Lithium Charger for up to 20s?

Batteries, Chargers, and Battery Management Systems.
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rg12   100 kW

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Lithium Charger for up to 20s?

Post by rg12 » Aug 11 2016 8:54am

Hey Dudes,

I'm doing some fixes for batteries and need to have multiple chargers around...

Do you guys know a charger that can charge up to 20s packs (don't need above 5A) that is not crazy expensive?
I charge mostly 13s 16s and 20s

Also, does a DC power supply (the one that I can change voltage and current digitally) lower the charging current automatically when topping the battery?

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brumbrum   100 kW

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Re: Lithium Charger for up to 20s?

Post by brumbrum » Aug 11 2016 9:04am

http://www.aliexpress.com/store/product ... 54257.html

These work fine and are a good price for a basic 20s charger. They will adjust it before buying if you want to have the cut off slighlty lower, for instance 83v (4.15v per cell) rather than the full 84v

rg12   100 kW

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Re: Lithium Charger for up to 20s?

Post by rg12 » Aug 11 2016 9:20am

Yeah but it doesn't have a variable voltage and current, it's only for 20s, so with this one I will have to buy 3 different chargers...

I found this which is very cheap 120v 3A but I wanted to know what happens if I don't stop the charge when it reaches the topping of the batter...will it slow down? will it cut the charge once full or will it blow the battery if I don't stop it in time?
http://www.aliexpress.com/item/KPS1203D ... 1ca5c452a9

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Re: Lithium Charger for up to 20s?

Post by Ypedal » Aug 11 2016 9:33am

ES site status page:
http://www.ypedal.com/ES/ES.htm
----------------
http://www.ypedal.com

rg12   100 kW

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Re: Lithium Charger for up to 20s?

Post by rg12 » Aug 11 2016 1:03pm

Ypedal wrote:http://www.ebikes.ca/shop/ebike-parts/c ... r7205.html

expensive.. but totally worth it !
Too expensive for me...

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amberwolf   100 GW

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Re: Lithium Charger for up to 20s?

Post by amberwolf » Aug 12 2016 3:20am

cheaper than a bunch of different chargers for differnet voltages (cuz it will do quite a range of different voltages, chemistries, charging profiles, etc). :)


But no, it isn't cheap. :/

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Re: Lithium Charger for up to 20s?

Post by rg12 » Aug 12 2016 6:43am

What about a DC power supply (the one that I can change voltage and current digitally)...
WIll it lower the charging current automatically when topping the battery? will it stop when full?

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amberwolf   100 GW

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Re: Lithium Charger for up to 20s?

Post by amberwolf » Aug 12 2016 3:19pm

It doesn't have any way to "know when to stop" or to auto turn off, so no it won't do that exactly.

But as long as it is set to a voltage the pack can tolerate without damage, then current will cease flowing because eventually the pack will reach the same voltage as the PSU.

However, that also means that topping off the pack will take longer than it mght witha smart scharger that "knows"when to slow and stop, because the dumb PSU will just follow the voltage/cell-resistance/current charge curve blindly, unable to raise or lower voltage automaticlaly to force the cells to charge at a constant rate up to the piont they need to not do that.

A smart charger can do that, and charge faster unattended, if it's correctly programmed for the type of cels the pack is made of.

Also, it's perhaps even more important to ensure the pack has a BMS if you use a dumb PSU because it can't detect a problem with the pack and shut off; the MBS has to do that.

A smart charger can (if it's programmed for it) stop charging if say, current goes back up after it was already dropping towards full charge (like if a cell went bad and shorted). A BMS would still be better in most of the cases like that, but sometimes just having a smart charger might prevent a fire-level pack failure.


I've done charging jsut about every way there is to do it...but I generally won't charge one unattended inside the house or near it, if it has no protections, unless it's contained in a fireprooof box (regardless of it's chemistry and type), even though I've had no unintentional fires during charging (there've been plenty of others to test those theories before me :( ).

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Re: Lithium Charger for up to 20s?

Post by 999zip999 » Aug 12 2016 4:45pm

Sounds like the safest way is to have a charger for each battery. I charger for three different voltage batteries is asking for trouble.

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Re: Lithium Charger for up to 20s?

Post by amberwolf » Aug 13 2016 2:43am

Safest? Only if you pay zero attention to what you're doing--which will lead you into trouble even with a separate charger for everything.

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Re: Lithium Charger for up to 20s?

Post by 999zip999 » Aug 13 2016 8:24am

Over time everyone will have a battery story And or charger story of kff. Yourself included. Some more then once.

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Re: Lithium Charger for up to 20s?

Post by skeetab5780 » Aug 13 2016 8:34am

Mine was like $76 shipped from china off ebay. Which was the most ive ever paid for a charger before. I figured it was going to be a crap shoot like everything on Ebay but to my surprise it works great and ive bulk charged for over a year with it now. It is plastic with a cooling fan inside. goes to around 84. something volts

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Re: Lithium Charger for up to 20s?

Post by rg12 » Aug 13 2016 12:54pm

skeetab5780 wrote:Mine was like $76 shipped from china off ebay. Which was the most ive ever paid for a charger before. I figured it was going to be a crap shoot like everything on Ebay but to my surprise it works great and ive bulk charged for over a year with it now. It is plastic with a cooling fan inside. goes to around 84. something volts
Yup, the Chinese are getting better...

Anyway, I guess I will go with 3 separate chargers then.

Thanks alot guys :)

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Re: Lithium Charger for up to 20s?

Post by redilast » Aug 16 2016 8:59pm

eTrike wrote:
rg12 wrote:What about a DC power supply (the one that I can change voltage and current digitally)...
WIll it lower the charging current automatically when topping the battery? will it stop when full?
I've used Meanwells to charge different voltages from 8S-28S. An adjustable power supply should be on everyone's bench IMO, but I've used one to charge when needed for a few years with good results. The one I have appears to do CC-CV just fine, but is very inefficient :oops:
How do you prevent the bench power supply from trickle charging which causes plating of metallic lithium to compromise the cells safety? I suppose one option would be to use a AC timer to shut off the bench power supply after a few hours. I wonder if some of the higher end power supplies have low current cutoff options in the software.

I've used a bench supply to charge Li-ions plenty of times, but pretty much always just have to set a timer to shut it off slightly before its done charging to prevent trickle charging.

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