Date: Sun, 13 Mar 2011 18:12:46 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Auxilliary batteries
In-Reply-To: <BLU0-SMTP28CAECCB7BFE0AC8C453F090CD0@phx.gbl>
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At 05:47 PM 3/13/2011, Gilles H Turmel wrote:<br>
<blockquote type=cite class=cite cite="">To my understanding the gel type
battery will only give me higher life expectancy of the battery with the
same autonomy as acid type. Is that a good assumption?</blockquote><br>
Gilles, try a different word for 'autonomy' or give us the word in
French...<br><br>
In the mean time - in order to get good life from any battery used for
deep-cycle applications, but *most particularly* from AGM and gel type
batteries, it is necessary to follow the correct charging regime which is
not possible with automotive-type voltage regulators. I would
strongly recommend to use either of these types only if you will also use
the necessary equipment for charging and for monitoring discharge.
It happens that my brother is making an installation of AGM batteries in
his boat, and in the course of discussing this with him I collected some
charging regimes from various AGM battery manufacturers which I will
quote below. Gel batteries will have similar requirements which
also can be obtained from the individual manufacturers.<br><br>
Yours,<br>
David<br><br>
<blockquote type=cite class=cite cite="">Optima Yellow Top, cyclic
application:<br>
Cyclic Applications:<br>
14.7 volts, no current limit as long as battery temperature remains below
125°F (51.7°C). When current falls below 1 amp, finish with 2 amp
constant current for 1 hour.<br><br>
Lifeline AGM, all:<br>
The following charging voltages are recommended for maximum battery life
for all Lifeline models. <br><br>
Charging Phase 12 Volt Battery <br>
Bulk/Absorb 14.2v - 14.4v<br>
Float 13.20v - 13.40v<br>
NOTES:<br>
1. Use midpoint values for most applications. Lower voltages may be
suitable for light-duty applications and higher voltages may be suitable
for heavy duty applications. <br>
2. For 24 Volt Systems, multiply 12 Volt setting by 2. <br>
3. Charge voltage should be adjusted if battery temperature varies by
more than 10°F from 77°F. Consult website for further guidance
(<a href="http://www.lifelinebatteries.com/" eudora="autourl">
www.lifelinebatteries.com</a>). <br><br>
Conditioning/Equalizing Charge: 15.5 volts for 8 hours <br>
Conditioning/equalizing should only be done when the battery is showing
symptoms of capacity loss. If conditioning/equalizing is necessary, first
go through the normal charge cycle. Once the battery is as fully charged
as possible, start the conditioning/equalizing charge. <br><br>
For maximum battery life, a battery must be recharged to 100% capacity.
Recharging to less than 100% may result in premature battery failure.
Lifeline batteries are not covered under warranty if they are not
recharged properly. For more information, please refer to our warranty
policy. <br><br>
<br>
DEKA:<br>
The charger must be temperature-compensated to prevent underor<br>
overcharging due to ambient temperature changes. (See Charging<br>
Voltage vs. Ambient Temperature chart on page 11.)<br><br>
Use only “voltage-regulated” or “voltage-limited” chargers.<br>
Standard constant current or taper current chargers must not be<br>
used. The voltage must fall in the range of the chart on page 11.<br>
Almost all applications require temperature sensing and voltage<br>
compensation. Beware, many chargers measure the ambient<br>
temperature which could be significantly different from the
battery’s<br>
internal temperature.<br><br>
Temp. Charge Float Temp.<br>
°F Optimum Maximum Optimum Maximum °C<br>
. 120 13.60 13.90 12.80 13.00 . 49<br>
110 – 120 13.80 14.10 12.90 13.20 43 – 49<br>
100 – 110 13.90 14.20 13.00 13.30 38 – 43<br>
90 – 100 14.00 14.30 13.10 13.40 32 – 38<br>
80 – 90 14.10 14.40 13.20 13.50 27 – 32<br>
70 – 80 14.30 14.60 13.40 13.70 21 – 27<br>
60 – 70 14.45 14.75 13.55 13.85 16 – 21<br>
50 – 60 14.60 14.90 13.70 14.00 10 – 16<br>
40 – 50 14.80 15.10 13.90 14.20 4 – 10<br>
. 40 15.10 15.40 14.20 14.50 . 4<br><br>
MK Batteries:<br>
<b>AGM Battery Charging<br>
STAGE END CONDITIONS ERROR<br>
Bulk Stage I<font size=1>1<br>
</b></font>Maintain Current <= 30 A per 100 Ah C<font size=1>20<br>
</font>Typically, Constant Current, but Constant<br>
Power, or Taper Charge Permitted<br>
End when voltage = 2.40 to 2.43 V/cell
(20<font face="Symbol">°</font>C)<br>
Max time (h) = 1.2 * DoD (Ah) / Avg. Current (A)<br>
If Max time is<br>
exceeded: STOP<br>
<b>Absorption Stage V<font size=1>1<br>
</b></font>Maintain Constant Terminal Voltage<br>
(Adjusting only for changing battery<br>
