[RE-wrenches] AGM battery charging, more details

Rick Cullen - Blue Sky Energy, Inc. rick at blueskyenergyinc.com
Tue Apr 26 10:54:38 PDT 2011


Wrenches,

 

There has been some discussion in the past few days regarding AGM batteries
and charge control switching to Float based on net battery charge current
matched to battery size and that our IPN-ProRemote product can provide this.
Let me briefly describe what this is and how it works.

 

We produce a family of charge controllers based on what we call the
Integrated Power Net, or IPN network. IPN compatible charge controllers may
operate standalone, but multiple controllers may also be combined and these
multiple controllers communicate over the IPN network and coordinate their
activities to charge the battery as a single coordinated charging machine.
The IPN network does not require special hardware or software as everything
is provided within the charge controller.

 

The IPN-ProRemote display may optionally connect to an IPN network of one or
more charge controllers and the IPN-ProRemote could be thought of as two
machines in the box, first a charge controller monitor and setup device, and
second a complete battery system monitor. A shunt is used as with other
battery monitors to measure net battery current, compute amp-hours from
full, etc. The IPN-ProRemote and charge controller(s) coordinate their
activities over the IPN network such that the controller has access to net
battery current and the charge control system can use this to switch to
Float when net charge current drops to user settable threshold matched to
battery size in amp-hours. A conventional timer is also provided as backup.

 

There is also some mention below of "what about diversion control?" Our
SB3024iL with the DUO-Option provides both PV MPPT and a separate Diversion
controller in the same unit which may also use the IPN-ProRemote.

 

 

Regards,

Richard A. Cullen

President

Blue Sky Energy, Inc.

 <mailto:rick at blueskyenergyinc.com> rick at blueskyenergyinc.com

 <http://www.blueskyenergyinc.com/> www.blueskyenergyinc.com

760-597-1642 x102

Fax 760-597-1731

 

 

 

 

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Hugh
Sent: Monday, April 25, 2011 11:06 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] AGM battery charging, more details

 

Hi Jamie,

 

Thanks for the link. I find the Rolls/Surrette instructions puzzling.  They
suggest a bulk phase at I1 (presumably 0.25xC20 which is fine), followed by
an absorb phase " The charger should maintain the voltage U0 until the
current tapers to I1"  This current I1 makes no sense to me in the second
stage, but the graph shows current dropping to 0.012xC20 which does make
sense and corresponds to the Fullriver instructions linked by Larry.


The proper charging procedure clearly requires that the charger/regulator
measures the charging current (not just the PV current and/or wind/hydro
current, since there may be a load). 

 

My questions to the Wrenches List is: "What hardware do wrenches use to
regulate the charge on an AGM battery?"  Does everyone use this Blue Sky
Energy device?  Is it possible to use AGM batteries with a conventional
diversion controller such as the Morningstar Tristar, and if so how do you
determine the transition from 2.45 V/cell to 2.3 V/cell?  Morningstar offer
a timed transition, but without knowledge of current or of SOC this is
rather less precise.

 

Both of the charging methods in the agm-faqs linked below (and in the
Fullriver document) require measurement of the charging current to determine
the correct transition from one stage to the next.  Measurement of dV/dt is
also suggested in the case of constant current charging.  Who actually
follows these guidelines, and can AGM batteries operate successfully
without?

 

thanks!

 

Hugh

 

 

At 18:41 -0300 25/4/11, James Surrette wrote:

Content-Type: text/html; charset=US-ASCII
Content-Description: HTML

Hi Hugh,

 

Here is the charging information for our AGMs.

 

Please let us know if you need anything else.

 

 <http://www.surrette.com/content/agm-faqs>
http://www.surrette.com/content/agm-faqs

 

Regards,,

 

Jamie

>>> "Starlight Solar, Larry Crutcher" <larry at starlightsolar.com> 4/25/2011
6:04 PM >>>
Hi Hugh,

An AGM battery is considered full when the current drops below a specified
amount. Lifeline, for instance, is considered full when current is less than

0.5 amps per 100AH. The Blue Sky Energy IPN Pro Remote
http://www.blueskyenergyinc.com/products/details/ipn_proremote/ will allow
you to program the transition into float mode based on the amount of current
flowing through a shunt. This can be very useful for your project that
involves opportunity charging. Multiple charge sources can be monitored by
the IPN Pro simultaneously. For us, it is the most ideal charger for VRLA
batteries.

