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Old 12-13-2017, 09:59 AM   #1
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Tap onto 6V batteries in parallel

Hi All,

I have 2 sets of 6V batteries in parallel (2 in each battery box). The PO had 5 positive leads off one battery in the 2nd battery set. Can you tap off the positive from the 1st box? That was a finding by the surveyor (too many leads on one post).

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Old 12-13-2017, 10:04 AM   #2
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Yes but it isnít the proper way. Run a lead to a terminal strip and then you can tap off the terminal strip as much as you want
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Old 12-13-2017, 10:07 AM   #3
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Originally Posted by Dave_E View Post
Hi All,

I have 2 sets of 6V batteries in parallel (2 in each battery box). The PO had 5 positive leads off one battery in the 2nd battery set. Can you tap off the positive from the 1st box? That was a finding by the surveyor (too many leads on one post).

Dave
Yes, if the loads are reasonable. If the two sets of 12V batteries are truly in parallel, and have a large enough cable connecting them, then the two positive posts are essentially at the same "potential" and are all one battery.

Again, this would not be true if the loads are large, e.g. >0.25C, in which case it is not a black or white threshold, either.

Theorists may argue minutia, but for all practical purposes, yes.
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Old 12-13-2017, 11:35 AM   #4
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Best solution is to install positive and negative buss bars and connect your 12 volt pairs of golf cart batteries to them. Then all of your other connections can be made to the bus bars. Blue Sea makes these.
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Old 12-13-2017, 11:50 AM   #5
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+1
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Old 12-13-2017, 09:32 PM   #6
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Best solution is to install positive and negative buss bars and connect your 12 volt pairs of golf cart batteries to them. Then all of your other connections can be made to the bus bars. Blue Sea makes these.


^^^^ This.

Not only does it ensure that you are getting good conduction at your battery post, but it cleans up the wiring tremendously. While you are at it, I would make sure that you have a fuse on the positive cable from the battery to your new buss bar.
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Old 12-15-2017, 07:30 AM   #7
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NAPA and others sell "military " battery connections.

These are about $5.00 each and square with 2 bolts thru each one.

They therefore can take 4 wires each with no problem, a terminal end under each bolt head or nut.

The good news is the wire terminal will touch the cast unit which passes the current with the least amount of resistance, especially compared to a steel or SS bolt with poor ampacity.

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Old 12-15-2017, 07:40 AM   #8
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To do the same I plan to use something like this



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Old 12-15-2017, 09:16 AM   #9
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To do the same I plan to use something like this



L
No offense, but a poor choice. The compression type lug doesn't adequately support the wire and provides only a single point of contact. If the connection ever loosens, the wire will be subject to arcing or shorting by coming apart. Minimal isolation between fused conductors. Far better to use a bus bar where a lug is crimped onto the wire and that is attached to the bus bar. Check to see if the pictured device meets ABYC standards, I think you'll find it does not. Go with Blue Sea hardware, far better.
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Old 12-15-2017, 09:53 AM   #10
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Quote:
Originally Posted by Dave_E View Post
Hi All,

I have 2 sets of 6V batteries in parallel (2 in each battery box). The PO had 5 positive leads off one battery in the 2nd battery set. Can you tap off the positive from the 1st box? That was a finding by the surveyor (too many leads on one post).

Dave
Add some positive and negative distribution busbars close to the positive and negative battery bank take off points, as shown below.




Ideally there are only a few things that get connected directly to the batteries themselves;

#1 Other series or parallel batteries.
#2 Positive and Negative System Take Offs
#3 Battery Temp Sensors (negative post or side of case only)
#4 Voltage Sensing

Everything else, and unless you have LiFePO4 voltage sensing can be at the distribution busbars, should be connected to the positive or negative distribution buses. Keep these busbars as close to the bank as is possible and the positive lead should have over current protection within 7" of the positive terminal. For fusing off the distribution bus there are many options including MRBF fuses, fuse distribution blocks etc.

The Marinco Pro-Installer line are quite good and they come standard with a cover for positive distribution. Just choose how many 5/16" or 3/8" studs you need. Generally you may have an inverter/charger, DC panel, windlass, thruster, alternator, charger, solar, wind, bilge pumps, head, VHF, etc. etc. all connecting to the distribution buses.






Four 6V batteries for a 12V bank in a series / parallel configuration should ideally be wired as shown..



When you add positive & neg distribution busbars it would look more like this:
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Old 12-15-2017, 11:49 AM   #11
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Post 10 shows the correct way to do things. Donít over look the fact that all the wiring and terminal connections are symmetrical.
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Old 12-15-2017, 11:53 AM   #12
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To do the same I plan to use something like this



L
Oh No. Button head hex, even/especially stainless are a bad choice. Bolts and ring terms for vibrating things like boats.
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Old 12-15-2017, 11:54 AM   #13
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Ditto...The post by CMS is the way to do it.
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Old 12-15-2017, 11:58 AM   #14
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Duly noted, thank you to fix my insanity

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Old 12-15-2017, 04:22 PM   #15
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Tap onto 6V batteries in parallel

Quote:
Originally Posted by Dave_E View Post
Hi All,

I have 2 sets of 6V batteries in parallel (2 in each battery box). The PO had 5 positive leads off one battery in the 2nd battery set. Can you tap off the positive from the 1st box? That was a finding by the surveyor (too many leads on one post).

Dave


How about this alternative?

Name:  74A9A3D9-F0F7-4D65-AF49-3E1701FDFE99-12670-000007388EC012EF.jpg
Views: 338
Size:  51.2 KB

http://www.boatsteer.com/battery.html
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Old 12-15-2017, 04:28 PM   #16
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Interesting. solves some problems.

But, Fail for me. Too much weight hanging off of a piece of lead.
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Old 12-15-2017, 04:29 PM   #17
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And what, give every wire its own fuse, no way to quickly isolate the bank?
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Old 12-15-2017, 04:35 PM   #18
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Depends how its wired.

Not every boat needs to be wired like a space craft.

As long as circuits are fused or protected with CBs....job done.

some people can still figure out how to isolate circuits if there is an issue.... pull hard, wire cutters, bolt cutters, machete, etc...

Boats need only be safe, no more complicated or adorned than the owner wants.

May not be pretty or fancy or expensive....but perfectly suitable as long as certain things are covered.
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Old 12-15-2017, 04:38 PM   #19
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Originally Posted by FF View Post
NAPA and others sell "military " battery connections.
...
More images for military battery terminal
Your links worked, but all the images show up as broken here.

I suspect due to those crazy long URLs.
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Old 12-15-2017, 10:37 PM   #20
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And what, give every wire its own fuse, no way to quickly isolate the bank?
Good points.

On my sailboat when I redid my batteries I ended up with 4 x 6v golf cart batteries. I had limited space to work with. I used this terminal fuse block from Blue Seas to add two terminal fuse blocks to the positive terminal. The voltage sensor wire ended up on the battery terminal, then on one fuse block was a #1 cable to main 12 panel, and the other fuse block had one smaller cable from the alternator and another from the charger. This solved some space issues as well as providing appropriate fuse protection for the wiring.

It would have been a bit better to run one large cable from the battery to a positive buss bar, but this was what I could fit.

http://www.go2marine.com/docs/2/4/7/2/247249F-f.jpg
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