Yes, the latter is handling about 28 watts, while your 24V@1A PSU is nominally 24 watts.Xamindar wrote:The 24V power supply is a 1A power supply which I figured is pretty close to roomba's 22.5v 1.25A power supply regarding power output.
This high-rate charging data illustrates a couple things:... I took measurements where the docking tab cable plugs into the HB board.
While charging: 18.5 volts, 1.55 amps
1) Your PSU is not holding voltage at the 24Vdc level.
2) Therefore, it is an unregulated PSU, probably a cheap 60Hz-transformer/rectifier based "wall-wart" PSU. We see here that when it pumps 1.55A into a load its output voltage has drooped to 18.5V. And is handling only a 20W loading. This application will result in heating the wall-wart, and Roomba's charging FETs and blocking diode (all three carrying the 1.55A current) will also be a bit hotter than when carrying the 1.3A to 1.4A at which an iRobot SMPS PSU limits current. Did you lay a hand on the wall-wart about half to one hour into the charging session? It is bound to be quite hot, since its secondary winding -- designed for one ampere service is carrying 50+% more than nominal, and same for the rectifier diodes in that WW (who knows how large their current handling margin might be(?).
Now, what is going on with this next bit of data?
I am assuming you have charged a battery of Li-ion cells which have some form of protective circuit in there which, ordinarily disconnects Li-ion cells from the cell terminals when charging is complete. But the "While charged" measurement shows there to be 0.14A still going through the system. It should not be the dc-equivalent of pulsed trickle charging, however, I have to admit that it could be the sum of the currents required to power the Home Base and the robot's +5V power supply, MCU, and associated charging control circuits. I do not know that anyone has made a baseline measure of that operating current.While charged: 22.8 volts, 0.14 amps
If this is true (say, 0.14A is required to run the HB and Roomba's charging control circuit) I could go up to point (2) and deduct that much current from the 1.55A value, leaving ~ 1.4A, to mitigate the Roomba components heating.
Of course it is good that you have licked the err5 issue. The bad part is: We don't know why the higher voltage helps that to happen!This to me seems acceptable. It has been working the past 4 days perfectly and no more errors. ...