Here's a link to some charging instructions for the Fullriver AGM:
http://www.fullriver.com/products/admin/upfile/Charginginstruction.pdf

Larry


----- Original Message -----
From: "Hugh" <hugh at scoraigwind.co.uk>
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Sent: Sunday, April 24, 2011 12:11 AM
Subject: Re: [RE-wrenches] AGM battery charging, more details


| Thanks, Larry for the detailed response
| >
| >
| >Generally, the manufacturers charge recommendations should be followed.
|
| Yes but the issue I have is to know when and how to switch from
| absorption to float.  The Tristar has its own decision process but is
| it correct?  And if not then are the settings suitable.
|
| >  If you take away the red paint, I believe the Rolls AGM is the
| >Fullriver DC series battery. We started selling Fullriver last year
| >and I was surprised to find the very high absorb voltage
| >recommendation. For the DC400-6 (415AH) in cycle use they recommend
| >charging at 29 to 29.8 volts and float at 27.6 @25C! That is the
| >highest AGM voltage settings I have seen from any manufacturer.
|
| That's my worry.
|
| >
| >My thinking about AGM's is that the float voltage and transition
| >current are much more important factors than absorb voltage and
| >current.
|
| Transition current is not in the vocabulary of the Tristar

| controller.  I am not aware of a product that has this feature aside
| from maybe some inverters.   I have read in an Outback manual that
| you should program the absorb time based on charge current
| measurements, but the logic of this depends on the battery being
| 'flat' to the same degree at the start of each charge - whereas wind
| and solar charging is not like that.
|
| >For most AGM's, initial charge current is almost unlimited. However,
| >Fullriver recommends current limiting and constant voltage for the
| >bulk/absorb cycle. Their current limit is .15 to .35*C20 rate. BTW,
| >make sure to adjust the temp. comp to 3mV/C/C for float. That is
| >lower than most.
|
| Tristar default is 5 mV/C/C but can be modified by RS232 lead and
| software intervention.
|
| >
| >Equipment in a 24 volt system should be fine up to 32 to 33 volts.
| >Check the specs.
|
| It's not me that has the problem it's the telemetry engineers.  I
| assume they read the manual.  But reduced temp comp helps.
|
| >
| >What I said about equalizing was that I had done it twice to my
| >personal AGM battery bank. After the battery is fully charged (<0.2A
| >per 100ah @ C20) I put each battery, not each string, on a current
| >controlled charger. The current setting is .05*C20.
|
| That is 5 amps for a 100Ah battery?  Does this not make them gas?
|
| >I don't use voltage regulation when I do this. Once the battery
| >reaches 2.58 V/Cell, I charge for about 4 more hours always
| >monitoring battery temperature. I use this process to recover AGM
| >battery capacity and it has been mostly successful with all
| >brands. No more puzzle.
|
| Thanks - AGMs are a puzzle to me but you make it sound pretty simple.
| I do still have an issue with controlling the charge rate using
| existing technology on an opportunity charging system where the
| battery may be in any state of charge when the wind starts blowing,
| or sun starts to shine.
|
| best wishes,
| --
| Hugh Piggott

_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org

This email and its attachments have been scanned by iConnection E-Mail
Firewall for viruses, spam, and malicious content. The information
transmitted in this email is intended only for the entity or person to which
it is addressed and may contain confidential/privileged material. If you
received this in error, please contact the sender and delete the material
from any computer. Any review, retransmission, dissemination, or other use
of this information by persons or entities other than the intended recipient
is strictly prohibited. %^^%


_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org

 

 

-- 

Hugh Piggott

Scoraig
http://www.scoraigwind.co.uk

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110426/f088bb50/attachment-0003.html>


More information about the RE-wrenches mailing list