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Smoother

Bought Charge Doctor. Now What Do I Do?

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So, I know what the Charge Doctor can be used for but I have no idea how to program it.  It has one button !!

I read this:

http://hobby16.neowp.fr/2016/11/12/autocut-adjustment/

from the maker's website, but I'm no closer to knowing how to program the 80% (or whatever) cut off for battery preservation.

I bought the V2 with two inputs, as I have 2 chargers, fyi.

Edited by Smoother

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Quick guide:

  • Disable caps lock:efef3d5527:
  • Set the CD to shut off by voltage instead of current (default setting). See http://hobby16.neowp.fr/ under "adjustement".
    TLDR: hold button down while connecting to power (but not too long or you fuck up the calibration, someone here managed to do that), set "upV" and the voltage itself. Just read the manual.
  • Your shut off voltage depends on your wheel voltage. With your 16S as an example, it's 67.2V = 16*4.2V (16 parallel batteries, instead of 20 for 84V).
    A typical cell is full at 4.2V and empty at 3.2V (1V difference). So 0% = 16*3.2V = 51.2V and 100% = 67.2V.
    Any percentage between must be interpolated, so for example 80% for a cell is 3.2V + 80%*1V = 4V, so 80% charge is 16*4V=64V.
  • The above isn't actually true, because it does not go linearly from empty to full. But it's close enough to get an estimate for the cut-off voltage you need. Set the CD to the estimate, see to what % it actually charges, and then adjust accordingly. I keep a table of what voltages give me what percentages (like 95%,90%,85%,80% etc.)
  • Doesn't matter how many chargers are connected to the doctor now.

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Thanks for the link to that page.  My CD is defying all my attempts to change the auto shutoff to 64V.  I've read it and re-read it multiple times.  I hope I don't break it before I get it right. I'm not sure if the translation to English is very clear.

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40 minutes ago, meepmeepmayer said:

Press/hold the button while in the "Auto" screen to set the the voltage (goes up to 85V then starts anew at the lowest value)

Thanks very much for your patience and cooperation.  That would have taken me an hour to type out.  The part that I couldn't find in the official instructions was you have to go up to go down.  I had no trouble going up, it was the down that was alluding me.  Got it first time, after using your instructions.

 

Thanks again.

EDIT Yes I've watched most of @Lukasz YouTube vids, including this one.  Good general information but do programming data.

and thanks @G.Rhum for that link.

Edited by Smoother

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@Smoother much Congrats to the Charge Doctor! :-) This tool should be provided by the EUC producers with every wheel they sell :-)

 

Just a tip: 90%, 65,8 Volt, should be more than good enough,while it is very good to take care of the battery,  theres no need to "over protect" them.

When you do 90% charges it should double the battery life, meaning 500 FULL cycles are just nothing.

500 FULL cycles woould be 500x840wh= 420000wh, divided by average 20wh/km(which is much, 16 should be average) = 21000km..... :-)

And after 500cycles the batterys are not meant to be dead, they just loose capacity.

Whats best on the charge doctor is that you always have in view how much watthours your consumption is/was and for controling what the battery capacity is and that there is no fault. The autostop mode is nice, but on 800-1600wh (all big batterys) even on a 100% charge the normal battery life should go much over the exspected wheel life......

Have Fun with the device :-)

 

@meepmeepmayer Very, very good description, should be saved for other users, as some haave trouble with the instructions of the CD and the auto stop setup!

Edited by KingSong69

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@Smoother, I also had lots of trouble understanding the instructions to the Charge Doctor which is why I ended up not buying it. However, doesn't the Charge Doctor also tell you the health of the individual cells? For the alone I would most likely buy it.

I use an electric Century clock which cuts power in 15/30/60/120/240 elapsed minutes, so say I ride my KS16s down to 40%. I plug it in and set the timer for two hours which gives me 80-90% charge. Fast and easy.

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5 minutes ago, LanghamP said:

@Smoother... However, doesn't the Charge Doctor also tell you the health of the individual cells? For the alone I would most likely buy it.

...

No. Not directly - but if one regards the shown "charged" Wh ( and beginning and end voltage) one sees capacity drops (aging/bad cells). 

Watching voltage versus charge current could also give some indicator for battery health (internal resistance)

To see the cell balancing beside the aging one would need to open the pack and solder cables to each cell (as @Cranium did -there are nice solder points on the bms). Differences in cell voltages are imho the best sign of for quite immediate troubles to come... And if seen early enough charging the lower cells to the level of the other cells to quickly repair the pack and prevent cell deterioration and the forthcoming cut out.

Especially if you charge everytime just to 80-90% and not from time to time full. (One gives the bms less time to balance the cells by this)

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On 1/12/2018 at 7:40 PM, LanghamP said:

@Smoother, I also had lots of trouble understanding the instructions to the Charge Doctor which is why I ended up not buying it. However, doesn't the Charge Doctor also tell you the health of the individual cells? For the alone I would most likely buy it.

