On 13 October 2010 11:47, IanCunningham <span dir="ltr"><<a href="mailto:ian.cunningham@nt.gov.au">ian.cunningham@nt.gov.au</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
We are starting to see some XOs show signs of heat distress while<br>
being left in the new XO power racks. I suspect it is also related to<br>
them not being turned off prior to charging and the confined space<br>
contributing to localized heating.<br></blockquote><div><br>What is your ambiant temperature? Does your charging rack have the
chargers built in? How hot do they get? In Samoa with 30C ambiant
temperature inside a classroom, we had 6 black australian style chargers
on a 6 way multibox, they were at 63, 66, 68, 68, 65, 57 degrees
Celsius (measured with a non contact thermometer). The XOs themselves
were hardly warm, even stacked several high (no racks in Samoa).<br>
<br>
You might find that the XOs aren't getting hot because they are packed
together in the rack but because the nearby chargers are heating them.<br>
<br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
What would be an average time to expect the XO to charge from flat to<br>
full? It may be beneficial to have a timer or an alarm to remind<br>
people to turn off the power rack and prevent over heating.<br></blockquote><div><br>How long does overheating take? If overheating is associated with charging, then turning the rack off after charging isn't going to help.<br>
<br>Does the XO 1.5 charge faster than the XO 1? I know it can draw more current from the charger which would suggest it does. Also, how do you define full? If you watch the battery voltage and current you will see that the charge tapers off as it transitions from constant current to constant voltage and may stay a long time balancing the cells inside the battery if the XO is new or hasn't been charged recently or the battery is sick. In a charge resource constrained environment (only 10 sockets and a class load of flat laptops?), knowing that you've got to constant voltage would be useful (but pulling the power at this point will prevent the BMS doing it's job).<br>
</div><br>
Tom<br></div>