Stupid question (1 Viewer)

[BusyBuilder]

If you have 200ah batteries, does that mean , in simple terms...you can draw 200amps for 1 hour?

 

[GrahamPye]

If you have 200ah batteries, does that mean , in simple terms...you can draw 200amps for 1 hour?

It depends on the battery type - possibly for a Lithium, no chance for anything with lead in it...

 

[Cush]

No such thing as a stupid question. In theory but you can never go that low so it’s not really your capacity. A lead acid shouldn’t be taken below 50%, a lifepo 20% . 200 amps in an hour would an incredibly high discharge rate. .

 

[Googlebot]

If you have 200ah batteries, does that mean , in simple terms...you can draw 200amps for 1 hour?

Yes.

That’s the total capacity as others have said. Lead acid you get 50% of it. Lithium much more.

 

[Richard n Ann]

If you have 200ah batteries, does that mean , in simple terms...you can draw 200amps for 1 hour?

In theory yes, or

100 amps 2 hours
50 amps 4 hours
25 amps 8 hours
12.5 amps 16 hours
6.25 amps 32 hours
3.125 amps 64 hours

But you wouldn't want to try and draw 200 amps, neither would you want to completely flatten the battery, but you probably know that bit

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[meanders]

It would be some cable to take 200A! About 35mm if my maths is right. A Busbar job.

 

[bigtwin]

In theory yes, or

100 amps 2 hours
50 amps 4 hours
25 amps 8 hours
12.5 amps 16 hours
6.25 amps 32 hours
3.125 amps 64 hours

As stated above, in theory.

In practice the Peukert effect comes into play where capacity reduces with increasing current draw such that you would not have 200Ah of capacity if you were drawing 200A. This is why you will see different battery capacities stated on a single battery (e.g. the C20 rate and the C5 rate). The most commonly stated capacity is at the C20 rate.

Ian

 

[bigtwin]

It would be some cable to take 200A! About 35mm if my maths is right. A Busbar job.

Some vehicles have 3kVA inverters that will pull close to 300A (for which, IIRC, Victron recommend using 2 x 50mm cables).

Ian

 

[Lenny HB]

In theory but you would completely bu**er a lead battery and as bigtwin pointed out you would quite mange to do it.
With Lithium it's almost possible.

 

[autorouter]

If you have 200ah batteries, does that mean , in simple terms...you can draw 200amps for 1 hour?

If you look at the small print you will find that it's specified for a number of hours. Usually 20 hours. So yes, you can draw 10 amps for 20 hours, and then the battery would be completely flat. That's what the battery manufacturers did to arrive at that 200Ah number.

They often give figures for the 100 hour rate, and the 5 hour rate. Typically the 100 hour rate will be more than 200Ah, maybe 220Ah. Also the 5 hour rate will be less than 200Ah, maybe 180Ah

However there is a limit to the amps that you can take from a battery, due to the buildup of heat internally. Some battery technologies are better than others. Gels don't like amps of more than C/5, so for a 200Ah battery that's only 200/5 = 40A. Lithiums are better, and some can take C/2 or even C, if permitted by the internal BMS.

If you actually want to take 200A from a 200Ah battery, you'll need a lithium with a good BMS.

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[VXman]

It would be some cable to take 200A! About 35mm if my maths is right. A Busbar job.

2500watts would take around 200amps (roughly) at 12 volt so its not an unusual amount for those using kettles or induction hobs.

 

[Spriddler]

A starter on an average 4 cylinder car draws about 200 amps and it certainly wouldn't keep a lead/acid battery grinding away for an hour, besides which at 200 amps the voltage would almost immediately drop substantially.