Geaux Time Posted January 5, 2017 Report Share Posted January 5, 2017 Might be a silly question but I don't know the answer. I am getting ready to install a new to me trolling motor. I'm upgrading to a 24V unit. I have a dual purpose group 27 battery that I was using for my old 12V trolling motor. Can I keep this one and just add another smaller group 24 battery next to it? I have Hobo's diagram that I will follow when I wire everything up. Just not sure about diff battery sizes and how or if that makes a difference. Thanks to all Link to comment Share on other sites More sharing options...
JEM Posted January 5, 2017 Report Share Posted January 5, 2017 It would work, but I would keep the batteries the same size if it were me. Both group 27, or both group 24. Link to comment Share on other sites More sharing options...
FROZEN Posted January 5, 2017 Report Share Posted January 5, 2017 1 hour ago, JEM said: It would work, but I would keep the batteries the same size if it were me. Both group 27, or both group 24. JEM is exactly right. Not a silly question. Batteries are confusing. Wiring up and installing even more so. First, follow your owners manual and its recommendations. If a used TM, download the manual and installation instructions from the web. I'm pretty sure not adhering to it will void any warranty that is left. In addition to what JEM said, exactly same physical size defined by the group number, you need the same type, I.e. gel, lead acid, or AGM. On top of that, the battery pair needs to be the same electrically. Same CA, same AMP hours, etc. Mismatched pairs will ruin both when charging in a 24v setup. The instructions will also tell you how to incorporate a cranking battery. Good luck with your purchase! Link to comment Share on other sites More sharing options...
Geaux Time Posted January 6, 2017 Author Report Share Posted January 6, 2017 Thanks! Next question...the manual states to use any lead acid battery with at least a 105amp hr rating. Since I'm using a 24V system, will two group 24's each having a 75amp hr rating suffice? I quickly browsed online and it looks like the group 24's and 27's go up to 90-100amp hr rating. Saw some 31's with 105amp hr. That is a BIG battery. Hard to imagine I would need two of those guys for an iPilot 70lb TM?? Also, I know AGMs have been discussed on here frequently but there seems to not be a consensus on their use for TMs. It's still lead acid correct? Link to comment Share on other sites More sharing options...
SCFD rtrd. Posted January 6, 2017 Report Share Posted January 6, 2017 Are you sure the manual states 105 amp hr. rating. Usually they require a certain reserve capacity rating. You don't need a group 31, either the 24 or 27 will work, however the 31 will last longer when you use the TM a lot. I have a 24 volt TM and use group 27's and they work just fine. I do charge mine every night after use. I also switched from lead acid to AGM. Got tired of adding water. The AGM's are maintenance free and maintain a charge longer when sitting idle. Sam's Club has good deals Duracell AGM. Link to comment Share on other sites More sharing options...
hurricane Posted January 6, 2017 Report Share Posted January 6, 2017 2 different batteries is not optimal but will work. You will basically only get the power and life of the weakest battery. AGM batterys are the best, they provide more power, last longer and charge faster. No, putting batts in series doesn't increase capacity (amp hr.). But think it says that 105 is recommend for best results, be fine just might not run as long as MK says. Link to comment Share on other sites More sharing options...
rubble Posted January 6, 2017 Report Share Posted January 6, 2017 In talking to the guru at Stealth 1, he says the best thing to do is buy the el cheapo batteries from Walmart and use a dc charging system. In his opinion the only other battery to use if you are wanting to spend the money is a single lithium battery to handle your deep cycle TM needs. I was in the market to get a cranking battery and 3 new TM batteries. I had the Stealth system installed and followed his advice but purchased Exides from a family member. It was worth it to me to pay a little more for the Exides for zero hassle if I return. I hate going in Walmart and dealing with them. Link to comment Share on other sites More sharing options...
rubble Posted January 6, 2017 Report Share Posted January 6, 2017 My previous wet cell Exides worked fine for about 4 years. Year 5 they were not holding a charge as well because one of the batteries was about dead. Link to comment Share on other sites More sharing options...
Geaux Time Posted January 6, 2017 Author Report Share Posted January 6, 2017 Thanks All. Yes, it says for "best results" use batt with at least 105ah rating. Guess I'll go with group 24 or 27 AGMs. My plan is to also install an on board charger as well so I'm not lugging them around before and after a trip to charge them. Appreciate the help as always! Link to comment Share on other sites More sharing options...
JEM Posted January 6, 2017 Report Share Posted January 6, 2017 That is a good idea! An onboard charger will make your life better, and a quality onboard charger will make your battery lives better. I would highly recommend a Powermania 3 bank charger. It is user selectable for the different types of batts and a lot of the high dollar custom bay boat manufacturers have switched to Powermania. A very quality charger for a little over $200. You won't regret it! Depending on how you fish, I would recommend at least the group size 27 batts for a 24V motor. Link to comment Share on other sites More sharing options...
Geaux Time Posted January 6, 2017 Author Report Share Posted January 6, 2017 I'll go to their website to check out that charger. Do you know off hand whether you can run a three bank and link the cranking battery up to it as well? Link to comment Share on other sites More sharing options...
Wanaflatsfish Posted January 6, 2017 Report Share Posted January 6, 2017 18 hours ago, Geaux Time said: Might be a silly question but I don't know the answer. I am getting ready to install a new to me trolling motor. I'm upgrading to a 24V unit. I have a dual purpose group 27 battery that I was using for my old 12V trolling motor. Can I keep this one and just add another smaller group 24 battery next to it? I have Hobo's diagram that I will follow when I wire everything up. Just not sure about diff battery sizes and how or if that makes a difference. Thanks to all check the post I made on battery chargers and information.... 1.) it's recommended to always use the same two size (and even makes) if possible batteries for optimal life 2.) They recommend even the same storage locations 3.) Charge immediately upon return from the water 4.) I would keep the older battery for the your "house" and get two series 27's as mentioned for a 24v system. 5.) AGM are the "preferred" but $$$ vs. water filled....but, a good DEKA or Interstate 27 will do the same as any AGM, just need to check the water more frequently. 6.) set up a good "blue seas brand" 1/2/all switch and you'll be fine for power and start up in the event you rundown the "house". dc Link to comment Share on other sites More sharing options...
polliwog Posted January 6, 2017 Report Share Posted January 6, 2017 Just remember when you are using an on board charger you need to have good air circulation to keep the charger from being over heated. I wrecked one in the console with the door closed during the summer. Link to comment Share on other sites More sharing options...
craSSh Posted January 6, 2017 Report Share Posted January 6, 2017 4 hours ago, Geaux Time said: I'll go to their website to check out that charger. Do you know off hand whether you can run a three bank and link the cranking battery up to it as well? Yes. I have a Guest 3 bank and it is hooked up to both TM batteries and a cranking/house battery. Link to comment Share on other sites More sharing options...
wayne Posted January 7, 2017 Report Share Posted January 7, 2017 The size of your boat comes into play also. . I didn't catch what boat we are talking about. . Bigger boat , bigger batteries! Two different size baterries is not as big a deal as one old and one new, the older one will fail and take the new one with it. . Link to comment Share on other sites More sharing options...
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