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why are there no limit-chargers?

hi there,

so I try to have my batteries sitting at 80% or something like that as they say it increases the lifespan of it a lot.

so I was wondering, why have I never come across a charger that lets me select how much I want to charge my pack? is there something I am missing? are BMS’ not capable of balancing cells when not completely full?

thing is, with certain boards (which are not merely for fun) I already know when I am going to need it next, so I can have it charge from 80 to 100% in about half an hour 10A in my case, so sacrificing spontaneity isn’t a thing for me personally.

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Your charger doesn’t know the capacity of your pack, so you’d have to either specify the amount of ampere hours to dump into the pack (a lot of smart chargers have this function) or specify the voltage it should charge the pack up to (I know of no chargers who do this of the top of my head, but you could set one f.e. to 11s, that way you get about 80% capacity if you charge to “full”).

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Best alternative is to watch your board charging and just pull the plug as soon as it reaches a satisfactory %.

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Most chargers don’t have the feature but with a smart BMS you can typically set up the end-of-charge voltage.

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There are. Here you go: Luna Charger 48V Advanced 300W Ebike Charger - Luna Cycle please note this one is only for 13s batteries

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Be careful with the ebike stuff. They lie all the time about voltages, especially places like Luna, so make SURE you are using the correct equipment.

Not saying anything bad about their products, just that the numbers they advertise often aren’t accurate.

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I didn’t know that :open_mouth: I had considered them at one point

That page you linked says “48V” for 13S which is actually probably a 54.6V charger.

edit: it does clarify lower down the listing, but not all products clarify

Just be aware of the ebike jive they use, that’s all. I’m sure it’s quality stuff. Just easy to buy the wrong thing.

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I’ve heard these chargers are quite nice. Probably the best designed out of the box option for this.

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Many BMS’ could be set up that way, if not already, but balancing isn’t really needed until a cell approaches 4.20V (or whatever its fully charged voltage is) to prevent over volting a cell.

Starting balancing at too low a voltage can actually unbalance a pack since the cells might not continue charging the same way they did up until that point (3.8V or whatever).

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I use a drok cc/cv attached to a dc power supply. It has around 10 memory settings. Which comes in handy. It also has a wireless display so I can sit inside and monitor my charge while sipping coffee or whatever… :joy:

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Cuz “chargers” are merely power supply with non-variable output.

I undercharge my packs with these.

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you know you can just get cheap 1000W server PSUs from ebay for like 20 bucks right?

I use a smart outlet and let it charge for like 30 mins or whatever after a ride. Not an exact science but it works for me.

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I think the issues is the term charger
I presume you calling a psu a charger just look at hobby chargers quite common thay let you pick your end voltage.

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Not just bike stuff look at power tools from Dewalt, makita, milwalki, bosh etc thay all say 18v when thay are 18650 2p5s so in reality 21v fully charged

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Just a side note…
IMO an important difference between a “charger” and just a constant-current (CC) power supply (which all chargers are) is that the charger knows when to stop. Typically when the bulk charge rate has dropped to 1/10th or 1/20th of its starting value. For example. A 10A charge would stop when the current dropped down to 1A or 0.5A (respectively).

Hook a CC power supply up to a pack and it will continue trying to charge the pack for as long as you leave it connected. This speeds up aging of the cells in the pack and should be avoided.

You can charge with just a power supply but that, IMO, doesn’t make it a charger.

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220€ :slightly_smiling_face:

0-130V
0-25A

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I have the cycle satiator and it is rad. You can program profiles with whatever amps and max volts you want. It has a screen with charge data and even graphs, plus lots of safety features and it’ll tell you what happened if anything goes wrong. Not to mention a solid reputation and customer service. Only downside is you gotta pay for what you get.

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I have the habit of charging overnight leaving the batteries hooked in the power supply. Never really paid attention to 1/10 cutoff as I most often terminate my charging process long after the packs’ current draw hits zero. So just how much damage does this habit incur to my packs?