Maximum charge rate.... What is 0.5c¹⁰amp ??

[SamDeleted]

Hi all

Looking at my agm powersafe batteries 12v 170ah , trying to figure out their maximum charge rate, data sheet says it's " 0.5c¹⁰A "

I think 0.5c makes 85ah , but not sure about about the to the 10th power . What does that mean ??

Any suggestions? Ty

 

[mikefitz]

Lead acid battery capacity is specified at certain discharge rates . Your battery specification should tell you if the rate is, 100 hours, 20 hours or 10 hours. The 10 hour rate is powering a load for 10 hours, full to empty.
According to Tayna batteries your Powersafe is specified at the 10 hour rate,

12V170FS EnerSys PowerSafe AGM Battery 12v 170Ah

12V170FS EnerSys PowerSafe V-FT VRLA Battery The EnerSys brand has been in the battery industry for over 100 years and is considered as one of the most trusted of the battery giants in the industry. Delivering energy storage systems and application solutions to customers globally. Known for...

www.tayna.co.uk

 

[SamDeleted]

Data sheet:

https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.enersys.com/493bb4/globalassets/documents/product-documentation/powersafe/v-ft/apac/powersafe-v-ft---application-guide-en-ps-vft-appg-001.pdf&ved=2ahUKEwiWs7WRp5r_AhWSZsAKHclUCbEQFnoECBsQAQ&usg=AOvVaw0ZdWNWeMSkcnmg5FC5G1zd

 

[SamDeleted]

Lead acid battery capacity is specified at certain discharge rates . Your battery specification should tell you if the rate is, 100 hours, 20 hours or 10 hours. My guess is your 170 Ah is at the 100 or 20 hour rate and the capacity at the 10 hour rate will be nearer 150 Ah.

I think 170ah is the 10hr rate from memory let me check

 

[SamDeleted]

@mikefitz

Capacity (C10)170 Ah

12V170FS EnerSys PowerSafe AGM Battery 12v 170Ah

The PowerSafe® V-FT Range with front positional terminals has been designed specifically for the use in applications that demand the highest levels of reliability and security. PowerSafe V-FT batteries are worldwide recognised as an excellent solution for Telecoms applications. The PowerSafe...

www.tayna.co.uk

But I'm more looking for the maximum charge rate

 

[mikefitz]

Max charge rate , cyclic use, from data sheet 0.5 C, 85 amps. Seems a bit high to me for an AGM battery, I would expect 0.2C to 0.3C.
Is the battery new or SH from a telecommunications application?

 

[Zwy]

Mike has it correct. The small 10 is denoting it is a 10 hour rated battery, in other words, at the 10 hour charge and discharge rate, the battery capacity is 170Ah.

Take the 170 divided by 10= 17A

17A x 0.5C= 8.5A charge rate typically used as a maximum

The battery can be charged at a higher rate, but that may affect battery longevity.

 

[Zwy]

Max charge rate , cyclic use, from data sheet 0.5 C, 85 amps. Seems a bit high to me for an AGM battery, I would expect 0.2C to 0.3C.
Is the battery new or SH from a telecommunications application?

From what I found on Enersys site, it is a telco application.

 

[Zwy]

Mike has it correct. The small 10 is denoting it is a 10 hour rated battery, in other words, at the 10 hour charge and discharge rate, the battery capacity is 170Ah.

Take the 170 divided by 10= 17A

17A x 0.5C= 8.5A charge rate typically used as a maximum

The battery can be charged at a higher rate, but that may affect battery longevity.

I'm editing here to prevent some confusion. I did look at the manual on Enersys and it did not have graphs. I did run across this manual, https://manuals.plus/enersys/v-ft-powersafe-battery-manual#axzz83697prdO

It is a VRLA battery and most of those are limited to max 0.3C. Most VRLA are charged at a constant voltage with current limiting. For this battery, 2.4V per cell max and needs to be compensated for temperature. Any charging will need temperature compensation.

According to this manual and the graphs contained within, it appears the battery would be fully charged in less than 4 hours hours at the 2.4Vpc rate. That would not be possible with 8.5A. The manual also states the battery is able to be fast charged and accepts high charge rates.

If I was charging this battery, I would use 0.3C rate as any maximum. I would also contact Enersys and ask them to explain the charge rate.

 

[SamDeleted]

Is the battery new or SH from a telecommunications application?

Ex telecoms , well used !

If I was charging this battery, I would use 0.3C rate as any maximum.

Yes very confusing , but I'll stick to 0.3c that sounds sensible

 

[SamDeleted]

0.5c10

10% to 80% in 5 hours

 

[SamDeleted]

AGM battery maximum charge rate

I am trying to calculate the maximum charge rate of my AGM powersafe batteries 12 V 170 Ah, the data sheet says it's "0.5c¹⁰ amps" I think 0.5 C makes 85 A, but not sure about the 10 to the

electronics.stackexchange.com

The smart folk over at stack exchange are just as puzzled , I'm going to ring the manufacturer tomorrow

 

[Warpspeed]

I have never understood why people wish to know what the absolute maximum of anything is, right up to the point of permanent damage or destruction, then decide to routinely run it at that level.

 

[Zwy]

I have never understood why people wish to know what the absolute maximum of anything is, right up to the point of permanent damage or destruction, then decide to routinely run it at that level.

One should know what the max charge rate should be so it is never exceeded.

 

[Warpspeed]

Yes quite so.
But many people do not seem to understand that de rating equipment is usually very necessary for long term reliability.

 

[Zwy]

Yes quite so.

But many people do not seem to understand that de rating equipment is usually very necessary for long term reliability.

I agree, I de rate items all the time.

 

[Warpspeed]

Quite often you can stress something to the max when its brand new without too many surprises.

But doing that regularly, can quickly age it to the point where it becomes unsafe and progressive damage sets in.

Manufacturers specifications, recommendations, and limits, need some understanding, and sometimes cannot be taken directly at face value.

 

[SamDeleted]

Yes quite so.
But many people do not seem to understand that de rating equipment is usually very necessary for long term reliability.

They are 11 years old so they're probably going to need a soft touch

BUT! It's very hard to derate when you don't know the rate in the first place

 

[Warpspeed]

BUT! It's very hard to derate when you don't know the rate in the first place

Haha, very true !