Sorry terry, don't understand what you're trying to say, is it that you need voltage meters on every single cell in the pack and lines. Which us a bit of overkill and completely unnecessary when you have the right setup. Are you saying you have to have voltage alarms on every cell in the pack and not just the lines. never seen that anywhere.T1 Terry wrote: ↑Mon Jun 26, 2017 11:20 am What method do you use to measure individual cell voltages? After seeing the photos of your set up you run separate 12v batteries in parallel so every cell would need to be monitored at the top and bottom of their state of charge. Just measuring the voltage at the 12v level doesn't actually tell you much at all as far as the individual cell voltages and checking cell voltages anywhere other than at the top end and bottom end of charge is meaningless because the voltage curve is nearly flat anywhere other than the 100% and 0% SOC. Anywhere in the range between 98% and 2% will not indicate if the cell is plus or minus a few Ah of the other cells within that battery group, but that much of a difference will certainly result in a damaged cell when either extreme is reached. Simply avoiding those charge and discharge levels won't help either because you don't actually know what state of charge each cell is at so you don't know when to stop charging.
T1 Terry
Having a charger that works for lifepo4, makes life much easier as does the superb cell balancers that don't just drain cells, but transfer energy between them and after more than 2 years of using this setup, am very happy. Still go round every now and then checking individual cells, but none are ever out of balance and even when they are charging with a big current inputs, they stay very well balanced. I had cell line voltage alarms/meters, but took them off after a year of this system because the system works so well and the cells seem to love it, especially as they get bulk charge to 3.5v per cell and not trickle using lead acid chargers.
When the charging stops, they are all in balance and none over 3.5v. The longer this system is in use, the better them seem to be working, simply because using dedicated chargers and balancers, removes all the problems using lead acid chargers, BMS, relays and other associated stuff that can create problems.
In the tests I've seen done, chargers that use float etc, end up ruining lifepo4 cells because they provide a very low input at high cell voltages and lifepo4 hate that. How I know this, slowie went round the world learning about these things before using them and got this information from the Canadian air force, who have been using and testing lifepo4 for well over a decade when he ran into one of their technicians. That's why he had dedicated lifepo4 charger controllers built, got rid of the bms and relays and made a real cell balancer, which you can now buy on ebay cheap and they work excellently.
There are no photo's of my systems here, just the 120ah portable pack, haven't posted any of the house or bus system anywhere.
Don't have 2 x 12v packs in parallel, that comment would be in regard to large amperage systems over 1000ah that they discovered were easier to control using 500ah blocks of cells charged separately and connected in parallel, or as individual systems running different things. Which is what I do on my house, 500ah for big constant use stuff and 200ah for small usage and lights, the two packs are not connected together and have separate chargers and controls. The bus when I finally get the chance to change the panels over, will be one 480ah pack, using 2 charge controller in parallel, no need to separate anything and one inverter, not 3 inverters used on the house.
Got this answer from a major battery charger manufacturer, the reason why there are no dedicated lifepo5 chargers on the market is because all manufactures have all their investment in lead acid technology and to change it, they would lose a lot of money. So they now claim their adjustable lead acid chargers can charge lifepo4 and other lithium, but when you look at the spec sheets the charging voltages are wrong, as are the set parameters. They all use a float settings of some description and the upper voltage settings are damaging to lifepo4, as is float, compensation and temp controls. Charging to 3.6v per cell, is not good for them at all, but 3.5v is perfect, as they settle to 3.45v and charging restart at 3.4v, means they are very happy and don't really cycle.
Everyone who knows about this technology, says the same thing, low voltage inputs at high cell voltages will reduce the life of cells dramatically, compared to their projected life and mine have been in use for 9 years and are happy lifepo4 cells that still provide full capacity. I can see them lasting for many decades with the right controls and usage regimes, as they are never stressed, so far have never been below 3.225v per cell, or over 3.5v. They have not been below 3.225v simply because they have never got below that voltage and when they have got down to that voltage on one or two occasions, checked each cell and all were the same, the balancers work where ever the voltage is, to balance cells.
You may have to explain what you mean in simple language, if I've misinterpreted what you've written.
Ask Bruce about balancing 16 cells in series (48v pack) 
Lots of theories out there about why cells 7 & 8 always give trouble but none have held up under testing.
that a good 
answer T1