I use an electric Century clock which cuts power in 15/30/60/120/240 elapsed minutes, so say I ride my KS16s down to 40%. I plug it in and set the timer for two hours which gives me 80-90% charge. Fast and easy.

@Chriull and @KingSong69 know more about this than I ever will, and their answers above are helpful and informative.  It is nice to be able to plug it in and forget it, regardless of the state of charge at the beginning.  When it hits your desired voltage, it just shuts off and it displays "OFF" so there is no uncertainty.  Just before I go out on a planned ride, I connect the charger directly to the wheel (old school style :D ) for a while and pump a little more juice in, knowing it will get sucked out within the hour. I do this with the belief that it's storing Li-ions at high voltage that is the killer, and not charging them that high; as long as you use it soon after.  I'm absolutely no Li-ion scholar, so If someone who is, tells me this is wrong, I'm listening.

@LanghamP the charge doctor is cheap and shipping is included.  Since I got one I feel like a EUC big boy, even though I can barely use its potential.  Go ahead and get one, you won't regret it.  Get the 2 input model and then you have the option to speed charge when an unexpected trip is needed. (I assume you have 2 chargers)  I wish I had done it a year ago.

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@Smoother To the point...:-)

Optimum would be to have the cells always between 30-80%(or 90%, regarding how long you want to longer their life)

And Exactly, even if you get them to 100%...then dont store them that long on this percentage. Means the best is to charge before a ride....not directly after ride. Its enough to charge to a 100% all 10 or 20 charges, to keep them balanced.

That are at least the main points...

Edited by KingSong69

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1 minute ago, KingSong69 said:

@Smoother To the point...:-)

Optimum would be to have the cells always between 30-80%(or 90%, regarding how long you want to longer their life)

And Exactly, even if you get them to 100%...then dont store them that long on this percentage. Means the best is to charge before a ride....not directly after ride. Its enough to charge to a 100% all 10 or 20 charges, to keep them balanced.

That are at least the main points...

Thanks for that confirmation.  I respect your battery knowledge, as demonstrated on the forum.

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AFAICS, no way to fully check individual lithium battery cell health unless you pull cells one by one and do a full charge-discharge test on something similar to a XTAR Dragon VP4+, checking also to see if the cells get too hot, from increasing internal resistance, and storing to later check if the cell holds it's charge. (I've slowly gleaned this info from the DIY Powerwalls forum and jehugarcia's YouTube)

 

Also, FWIW, Tesla cars have a built-in charge limit slider in their OS that basically lists 50-90% charge as "Daily", with the 90%-100% listed as "Trip", falling in-line with BatteryUnviersity.com's studies.

teslavbmwvporsche_09.jpg?mode=max&quality=90&scale=down

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7 hours ago, KingSong69 said:

@Smoother To the point...:-)

Optimum would be to have the cells always between 30-80%(or 90%, regarding how long you want to longer their life)

And Exactly, even if you get them to 100%...then dont store them that long on this percentage. Means the best is to charge before a ride....not directly after ride. Its enough to charge to a 100% all 10 or 20 charges, to keep them balanced.

That are at least the main points...

I keep most of my wheels between 40% to 90% except for my S1 which undercharges. However, I both live and work on the top of two hills, and so not 100% charging is more a safety concern over a longevity concern.

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So let me raise something I've been thinking about for a while. We always discuss charging to a certain percentage. What that is is up to the users preference. But a percentage of what? Max voltage or max capacity. I've done extensive logging of my V8 doing a full charge on my two chargers (standard and eWheels fast charger). Charging to 85%of wheel capacity on my fast charger requires a charge to 83.9v. This is near max voltage although only briefly and as the cells are only at 85% actual capacity the resting voltage after 15 - 20 minutes drops to about 82.5v. High voltage is generally considered the nemesis of battery health and my peak voltage almost touches 4.2v/cell, however it doesn't sit at that voltage during a saturation phase or at rest mahjong me feel this is ok. Charging to 85% of max voltage would actually result in a charged capacity of more like 70% of maximum. A significant reduction of capacity for 480Wh pack that only has 420Wh actually available for use anyway. 

So. What is the consensus. % of max voltage or % of max capacity. Battery University seems to touch on both in different articles. 

Edit: As rightly mentioned later when I talk of percentage of voltage I mean a percentage of the usable voltage range for a Li-Ion cell (1.2v usually) not 85% of 4.2v.

Edited by WARPed1701D
Made clear voltage percentage range.

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^^^^

My guess is different wheels have different percentages for the same voltage. It's whatever value people assign to it, with the idea that 100% charge = full voltage, and even that isn't guaranteed as Ninebot S1 is 100% < full voltage.

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26 minutes ago, WARPed1701D said:

So. What is the consensus. % of max voltage or % of max capacity. Battery University seems to touch on both in different articles. 

Voltage after resting would make sense. The voltage while charging or immedeately afterwards depends also on the charging current. % of max capacity is harder to obtaun.

