Steve.....15 hours of Absorb charge!? Is this just during the initial
charge during commissioning? to set the Flexnet DC calibration?
Thanks for the clarification...
Cheers,
Kirpal Khalsa
Renewable Energy Systems LLC
---------- Forwarded message ----------
From: Steve Higgins <st...@surrette.com>
Date: Tue, Apr 30, 2013 at 12:31 PM
Subject: Re: [RE-wrenches] 24V Rolls Charging Parameters?
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Wayne, ****
** **
Sorry about the delay!… I’ve been in wonderful sunny Nigeria dodging
kidnappers and car bombs… ****
** **
** **
All Rolls batteries require a bit hotter voltage when charging and
especially when you are using multiple parallel strings. ****
** **
With that system I would suggest if you are using the Outback Temp
Compensation.****
** **
Inverter: ****
Bulk/Absorb 29.2 (2.45vpc)****
Absorb Time 15 Hours. (I’ll explain why below)****
Float 26.4 (2.2vpc)****
EQ 31.8 (2.65vpc)****
** **
Charge Controllers: ****
Bulk/Absorb 29.4-29.6. ****
Normally I set the controller a bit higher than the inverter
just so my charge controller don’t back off if my inverter is also charging
the battery.****
Absorb Time 4.5 Hours (Time=.42 * 3280 (C20 Rate) / 320amps (max current of
charge controllers) =4.13… Rounded up to 4.5 Hours. This can be adjusted
depending on monthly SG measurements and or water use. ****
Float 26.4****
EQ 31.8****
** **
Flexnet DC****
** **
End Amps 2% of Battery bank Cap. 65 amps. ****
Charge Voltage 29.0****
Met Time 1-3 min. ****
** **
Battery Charge Factor 90%****
This means if you take out 100 amps it’s going to put back
110% before it determine the batts are full. ****
** **
The reason for the longer Absorb time is the Flexnet DC determines full
charge by three parameters. ****
** **
**1. **Absorb Time Completion****
**2. **End Amps/Charged Voltage****
**3. **Battery Charge Factor. ****
** **
IF ANY ONE OF THESE (OR Statement in the Logic) PARAMETERS ARE MET, AND THE
FNDC SEE’S A 60 SECOND DISCHARGE IT WILL RESET THE SOC METER TO
98,99,100%. It’s better to set the Absorb timer longer and force it to
use the End Amps or BCF%..****
** **
The absolute worst way to charge a battery is by running a timer, all the
inverter manufactures do it because it’s a cheap (but somewhat effective)
method of charging a battery that works as long as you set the absorb timer
correctly. Plus a sulfated battery will rise in voltage too early
potentially causing issues with charging. ****
** **
The best way is measuring the amount of current and shut off the charger
when you hit about 2% (New battery) of the battery bank capacity. ****
** **
Many people make two mistakes when setting up the flexnet dc… ****
**1. **Leaving the absorb timer set at default… this will cause the
flexnet dc to think the batts are full and will reset the soc to 100%
early. ****
**2. **Not forcing a manual full charge prior to connecting the
Flexnet DC… The Flexnet DC when first powered up will assume a full 100%
state on the batteries. Many battery guys know that when they first
install them they are usually only at 60-80% SOC. This will cause
incorrect measurements of SOC from day one. ****
** **
Hope this helps. ****
** **
** **
** **
** **
*Steve Higgins
Technical Services Manager
***M: +1.206.790.5840
F: +1.902.597.8447
*Surrette Battery Company
*Exclusive manufacturer of
<http://www.rollsbattery.com>
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