2-6 Volt Batteries In Series Instead Of 1-12 Volt (Update!! )

[MDBowHunter]

I pretty much fish a few of the reservoirs in my area and with them being eletric motors only, and sonce I can't afford the motor I want. With that being said I've been told by a few other guys that if I run 2-6s in series instead of one twelve that I would get way more run time. FYI I'm running two 55s on the transom to get around with and a 55 24volt bow mounted trolling motor for fishing. If my math is right I have it figured that I could get 6.5 hours of run time at full speed with 2-6s , now doing the same math for 1-12 it figures that I should 2.5 hours run time at full speed. Which seems to be about right, unless it's real windy then obviously I get less. what some of your thoughts on this for the guys who have done it. Thanks in advance for all the replies...

[Wayne P.]

Your math is flawed.

 

Two parallel 6V batteries is 6V. None one makes a 6V trolling motor.

 

Put them in series and you will have 12V.

[MDBowHunter]

Your math is flawed.

 

Two parallel 6V batteries is 6V. None one makes a 6V trolling motor.

 

Put them in series and you will have 12V.

I changed it to series that was just a brain fart, and your right they don't make 6volt trolling motor batteries. But they do make 6 volt golf cart batteries that are made to be charged daily and they say they can last up to 10 years.

[Wayne P.]

Some that have the 48V, 60V. or 72 V electric outboards use the golf cart 6V batteries for their amp capacity.

[MDBowHunter]

I run my 24 volt bow mount on 2-12s in series and it goes all day on two batteries, though I've never really timed how long that one actually run, plus that only runs on like half speed while fishing...

[SHaugh]

When it comes to run time, amp hours are amp hours.   So if the amp hours on your 2 - 6 volts in series is larger than the 12 volt you will get more run time.  The advantage of 6 volt golf cart batteries is that they are made very well, true deep cycle batteries, and designed to last a long time.   They will usually hold their capacity over time longer than cheaper 12 volt batteries.   So if the cost make sense then I'd go for the 6 volts.

[Way2slow]

Ok using the same 20 hour rating most deep cycle TM batteries are rated at, the Trojan T105 golf cart battery is going to be 225 Ah, which is just about twice the capacity of most group 27 DC batteries. Because of their size, they will be more efficient at the typical loads you are running so yes, if you get 2 1/2 hours out to two group 27 DC batteries you should get over 6 hours from a bank of GC batteries.

However it's going to take four GC batteries to get 24 volts. They are going to weigh approx 65 pounds each and they are not cheap. Also remember, when running series batteries, they need to be like batteries. You can't mix old with new, different sizes, or different capacities.

Also realize, batteries should be charged at 10% of their capacity, so when running a bank of four GC batteries, you are going to need a 24 volt 20-25 amp charger, an old 24 volt GC charger. Those are not cheap either.

[J Francho]

I can pretty much guarantee that it's been thought of and doesn't work. Get yourself a marine deep cycle. The only way to increase run time is to add batteries.

[SHaugh]

It's pretty easy to see if you put what you are talking about side by side...   Batteries are pretty much the same stuff no matter what voltage.  More stuff = more electricity.

 

2 of these expensive monsters of course is going to give you more electricity than 1 12 volt marine battery:

 

http://www.amazon.com/Trojan-Volt-Battery-T-105/dp/B004UJXPYU

 

but it would be just as easy and cheaper to run parallel 12 volts up to the amp hours you want.

[J Francho]

I can't think of any reasons to chuck down $1400 to run my trolling motor, lol.

[MDBowHunter]

Ok using the same 20 hour rating most deep cycle TM batteries are rated at, the Trojan T105 golf cart battery is going to be 225 Ah, which is just about twice the capacity of most group 27 DC batteries. Because of their size, they will be more efficient at the typical loads you are running so yes, if you get 2 1/2 hours out to two group 27 DC batteries you should get over 6 hours from a bank of GC batteries.

However it's going to take four GC batteries to get 24 volts. They are going to weigh approx 65 pounds each and they are not cheap. Also remember, when running series batteries, they need to be like batteries. You can't mix old with new, different sizes, or different capacities.

Also realize, batteries should be charged at 10% of their capacity, so when running a bank of four GC batteries, you are going to need a 24 volt 20-25 amp charger, an old 24 volt GC charger. Those are not cheap either.

I'm currently taking 4-12s to go most of the day, so if I could change 4-12s for 4-6s I figure I should be saving a little weight. ( But I've never weighed a 12 volt battery to see what they weigh) My batteries come out of my boat and get stored in the garage after every trip so why can't I just charge then one at a time? I only fish one day every weekend so the charging time realy ain't a biggie. I know for a fact that guys are running this setup, I'm just tryin to verify what they're telling me as these are guys I see at the ramp pretty much every weekend and not friends. I need to buy 4 new batteries anyway this year and the cost isn't superbad on the 6s, so I was thinking why not, since my batteries are getting old...

[MDBowHunter]

I can't think of any reasons to chuck down $1400 to run my trolling motor, lol.

Batteries are $150 a piece x 4 is $600, I'm buying 4 new batteries anyway so to a couple hundred more for twice the run time and a longer battery life. Seems almost crazy not to think about it

[J Francho]

The link above puts them at 350. Its your money. Sounds like you have something else going on - I get more than 12 hours on two 12v and my 80# TM on a 22' bass boat.

[Thornback]

Are you saying you will be willing to run a 12v trolling motor on 6v? I would not advise that. Two batteries of the same voltage, connected in series, will give you twice the volts but at the duration of just one battery and the same amps as one battery. If you are after duration, and have a 12v trolling motor, you need to connect two 12v batteries in parallel. That gives you 12v at the single battery amp, but twice the duration of one battery. The parallel connection is the same as you use when you jump start a car. Because you are doing electric motors only I would also install a meter on the battery so I could tell how much juice I had left at any given time.  

