[RE-wrenches] 24 vs. 48

Tue Jan 17 19:03:52 PST 2012

No Problem Jay,

I tried to make it clear that I wasn't really talking about your specific
case, but about a more general case. Sorry that that wasn't helpful to you.

I have benefited because it does reinforce my thinking that in some specific
cases that I am looking at based on high capacity 2v cells, there is a size
range where a 24V system may in fact be the best choice. 

Thanks and good luck with it out there.

Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jay Peltz
Sent: Tuesday, January 17, 2012 6:03 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] 24 vs. 48

Hi Mark

I think it's other things that help to determine it Array size and therefore
# of CC Battery size and # of parallel banks Inverters and cabling

This system at 24v requires 2 CC, 4 parallel strings and dual 4/0 cables  vs
a 48v would be single CC, 2 strings batteries and a single 4/0.

In the it's just cheaper in this  case and better in terms of battery design

My thoughts
Jay

Sent from my iPhone

On Jan 17, 2012, at 11:19 AM, "Mark Frye" <markf at berkeleysolar.com> wrote:

> Interesting.
> 
> I can choose an OB VFX3524 w/ 85 ADC or an OB VFX3648 w/ 45 ADC of 
> charging capacity.
> 
> And assuming that I need C/10 during bulk charging (and the importance 
> of this is really what I am asking about) then:
> 
> VFX3524: 85 ADC * 10 = 850 AH * 24 VDC = 20.4 kWH battery bank
> 
> VFX3648: 45 ADC * 10 = 450 AH * 48 VDC = 21.6 kWH battery bank
> 
> OK, so it's about a wash either way in terms of stored energy.
> 
> But assuming for the moment that distances are short and the initial 
> difference in copper costs are small, wouldn't you rather have half 
> the number of individual cells to maintain...less watering, less SG 
> measuring, lower overall "part" (individual 2V cells) count?
> 
> Mark Frye
> Berkeley Solar Electric Systems
> 303 Redbud Way
> Nevada City,  CA 95959
> (530) 401-8024
> www.berkeleysolar.com
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of R Ray 
> Walters
> Sent: Tuesday, January 17, 2012 10:38 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] 24 vs. 48
> 
> The only advantages of 24 v are that you can create smaller KWH 
> battery banks, and that Bergey's XL.1 was only available in 24 v.
> Anytime the design allows, I jump to 48 v.
> 
> R. Walters
> ray at solarray.com
> Solar Engineer
> 
> 
> 
> 
> On Jan 17, 2012, at 11:11 AM, Nathan Jones wrote:
> 
>> 
>> 
>> Mark,
>> It would seem to be a wash. As the voltage is halved the amperage is
> doubled in the battery bank. This would seem to require doubling the 
> charging amperage so nothing is gained. On a system of any size the 48 
> volt gets the default nod here. Charge controllers handle twice the solar.
> Parallel battery strings are eliminated, or at least held to two. Wire 
> sizing might be reduced on the low voltage side of things. And much 
> easier future expansion possibilities, too.
>> Cheers,
>> Nathan Jones
>> Power Source Solar Inc
>> 
>> 
>> ------------------------------
>> On Tue, Jan 17, 2012 10:56 AM CST Mark Frye wrote:
>> 
>>> Not really on topic to Jay's question, but...
>>> 
>>> Is 48v always better than 24v?
>>> 
>>> How important is bulk charging current to overall battery life?
>>> 
>>> In some cases, isn't it better to use a 24v inverter/charger which 
>>> can develop a higher charge current for a battery bank that has a 
>>> higher AH rating?
>>> 
>>> Mark Frye
>>> Berkeley Solar Electric Systems
>>> 303 Redbud Way
>>> Nevada City,  CA 95959
>>> (530) 401-8024
>>> www.berkeleysolar.com
>>> 
>>> -----Original Message-----
>>> From: re-wrenches-bounces at lists.re-wrenches.org
>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of jay 
>>> peltz
>>> Sent: Tuesday, January 17, 2012 8:43 AM
>>> To: RE-wrenches
>>> Subject: [RE-wrenches] battery buss bars
>>> 
>>> Hi All,
>>> 
>>> Where do I find buss bars for a battery parallel problem?
>>> 
>>> I've got to fix a brand new ( not me) system, that has 4 sets of 
>>> L-16's at 24v.
>>> Yea yea why didn't they go to 48?
>>> 
>>> So I want to use buss bars to parallel them, and looking for premade
> ones.
>>> 
>>> Thanks in advance,
>>> 
>>> Jay
>>> 
>>> Peltz power
>>> 
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