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Old 05-22-2021, 04:20 PM   #1
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Transition from 12v to two 6v

We have a Wolf Pup 17JG and are switching from one 12v battery to two 6v golf cart batteries. Iím connecting them in a series to get 12v. Is there anything else I need to do with this transition? Thank you!
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Old 05-22-2021, 07:36 PM   #2
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Sounds like you got it. Just be sure to hook the positive lead going to the trailer on the positive terminal of one battery and the negative lead going to the trailer to the negative post of the other battery.
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Old 05-22-2021, 08:20 PM   #3
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Originally Posted by Kiley70 View Post
We have a Wolf Pup 17JG and are switching from one 12v battery to two 6v golf cart batteries. Iím connecting them in a series to get 12v. Is there anything else I need to do with this transition? Thank you!
I would suggest you use at least a 6ga wire to interconnect the two batteries, 4ga would be better. But nothing less than 6ga.

Just my two cents...
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Old 05-22-2021, 11:41 PM   #4
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Thanks guys! I ended up using a 4ga connection and seems to work fine. ��������
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Old 05-23-2021, 04:51 PM   #5
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Thanks guys! I ended up using a 4ga connection and seems to work fine. ��������
4ga is great for two batteries. If you ever increase to 4, 6, or more batteries, and then you'll most likely install an inverter too, that will be the time to reevaluate your wire size needs. Congrats on a job well done. How about a picture or two of your project?
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Old 05-23-2021, 05:32 PM   #6
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I switched mine a couple of years ago. It made a big difference.
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Old 05-23-2021, 07:53 PM   #7
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Always wondered why people do this...

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Originally Posted by baint View Post
Sounds like you got it. Just be sure to hook the positive lead going to the trailer on the positive terminal of one battery and the negative lead going to the trailer to the negative post of the other battery.
I always wondered why people do this. The alternative seems to be electrically equivalent.
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Old 05-24-2021, 02:43 PM   #8
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Larry-NC, I am confused about what you are saying. Are you saying pos lead to neg batt terminal and neg lead to pos batt terminal are equivalent to proper connection?
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Old 05-24-2021, 03:36 PM   #9
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I always wondered why people do this. The alternative seems to be electrically equivalent.
Larry, I couldn't begin to succinctly explain it. Take a look at this article, I think it does a good job of explaining it.

https://caravanchronicles.com/guides...s-in-parallel/

But also realize the article talks about two 12v batteries in parallel.

The OP is using two 6v in series to make 12v. He has to take the positive from one battery and the negative from the other battery to get 12v.
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Old 05-24-2021, 04:15 PM   #10
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Thinking this all the way through

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Originally Posted by Mikec557 View Post
Larry, I couldn't begin to succinctly explain it. Take a look at this article, I think it does a good job of explaining it.

https://caravanchronicles.com/guides...s-in-parallel/

But also realize the article talks about two 12v batteries in parallel.

The OP is using two 6v in series to make 12v. He has to take the positive from one battery and the negative from the other battery to get 12v.
You are correct. My comment does not apply to the OP's question, since he is using two six-volt batteries in series. My comment applies to the situation with two twelve-volt batteries in parallel.

To keep the discussion clear, I've attached a drawing. The author of the cited article argues that batteries in parallel should be connected as shown in Figure B, not Figure A.

In the article you cited, the author argues that the second battery will see a lower charge voltage because of the voltage drop in both cables. He even suggests that the difference could be as great as half a volt.

He fails to take into consideration a basic fact about flooded lead acid batteries--that as the charge cycle completes, less and less current is applied to the battery. As the pair of batteries charges, the voltage drop decreases until, at the point where the batteries are fully charged (float voltage), there is no difference in the voltage at both batteries. The result is that the second battery becomes fully charged after a very, very short time after the first one.

The author of the cited article suggests that the voltage drop across the extra cable on the second battery is 0.5 volts. Let's see if this is realistic. Suppose that AWG 4 cable is used and that the cable is 1 foot long. The resistance of AWG 4 wire is .2485 ohms per hundred feet (Electrical Wire Gauges). That's 0.002485 ohms for a foot of wire. Exactly how much current would you have to draw to drop half a volt in that foot of copper wire? I=V/R=0.5/0.002485=201 Amps! A WFCO 8955 converter can't supply that much current--only 55 Amps. The example is inflated a bit to make the author's point. And there's not much in a camper that draws a sustained 200 Amps.

Remember the audio fanatics who insisted you had to run AWG 8 to your four watt speakers or the audio would be bad--and insisted that he could hear the difference?

The author also argues that the second battery is delivering less power than the first because of the extra resistance in the path. It's true, but for every bit less you're drawing from the second battery, you're drawing more from the first one. When the load is turned off, the second battery will actually charge the first one as their voltages become equal.

