AndyH wrote:I have yet to see a chart from a fully charged/saturated battery that shows that the DC-DC is providing more than 13.5VDC...
I have never provided such a plot, but I have discussed on many occasions in this forum (10s of times) that the battery voltage in the LEAF does go to 14.5V when either the LEAF is started or charging begins. But when I have plotted voltage data (that I recorded manually) from my LEAF's battery, I have only ever plotted a series of resting voltages (connected by straight lines, which is not really what occurs between the points), so you have never seen a plot from me with voltages over 13V.
That said, 69800 has provided a couple of plots of battery voltage which DO show the 14V+ voltages which come from the LEAF. One was here
. 69800 has provided me with the raw data from that plot and I have recreated that chart using Excel, Here it is:
The portion up until April 7 is the result of a charge by an external Battery Tender. (The Battery Tender may have been removed sometime during the day on April 6.) After that, it is all LEAF. You can find the periods when the LEAF was charging or driven by looking for the 13.1V plateaus. Those plateaus are the float phase of the three-stage charger in the LEAF. At the beginning of many of these, you will see a spike up to above 14V. That is the absorption portion of the three-stage charger in the LEAF. The reason you do not ALWAYS see this phase of the charging is that 69800's data acquisition system was sampling only every five minutes. As I mentioned in a very recent thread
, the LEAF's charger often dwells in the absorption phase for less than five minutes. Sometimes it stays there less than thirty seconds. As a result these spikes will not always be caught when the voltage is sampled only every five minutes.
AndyH wrote:... - and we all know that is not enough to fully charge a flooded lead-acid battery.
Hopefully everyone can agree on that point!
AndyH wrote:Bottom line: I've seen people 'say' it's a charger (though ingineer appears to make clear it's a DC-DC),...
Like many modern battery chargers, it's a charger that's a DC/DC converter. They are one and the same thing.
AndyH wrote:...but haven't yet seen a trace that actually looks like a two- or three-stage lead acid battery charger profile.
I agree that the charging profile from the LEAF doesn't look like a lot of traces you would see from other chargers. There are two main reasons for this: 1) It has such a high charging current that the Bulk charging phase occurs almost instantly and 2) It (usually) does not dwell at the absorption voltage (14V+) long enough to properly charge the battery. That second reason is my major beef with LEAF's battery charger.