| Author | Message | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1326 Registered: 10-2006 Posted From: 99.173.20.243  Rating: N/A |
Many confusions in how to hook up more than 2 batteries in a house batt bank. Here is one fellows method, http://www.smartgauge.co.uk/batt_con.html FF | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1023 Registered: 3-2007 Posted From: 71.55.1.12  Rating: N/A |
Thanks FF That is definitly different but I think more effective. Gomer | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1327 Registered: 10-2006 Posted From: 99.173.20.243 Rating: N/A |
ITS mostly only worth the effort for the folks that expect 6-8 years out of the house set , and live by their SOC meter. FF | ||
| Jim Wilkerson (Wagwar)
Registered Member Username: Wagwar Post Number: 123 Registered: 12-2009 Posted From: 99.109.187.242 Rating: N/A |
Thanks FF, There is a very interesting article on the amp counter type of battery monitor. He says they can be very inaccurate and easily get out of sync. My TRACE inverter manual also mentions a type of cabling called 'cross-linking'. It does not, however, explain the purpose or why it is better. jdw | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 604 Registered: 8-2004 Posted From: 98.204.115.204  Rating: N/A |
Is this better than a big copper strip battery connector and the cables taken off this???? | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1118 Registered: 8-2006 Posted From: 99.39.12.225 Rating: N/A |
Well, this link was published here and very well discussed a couple of months ago. I made some comments then about the theory and an error in the calculations. Remember Chuck? Apparently the Brit added the internal battery resistance to each of the 2nd, 3rd, and 4th batteries in the circuit, to get that much difference in resistance, and resultant current flow. If we measure the total length of BOTH the positive AND the negative cables, on his first alternate suggestion, connecting the positive to the upper left, and the negative to the lower right, we find that the total current-flow length is exactly the same for all four batteries. The positive connection on the first battery has the shortest cable length, while it also has the longest negative cable length, and so on... My point in suggesting doing it this way is simply cost, there is just no payback in buying a whole lot of expensive terminals and connectors, as a result of faulty math. G | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 1201 Registered: 1-2003 Posted From: 67.142.130.23  Rating: N/A |
Once again I am with George on this. I don't know what "PC simulator" program this guy is using, or why the mathematics is too "horrific" to show, but it would seem he is guilty of exactly what he disdains in point "A" at the very top of his thesis. He needs to go back to EE-101 and re-learn Kirkoff's Law. The method described in example 4 is no better than example 2 in terms of balancing the load on all four batteries -- the loads are in exact balance in both methods, notwithstanding his assertion under number 2. Example 4 uses more cable length overall, while the current path for each battery in method 2 requires one more connection than for method 4, so overall losses between the two methods are similar but might show a slight difference. Moreover, the method described in example 4 only works for numbers of batteries that are an exact power of 2. So you can do it with 2, 4, or 8 batteries, but not with 3, 5, or 6. Whereas method number 2 works for any number of parallel batteries. Method 3, BTW, also works for any number of batteries and remains the method providing not only perfect balance, but the least overall loss in the system, because the number of connections in the circuit for each battery is minimized. However as noted it requires additional hardware and space. FWIW. -Sean http://OurOdyssey.BlogSpot.com | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1936 Registered: 12-2000 Posted From: 174.89.177.216  Rating: N/A |
Great timing... I spent some time last weekend cleaning up the terminals and grounds on a Freightliner with a 3 battery, 12 volt bank... Can you guess which battery tested bad, and how the cabling was arranged? Yup, manufactured dogbone connectors, with the connections to the truck both at the same end of the line of batteries. Battery furthest from the connections tested bad. Luckily, the ground cables were just long enough to let me reverse the dogbone on the negative to get the cabling balanced. Amazing, this appears to be the stock install. happy coaching! buswarrior | ||
| Edward J. Sommers (Sommersed)
Registered Member Username: Sommersed Post Number: 58 Registered: 10-2004 Posted From: 148.63.161.138 Rating: N/A |
Jerry asked about 'cross-linking'. I call it cross connecting. In my case, I have eight golf cart batts wired for 24 volts, so four batts wired in series sitting alongside another four wired the same and the two ends batts wired pos to pos, and neg to neg in the usual manner. In addition, in cross connecting, the positive posts are connected at all points as well . . . IE at the 6,12,and 18 volt points as well. Keeps all batts voltage more balanced. These connections only need about a number 4 welding cable. Ed | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1119 Registered: 8-2006 Posted From: 99.39.12.225 Rating: N/A |
If I read what Ed said correctly, cross-connecting the positive posts does nothing. To accomplish ANYTHING, the individual negatives would have to be connected also. The only way an imbalance would occur is if an individual battery loses capacity. Then, if they were cross-connected both + & -, the poor battery would discharge the good battery across from it. G | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 137 Registered: 1-2010 Posted From: 68.151.225.213 Rating: N/A |
So George. In this configuration is there any way to set up the banks that one bad battery doesn't take the others with it? This has been a great thread for me as I am trying to decide how much and what configuration I want for house batteries Thanks Les | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1120 Registered: 8-2006 Posted From: 99.39.12.225 Rating: N/A |
