XM-3500Li Best Charging Practices?

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zarlor
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XM-3500Li Best Charging Practices?

I've heard plenty of great reasons from folks here for using a BMS on the 20 cells in this scoot. But so far the BMS systems I've mainly been hearing about are home-builds. Suffice to say that my electronics skills are not nearly up to par as most folks here and finding the time to not only make something like that, but to learn enough to figure it all out as well is a tod more than I can handle at this moment.

So for those of us on the non-BMS side of things, what is the best way to use this charger?

I'd seen a lot of discussion on the XM-2000 about making sure you unplugged the charger when it topped out the batteries. But this charger does that on its own... or it goes into some kind of "trickle charge" mode, whatever that may mean beyond what it seems to me it means. So, again remembering that I don't have a BMS to help me out on this, should I unplug the charger when it finally cuts off, or should I leave the charger connected whenever I'm charging up? Or should I just leave it connected for some extra amount of time after the initial cut-off?

Iccarus
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Re: XM-3500Li Best Charging Practices?

Zarlor, Good questions...I wish someone would answer them. What does it mean if your cells are only charging up to only about 3.4v on average? Damage? I can monitor all cells while driving now and noticed that while all cells appear balanced at rest, when driving some cells drop much more than others. My guess is these are weaker cells.(slightly damaged?)I think by replacing these one can limit further damage. Thanks for the tips on what to carry on the road...very helpful.

2008 XM3500li Mods/Kelly KBL12251/84v 28cell 40AH pack/ Variable regen brake trigger on left brake handle/Givi/Cycle Analyst/Homemade BMS

KMX Typhoon Home build (recumbent pedelec) with two Astro Brushless 3220motors/twin castle Phoenix ICEHV 160/ Cycl

antiscab
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Re: XM-3500Li Best Charging Practices?

results from my bench testing (of a TS LFP40aha 3.2v 40AH):

if you charge a cell to 3.4v, until current falls to 0.05A or less, the the cell is fully charged.

so it depends what current your charger terminates charging at in the CV stage.
if it is more than 0.1A, you are undercharging. as for how much, i havent tested that far.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Iccarus
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Re: XM-3500Li Best Charging Practices?

Thanks matt, I've seen that others have said they were topping out at 3.7v average so I thought I might have damaged the cells. I was running 24 cells with a new 87v 15 amp charger I got from elite power solutions. Mountain Chen said I would damage the cells do to to low of cutoff voltage (set for 20 cells) to bad it's not programable. She got about 52mph with 24 cells but I removed them for now. Just found out I might not be able to get my plates also. It aint easy being green!

2008 XM3500li Mods/Kelly KBL12251/84v 28cell 40AH pack/ Variable regen brake trigger on left brake handle/Givi/Cycle Analyst/Homemade BMS

KMX Typhoon Home build (recumbent pedelec) with two Astro Brushless 3220motors/twin castle Phoenix ICEHV 160/ Cycl

antiscab
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Re: XM-3500Li Best Charging Practices?

i would suggest, rather than muckign about with the controller LVC,
getting a AH counter such as a cycle analyst, and/or a per cell voltage checker such as a paktrakr.
on my setup i run both.

try and avoid discharging to 2.5vpc.
everytime you go just a little bit to far, you are causing well above average wear on the batteries.
because the wear is above average at just a little more discharge, the lower cells will become much worse faster than the stronger cells.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

zarlor
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Re: XM-3500Li Best Charging Practices?

On the stuff to carry, glad I could be of help. (It's in Gary's "My XM-5000li Experience" blog post: http://visforvoltage.org/blog/garygid/5667 for those wondering what this was.) I'm no expert bike rider, though, so I don't doubt I might be missing some stuff or that others have some stuff they prefer instead or that would be better to pack then what I take. Come to think of it, some kind of document sleeve taped into my Givi trunk might be a good idea to hold my registration and stuff... hmm....

Lenny Zimmermann
Metairie, LA

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