Battery Cell Rating 1

[CuriousElectron]

Greetings All,
I have a question - I see a battery cell nameplate having a rating of 105AH 8 HR to 1.75VPC. Does this mean that the ampere hour capacity of the battery cell is 105AH? Why is "8 HR" included in the nameplate data..is this indicating that the battery can produce 13.125Amp discharging over 8 hour period and the voltage at the end of discharge cycle will be 1.75VDC?
Thanks for explanation.
EE

 

[jghrist]

You are correct. Amp-hours at other than constant current for 8 hours will be different from the rating. The capacity for other duty cycles varies by battery type and manufacturer.

 

[RRaghunath]

Higher the discharge from battery, lower will be its duration (for a given End of Discharge or EOD voltage).
For example, if one decides to drain the battery at the rate of 21A, the battery would reach EOD voltage earlier than 5 hours, which means the effective AH rating will be < 105AH.

 

[sushilksk]

Temperature is missing in this rating. 105AH will at a particular temperature (Normally 27 deg C).

 

[che12345]

Dear Mr. CuriousElectron (Electrical)(OP)18 Aug 22 20:34
"...#1. battery cell nameplate having a rating of 105AH 8 HR to 1.75VPC. Does this mean that the ampere hour capacity of the battery cell is 105AH? . #2. Why is "8 HR" included in the nameplate data..#3. is this indicating that the battery can produce 13.125Amp discharging over 8 hour period and the voltage at the end of discharge cycle will be 1.75VDC?..."
#1. Yes. See more detail following.
#2. The 8 h is stated to define the duration of the constant current discharge. With higher discharge current, the voltage will drop to 1.75V at a time < 8h.
#3. FYI: e.g. a X brand 105Ah battery would drop to 1.75V when discharge at (13A for 8h); (22A for 4h); (19A for 5h) ....usually at 25deg C. But a Y brand may differ. Refer to the manufacturer data sheet for the discharge current and the duration.
Che Kuan Yau (Singapore)

 

[Parchie]

@Curiouselectron,
The 8-hour rate is the published guaranteed duration that the battery was tested. It simply means for that 105 AH battery, it delivers 105/8 = 13.125 amperes for 8 hours or nearly around that duration. The 1.75 VPC is the cutoff voltage where the battery voltage tapers off from the voltage at the start of the discharge event. That would be 1.75V X 6 cells = 10.5 V at the terminals of the 12V battery.

 

[che12345]

Dear Mr. CuriousElectron
@ Mr.Parchie (Electrical)21 Aug 22 12:59
"....The 8-hour rate is the published guaranteed duration that the battery was tested. It simply means for that 105 AH battery, it delivers 105/8 = 13.125 amperes for 8 hours or nearly around that duration..."
1. I am of the opinion that the Ah rating is NOT simply discharge current (A) x duration (h). In my post dated 20 August, I came across a 105Ah battery states a) (13A for 8h); b) (22A for 4h); c) (19A for 5h)..... where a) [13A x 8h =104Ah]; b) [22A x 4h = 88Ah ]; c) [19A x 5h = 95Ah ].
2. It is clear that a battery may be used at any discharge current. When discharge at a higher current, the duration and Ah rating would be lowered.
3. Summery: Refer to the manufacturer data sheet; select the discharge current(A), duration (h) and the end voltage (V) i.e. the load minimum working voltage (V).
Che Kuan Yau (Singapore)

 

[Parchie]

@ che12345 (Electrical),
There is nothing more behind battery nameplates. Those figures tell you the rating of their products with regards to their actual performance capabilities. As part of their product quality assurance, manufacturers test some samples of each production run to verify whether their published nameplate is true and maintained. The best testing is load testing batteries or what-have-you to getting a fix the published ratings.