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Rockbox mail archiveSubject: Re: AW: AW: AW: Bug: Battery Charging with low voltageRe: AW: AW: AW: Bug: Battery Charging with low voltage
From: Jerry Van Baren <gerald.vanbaren_at_smiths-aerospace.com>
Date: Thu, 3 Feb 2005 15:51:43 -0500 Linus Nielsen Feltzing wrote: > Matthias Klumpp wrote: [snip] >> That way it was continuing chargeing, so I found it in this state (I was >> never seeing exactly the time it went to the browser). > > >> What do you think ? > > > Well, the batteries are obviously not charged enough. Or they are worn > out. I guess your usage pattern, where you charge them with a very low > voltage for only 30 minutes at a time, isn't very good for the batteries. [snip] >> I'm using 2000mAh batteries. >> Do you think it's worth to repeat the test of your SW with some lower >> capacity batteries ? [snip] >> As increasing the charger voltage will not solve my problem (as m.a.), >> any >> ideas what could be done ? > > > Not really, other than starting the charging immediately instead of > waiting for a stable battery voltage reading. > > Linus > _______________________________________________ > http://cool.haxx.se/mailman/listinfo/rockbox Throwing in my free advice (and worth almost as much)... Looking at powermgmt.c I picked out the following two snippets of code. The first snippet shows that if the deltaV charge completion isn't satisfied, all charging (trickle AND top-off) is disabled, leaving the recorder running strictly on batteries (i.e. DISCHARGING, even though it is plugged in). In my limited experience, the deltaV detection is fairly tricky: the amount of voltage that the charge voltage declines by is quite small (and may be masked by other things happening like disk accesses). IMLE, deltaV detection doesn't happen quite often. I don't know how battery age or starting charge state conditions affect the deltaV, the pessimist in me says "porrly". if (charged_time > charge_max_time_now) { DEBUGF("power: charged_time > charge_max_time_now, " "enough!\n"); /* have charged too long and deltaV detection did not work! */ powermgmt_last_cycle_level = battery_level(); powermgmt_last_cycle_startstop_min = 0; charger_enable(false); snprintf(power_message, POWER_MESSAGE_LEN, "Chg tmout %d min", charge_max_time_now); /* disable charging for several hours from this point, just to be sure */ charge_pause = CHARGE_PAUSE_LEN; /* no trickle charge here, because the charging cycle didn't end the right way */ charge_state = 0; /* 0: decharging/charger off, 1: charge, 2: top-off, 3: trickle */ The second snippet I cut out because the max charging time is algorithmaticly dependant on the battery capacity setting. If you have high capacity batteries (which Matthias has) but don't have this configured correctly in your config settings, this will aggrevate the charging problems because you will be charging to 135% * (450 minutes) without scaling for the higher capacity batteries. } else { /* calculate max charge time depending on current battery level */ /* take 35% more because some more energy is used for heating up the battery */ i = CHARGE_MAX_TIME_1500 * battery_capacity / 1500; charge_max_time_now = i * (100 + 35 - battery_level()) / 100; if (charge_max_time_now > i) { charge_max_time_now = i; } snprintf(power_message, POWER_MESSAGE_LEN, "ChgAt %d%% max %dm", battery_level(), charge_max_time_now); OK. Here are my humble opinions: 1) We should always do a top-off charge. This is only slightly more aggressive than a trickle charge. Currently, if the deltaV charge termination isn't detected, top-off doesn't occur. This is BAD IMHO. 2) We should always trickle charge forever. Remove all algorithmic trickle disabling (unless turned off in the configuration). Currently, if the deltaV charge termination isn't detected, top-off doesn't occur. Disabling is unnecessary IMHO. Rationale: Given our charging capacities vs. battery capacity, the trickle charge PWM control (which is allowed to use a maximum charge current of 40% of the full strength charge and throttles itself down to as little as 1.7%) is always safe to run the charger at this level indefinitely. gvb _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2005-02-03 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |