[RE-wrenches] RETURN AMP SETTING

Mon Jul 26 06:27:53 PDT 2010

Sorry all… I was out on a little three day vacation. 

I usually program return amps setting to usually 2-3% of the overall battery bank capacity. 

Usually and depending on the battery type or manufacure when the current passing from the charger to the battery drops to this Return amp setting technically the batteries are charged.  

Because batteries are technically buckets of water with holes in them, they will never stop pulling current, nor will they never be fully charged.   What happens is they start to draw a minimum of charge current from the charger.   This “Maintenance current” usually is between 2,3,4,5 percent of the overall battery bank capasity. 

With the Return amps setting you can get the batteries close to that charged setting. 

Steve Higgins. 

Sr Application Engineering Mgr

Sub-Saharan Africa Business Dev Mgr. 

Outback Power Systems. 

19009 62nd Ave Ne 

Arlington Wa 98223

360-618-4313

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dana
Sent: Thursday, July 22, 2010 8:37 AM
To: 'RE-wrenches'
Subject: [RE-wrenches] RETURN AMP SETTING

Chris Freitas of Outback can you chime in here?

Thanks,  Dana Orzel

Great Solar Works, Inc

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

Responsible Technologies for Responsible People since 1988"

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Darryl Thayer
Sent: Wednesday, July 21, 2010 8:35 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] RETURN AMP SETTING

That is a good question, I have not an answer, but of course it should be based on the amp hour of the battery bank, absorb charging voltage, and of course the charging source in the case of generators.  Following Ron's advise start at C/5 for SOC less than 50% then C/10 till about 70% SOC and then C/15 till 80% then C/20 to 90 %. the problem we have no way to set these values, Perhaps Ron could give is a routine?  The closet to SOC charging is the Outback and then the Magnum but both miss the goal.  

--- On Wed, 7/21/10, Dana <dana at solarwork.com> wrote:

From: Dana <dana at solarwork.com>
Subject: [RE-wrenches] RETURN AMP SETTING
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Date: Wednesday, July 21, 2010, 5:54 PM

As the % of full charge is related to the of degree absorption & gravity [the denser & more charged acid descending, and lighter acid rising] @ what point in the absorption would be prudent to stop charging?

I used to cut off the charge on the Trace SW series at 12 “return amps”, VS. the factory default I think was at 5 amps.  This has & continues to work well but I never had anyone really answer this function clearly.

Is there a battery manufacturer  or wrench that would care to comment on the:  

The minimum “Return” amps to disconnect for a “full” charge?

OR

The time required per 100 AHR after reaching the Absorption point setting for the mix to occur?

I realize that battery construction, battery condition, age and temperature and the current power usage will also play into this factor and it may not be a simple answer.

 Dana Orzel

Great Solar Works, Inc

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

Responsible Technologies for Responsible People since 1988"

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
Sent: Wednesday, July 21, 2010 4:25 PM
To: Allan at positiveenergysolar.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

Allen,

Can I infer that if you are shutting off the gen before charge rates drop in absorption that you are running only briefly in the absorb phase? Or do your charge currents remain high through out an extended absortion phase?

Perhaps you have plenty of PV which you rely upon to bring the batteries up through the absorption phase, once the gen is shut off.

I would be interest to learn more about your approach to this.

Thanks,

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

________________________________

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan Sindelar
Sent: Wednesday, July 21, 2010 3:17 PM
To: re-wrenches at lists.re-wrenches.org
Subject: Re: [RE-wrenches] Propane Generator, Dual Outback Inverters

The Onan RS20000 shown in the generators article in HP 131 page 98 has performed flawlessly as backup support to an Outback quad-stack of VFX3648s. Differences, however, are that this 20kW gennie charges four inverters, rather than two; the elevation is 6,600 feet for about a 20% output deration; there are no huge loads above charging draw; and the client is aware enough to shut it off before absorption reduces the charge rate - all different conditions than you have described, as the gennie is usually fully loaded and running in balance.

Darryl is right about the amount of words necessary.

Allan Sindelar
Allan at positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com <http://www.positiveenergysolar.com/> 

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