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Im looking to change from a 24 volt trolling motor to a 36. Can I get away with only 3 batteries or should I go to four? I have an 08 Cougar FTD. I have a radio and two graphs. I usually dont fish with the radio on, but will three batteries be ok while running a graph and a trolling motor all day?
I dont like the idea. The newer DFI motors do _not_ appreciate your attempts to crank them with less than ideal battery voltage. If you fish in current for a couple of hours, you may well discover that you cant crank your motor to get back to the ramp. Id either stick with the 2×12 setup and run 24v, or I would add a third TM battery. In my first boat I ran everything off of one battery and had good success. But if you are running a DFI motor they really dont like low voltage. Trolling many miles back to the ramp is the pits. Ive done it more than once for other reasons… I also think you will see less interference on your sonar units by using separate power supplies for them as opposed to the trolling motor. Just make sure the grounds are tied together properly.2008 Pantera Classic2014 Mercury Pro XS 200
The three battery system should be fine for you if you run a large cranking battery and not a small one. We have voiced our thoughts on this many times here.
I struggled with this issue as well and decided to go with the four battery set up with the cranking battery being that Sears Premium battery that provides 1150 CCA. Several that i spoke with said the three battery system would do fine, but I decided to go with four batteries for peace of mind. There is plenty of room in the bilge area of the Puma and Cougar for four batteries. Good luck, Corky
a no start after fishing a good part of the day. Easy change over and piece of mind and not allot of money. Actually found a nice 1 bank maintainer and was able to leave my 3 bank charger as is……
while I am sure you guys know what you are doing, Ive been in electronics for a +long+ time, and the idea of hooking up dissimilar batteries in series makes my skin crawl. I dont even replace a single TM battery when it goes bad, I replace both at the same time, for the same reason… You really want the same internal resistance on all 3 batteries when they are hooked in series.2008 Pantera Classic2014 Mercury Pro XS 200
research. If necessary I will make the change but seems more in performance then issue over causing issues but I could be wrong. Seems that dissimilar batteries might cause performance issues over time…….I wil do some research… Thanks If a plane can handle it….I found this seems to suggest no issue except the possible damage to the weakest battery. Remember my starting battery is isolated from the 3 trolling batteries “Connecting different VOLTAGE packs in parallel is the only scenario presented here that has the potential for a fire. This is because the higher-voltage pack will force charge the lower-voltage pack at a very high rate, causing heating in the pack and/or an overvoltage situation in one of the cells. Where you will NOT cause a fire: 1. Connecting different voltage packs in SERIES. This is a common practice used to achieve high-voltage packs for larger planes, such as a 6S and a 4S connected together to make a 10S. 2. Connecting same-voltage, but different CAPACITY packs in parallel. This works, but is not a recommended practice. Theoretically, there shouldnt be any technical reason why it wouldnt work, as long as you keep your draw below the combined capacity of the two packs. Nothing bad has happened on record, but LiPolys are expensive and most people simply cant or dont want to afford to lose a pack to some unknown issue with using mismatched packs in parallel. 3. Connecting different CAPACITY packs in series. The worst thing that can happen here is the weaker pack gets damaged or destroyed by being overdrawn. If care is taken to base decisions on the weakest link in the chain, theres no technical reason it wont work. Once again, however, LiPolys are expensive and people generally do not want to take the risk of running into an unknown problem with such a configuration. “Last edited by Mark5795 on May 23rd, 2009, 12:48 pm, edited 1 time in total.
We have used the three battery system for over a decade since the production of the Tour 767 & 772 MotorGuide trolling motors. It will work fine if you have a larger cranking battery and the drain will not be any different there.
The biggest issue I have seen is that if you connect 3 batteries in series, where one is a lower AH capacity battery, then that battery can be destroyed during use. Not explosively destroyed, but it can actually become reverse-charged which will render it useless. Ive seen this more often in NiCd battery packs where a single weak cell in a 4.8v battery pack (4 1.2v NiCd batteries in series) will go into reverse charge and you now are left with a 3.6v pack. Worked on a silly truck a few years ago, where it used 3 12v batteries in series to operate hydraulic pumps to make the thing jump, tilt, etc. He thought his pumps were going bad, but it turned out to be one battery that was at below zero volts, and acting like a big resistor between the other two severely limiting current draw ability. Hence my reluctance to do anything but replace all series batteries as a group.2008 Pantera Classic2014 Mercury Pro XS 200
The same issue OT57 could be in any system which requires using the batteries as connection point. Thus the pass through for voltage gains. If your four cell flashlight has one of those 1.5 volt D cells fail, then it also renders the flashlight useless. That situation exists unless you have a 36 volt pack, which would then be suceptible of failure, only then you only have one to replace. Which brings up a whole nother topic and something for the future. BCB
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