Omni SRB-6V4 6v 4Ah lead acid battery capacity test @ 5-hour drain rate

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d_t_a
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Omni SRB-6V4 6v 4Ah lead acid battery capacity test @ 5-hour drain rate

I bought a new "Omni" brand (this is a more well-known reputable local brand)  6v 4Ah lead acid battery for one of the rechargeable lanterns at home.  I decide to test its capacity as a benchmark reference. I used EBD-USB+ and alligator clips (note that the alligator clip and wires likely have some resistance drop so it may not be that accurate..)

 

The Omni website doesn't have a detailed specs so I just cross-referenced other branded 6v4Ah Pb batteries to get the 5-hour discharge rate (0.2C), which is around 0.67A.   I also am not sure what cut-off voltage to use, I might have set too low @ 4.20v (have I damaged the battery slightly?)   Probably 5.10v is a correct cut-off voltage? 

(I checked data and @ 5.20v, the capacity readout was already around 3700mAh.)

 

(When in use in the rechargeable lantern, I believe the lantern may not have a low-voltage cut-off and it just tries to drain the battery completely??)

 

This seems like a good battery, it was priced at Php350 (around US$7).

I weighed the battery to be 672 grams.

Edited by: d_t_a on 11/11/2017 - 23:49
d_t_a
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I then charged it using a 6v2A PB charger I bought during Banggood’s flash sale 2 months back (received it just recently).
It’s labeled a YASO-0602:

https://www.banggood.com/6V-Sealed-Lead-Acid-Rechargeable-Car-Battery-Ch...

Charging the drained Omni 6v4Ah battery shows this graph:

So far this is my only stand-alone 6v lead acid battery charger (my only other method of charging is by placing inside the rechargeable lamp and plug to outlet for charging)

(I wonder if using a hobby charger like iMax B6, ISDT, iCharger will charge in the same way?)

Not sure if it’s a “good” charging curve but it looks good. Seems to take about 3 hours to charge to near-full.

reading the above graph:
- charging rate starts at around 1.8A (from 6.6v to 6.9v) and slowly decreases charging current [charger’s indicator is red ‘charging’]
- when voltage reaches 7.0v, the charging current starts to drop more quickly (note: the voltage readout is NOT the battery, but the charger; since I connected the EBD-USB+ to the charger’s alligator clamp and then the output to another USB-alligator clamp to the lead acid battery)
- the voltage increases slowly from 7.0v up to 7.3v, with charging current decreasing around 1.7A down to around 0.4A when it reaches 7.3v
- then the voltage drops suddenly to 6.9v and current is around 0.2A (slowly decreasing) [ the charger’s indicator turns from red to green at this point ] I think the charged capacity reading when it turned green was around 3800mAh

(I think it’s called ‘float’ charge when charger indicator turns green)

(note: the voltage reading of the EBD-USB+ is the voltage output of the charger, not the voltage of the battery)

The charged capacity seems to nearly match the discharged capacity.

d_t_a
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Pics of the Omni SRB-6V4

The labels indicate “max initial charge current < 1.2A”
the lead-acid charger I used was charging at an initial current of 1.8A, will this have damaged the battery?