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I bought this new battery really cheap (it is really small and i needed a small 12v battery) but i am not sure of some things. First of all, it says it is 1.3Ah/20HR. Does that mean that it can deliever 1.3Ah for 20 hours? Like, i could power a 12v 1A light bulb (estimately...) for 20+ hours from it? Second of all, is this a deep cycle battery? ( i do not speak polish, so i do not understand the label). If i fully discharge the battery (9-10 volts) will it lose its capacity to store charge, or there is no problem? What is its optimal voltage? I used some rough google translate and it turns out that the "standby voltage" is 13.6-13.8 volts and the "usage" voltage is 14.5-14.9 volts. Isn't that too much for a 12v battery? Right now it is at 12.6V. Is it undercharged? Also, what is the voltage needed to charge it and is it a bad idea to charge it with a stepped up 5v power supply? (Phone charger, stepped up to the battery voltage required for charging)

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    \$\begingroup\$ 1.2Ah = 1.2 Ampere Hours = It can deliver 1 A for 1.2 hours, or 1.2 A for 1 h. \$\endgroup\$
    – Marcus Müller
    Commented Mar 20, 2017 at 21:47
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    \$\begingroup\$ 1.3Ah / 20h = 65mA \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Mar 20, 2017 at 21:54
  • \$\begingroup\$ 1.to put things into perspective: 1.3 Ah is not very much. My single AA NiMh recharhable battery deliver 2.3 Ah, at 1/10 of the voltage, so ten of them, which would be comparable in size to what you have, would have the same voltage, but roughly twice the energy. \$\endgroup\$
    – Marcus Müller
    Commented Mar 20, 2017 at 22:01

1 Answer 1

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How to charge this (SLA) battery?

Ideally:

  • CC using C/4 rate = 1.3A /4 = 325mA max whenever Vbat drops below 70% SoC or ~2.1V/cell or 12.6V in your case.
  • two-stage CV, if outdoors, apply a -4mV/˚C/Cell temp compensation for Vmax charge voltage above room temp. This is to charge the absorptive layer capacitance which has a much longer ESR*C time constant.

  • Use pulse float charge followed by measurement of no load decay rate in 1hr.

  • it is not a deep cell voltage battery. Sealed lead acid battery manufacturers do not recommend deep discharge, as this damages the battery (greatly reducing its life)

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Absorption Charge Voltage 1 
   V OUT1 ‡ 14.2 14.4 14.6 V  (min typ max)
Absorption Charge Voltage 2 & Float Charge Voltage 
   V OUT2 ‡ 13.5 13.65 13.8 V (min typ max)
Battery Capacity Threshold Voltage V TH 12.9 V After 2 mins
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