery’s capacity based on that 20-hr discharge rate. Common group-31, and group-27 bats are around 105a/hrs. Your Trojan (excellent battery, btw) is 85a/hrs…that’s about right for a group-24 battery, and some gel group-27.<br /><br />Group numbers are a std for the physical ‘fit’ size (H x W x D) of a battery and have no reference to a bat’s capacity, tho bigger obviously should imply more capacity. So all group-24 batteries will ‘fit’ in the same space, all group-27 bats will fit in the same space, etc. Based on what the manf says, you want a minimum of a group-27 battery, a group-31 would be better if it will fit on your boat.<br /><br />The last pair of specs in your post refers to the batteries ability to cough up very high-amps at a couple diff temps. They are commonly referred to as CCA (cold cranking amps), what a bat can deliver for vehicle starting applications at 0-deg F, and MCA (marine cranking amps) for starting boats at or above 32-deg F. MCA is done at 32-deg F because you get a bigger amp punch when a bat is warmer than 0-deg, and since boats aren’t going anywhere in frozen water (think: ice below 32-deg F). The CCA spec is of little value for boats, except maybe to compare bats.<br /><br />Someone else can weigh in what the benefits of recharging your bat asap after trolling.

 

[nightvision]

Re: battery question

Like Oz said, the slower the discharge, the more amps a battery will cough up. The std spec for a/hr is based on a 5% rate of discharge, or 20-hrs of discharge (20hrs x 5% = 100% discharge). At 5% you get a reasonable amount of energy for the greatest length of time.<br /><br />There is a curve for other rates of discharge. This becomes important when using limited battery resource for high-amp demands, like trolling motors and house banks. Manf of quality bats, like your Trojan, publish the discharge curves for their bats.<br /><br />Aldo is correct, there are more specs for a battery than you can shake a stick at. They go on for pages and pages and pages. A couple of my personal favs are ‘float life’ - how long before a bat dies if left on a float charge, and ‘short circuit potential’ - how many amps would a bat cough up if it had theoretical unlimited capacity and you dropped a wrench across the posts.<br /><br />Nightvision – you said the manf recommended a 105a/hr battery. We talk about a battery’s capacity based on that 20-hr discharge rate. Common group-31, and group-27 bats are around 105a/hrs. Your Trojan (excellent battery, btw) is 85a/hrs…that’s about right for a group-24 battery, and some gel group-27.<br /><br />Group numbers are a std for the physical ‘fit’ size (H x W x D) of a battery and have no reference to a bat’s capacity, tho bigger obviously should imply more capacity. So all group-24 batteries will ‘fit’ in the same space, all group-27 bats will fit in the same space, etc. Based on what the manf says, you want a minimum of a group-27 battery, a group-31 would be better if it will fit on your boat.<br /><br />The last pair of specs in your post refers to the batteries ability to cough up very high-amps at a couple diff temps. They are commonly referred to as CCA (cold cranking amps), what a bat can deliver for vehicle starting applications at 0-deg F, and MCA (marine cranking amps) for starting boats at or above 32-deg F. MCA is done at 32-deg F because you get a bigger amp punch when a bat is warmer than 0-deg, and since boats aren’t going anywhere in frozen water (think: ice below 32-deg F). The CCA spec is of little value for boats, except maybe to compare bats.<br /><br />Someone else can weigh in what the benefits of recharging your bat asap after trolling.

 

[nightvision]

Re: battery question

Hi all,<br />I looked up the specs for my trolling motor and it said Max AMP Draw is 42. Will my group 24 be able to to handle this motor and about how long will it last. If I nee a new one, do you recommend a group 27 or 30?<br /><br />sorry for the repeat post above.

 

[18rabbit]

Re: battery question

What you are asking is a ‘fit’ question, i.e., what ‘group’ size should you get. What the manf is recommending, and what I am thinking is based on the amps you need, not the physical size of a battery.<br /><br />What do you need, how long do you want to troll around in the sun? From your answer we can work backward to the a/hrs you need and then the group/size of the battery(s) to get those a/hrs. Note the little ‘s’ on “battery(s)”.<br /><br />Here’s your battery, from trojan-batteries.com:<br /><br />Group: 24<br />Type: 24TM (marine & RV dual purpose)<br />Volts: 12<br />Mins @ 25amp load: 135 minutes<br />Mins @ 75amp load: 34 minutes<br />CCA: 550<br />MCA: 675<br />5hr rate: 66a/hrs<br />20hr rate: 85a/hrs<br />weight: 44lbs<br /><br />You can play with the battery you have, but you’ll get less than 1-hr of trolling from with a 48amp load.<br /><br />When you replace that bat, I suggest true deep-cycle battery(s), either a Trojan group-30H, type SCS225, 130a/hrs, 66lbs, or a couple group-27s, type SCS200, 115a/hrs each (230a/hrs total), 60lbs each (120lbs total). Two group-27 bats in parallel will give you 230a/hrs to work with, of which 115a/hrs are useable.<br /><br />If you want to go with AMG bats the Trojan group-4D, type 4D-AGM will give you 165a/hrs, weights 115lbs. And don’t overlook the NorthStar Dual-Pro Lightening batteries for trolling. They can go to 100% discharge and bounce back, for about 400 or 500 cycles. Only take them to 50% discharge and they might outlive your trolling motor.<br /><br />http://www.cabelas.com/cabelas/en/templates/product/horizontal-item.jhtml;jsessionid=GPOSA1R4EJ3MXTQSNOFSCO4OCJVY2IWE?id=0014373015306a&navCount=0&cmCat=srchdx&cm_ven=srchdx&cm_ite =srchdx&CM_REF=http%3A%2F%2Fwww.google.com%2Fsearch%3Fhl%3Den%26lr%3D%26q%3Dbattery%2Bdual%2Bpro%2Blightning&_requestid=36800

 

[nightvision]

Re: battery question

Hi all,<br />Thank you very much for all the information. I think I will need to get a new battery. I appreciate your input.