Les, A series-parallel connection is a necessary evil to get Amp Hours of capacity. Honestly, I wouldn't worry about it. My comment above was due to there being no advantage at all to connecting the positives only. It wouldn't do any good to connect only the negatives either. Connecting both terminals on the individual batteries won't help appreciably, and will cause more problems as soon as there is any variance between batteries. The heck of it is, that in a series-parallel setup, when one battery has a cell short, it will discharge the other pair down to the voltage of its pair. In the case above of eight 6 Volt batteries used to provide 24 Volts, one bad cell in one battery will discharge the other group of four a couple of volts. When you suddenly start losing capacity, get out the hydrometer, and you will find a bad cell. If it makes you feel any better, trying to avoid discharging the other group of series connected bateries in a series-parallel group, by buying two large 12 Volt batteries and connecting them in parallel, won't insure you either. The bad one will still discharge the good one(s.) G | ||
| Edward J. Sommers (Sommersed)
Registered Member Username: Sommersed Post Number: 59 Registered: 10-2004 Posted From: 148.63.161.138 Rating: N/A |
Well George, cross connecting may not work for you but there are some things I will always have on my battery banks. Those are cross connections, full time De-Sulfator installed from the get-go, MPPT charge controller with more volts going into the controller than batt array wired configuration, and a roof full of solar panels (currently 1200 watts). I also use a Vanner equalizer, which is itself a type of cross connection. Ed | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1121 Registered: 8-2006 Posted From: 99.184.10.70 Rating: N/A |
Ed, I didn't say anything about "De-sulfators, MPPT charge controller, Vanner equalizers...," or other cross-connections. What I did say, and will say again, is that cross-connecting the positives does nothing. I also said that to accomplish anything, the individual negatives would have to be cross-connected also. Connecting two positives together, without connecting the corresponding negatives, does the same thing as only connecting the positive cable to the positive battery terminals, nothing. I really don't want to get into splitting hairs 3 ways. BUT, if you draw eight 6 Volt batteries in two groups of 24 Volt series-parallel, you will see that the positives are already connected on two batteries, AND the negatives are already connected on two batteries. This means that the jumper applied to the positive terminals of the batteries with their negative terminals connected to the bus ground (the 6 Volt point) does whatever you think it does, (because their negatives are connected thru the ground cables) and the next TWO jumpers do NOTHING. IF equalizing the batteries side to side did something, you would notice that the batteries in the 6 Volt position lasted much longer than those in the 12, 18, and 24 Volt position, because the first jumper actually works, because the negatives are connected by the grounds. G (Message edited by George_todd on October 22, 2010) | ||
| Edward J. Sommers (Sommersed)
Registered Member Username: Sommersed Post Number: 60 Registered: 10-2004 Posted From: 148.63.161.138 Rating: N/A |
George, I understand what you are saying, and I just stated what I do. You just do not understand what I said to begin with. Perhaps, If you really want to know about these things, I recommend http://groups.yahoo.com/group/12VDC_Power This is my last word on the subject. Ed | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1122 Registered: 8-2006 Posted From: 99.172.180.11 Rating: N/A |
Ed, You posted "...the positive posts are connected at all points as well,...IE at the 6,12, and 18 volt points as well." I understand that CLEARLY, which is why I say for the third time that the jumpers on the 12 and 18 volt positive points only don't work, period. I also say that IF equalizing the batteries by cross-connecting BOTH the positive and the negative terminals worked, the "6 Volt pair" of batteries would greatly outlast the other three pairs. If you don't want to draw the batteries on a piece of paper, and try to draw the current path you are proposing, so be it. This is my last reply, as saying it three times is enough. Please also note that no one else here has posted a correction. G | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 1424 Registered: 7-2006 Posted From: 97.226.165.107  Rating: N/A |
Many years ago....good grief....2001 if memory serves correct..., I was a "newbie" on this and other boards regarding the subject of "buses". What great progress and education since then...so much information from the experts and all for "free" (thanx, Ian, et al). To think I have completely converted, from seats..  ...to a full functioning, albeit not without a hitch or two, full conversion, is mind boggling. Many times I thought to myself..."they have to be kidding" when I did not comprehend or past experience had taught me somewhat differently; but alas, I must admit, the "experts"...the ones who make their living ...or a lifetime of experience doing what many of us are just starting to experience,...are spot on. True, much of their advice needs to be assimilated...mulled over...perhaps verified to just "prove to our uneducated (dumb?) selves" that they, indeed, do know what they are talking about. But in the end, it turns out, for me at least, that "they" are most usually correct...as were most of my mentors in life. We all, surely, have a different way of doing things; perhaps out of ignorance of a subject, maybe out of vast experience of not knowing better because it works, perhaps out of just plain ego and yes, because of just good old day by day trying over a lifetime... Anyone relate to what I am saying? Many are those who have superior knowledge on various subjects...out of education, experience, tenacity, out of dedication or pursuit of a professional career. And I personally thank all who have posted....for their willingness to "share" their personal "expertise". That's X-actly how I converted my coach...I could name names...but some might be left out. Many thanx to all of you...and you know who you are...some are no longer with us, for various reasons...Thanx to them as well. RCB | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1123 Registered: 8-2006 Posted From: 99.172.180.11 Rating: N/A |
Well, Somebody should have corrected me, and I owe an apology. Cross-connecting the positives on its face does nothing, but because the positive on the second battery is connected to the negative on the first, the 2nd positive jumper serves as the 1st negative connection, and so on. What does a cross-connection really do? Lowers the voltage of a good battery down to the voltage of a weak one. G |