acdoctor
Solar Enthusiast
Best practices would be a bench power supply set to constant voltage of 14.4 to 14.6 and charge each unit amps goes to 0.5 amps.
Manual balance of new bank question FOLLOWUP Question
- Thread starter kanelr
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acdoctor
Solar Enthusiast
What you are doing is similar to building a battery from individual cells in that the only way to get all to the same state of charge is to have them all completely full or completely empty.
Look up top balancing
Look up top balancing
meanwhile I want to literally reverse all battery locations and see if the higher difference remains on the neg connect side after letting the panels warm them up a little. I have time and it will help prove or disprove my wiring worries.Attached 2 pix first is factory suggest and what i did , second is victron classis sp for reference. the only diff is the nature of the commons or busses.
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Consider using this to boost charge the low battery set.
acdoctor
Solar Enthusiast
You could certainly swap them around to see. I don’t see a problem with your layout. Paralleling resistance is everything, but you know that that’s why you have attempted a buss bar configuration. I don’t like the execution though.
I don’t believe those crimped terminals are designed for thhn wire. I would have used all welding or locomotive cables.
I would have at a minimum soldered the connections where you have the split bolts. I also would have soldered the terminals. The wire should go all the way from first to last battery.
I don’t believe those crimped terminals are designed for thhn wire. I would have used all welding or locomotive cables.
I would have at a minimum soldered the connections where you have the split bolts. I also would have soldered the terminals. The wire should go all the way from first to last battery.
Hi The crimps are each labeled for gauge and sized right, although thats not exactly what your asking you mean contact area I believe. Once I have everything right I plan to flow solder into all crimps and split bolts (not threads). the wire was free, big enough and I have to make do. Will do all possible mini tweaks later ( used to build slot cars, I get it - every 1/10% adds up) As to the wire PLEASE ADVISE I posted here to learn. no pride here so what would you add /change? I have about sixteen extra of the7" #2 jumpers and twelve 36" long 2/0 all with crimped loop on ends, plus some with one end raw. My main negative from bank thru shunt and to inverter is about 20" shorter than the positive. Also about the crimp lugs- the surface area is not the fattest so I am careful to best center them under washers and etc for most contact area at least.
did that last night, on to the swap per below......
acdoctor
Solar Enthusiast
If you have not swapped them around yet. I would disconnect all the wires from batteries and grab a ohm meter ( not one of those that goes to 200 ohms). Check every connection. If there are different readings Log them on your diagram. You may see a pattern.
The biggest thing I would do is get the solder flowing.
The biggest thing I would do is get the solder flowing.
Hey I thank you for making me think. If you look at the posted collage the back buss isn't really wired like my drawing, and the shiny big split bolts etc must had distracted us here's the first well duh!
The path I chose to tie the rear row into the "buss" has about 10" more length than the front row because I ran the short jumpers not at 90 degrees to buss look a the 'yellow' line that's at least 70" of cabling I didn't account for. I will fix that (see why I didn't yet solder haha)
But still the left bank after sitting for 12 hours are still all 13.49 v (now) and the right bank that was ALL 14.04 vary about .01 each below 14.01 . Will re wire bulk and test after manual top off tonight etc have good night and thanks. BTW my ohmmeter does not go low enough will get another
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Well I reworked the rear buss eliminating 77” of wire I didnt lnow i had compiled, and filled in the crimps with solder. It just looks more dialed in. I also played whack-a-mole trying to top balance one at a time while stringing wire. Testing saturday
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yes
Can I get an opinion? Ok so here's the update. System is performing well with nominal loading. Enough juice to run our very active sump pump, the lighting, computers/monitors, and some comfort fans. I think it will support the refrigerator at least in the daytime when sun is out (using relay). Mission was to have backup of critical systems and that's reliably accomplished, now to cut bills a little....
Today I'm adding 2 more batteries to the s/p setup, followed by six more panels. I want to "fold" in these last two batteries while they are all still within a few months of the same age, and for this S/P configuration this would be the max that's practical (five pairs). My top and bottom voltages have been great with seldom any difference, and, as I planned to do a quarterly manual balance /checkup anyway, this is the time. QUESTION. Should I pre charge the 2 new batteries first or bulk 'em all first and then get particular with a manual balance after that? The 8 in place are at 13.25 (26.50), under light load and overcast since dawn,, and that the new two batteries are both 13.16 each (they have been sitting for more than a week since they arrived, i think that speaks well of quality control). What would you start with as far as adding the new batteries?
Today I'm adding 2 more batteries to the s/p setup, followed by six more panels. I want to "fold" in these last two batteries while they are all still within a few months of the same age, and for this S/P configuration this would be the max that's practical (five pairs). My top and bottom voltages have been great with seldom any difference, and, as I planned to do a quarterly manual balance /checkup anyway, this is the time. QUESTION. Should I pre charge the 2 new batteries first or bulk 'em all first and then get particular with a manual balance after that? The 8 in place are at 13.25 (26.50), under light load and overcast since dawn,, and that the new two batteries are both 13.16 each (they have been sitting for more than a week since they arrived, i think that speaks well of quality control). What would you start with as far as adding the new batteries?
Hi quoting your post from months ago. After finding all that imbalance I am glad now that I didn't (at that time) solder. I agree about the execution and have improved. The crimps test out well and have soldered all crimps as well (beautiful shiny non-cold solder joints). I used to wind armatures and so forth so I don't mind seeking accurate results. Everything expect the batteries and inverter were made from free stuff, even the 4/0 and 2/0 was free (bought the split bolts), so I had to use what I had. Dialing it in will be the art..... but so what's new, ya know?
Absolutely DO charge the new batteries to be a perfect match for the existing battery packs. They are not yet close enough, this voltage differential would cause very high current into the lower-voltage new ones (if they were to be connected in their current state). The BMS within each of the new packs might or might not be able to detect that overload before burning out
I would charge to 13.25 each, and then connect. I would not bother with "top balancing" followed by voltage reduction (via loading) on the two new packs. But I would want the voltage to be within 0.020 volts, on the pack as a whole, before putting them into the same string(s) as the other ones.
Gotcha thanksAbsolutely DO charge the new batteries to be a perfect match for the existing battery packs. They are not yet close enough, this voltage differential would cause very high current into the lower-voltage new ones (if they were to be connected in their current state). The BMS within each of the new packs might or might not be able to detect that overload before burning out
I would charge to 13.25 each, and then connect. I would not bother with "top balancing" followed by voltage reduction (via loading) on the two new packs. But I would want the voltage to be within 0.020 volts, on the pack as a whole, before putting them into the same string(s) as the other ones.
acdoctor
Solar Enthusiast
For the best results charge the new ones to 28-29 volts they will settle after charging don’t worry about that. Charge the current bank to full 28-29 volts and install the new ones in the bank.
Glad to hear you are working the kinks out.?
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