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Post by fish on Jul 19, 2024 14:36:10 GMT 12
I'm a fairly simple guy. I like to keep systems simple. If I don't know exactly how something works, and I can't see a clear and defined need for it, then I wouldn't use it.
If it were me, first step would be to see if there is a balance problem. Use the standard $20 (or maybe $60 for a posh one) volt meters and see if any of the batts show a different voltage. If they do, investigate more deeply, which would be to take them out of service, rest for a day, then check each batt's resting voltage. If there is a difference, then, what to do?
I'd charge them individually off a mains charger* till full tail charge is achieved, rest them for a day and check their voltage again.
* noting you are in rural so the old mains charger may be problematic, but I'm sure you have many means to achieve the same outcome. Easy to take them out of service if they're on the boat, not sure how easy that is if you are using them 24/7 in rural, but if they aren't going lower than 90% you aren't working them hard.
The other point to consider is batteries do die, and often there is zero you can do about it. You could do a cursory check of individual battery voltage, and if one is shitting itself, well, just start planning to replace it some time in the future (hopefully years, not months).
Unless they are still in warranty. In which case, don't touch them, take them back to the supplier and get them to sort.
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Post by Battery Guy on Jul 20, 2024 9:38:07 GMT 12
Sorry I posted a image of the optimal cabling that failed!
On your diagram the black feed or the red feed should be moved to the bottom 2s pack.
Also the cables in each 2s should be exactly the same length and size and thus the same resistance.
The fuse is to protect inrush between the packs due to a failed battery. If the batteries in one of the 2s packs fails closed all the energy in the other 2s pack will go into it and cause a fire. Extremely unlikely to happen, but technically possible.
Balancing is about taking excess current during charging that's damaging a cell and sending it to adjacent cells.
So let's say one of your batteries are in good nic but your other three are old and sulphated. Eg maybe you had a warranty claim on one battery
Now when charging that battery will reach fully charged before the others. As the others are continuing to absorb charge that good battery is now being over charged. The purpose of the balancer is to divert the excess current being delivered to the good battery. This can and usually is done passively, a balancer just burns off the excess as heat... Sometimes it's active and the balancer actually diverts the excess current to the other batteries... Active types are usually more expensive and only make sense where every amp counts eg solar and not grid
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Post by GO30 on Jul 20, 2024 11:04:43 GMT 12
Good stuff Thanks. Oh so that's what the magic black boxes do,divert around issues. Negative take off now lead changed to bottom right. All leads between the batteries are very LARGE with swaged ends. All leads are the same length. Batteries are only 4-5 years old No variation detected after 2hrs of rest We do have a decent genny and a Victron 24V 30amp charger. Gave it max on installation, never used them or even considered it since. After a few days of a little above average use, some heavy stereo use yesterday, less than ideal solar conditions and the Wa in inadvertently turning lectric blanket onto full noise early evening, come 10pm the bank was down to 25.1V. Our one total lack of insulation mitigator, the lectric blanket. I hate getting into cold beds and if it is 5 degrees outside it is also 5 degrees inside so scored the blanket not long ago. So nice jumping into a nice warm bed, at which stage the blanket is turned off. Yes Mr Fish, running a KISS system is ironically far from stupid. Besides I built it and I can be stupid so it has to be simple  |
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Post by GO30 on Sept 4, 2024 10:02:57 GMT 12
I scored a battery monitor, Victron BMV 712, so I can accurately tracks amps in and out. It comes with a shunt and all you need for $310 inc odd retail ex L&B, not too shabby I thought, not that I pay that being trade custy. $240 inc as I know you're wondering  They say monitor 'mid point' if you have a battery bank.
In the manual I spied this -
Followed by this one
Note they are both 24V related.
Makes sense when you think about it.
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Post by fish on Sept 4, 2024 10:19:18 GMT 12
I scored a battery monitor, Victron BMV 712, so I can accurately tracks amps in and out. It comes with a shunt and all you need for $310 inc odd retail ex L&B, not too shabby I thought, not that I pay that being trade custy. $240 inc as I know you're wondering They say monitor 'mid point' if you have a battery bank.
In the manual I spied this -
Followed by this one
Note they are both 24V related.
Makes sense when you think about it.
I was just looking at the Victron BMV712 yesterday and day dreaming. I have a whoflungdung battery monitor, that I think was about $30 or something (maybe $50 delivered) that has been very handy. But there is a victron shunt that is fully bluetoothed, so I can programme it and track everything from my phone. If I change anything on my solar / battery management system I have already decided I'm going full victron on everything. I have solved a first world problem on my boat, which possibly warrants its own thread, but I see my power consumption going up substantially and am plotting how to get a very large solar panel onto the old kauri log. |
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Post by GO30 on Sept 4, 2024 10:49:47 GMT 12
That Victron monitor is the bluetooth version so we probably have the same shunt, it and the wiring needed comes with the head as standard.
That model also has a AUX port which I can hook in a second battery/bank and/or temp monitoring and some other stuff.
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Post by GO30 on Sept 22, 2024 9:42:15 GMT 12
Ok so I got my battery monitor in and it was fun. One set of instructions said this, the other said that and neither had a key bit of info. What's more the unit came complete with an already popped fuse, that was real fun when trying to workout why a blank screen, but we got there.
So far it's confirmed what I thought, we have battery bank to burn. Went extra hard on power consumption during the no charge hours, ran lectric kettle, microwave and toaster a few cycles each on top of all lights on maximum, woke up to a bank reading 79.8%.
Monitor said bank was back at 100% at 8:26am. But the controller still showed good amps flowing in, in the 4-5amp range, which is well above average for 'sun is out' which suggests to me the bank is not 100%. Add in it is 8:30am and the sun is still 60-70 degrees off the panels and me guts (that have been fiddling with solar for 25+ years) is saying 100% by 8:30, is a Darryl Kerrigan moment, 'Tell the monitor it is dreamin'. The monitor 'self selected' 200ah bank and it being 100% full at 26.4V. The controller runs the bank up to 28.8V before tapering back. That'll be where the amps still flowing in are coming from.
The batteries themselves have this on them -
200Ah @ 20hrs (they are GEL built for solar hence use the 20hr rather than the 10hr rating)
Rated 12V
Float charge 13.5-13.7V
Boost charge 14.1-14.4V
Life cycle 1422 @ 50% DoD (not getting even close to 50% so be interesting to see how long they run, currently approaching 4 years in use)
Anything in all that anyone reckons I should tweak?
I also installed a 'battery mid point monitor', the unit comes with a second lead to do that or suss temp and a few other options but after this thread I decided mid point could be handy. But it instantly comes up with a caution about too wide a variance. The unit is set to alarm at 1.5% but the unit is showing over 65%. A multimeter showed 0.08V difference. As it appears mid point measuring involves cauldrons and other such things I'll have to dive deeper into that.
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