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Omnipower 260Ah batteries (yellow)


MJG
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Hi everyone, (Newby)

I'm preparing for winter Loadshedding. I bought a Synapse 3kVA inverter and would like to know if the Omnipower 260Ah battery is a good unit to consider using?

The technical detail on discharge and lifespan are greek to me.

So, basically is this battery okay or does anyone have some experience with them.

TIA

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1 hour ago, MJG said:

I'm preparing for winter Loadshedding. I bought a Synapse 3kVA inverter and would like to know if the Omnipower 260Ah battery is a good unit to consider using?

Search around a bit on this forum. In fact, the best would be to go to google, and add "site:powerforum.co.za" to you search terms. Search for omnipower.

I remember there were a handful of disappointments where they did not quite live up to their promise.\

Also note that the 260Ah rating is a C/100 rating. Its real C/10 rating is more like 200Ah. I'll say more about this below.

1. The Ah (amp-hour) rating is the capacity of the battery. A 200Ah battery can in theory give 1A for 200 hours, or 200A for one hour (or 100A for 2 hours, or 50A for 4 hours, etc) before it is empty. I say in "theory" because there are limits to how fast a battery can be charged and discharged.

2. The shortest time that you can charge/discharge a lead acid is 5 hours, and this is not recommended. It is better to do it over 10 hours.

3. Discharging or charging a battery too fast causes energy to be lost. This is known as the Peukert effect. If you work a battery too hard, the usable capacity becomes less. The industry standard is a C/20 discharge rate (discharge over 20 hours). The C/20 rate for the above battery is around 10A and it will be empty after 20 hours.

4. This is why I say the above battery is not really a 260Ah battery. To get that figure the manufacturer used a C/100 rate, or around 2 ampere. Due to the Peukert effect, you get more useable capacity if you discharge slower, but this is not a realistic number for home use. For home use the C/10 rate is more accurate.

5. Lifespan. The battery can be charged and discharged a certain amount of times. The deeper you discharge it, the fewer times you can do it. The standard advice is to not discharge the battery below 50% SOC, in other words to not use more than half of its capacity. When you do this, a good AGM battery (like the above) should give up upwards of 600 cycles, possibly even more than 1000. A good flooded bttery will give upwards of 1500 cycles. In other words, you can discharge them (halfway) and recharge them 1500 times before the battery will have lost half its capacity and become incapable of doing the original job.

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