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FWC factory twin battery parallel hookup question

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#1 pollux

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Posted 23 July 2017 - 02:25 AM

The following photo was taken from FWC's operation manual.

 

The two batteries are hooked up in parallel. It shows the charging cables all connected to one battery.

 

my Eagle camper's batteries are connected this way by FWC.

 

Is this setup correct?

 

I think all the negative wires should connect to the other battery.

 

ny2w2Z.jpg


Edited by pollux, 23 July 2017 - 02:47 AM.

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#2 pollux

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Posted 23 July 2017 - 02:33 AM

This video show the battery connected in parallel. External cables are connected on either side of the battery group.

 

 https://youtu.be/kd0qwLE5aNI

 

and this photo shows positive and negative wires connected to separate batteries 

 

maxresdefault.jpg


Edited by pollux, 23 July 2017 - 02:39 AM.

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#3 rando

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Posted 23 July 2017 - 03:14 AM

Technically you are correct, the positive leads should be connected to one battery and the negatives to the other.   Practically speaking in an application like this (relatively low current, short leads) it probably doesn't matter.   If you wires are long enough, there would no harm in moving either the positive or negative leads to the other battery.


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#4 PaulT

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Posted 23 July 2017 - 04:52 AM

One difference to keep in mind between the two photos is orientation of batteries.

First photo shows left battery positive at bottom and right battery positive at top.
Second photo shows both batteries positive at bottom.

Another thing to keep in mind is inconsistency of cable colors.

Top seems to be consistent in use of red for positive and black for negative.
Second uses black for both positive and negative with one red wire on positive.

They both appear to be 12v batteries wired in parallel.
Go to Harbor Freight, Home Depot or other store, buy a DMM and determine voltage polarity to put your mind at ease. One lesson to be learned here is that FWC used common color coding and the video did not. The DMM tells you for sure if a wire is positive or negative. Learn to use and trust your instruments

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#5 pollux

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Posted 23 July 2017 - 06:05 AM

Ignore the wire color issue, this diagram by others should be more clear.

It is apparent that FWC's wiring is different.

 

12-battery-diagram.gif


Edited by pollux, 23 July 2017 - 06:10 AM.

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#6 ntsqd

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Posted 23 July 2017 - 02:22 PM

That diagram, as Rando pointed out, is the preferred wiring design for a battery bank of any size. A survey of large battery banks will find them wired this way. In a pop-top I would do it the same way because I'm me, but I agree with Rando that it not being done that way probably isn't a big deal.


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#7 Miketeleskier

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Posted 01 August 2017 - 04:05 AM

The hook up looks OK to me.  However, I strongly suggest that a knife switch or an inline fuse be put between each battery and the camper wiring.  That would allow the two batteries to be used together or one at a time.  If one goes bad (when one goes bad), the bad one will establish the maximum capacity of the system so that neither will hold a charge.


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#8 Jack

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Posted 04 August 2017 - 10:42 PM

The best solution is to go with two 6V batteries in series. AGM golf cart batteries are a good buy due to the volume.

 

If you have one battery in parallel go bad, it will quickly draw down the good battery. The most common failure mode is a failed cell in a battery, creating a lower voltage that causes the good battery to "charge" the bad battery. Finding this out in time to prevent significant damage to the good battery is not likely.

 

Since batteries loose capacity (amp hours) somewhat differently over time, the better battery in parallel will be drawn down a bit faster than the other. This is not  major, maybe a few percent off the life of the batteries.


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#9 Squatch

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Posted 05 August 2017 - 04:08 PM

The hook up looks OK to me.  However, I strongly suggest that a knife switch or an inline fuse be put between each battery and the camper wiring.  That would allow the two batteries to be used together or one at a time.  If one goes bad (when one goes bad), the bad one will establish the maximum capacity of the system so that neither will hold a charge.

 

Another option is a marine battery switch. These wire the cables into it parallel. You can choose to charge either or both batteries or disconnect both from the camper. This allows you to keep one battery charged in reserve in certain circumstances that might need that.

 

https://www.westmari...ASABEgLjfvD_BwE


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#10 fwctaco

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Posted 06 August 2017 - 06:42 PM

From a circuit theory perspective, connecting positive out to one battery and negative out to the other battery only matters when connecting batteries in series.  There is a negligible amount of resistance added by the wires and connections to the second battery, but it will not affect operation, and when wired either way, the resulting circuits are equivalent.

 

AFAIK, the newer FWC models already include a master battery shut off switch.  I would not bother adding a switch or fuse for each battery as it is relatively easy to disconnect one of the batteries from this setup by simply removing the wires, and you are probably replacing both batteries at that time unless one battery turns out to be defective early on.


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