I have three serial strings in my power pack. Of course, these strings are connected in parallel.
Some time ago, I found a website (that I can no longer locate) that was talking about the merits of cross linking the strings of a battery pack. The picture on the website showed, best I can recall, that each terminal in a string was connected to the identical terminal in the adjacent string. Benefits claimed that the cells were not as likely to fluctuate as much as non-cross-linked systems.
Is there any truth to this? Good idea, bad idea?
I do not have any actual experience doing this but it seems to make sense and I had suggested it before as an option.
It would make it a lot easier to spot a bad battery, or at least narrow it down to 3, in your case, very easily.
It makes perfect sense electrically, at least to me.
Like most stuff, it probably has valid pros and cons and deciding which is more important for each application will be the fun part.
More hardware means higher cost and more possible points of failure, too.
An interesting subject for discussion.
Tom
That is an english site.
And yes the way the diagram showed the wiring of the batteries and the losses measured it was by far the best wiring config.
It looked a bit odd, but in regard to efficiency and losses it was light years in front.
I may still have a link buried somewheres.
this one ? http://www.smartgauge.co.uk/batt_con.html
That looks to be it!
Valuable info to be sure but this is not the website I was looking at. The website I saw had multiple serial strings and crossconnections between adjacent terminals of each string. I'll keep hunting until I find it, if it's still there.
My pack is not even close to what a lot of you folks have, still, I have over 4K invested in the pack. I'm all for doing anything that can give me 1 more amp for one more day .....
I am interested if you come up with some better wiring configs as I want to add 4 x L16h's to the 870 amp @ 24 volts I gave my son.
Doubling the diameter of the leads if they are twice as long should reduce resistance and losses and I stand corrected if this is not correct.
That will mean there are 3 x strings of 435amp hour batteries to connect. (12 batteries in total)
Ant takers?
Quote from: russ_drinkwater on December 17, 2016, 03:24:05 PM
Doubling the diameter of the leads if they are twice as long should reduce resistance and losses and I stand corrected if this is not correct?
Russ;
Well, if you double the diameter your resistance per unit length will go down A LOT. My math sucks but you end up with way more than 2X the conductor that way. 2X Diameter not guage, however. Just my opinion.
(Area of circle = π r²) the r² bit makes the cross section go up exponentially (I think that is the term)?
Tom
there is that old RoT (rule of thumb)
to determine the wire size needed to double or halve the wire you have, subtract or add 3 to the AWG number....
so 7AWG is ~2 x as big as 10 AWG, and 13 is ~1/2 the size of 10 AWG wire
Quote from: daloniga on December 10, 2016, 04:08:33 PM
I have three serial strings in my power pack. Of course, these strings are connected in parallel.
Should not have more than two (2) strings in parallel if you value your battery bank. Having 3 is looking for trouble.
How does 40 Rolls s-550
5 strings 48 volts , 50% dod 7 years so far...
It's all about being wired right.
IMHO
George
Quote from: sigp2101 on December 20, 2016, 02:14:46 PM
Should not have more than two (2) strings in parallel if you value your battery bank. Having 3 is looking for trouble.
It would not surprise me in the least. Mama always said I had the tendency to fall out of the stupid tree and hit every branch on the way down. :-)
Quote from: grgdgreek on December 20, 2016, 02:31:37 PM
How does 40 Rolls s-550
5 strings 48 volts , 50% dod 7 years so far...
It's all about being wired right.
IMHO
George
George,
How are these strings wired? What does "dod" stand for?
I found a related article tonight but the pictures in the PDF seem to imply this is more geared toward battery powered tools. The text makes my eyes cross:
http://www.freepatentsonline.com/EP1780819A1.html (http://www.freepatentsonline.com/EP1780819A1.html)
DOD = depth of discharge.
Quote from: Westbranch on December 13, 2016, 03:59:02 PM
this one ? http://www.smartgauge.co.uk/batt_con.html
Diagram #2
George
Looks awfully similar to what I am doing with my three strings. However, folks, I am having something going on that I should be slapped silly for doing. I think I caught the issue early enough not to cause significant damage. Give you a hint...my three Classics are really strong and was doing things that shouldn't be done. On my YouTube channel I explain it...check it out if you want. Oops.
Quote from: Chris DIYer on December 23, 2016, 09:05:18 PMOn my YouTube channel I explain it...check it out if you want. Oops.
Frankly, not many folks will go hunt down your YouTube channel so posting a link would work much better.
Just a heads up.
Tom
(http://www.smartgauge.co.uk/images/batt_new_2.gif)
This looks odd but it's actually quite simple. What has been done here is to start with 2 pairs of batteries. Each wired in the proper "cross diagonal" method. Then each pair is wired together, again in the cross diagonal method.
Notice that for each individual battery, the current always goes through a total of one long link and one short link before reaching the loads.
This method also achieves perfect balance between all 4 batteries and may be easier to wire up in some installations. Many thanks to "smileypete" from www.canalworld.net/forums for this idea.
http://www.smartgauge.co.uk/batt_con.html
VT;
I get how this works and it is somewhat sneaky smart. It just makes my head hurt looking at it as a whole. :o Once you trace the paths individually it gets more clear.
One situation where more connections makes sense in a way.
Tom
How does that work on 12 x 4 volt tubs?
Don't you only have a single, series string with the Rolls 4V cells, or have I missed something?
You can do the same with 4Vdc Tubs that are Series /Parallel on trying to increase the Amp Hr's
VT
I run two separate banks of 24 volts on separate ergs and panels.
Inverter draws off both banks.
Quote from: russ_drinkwater on January 05, 2017, 06:42:28 AM
Inverter draws off both banks.
how does that work? Are both battery banks somehow connected to the inverter's DC input?
dgd
Yes I run a an isolator switch 4 position. Off, bank 1, bank 2 or bank 1&2 together. When I had the smaller bank of trojans I would run the house on the trojans during the day and switch to 1 bank of the rolls overnight. Now I have the two banks of rolls up and running I found the
2700 amps @ 24 volts did not need any switching between banks. So I just draw off the 2 banks together unless it is really overcast for a long period and then I switch to grid tie and monitor battery health or wait for finer weather.
The overload switch in that link is a tad small at 100amps and dumps out if we use a chip cooker or the like! :o ;D
Wife is trained up and switches or when necessary, even checks the classics for voltages and soc! :o ;D
Working on her and the electrolyte levels next! :o :'( ;)