[LunkercityVB]

The group 27 deep cycle weigh roughly 50lbs each depending on manufacture, the golf cart 6v weigh roughly 65-67lbs. Do the math but wouldnt be too much heavier.  

[MDBowHunter]

https://m.interstatebatteries.com/product/2147384911-4195161613-4195237385-4195237384-2147384722-2147384898-4195161580-4195161608-4195161578-4196125068-4196125103-2147384903/GC2-XHD-UTL

I have a friend that owns an auto parts store and will give them to me at cost since I take him fishing, so the price should be better then that

Two batteries in parellel will double the amps and could possibly catch fire, running them in series doubles volts so you would have the 12 that you need. The extra run time comes from the 6 volt battery, check out the amp hour rating versus the 12.

[MDBowHunter]

My reasoning for doing this is for me to get wher I'd like to go in the reservoir that I primarily fish I'd need to add 2 more to my already 4 so that would make 6-12s that Id be carrying. If I can double the run time just by switching over to 6s plus stay with 4 batteries instead of 6-12s that would be awesome.

I'm running a 18' extra wide Jon boat with home built decks so the boat is heavy and eats batteries while we're traveling. Like I said when I'm fishing Im running the bow mount, and they last all day.

[SHaugh]

When it comes to batteries you can almost do it by weight.   four 65 lb 6 volt batteries are going to give you more juice than  four 55 lb 12 volt batteries.   The benefit that you will derive from the golf cart batteries is that they are made from better stuff... which is why they cost more.   6 months down the road the 6 volts might retain more of their capacity than the 12 volts because they are better batteries.  

[MDBowHunter]

Also this boat is set up just the couple reservoirs that I fish with it. Here in MD if we use our boats in the reservoirs here we have to sign stating that the boats will be in no other bodies of water due to them d**n zebra mussells

[SHaugh]

Reading your post again I don't think you're doing the math right.   Each 12 volt battery gives you 105 amp hours.  Or 4 batteries x 105 = 420 total amp hours.

 

Each 6 volt battery pair wired in series will yield 225 amp hours , so you will have a total of 450 amp hours with four 6 volt batteries.

 

the difference between the 2 is only 30 amp hours.  You will not double your run time you will only gain 7% total capacity or run time.

[Way2slow]

Yes, you are correct in your idea that four GC batteries will give you a longer run time than most any bank of four 12 volt. You also have to look as the Ah rating on the GC batteries, the Trojan T105 is what it says and is one of the most common in industrial equipment, I have installed a bunch, and serviced bunches more. You can buy cheaper, you can usually find Trojans cheaper than that Amazon price. Just be aware, cheaper sometimes means lower quality, and lower capacity.

You mention getting 10 years out of them, well maintained, and for your application, you might, but I would not bet on it. Six to eight, and eight is a stretch, is much more common to see. To get that life from one, a high quality charger is critical. Does not matter if you are charging one at a time or all four in series, you still need a charger that deliver 10% of the capacity, or 20-25 amps at 6, 12, or 24 volts, depending on how you connect it. You also want a charger that is not going to put more than about 7.3 volts per battery into them.

If you charge a battery too slow, it can stratify, the acid and water separate, with concentrated acid at the bottom and a much weaker solution at the top. Charge them at too high of voltage and the plates can be damaged. So, if you are going to spend big bucks for batteries, don't kill them by skimping on the charger. Check around on ebay and golf cart shops, you might find a used 24 volt GC charger at a reasonable price.

I think I have a couple, but they've been sitting around for at least 10 years so I would not put much hope in the capacitors still being good.

Another thing you need to be aware of trying to do one at the time, when a battery is below about 80% charge, it will start to sulphate in less than 24 hours, so you would not want a long delay time between the first and fourth battery.

[00 mod]

My suggestion is to get th 12v batteries AND a bigger TM.  The harder your tm has to work, the longer you have to draw.  I have a similar boat, extra wide jon with decks and erveything.  I have a 80lb 24v TM and I can go all day in current without using half my battery life.

 

Jeff

 

[Rented Mule]

yes, it has been thought of before, and yes it works.

 

If'n you been around long enough, some of you may remember in the early 80's a lot of boats were running what was called the Bass one system. 2  6 volt golf cart batteries. I had one of the first 18' Stratos ever  made, it came rigged with the bass one system. I used 2 interstate 6 volt golf cart batteries and a cranking battery as well. That was a great system, I ran the boat that way for at least 25 years. Never had a problem, and I fished a lot of electric motor lakes only. At that rate, I went through batteries about every 2.5- 3 years.

 

But over the years, the popularity of that system faded, but I'd run the same set up again in a minute.

[J Francho]

Running 4 to 6 batteries for today's 24 and 36 volt systems is pretty unpractical. That's why bleeding edge tech for this is in lithium.

[SHaugh]

I've wondered about this problem before.   I have a 30 lb motor that I can run all day on an $80 Walmart battery... 6 - 8 hours trolling on speed 2.  And still have plenty of battery left to get back to the ramp.    I bought a 40 lb motor and  doing the same thing on the same lake it only lasted about 3 hours and had totally drained my battery dead. (Which is why I remember rowing back to the ramp so well)....

 

So the question in my mind is why is a 30 lb motor so efficient ?   Questions like:   Why not try a bank 4 30 lbs 12 volt motors instead of a big 24 volt motor ?    Why not just buy a 30 lb motor for your fishing maneuvering and leave the big motor for only traveling ?       Some ideas to think about...