[RE-wrenches] Sealed battery test/maintenance

[Darryl Thayer]

HI all
the resistor bank that I used was the 240 volt water heater elements.  They seem to be quite cheap/  They do glow a real dull red on 24 volts, and I will try to measure the resistance.  for adjustment use a parallel set of 500 watt halogen work lamps. I use a combiner box and MNsolar breakers, the 1/2" wide ones.  connect the switches to recpticles, and the elements to cord ends.  and you can put a duplex recpticle to connect two loads in series.  
Darryl  


--- On Wed, 12/17/08, Peter Parrish <peter.parrish at calsolareng.com> wrote:

> From: Peter Parrish <peter.parrish at calsolareng.com>
> Subject: Re: [RE-wrenches] Sealed battery test/maintenance
> To: glenn.burt at glbcc.com, "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Wednesday, December 17, 2008, 11:22 AM
> I am very interested in this thread as we too have about a
> half-dozen
> grid-tied battery backup system in the field. I used to be
> a ham radio
> operator and I remember using large, wire-wound resistors
> encased in an
> aluminum casing. The case could be bolted to a heat sink. 
> 
> I looked up one of these puppies and found them rated up to
> 50W continuous.
> 
> Here is a simple tester:
> 
> Assume a single 12 V battery. If you want to test battery
> banks, I think
> that that would be a different ballgame altogether.
> 
> Use a number of 5 ohm / 50 watt resistors in parallel. The
> number you use
> depends on the current you want to test to. Assuming that
> you want to run at
> C/20, here is how you determine how many resistors you
> need.
> 
> A 5 ohm resistor will draw 2.4 amps. Assuming C/20, a
> single resistor would
> be an appropriate load for a 48 Ah battery. The power drawn
> is 28.8 W which
> is fine for a 50 W resistor as long as it is bolted to a
> good heat sink. Two
> 5 ohm resistors will draw 4.8 amps, appropriate for a 96 Ah
> battery. The
> general formula is "battery capacity divided by 48
> gives you the number of 5
> ohm / 50 W resistors you need in parallel". The power
> dissipated in each
> resistor will always be the same regardless of the number
> in parallel.
> 
> I will probably rig one of these loads up one day soon if a
> better solution
> isn't out there already.
> 
> One could add a high current switch or DC rated circuit
> breaker, voltage
> probe point and a high precision shunt to measure current.
> 
> I have no idea what sort of voltage as a function of time
> should be. Has
> anyone spoken to battery manufacturers about the specs
> under C/20?
> 
> - Peter
> 
> Peter T. Parrish, President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com 
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
> Behalf Of Glenn Burt
> Sent: Wednesday, December 17, 2008 7:41 AM
> To: 'William Miller'; 'RE-wrenches'
> Subject: Re: [RE-wrenches] Sealed battery test/maintenance
> 
> Thanks for the reply William,
> 
> When you load the battery bank, are you using the inverter
> as the source of
> the load (obviously with its loads), or do you use an
> independent DC load
> like a carbon pile (auto battery tester)?
> 
> Glenn 
> 
> -----Original Message-----
> From: William Miller [mailto:wrmiller at charter.net] 
> Sent: Tuesday, December 16, 2008 2:07 PM
> To: glenn.burt at glbcc.com; RE-wrenches
> Subject: Re: [RE-wrenches] Sealed battery test/maintenance
> 
> Glenn:
> 
> There are a combination of tests, none as decisive as we
> might like:  Load
> the battery bank and test per cell voltage (more often we
> find warm
> connections revealing related problems).  Measure the at
> rest voltage.
> Measure voltage over time at load.  If you are serious
> about this, establish
> base lines when batteries are new.
> 
> Good luck.
> 
> William Miller
> 
> 
> At 09:55 AM 12/16/2008, you wrote:
> >Good Holiday Season to all:
> >
> >Does anyone have a sealed (gel & AGM) battery
> test/maintenance 
> >procedure they would feel comfortable sharing with the
> group?
> >I have been tasked with creating one for our company
> now that we have 
> >more than a couple of grid tied systems with battery
> backup.
> >
> >Hate to re-invent the wheel with so much talent
> available here.
> >Thanks in advance!
> >
> >Regards,
> >
> >Glenn Burt
> >Technical Specialist
> >
> >Renewable Power Systems, LLC
> >PO Box 967
> >Averill Park, NY 12018
> >V: 518-674-5808
> >C: 518-810-3174
> >F: 518-514-1175
> >E: gburt at RPSPower.com
> >www.RPSpower.com
> >
> >
> >
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