Mike, thanks for the mental challenge. Write back if there's anything that's not clear.
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Old 05-24-2021, 04:45 PM   #11
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You are correct. My comment does not apply to the OP's question, since he is using two six-volt batteries in series. My comment applies to the situation with two twelve-volt batteries in parallel.

To keep the discussion clear, I've attached a drawing. The author of the cited article argues that batteries in parallel should be connected as shown in Figure B, not Figure A.

In the article you cited, the author argues that the second battery will see a lower charge voltage because of the voltage drop in both cables. He even suggests that the difference could be as great as half a volt.

He fails to take into consideration a basic fact about flooded lead acid batteries--that as the charge cycle completes, less and less current is applied to the battery. As the pair of batteries charges, the voltage drop decreases until, at the point where the batteries are fully charged (float voltage), there is no difference in the voltage at both batteries. The result is that the second battery becomes fully charged after a very, very short time after the first one.

The author of the cited article suggests that the voltage drop across the extra cable on the second battery is 0.5 volts. Let's see if this is realistic. Suppose that AWG 4 cable is used and that the cable is 1 foot long. The resistance of AWG 4 wire is .2485 ohms per hundred feet (Electrical Wire Gauges). That's 0.002485 ohms for a foot of wire. Exactly how much current would you have to draw to drop half a volt in that foot of copper wire? I=V/R=0.5/0.002485=201 Amps! A WFCO 8955 converter can't supply that much current--only 55 Amps. The example is inflated a bit to make the author's point. And there's not much in a camper that draws a sustained 200 Amps.

Remember the audio fanatics who insisted you had to run AWG 8 to your four watt speakers or the audio would be bad--and insisted that he could hear the difference?

The author also argues that the second battery is delivering less power than the first because of the extra resistance in the path. It's true, but for every bit less you're drawing from the second battery, you're drawing more from the first one. When the load is turned off, the second battery will actually charge the first one as their voltages become equal.

Mike, thanks for the mental challenge. Write back if there's anything that's not clear.
Thanks Larry; what you said makes sense. But I'm not sure my calculator even has that many decimal places! LOL! I though his .5v drop within 1ft was exaggerated. So maybe philosophically it's the "right way" to do it, but pragmatically it doesn't really matter. We camp on two Battleborn lithium batteries in parallel, and rarely boondock at that. Since I had to replace all the wiring because of my shunt and inverter, I wired it his way. But I don't, or can't, see any gain or loss either way.
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Old 05-24-2021, 05:02 PM   #12
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Clearly mark the Pos (+) and Neg (-) cables before disconnecting them from the current battery. RVs do not always use wire color conventions you might be used to.
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Old 05-26-2021, 06:15 PM   #13
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Pics of Project

Mikec557...

Here are a couple pics for you.
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Old 05-26-2021, 07:24 PM   #14
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Mikec557...

Here are a couple pics for you.
Wow! That looks great!
Where'd you get that battery box? I'd love to hide my two lithium batteries in something like that.

Thanks for posting the pics.
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Old 05-26-2021, 07:28 PM   #15
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Thank you! It took some searching for the box but found it at one of the dealers in Denver. I think it worked out pretty well.
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Old 05-26-2021, 07:42 PM   #16
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Thank you! It took some searching for the box but found it at one of the dealers in Denver. I think it worked out pretty well.
Looks really nice. What's the top look like? How is the top kept in place?
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Old 06-06-2021, 09:39 AM   #17
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We have a Wolf Pup 17JG and are switching from one 12v battery to two 6v golf cart batteries. Iím connecting them in a series to get 12v. Is there anything else I need to do with this transition? Thank you!


What is the advantage of using 2 6 volt batteries? We have a Wolf pup 16BHS. Based on my reading in this forum it sounds like the 12V fridge is going to drain battery quickly. I am trying to figure out what to do.
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Old 06-06-2021, 09:55 AM   #18
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"Golf cart"

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What is the advantage of using 2 6 volt batteries? We have a Wolf pup 16BHS. Based on my reading in this forum it sounds like the 12V fridge is going to drain battery quickly. I am trying to figure out what to do.
The batteries in question are golf cart batteries. These are bigger (more volume=more amp-hour capacity), and they are designed to be drawn down deeper than general-purpose batteries. If someone made a 12-volt battery with volume equivalent to two golf-cart batteries, it would be equivalent, but they don't. If they did, it would weigh over 100 lbs., be difficult to manage, and be very expensive. Golf cart batteries are something of a commodity and there is a certain amount of price competition.
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Old 06-06-2021, 10:08 AM   #19
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WOW Post 1 & 2 nailed it 100% and from there the rest just got muddied up.

if your new and looking how to do it just read post one and stop.

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