temperature)<br>
Voltage = 2.40 to 2.43 V/cell (20<font face="Symbol">°</font>C)<br>
Without the optional accelerated finishing stage,<br>
maintain charge until current acceptance drops by<br>
less than 0.10 ampere over a 1 hour period<br>
Max Time: 12h<br>
With optional accelerated finishing stage end<br>
when current = I<font size=1>2<br>
</font>Max Time: 6h<br>
If Max time is<br>
exceeded: Goto next<br>
stage<br>
If Current exceeds<br>
8 A after dropping<br>
below 6 A: STOP<br>
<b>Optional Accelerated Finishing Stage I<font size=1>2<br>
</b></font>Maintain Constant Current:<br>
1 to 2 A per 100 Ah C<font size=1>20<br>
</font>Charge for 1 to 4 hours based on Ah accumulated<br>
in first two stages:<br>
<25% of C<font size=1>20 </font>– 1 hour<br>
25% to 50% of C<font size=1>20 </font>– 2 hours<br>
>50% of C<font size=1>20 </font>– 4 hours<br>
If Voltage exceeds<br>
2.80 V/cell: Goto<br>
next stage<br>
<b>Optional Float Stage V<font size=1>2<br>
</b></font>Maintain Constant Terminal Voltage<br>
(Adjusting only for changing battery<br>
temperature)<br>
Voltage = 2.25 V / cell (20<font face="Symbol">°</font>C)<br>
No time limit<br>
This step is generally unneeded if<br>
(1) zero load is present when device is not in<br>
operation, and (2) device duty cycle does not<br>
include periods of non-use exceeding 3 months.<br>
To compensate for battery temperature not at
20<font face="Symbol">°</font>C, subtract 0.005 V/cell for each
1<font face="Symbol">°</font>C above 20<font face="Symbol">°</font>C;
add<br>
0.005 V/cell for each 1<font face="Symbol">°</font>C under
20<font face="Symbol">°</font>C.<br>
Applies to East Penn’s 8A Line product.<br><br>
You can find all this stuff better formatted and more complete on each
mfrs website. Google agm batteries and one of the top results will
be a list of brands.<br><br>
My point is that the makers care enough to specify very rigorous charging
regimens including continuous battery-temp measurement and
bulk/absorption/float charging, either unconditionally or for all cyclic
applications. Some (Optima for example) say if you're using it as a
starting battery you can hook it to an automotive-type regulator within x
voltage limits. Some (Lifeline, for example) do not allow that
under any circumstances and will void your warranty if you do it (more
correctly, if you don't keep the thing correctly charged they won't honor
the warranty; language is above in the Lifeline section).*<br><br>
*Incidentally, the one that mentions the harmful qualities of ripple then
goes on to describe a test procedure that won't tell you anything about
ripple. But every digital voltmeter I've ever used, the AC ranges
will reject DC and will be good up to 400 Hz or so, so if you have one
with a 2V AC range you can directly measure LF ripple on the charging
line.<br><br>
It's your call; they're your batteries. But I want to say wake up
and smell the coffee - the equation is clear: if you can afford AGM
batteries then you can afford the right gear to take care of them.
People who say that the three-stage regulators are ridiculously hard to
wire up have fallen victim in some way to the "electricity is
magic" myth. Slow down, read the manual/hookup diagram a few
times until you understand who does what to which. Once you
understand what's going on, the physical wiring is no big deal. Off
the top of my head, you've got, minimum:<br><br>
Temp sensor to battery post (twisted pair)<br>
+12 supply from ignition switch<br>
Power ground (B-)<br>
Current source (or sink) to alternator field<br>
+sense to B+ at battery<br>
-sense to B- at battery (may be combined with system ground, above)<br>
sense input to drop to float voltage if halogen lights are running, since
they're intolerant of high voltages. With more and more LED
lighting halogens are probably dodos at this point.<br>
Analog or digital adjustment for base charge voltage(s) before temp
compensation<br>
Analog or digital adjustment for absorption charge time, since it's not
economically feasible to get the last few watt-hours in given the cost of
gasoline.<br><br>
Optionally:<br><br>
Pushbutton to immediately drop to float until next restart<br>
Remote indicators for what mode the regulator is operating in and for
error conditions.<br><br>
Further fancies:<br>
The device may incorporate automatic charge switching between banks,
automatic paralleling of banks while charging, automatic solar charge
controller, instrumentation, maybe bunch of other things. Each of
those things will have its own set of wiring requirements - consider them
separately and they won't seem so complicated.<br><br>
:)<br>
d </blockquote></body>
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