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  #1  
Old 12-18-2016
CaptainPat CaptainPat is offline
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Default LONGER BATTERY LIFE! Cross Diagonal Battery Wiring

Being a elec engr,, I started looking for info on battery wiring and came across the following information on the best way to wire a bank of batteries. (See link & drawings below)
Instead of feeding the ± loads from the same end of the battery bank, the "better" method is to feed the POSITIVE load from one end of the bank and the NEGATIVE load from the "cross diagonal" (other end) of the bank.

It is not intuitive, but the difference is dramatic for a simple change, and the article states that the bottom battery life will be ½ that of the top battery with the "not good" method. The "better method" probably charges the batteries better also.

So, I have to install some new battery cables and will be wiring something like these suggestion. I have 6 Trojan T105 6VDC batteries, so there may be difference with the series/parallel connection for 12VDC. I will post an update if I ever get off work! And, YES Randy I will post some pics!

P.S. If this has been discussed in a diff thread, lt me know please!

Merry Christmas!
Pat

Good link!

http://www.smartgauge.co.uk/batt_con.html



NOT GOOD METHOD



MUCH BETTER Method

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  #2  
Old 12-18-2016
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interesting that theres a big change in performance by moving the cables.
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  #3  
Old 12-18-2016
Neillynwood@aol.com Neillynwood@aol.com is offline
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Something to do with magnetic pull I guess
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Old 12-19-2016
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Quote:
Originally Posted by Neillynwood@aol.com View Post
Something to do with magnetic pull I guess
Yep,the rare lead magnets at work..
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  #5  
Old 12-19-2016
CaptainPat CaptainPat is offline
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Here's some more info. I'll look at my setup and post a follow up tomorrow.
All info leads to cross diagonal connecting of both chargers and loads.

Pat




Figure 13: Four Batteries in Series / Parallel (Example 2), One Charger
Just one more comment about voltage imbalance while charging current is being applied. Figure 13 shows two wires highlighted, the blue one designated W1 and the green one designated W2. Interestingly enough, if the connection at battery D positive terminal is moved to battery C positive terminal, without changing the connection at battery A negative terminal, then a voltage imbalance will exist. Do a thought experiment. Take a pencil and trace the path of the charge current from the output, positive terminal of the 24 volt charger, through the wires, and the batteries, through W1 and back to the output, negative terminal of the 24 volt charger.
Now go back to Figure 12 and look at the green wire designated W3. With 2 independent chargers connected, the blue wires W1 & W2 correct the voltage imbalance that would exist in the individual, parallel connected battery packs. The green wire W3 does absolutely nothing in terms of charging the batteries. In fact, it can simply be removed because NO CURRENT flows through it while the two groups of batteries are being charged.

Figure 12: Four Batteries in Series / Parallel (Example 2), Two Chargers
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Old 12-19-2016
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Quote:
Originally Posted by CaptainPat View Post
Being a elec engr,, I started looking for info on battery wiring and came across the following information on the best way to wire a bank of batteries. (See link & drawings below)
Instead of feeding the ± loads from the same end of the battery bank, the "better" method is to feed the POSITIVE load from one end of the bank and the NEGATIVE load from the "cross diagonal" (other end) of the bank.

It is not intuitive, but the difference is dramatic for a simple change, and the article states that the bottom battery life will be ½ that of the top battery with the "not good" method. The "better method" probably charges the batteries better also.

So, I have to install some new battery cables and will be wiring something like these suggestion. I have 6 Trojan T105 6VDC batteries, so there may be difference with the series/parallel connection for 12VDC. I will post an update if I ever get off work! And, YES Randy I will post some pics!

P.S. If this has been discussed in a diff thread, lt me know please!

Merry Christmas!
Pat

Good link!

http://www.smartgauge.co.uk/batt_con.html



NOT GOOD METHOD



MUCH BETTER Method

I have seen this arrangement before and I understand what you are showing. Would you consider this a better arrangement than having each positive and each negative cable terminate at a common distribution point
BTW - I am not a fan of any type of battery daisy chaining - but what DUINO
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Old 12-19-2016
CaptainPat CaptainPat is offline
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From KC:
"Would you consider this a better arrangement than having each positive and each negative cable terminate at a common distribution point?"

No, In fact "having a common distribution point" is better than the "Cross Diagonal". The key to "having each positive and each negative cable terminate at a common distribution point" is to have all the positive cables the same length, and have all the neg's the same length. (Too much trouble).

There is one other "better" method ID'ed also in the link. But, those require much more effort, investment and only incremental returns. So, we are probably splitting BCH's with those.


I think the "Cross Diagonal" method solves for the Pareto Principle 80% of the benefit for 20% investment. This IS worth the effort!

It is important to hook the charger up as "Cross Diagonal" also!! (Last sentence in the smartgauge.com link)

Check the SmartGauge.com link.

I'm going to bed!
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  #8  
Old 12-19-2016
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I wired my house batteries using the " much better method", suggested by Don Bradner in a thread I can't find....
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Old 12-19-2016
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Pat, a huge THANK YOU for sharing some knowledge that I was totally unaware of. I have wired my share of battery trays and used 4/0 cabling to minimize the resistance between the individual batteries, but always felt that there had to be a better way. (Sort of like knowing that SOMEHOW, there could be a tunnel from Naples to Key West ) Using independent cables to each battery from a common post always seemed to generate more resistance due to the added connections and crimps. Furthermore, few junction blocks (with the exception of this one- https://www.bluesea.com/products/210...3_8in-16_Studs) ever seemed suitable for connecting multiple batteries to a single supply cable.

When testing batteries for myself and others, I'd usually find a slight difference in the specific gravity of the first pair of cells (closest to the supply and delivery connections) as compared to the last pair in the group. (I normally wire an array of 6V Golf Car batteries). This article appears to explain that phenomenon and is fully in line with what I was observing. I'm heading to the garage today, 4/0 in-hand, to make a longer ground cable that will extend back to my last stud on the ground side.
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  #10  
Old 12-19-2016
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Harold,Cat&Sam Harold,Cat&Sam is offline
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Thank you for the Christmas gift of knowledge

Merry Christmas
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