Re: 96v (16x6v) 21600wh VS 156v (13x12v) 21840wh (one more question)

[Richard Acuti]

Hey John,

Thanks for the great explanation.  I've been reading this from the sidelines. It seems to me that Peurket's really makes lead batteries a PITA to use. If it weren't for the cheap initial purchase price compared to other batteries, I bet we'd all be using something else.

I toyed with the idea of putting NiCd's in my car but I couldn't seem to pack enough BB600's in to achieve the same voltage that I get with my 8v's. The immunity to cold, and longevity seemed to outweigh the hassles of watering so many batteries.

Hm...maybe I should have done it after all. Here's a question- Do NiCd's suffer from the same amount of voltage sag when you load them? I don't know what the internal resistance is vs. Pba batteries.

Thanks.
_______________________________
Message: 4
Date: Sun, 06 Jul 2008 17:46:23 -0400
From: Neon John
Subject: Re: [EVDL] 96v (16x6v) 21600wh VS 156v (13x12v) 21840wh
To: Electric Vehicle Discussion List
Message-ID:
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(snip)

________________________________

Rich A.
Maryland
http://www.austinev.org/evalbum/371.html
http://patriotfuel.blogspot.com/




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[Phil_Marino]

>
> Hey John,
>
> Thanks for the great explanation.  I've been reading this from the sidelines. It seems to me that Peurket's really makes lead batteries a PITA to use. If it weren't for the cheap initial purchase price compared to other batteries, I bet we'd all be using something else.
>
> I toyed with the idea of putting NiCd's in my car but I couldn't seem to pack enough BB600's in to achieve the same voltage that I get with my 8v's. The immunity to cold, and longevity seemed to outweigh the hassles of watering so many batteries.

Pack voltage alone doesn't tell you much about a car's performance or range. You could get better range and performance with a lower voltage pack, if it could produce more current ( and had higher total watt-hour capacity).  

After all, you could buy and install a couple of hundred NiCad AA cells, and you'd have lots of voltage, but, it wouldn't drive the car very far or fast ( or, at all)

As to voltage sag, I'm no expert on NiCads, but I believe they generally have low internal resistance, and so might have less voltage sag than flooded lead acid batteries.

Phil Marino

>
> Hm...maybe I should have done it after all. Here's a question- Do NiCd's suffer from the same amount of voltage sag when you load them? I don't know what the internal resistance is vs. Pba batteries.
>
> Thanks.
> _______________________________
> Message: 4
> Date: Sun, 06 Jul 2008 17:46:23 -0400
> From: Neon John
> Subject: Re: [EVDL] 96v (16x6v) 21600wh VS 156v (13x12v) 21840wh
> To: Electric Vehicle Discussion List
> Message-ID:
> Content-Type: text/plain; charset=us-ascii
>
> (snip)
>
> ________________________________
>
> Rich A.
> Maryland
> http://www.austinev.org/evalbum/371.html
> http://patriotfuel.blogspot.com/
>
>
>
>
> _________________________________________________________________
> Making the world a better place one message at a time.
> http://www.imtalkathon.com/?source=EML_WLH_Talkathon_BetterPlace
>
> _______________________________________________
> For general EVDL support, see http://evdl.org/help/
> For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev
>

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[Lee Hart]

Phil Marino wrote:
>> It seems to me that Peukert really makes lead batteries a PITA to
>> use. If it weren't for the cheap initial purchase price compared to
>> other batteries, I bet we'd all be using something else.

Except that all batteries have a Peukert effect to some extent. It's
because all batteries have series resistance. All Peukert did is to
graph the *actual* amphour capacity to a defined end-of-charge voltage
as a function of load current. He noticed that the curve becomes an
approximately straight line if graphed on log graph paper.

We still use lead-acid batteries simply because they are cheap; and for
most people, cheap trumps everything else.

> As to voltage sag, I'm no expert on NiCads, but I believe they
> generally have low internal resistance, and so might have less
> voltage sag than flooded lead acid batteries.

Correct. As a rule, nicads have very low internal resistance. Thus their
Peukert effect is low enough to ignore in many applications.

It is possible to make lead-acid batteries with similarly low internal
resistance (Bolder cells, for example); but then they aren't cheap!

--
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

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