[RE-wrenches] AGM battery charging, more details

Tue Apr 26 04:55:25 PDT 2011

For what it's worth, I use a Balmar Regulator on boats for engine alternator
charging. The Balmar times how long it takes to go from SOC to your setpoint
absorption voltage. That time determines absorption time. It does this each
and every charge. Not as accurate as measuring current but it does a good
job.

Larry Liesner

On Tue, Apr 26, 2011 at 2:06 AM, Hugh <hugh at scoraigwind.co.uk> wrote:

>  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
>
> _______________________________________________
> 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
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110426/ac7cf2f8/attachment-0004.html>