Or just use a water heater element:
http://store.mwands.com/images/products/secondary/12v_300w_element_02.jpg
http://inspectapedia.com/plumbing/Water_Heater_Element_Ohms_AOSs.jpg
ryan
On 9/19/14 7:39 AM, Chuck McCown via Af wrote:
signature
Cheap (free) load resistors can be made from full rolls of 14 gauge wire.
2.5 ohms per 1000 feet. Get two 1000� rolls and you have a 5 ohm
resistor. 9.8 amps from a 48 volt battery. I put them in a bucket of
water to dissipate the heat and keep them from getting heat damage to
the insulation.
Then you can return the wire after you are done...
*From:* David via Af <mailto:af@afmug.com>
*Sent:* Friday, September 19, 2014 7:04 AM
*To:* af@afmug.com <mailto:af@afmug.com>
*Subject:* Re: [AFMUG] battery tester
We are able to time of discharge by reviewing graphs from our CTMs
once AC power has stopped.
Depending on what the overall current draw is which we find by the
load in watts on each port of the CTM.
Its not 100% but it gives me a good idea about what we should get out
of a AGM 100ah battery.
On 09/18/2014 02:57 PM, Chuck McCown via Af wrote:
Telemetry.� Just watch the slope of the discharge voltage at
night.� I have tried to use impedance meters several times at
different companies and cannot get results that predict failures.
�
If you have a battery that should last several days, disconnect the
solar panels and watch the telemetry.�
�
*From:* Randy Cosby via Af <mailto:af@afmug.com>
*Sent:* Thursday, September 18, 2014 1:06 PM
*To:* af@afmug.com <mailto:af@afmug.com>
*Subject:* [AFMUG] battery tester
�
Does anyone have a recommended battery tester for AGM and Gel
batteries at solar sites?� I have batteries from 100AH to 225AH.�
Most of the automotive models seem to be concerned with cold cranking
amps, pretty irrelevant for us.
--
<http://www.infowest.com/> Randy Cosby
InfoWest, Inc
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