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<?xml-stylesheet type="text/xsl" href="https://community.arm.com/utility/feedstylesheets/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" xmlns:wfw="http://wellformedweb.org/CommentAPI/"><channel><title>LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/developer/tools-software/tools/f/keil-forum/23687/lead-acid-battery-charging</link><description> 
I think that I used to know about battery charging but as 40 years
go by ...... 
I need to charge a 75AH battery. In my days it used to be considered
that a 10 hour charge/discharge (ie 7.5 amps per hour) rate was most
efficient. However I do not believe</description><dc:language>en-US</dc:language><generator>Telligent Community 10</generator><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/77152?ContentTypeID=1</link><pubDate>Fri, 13 Feb 2009 06:32:32 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:41426e1e-05be-4e49-aa5d-ebfc612583c3</guid><dc:creator>robert morley</dc:creator><description>&lt;p&gt;&lt;p&gt;
Yeh sorry to all. My Google search threw up this forum - clearly
the wrong place but thanks for the info anyway. Once again my
apologies.&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/101628?ContentTypeID=1</link><pubDate>Thu, 12 Feb 2009 12:20:42 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:7910b066-9f72-4c83-ab93-8e10e14f0363</guid><dc:creator>ImPer Westermark</dc:creator><description>&lt;p&gt;&lt;p&gt;
I find it a bit cute that the most common li-ion cell used to
build battery packs - the 18650 cell - is said to be 18mm in diameter
and 650mm long. That is more than two feet long ;)&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/89564?ContentTypeID=1</link><pubDate>Thu, 12 Feb 2009 11:59:17 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:150f97c9-455b-4bb8-83d0-9e7576e58149</guid><dc:creator>Andy Neil</dc:creator><description>&lt;p&gt;&lt;p&gt;
This might be getting a bit dated now; eg, there is no mention
that NiCd is no longer allowed to be sold in Europe...&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/55402?ContentTypeID=1</link><pubDate>Thu, 12 Feb 2009 11:00:32 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:ce3b4db7-74f8-4696-91e5-3d1c642af38e</guid><dc:creator>Neil Kurzmam</dc:creator><description>&lt;p&gt;&lt;p&gt;
Look at &lt;a href="http://www.batteryuniversity.com/"&gt;www.batteryuniversity.com/&lt;/a&gt;&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/55403?ContentTypeID=1</link><pubDate>Thu, 12 Feb 2009 09:42:02 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:4e8bac56-a23b-4015-ac3a-5ec1d1cf5b92</guid><dc:creator>ImPer Westermark</dc:creator><description>&lt;p&gt;&lt;p&gt;
Somehow, your memory may be playing tricks on you :)&lt;/p&gt;

&lt;p&gt;
NiCd and NiMH batteries are normally charged with a constant
current, where you may specify that you charge with C/10 for 14 hours
to get a full battery. Of course, this has now often been replaced by
extreme quick-chargers where you need to constantly measure the
temperature and voltage while pushing whatever current you can
through them.&lt;/p&gt;

&lt;p&gt;
But a lead-acid battery is charged by a constant voltage, and the
battery will then consume the current it needs in relation to its
current charge level and the charge voltage.&lt;/p&gt;

&lt;p&gt;
So a lead-acid charger normally has a constant-current regulation
for very empty batteries, i.e. it varies the voltage to keep a
maximum current low enough that the battery doesn&amp;#39;t cook. A normal
car charger often has a switch where you can change this maximum
current - a motorcycle battery requires a way lower max current since
it is so small.&lt;/p&gt;

&lt;p&gt;
As soon as the battery gets charged enough so that the charge
current drops below this max current, the charger will switch to
constant-voltage charging. This voltage should be lower if the
charger is built for constant charging and higher if it is intended
for quick-charging of an empty battery. Good chargers can auto-select
this, i.e. they start with a high voltage and run for a number of
hours or until the current has dropped to a specific level. Then they
enters maintainance charging by reducing the constant voltage to a
lower level.&lt;/p&gt;

&lt;p&gt;
What follows from this is that you may not use a high-capacity
charger to charge a small lead-acid battery because the max current
in the constant-current part of the charge cycle is so high that it
will cook the battery.&lt;/p&gt;

&lt;p&gt;
But you can charge a big battery with a small charger. It will
just mean that the charger will spend way more time being
current-limited before it switches to the constant-voltage mode, i.e.
the charge time will be very slow.&lt;/p&gt;

&lt;p&gt;
Another thing is that high-end chargers can also pulse-charge the
battery. One reason for pulse-charging is that you control the charge
current with the charge voltage. So a higher charge voltage gives a
higher current. By going for very high voltages in short bursts, you
can revive an old and tired battery.&lt;/p&gt;

&lt;p&gt;
Another reason for pulse charging is that the charge current will
slowly reach zero when the battery voltage gets closer to the charge
voltage. In short, the energy you get into the battery is much higher
for an empty battery than for an almost full. With pulses you can
continue to keep up the charge speed all the way until you switch to
maintainance mode.&lt;/p&gt;

&lt;p&gt;
When you get your lead-acid battery, you will often find charge
information written on it. If not, then get the datasheet. The charge
information will tell what the maximum initial charge current is,
i.e. the current limitation to use for an empty battery. The
information will also show the charge voltage to use if
quick-charging (cyclic use) or if you charge it continuously 24x7.
The datasheet will normally improve on that by showing how you can
adjust the current and voltages depending on surrounding
temperatures. A cold battery can stand way higher charge currents
before it cooks.&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: LEAD ACID BATTERY CHARGING</title><link>https://community.arm.com/thread/55404?ContentTypeID=1</link><pubDate>Thu, 12 Feb 2009 09:33:27 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:0234176b-b24c-443c-9277-22042b93c5de</guid><dc:creator>Andy Neil</dc:creator><description>&lt;p&gt;&lt;p&gt;
What makes you think that this is the place to ask?&lt;/p&gt;

&lt;p&gt;
See: &lt;a href="http://www.keil.com/forum/"&gt;http://www.keil.com/forum/&lt;/a&gt; - what
does it have to do with Keil products?&lt;/p&gt;

&lt;p&gt;
Are you intending to make amicrontroller-based charger?&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item></channel></rss>