Details to this topic:

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

For table 2 for example cut off voltage of the charger is taken along with the capacity. They take the value which makes sense in the context.

For battery lifetime prolongation imho the reference mostly to % of the capacity or voltage (after resting). Both of this value are very correlated.

Just as already @LanghamP wrote, the shown capacity from the wheel is quite "useless"

Edited by Chriull

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1 hour ago, WARPed1701D said:

But a percentage of what? Max voltage or max capacity.

It is certainly not percentage of max voltage. Percentage of max voltage minus min voltage should work reasonably well. That is, percentage of the voltage range, which is about 12-13V with the 84V charger. This is a reasonable approximation for the capacity in Wh.

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54 minutes ago, Chriull said:

Voltage after resting would make sense. The voltage while charging or immedeately afterwards depends also on the charging current. % of max capacity is harder to obtaun.

Details to this topic:

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

For table 2 for example cut off voltage of the charger is taken along with the capacity. They take the value which makes sense in the context.

For battery lifetime prolongation imho the reference mostly to % of the capacity or voltage (after resting). Both of this value are very correlated.

Just as already @LanghamP wrote, the shown capacity from the wheel is quite "useless"

Indeed from previous discussions I learnt that the change current greatly alters the charge graph with higher currents shifting the transition from constant current to constant voltage sooner. My 2.5A charger (0.4c) requires a 83.9v cutoff for 85% pack capacity whereas my 1.5A charger (0.25c) only needs 83.3v.

My concern was raised by the paragraph below table 3 on this page 

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

where peak charge voltage is discussed and I became unsure if reaching near 84v (even if only briefly for a 85% capacity charge ) would result in similar cell degradation to a much longer saturation charge (to 100% capacity, as peak charge voltage is not much different) . Peak Charge Voltage is not well defined so I took it literally to assume any time above the suggested voltages in table 4 would lose any charge limiting benefit even though such an assumption didn't make much sense to me. I'm happy with my setup of charging to a percentage of total capacity rather than usable voltage range (which almost everyone else here uses)  but wondered what the feeling was among the battery gurus. 

Edited by WARPed1701D
Edited to make percent of voltage range clear

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5 minutes ago, Mono said:

It is certainly not percentage of max voltage. Percentage of max voltage minus min voltage should work reasonably well. That is, percentage of the voltage range, which is about 12-13V with the 84V charger. This is a reasonable approximation for the capacity in Wh.

Correct. I should have made it clear that for percent of voltage I was using 3.0v to 4.2v range as the basis for 0 and 100 percent of my cells (LG MH1). 

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1 hour ago, WARPed1701D said:

Correct. I should have made it clear that for percent of voltage I was using 3.0v to 4.2v range as the basis for 0 and 100 percent of my cells (LG MH1). 

As @Keith suggested a little while ago, the lower value is more like 3.4V. While the cell can go down to 3.0V, there is only little capacity left below 3.4V.

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4 hours ago, WARPed1701D said:

...

My concern was raised by the paragraph below table 3 on this page 

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

where peak charge voltage is discussed and I became unsure if reaching near 84v (even if only briefly for a 85% capacity charge ) would result in similar cell degradation to a much longer saturation charge (to 100% capacity, as peak charge voltage is not much different) . ...

As they are talking in table 3 from 100% charge this 4,2 peak voltage/peak charge voltage is for "saturation" charges (where one does not cut iff at a certain voltage threshold but continue with the normal liion charging with this max voltage).

Your cells "recover" from the almost 4,2V quite immedeately - the degratation figures in table three are over one year!

As a 100% charge at 25°C does just 4% degratation over a year i would also not worry too much about full charges...

Edit: read in the wrong column - degratation is 20%... Does not change much for this specific short time stress, but for "normal" storage....

Edited by Chriull

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40 minutes ago, Mono said:

As @Keith suggested a little while ago, the lower value is more like 3.4V. While the cell can go down to 3.0V, there is only little capacity left below 3.4V.

So, let me get this straight.  We use batteries that are fully charged at 4.2V but are effectively dead at 3.4V, ---0.8V less?  That almost sounds like a failed product, other than for all the successful devices using them.

A second question.  Why does a battery with 3.4V/3.2V have no useful energy left in it when a brand new AA or AAA or C or D conventional battery starts around 1.5V?

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1 minute ago, Smoother said:

So, let me get this straight.  We use batteries that are fully charged at 4.2V but are effectively dead at 3.4V, ---0.8V less?  That almost sounds like a failed product, other than for all the successful devices using them.

A second question.  Why does a battery with 3.4V/3.2V have no useful energy left in it when a brand new AA or AAA or C or D conventional battery starts around 1.5V?

Yeah, from my understanding from reading and personal experience the rubber band analogy is that almost all the energy is stored in the final stretch.

I had a few experiences with my drones dropping out of the sky when I didn't understand voltage readings.

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