KID charging lithium ion

[ke6cvh]

Hello,  We have a PECOLO trike here that runs off two battery banks of 18650 lithium ion cells.  I'm assuming there is a BMS but need to confirm from mfg.  When fully charged the dash digital voltmeter reads as much as 52.1 and mostly 51 volts.  Is the lithium ion selection on the KID for banks with BMS, battery management system, or does it sense the delta V and stop charging after negative going voltage or possibly current decrease sense?  Or is it just a fixed but adjustable voltage?  The roof area of this vehicle is perfect for 6 Sunpower 50w flexible portable panels with maxeon cells (copper backing to reduce cracking and other stress failures).  These are the 21.5 % efficiency and I think even higher recently cells.  The induction motor is 5.0 hp and this trike can handle 7 adults including driver so the 300w is not much really but it will charge while driving and more importantly will charge when the vehicle is resting or parked.  Also, the cool factor of course.  I will try to find out more on these battery banks but it would help to also know more about the lithium ion charging on the KID.  Can I change the voltage on it for example to fine tune it?  Some test data done by folks have shown up to 1800 cycles, a considerable life expectancy jump, when the lithium battery is only charged to 80% as heat is one of the big killers of these and towards last part of charging cycle more heat is generated.  Tweaking the KID just right would be a very nice feature in lithium ion option.  Literature does not seem to describe it and I cannot just select that then see what happens.  Best regards, Mike Kendall

[ClassicCrazy]

I did not know the Kid had any special lithium battery charging selection .
For my ebike with an ebike charger it charges constant current to a certain voltage , and then drops the current much lower - and this lets the BMS do it's work or balancing any low cells When the voltage gets to the high point the charger quits charging unless the voltage drops again  . So if there is a cell that is being balanced and the voltage of the pack drops the charger starts up again though in the low current mode . Usually though once it gets to the done stage it is done.

I am not sure how  you would duplicate that on the Kid if your lithium charger and bms work the same as my ebike charge does.  It gets confusing how to set the Kid up and depends on if you don't have any other loads on the system . Then perhaps you could set the Absorb voltage to cut off at a certain point and have the current output also limited to a certain amount of amps. So not sure how you would terminate Absorb  - maybe by using an ending amps setting ?  After it goes from Absorb to Float then you have another voltage setting you would have.

I think it really depends on your built in BMS and you would want to ask the battery manufacturer if the Kids settings would work. It doesn't seem like anyone is making a solar controller now that is specifically designed for lithium batteries. Almost seems like running the smallest sized inverveter that would handle whatever AC charger is designed to charge your battery pack is the way to do it. Samlex makes various sized smaller sine wave inverters .  Of course there is some inefficiency in converting voltage up and then back down again but if you have enough extra power that might not be a factor.

Larry

[ke6cvh]

Hello,

  On page 21 of the manual under the available selections for battery type there are two that may apply.  They are lithium and custom.  However, it does not show what programmable parameters are available under either on.  Yes, I'm assuming there is a BMS on the batteries and verifying.  I also asked the manufacturer to provide specific needs for the BMS.  Because I am seeing a charged voltage highest over the months of 52.1 volts after charge I do need to know more from both the etrike manufacturer and from Midnite solar.  In today's world of liabilities I am willing to shoulder any risks as long as I can get the information I need to accomplish it.  It would be a very nice application and should be very doable.

Best regards,
Mike Kendall

[ClassicCrazy]

Mike,
Have you dug around on the Endless Sphere ebike forums ?
A lot of detailed technical lithium battery info on there - a lot buried in various topics
I just did a bit of search and looking to see if I could find some answers to your questions on how to set up an MPPT controller to charge lithium.
20 pages in this topic - I haven't read the whole thing and discussion rambles. I went to page 20
https://endless-sphere.com/forums/viewtopic.php?f=3&t=28436&hilit=lithium+mppt
Since this fellow doesn't have enough PV to step down he is using cheap MPPT that boosts voltage up
https://www.youtube.com/watch?v=FRW5PdDkhP0
I may have to get one of those to play around with for single panel charging the ebike
https://www.ebay.com/itm/LCD-MPPT-Solar-Regulator-Charge-Controller-24-36-48-60-72V-Boost-MPT-7210A/112451914404?hash=item1a2ea80aa4:g:uBcAAOSwceNZSz-X

Let us know what you figure out . Guess I will have to fire up the Kid which I don't have online right now and see if I can find the Lithium menu you mentioned.   Seems like there is never any easy answers when it comes to charging lithium batteries.

Larry

[ke6cvh]

Hi Larry,  Thanks for the reply.  I looked at the link and the picture on the link.  It might be a tad different with an e-trike as this is a vehicle designed for 7 adults with the driver.  The available roof top space is perfect for six Sunpower 50w panels.  Those in series are in the range for a Midnite solar 150v input charger.  Working voltage per panel is 18v so that is 112v which is really good.  We have plenty of solar to charge from at the house.  My intention is to lessen the strain on the batteries a little bit.  If i have 300w of panels and I get 125w out of them that is still significant if the vehicle is parked for any length of time not counting the charging taking place while enroute.  There is also the additional cool factor (if one thinks an apple green colored trike is cool which most do here in the Philippines).  Available real estate on a bicycle is likely only when parked and panels are set out on the grass or something.  Best regards, MIke

[ClassicCrazy]

Well if you are only going to help the lithium batteries then I would think you just want to set the voltage to whatever 80 or 90% is - kind of like you would do for bottom balance charging. Also current regulate for whatever the batteries specs say. Then you could use the regular charger to top them off as needed and top balance them.  Look up bottom balancing lithium batteries  - there is info here on the group and also on the web.

Larry