Battery information

pitfalls in using long strings of series-connected lead-acid battery cells PDF
http://www.battcon.com/papersfinal2004/symonspaper2004.pdf

Maintenance log sheet
http://www.trojanbattery.com/pdf/BatteryMaintenanceLog.pdf

Excessive sediment
http://navalfacilities.tpub.com/mo200/mo2000152.htm

SLA Battery Charging (powerstream)
https://www.powerstream.com/SLA.htm

Life Extension Through Charge Equalization of Lead-Acid Batteries
http://www.theequalizer-bacs.com/files/117265231.pdf

Charger Output AC Ripple Voltage and the affect on VRLA batteries
http://www.cdtechno.com/pdf/ref/41_2131_0212.pdf

Energy Unlimited - Victron

‘Energy Unlimited’, in which subjects often creating doubts are discussed in detail.

Autonomous energy supply. Power provision in boats and other water based craft. Concentrates on lead acid. PDF download in: Deutsch, English, Francais, Nederlands, Swedish. Or complete the form for a hard copy.

https://www.victronenergy.com/orderbook

PDF: Self-Discharge and Passivation Phenomena in Lead-Acid Batteriesduring storage

The passivation of the negative plate brings about the shortening of the discharge time without changing substantially the discharge potential.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1025.5441&rep=rep1&type=pdf

A rule of thumb is that for a 1 hour discharge rate (i.e. drawing 10 amps from a 10 amp hour battery, or 1C) you will only get half of the rated capacity (or 5 amp-hours from a 10 amp-hour battery).

Good article, but I do have one point:
For lead acid at least, I would always consult the data sheet. Some 12Volt 12 AH sla are rated at 5 hours discharge period, or even 2. A Chilwee 6-DZM-12 fx, is rated 12 Amp-Hours over 2 hours. At the standard 20 Hour rate spec, it gives 16 AH. Even a budget PL12-12 from Ebay is rated at 6.3 AH over 30 minutes.

If you have a choice, try to get your system to charge within the range suggested by Bosch's newer graph. 14.5 volts at moderate temperature is not a bad target. The improvement in life and performance of lead/calcium and hybrid batteries will be worth it!

https://www.landiss.com/battery.htm

VRLA Battery Float Charge: Analysis and Optimisation. PDF
https://ir.canterbury.ac.nz/handle/10092/5594
or
https://core.ac.uk/display/35465760

microstructure and corrosion effects. It is English from the contents onwards.
http://eprints.uanl.mx/9580/
or
https://core.ac.uk/display/76599708

What, you don't use them any more?

I have in front of me a NASA publication on the care and feeding of NiCd batteries, as learned from 30 years in space satellite operations. What follows here are some excerpts from this text organized in some potentially useful manner.

http://users.frii.com/dlc/battery.htm

NiCad aircraft battery.saft.pdf
http://www.tracebatteries.ru/d/476379/d/omm_2017-05-17.pdf

RE:
Life Extension Through Charge Equalization of Lead-Acid Batteries, and VRLA Battery Float Charge: Analysis and Optimisation. from above.

Equalization is a none starter for me. It causes plate shedding due to excess bubbling, which you can hear, and even expensive charger/maintainers do it. A decently powerful desulphator will do a better job, without excess bubbling (actually, with very little bubbling at all) with less stress, and greater efficiciency.

As far as VRLA float goes, 13.45v works for me. As an example, I have 6 AGM 12v batteries in parallel that are with one exception, 12 Ah. The other is 7.2 Ah. Total float current drops to 8 or 9 milliamps, then slowly reduces further until the charger regulator IC minimum working current limit is reached (seems to be around 6 milliamps), where the IC shuts off. Quite some time later the battery voltage has dropped slightly to a point where the current needed is now greater and the regulator is enabled again. Could this be classed as "mini cycling"? I do not believe so since the batteries are still well within the state of surface charge.

EDIT: The charge module is a CC/CV module from ebay, with a 40 volt max input, and 6 amp capability. The 40 volt input is important to me because I can run it from the old, low power HP printer psus I have (32 volts, 333 mA up to 1.5A) The regulator IC is a XL4016 if memory serves, so any stated ratings for more than the ic spec are incorrect (though they are also under-rated by others), and they are 150 watt.

I have no adverse effects to report. Total current draw from a 14.4 volt charger on the whole setup is less than 200 milliamps, and that sounds fine to me. Perhaps you may think something is amiss due to the low current levels? A cheap drop tester will glow orange on individual batteries tested seperately and over 9 volts maintained (not as much on 7.2 amp one).

It goes without saying that I have "intervened" at an early stage, and will do so again if I think it's needed. That is what I attribute the performance to.

Dont forget the designed failure mode is plate destruction on float charge.

After all that, what I'm saying is, experiment.