How should my charging solution be?

Hi! I’m kinda new to the eskate community, and I’ve been doing a lot of research. The one place where I get a little lost, is when it comes to the charging solution. Im thinking about using 2x 4s 5000mah 20c Lipo batteries and wire them in series. Then, wire the balance cables into a bms, the negative of the batteries aswell (i think, correct me here please). Then to the charger, I need a 33,6V balance charger, with a charging port.

Links provided: Batteries: ( ) Charger: ( )

Charging port: ( ) or ( )

BMS: ( )

Looks good, with a few caveats. 20c is a little low for a 5000mah pack, you’ll end up with significant voltage sag and it’s less than ideal for the health of the batteries. 30c or greater is recommended.

The BMS you linked is only good for 30 amps, so unless you’re willing to limit yourself to that, you’ll have to bypass it for discharge, or get one that can handle more power.

First you need to decide whether you’ll run your BMS in discharge mode (and charge mode also) – or bypass it - and only use it for charging.

That BMS is probably overkill for running in bypass mode, and probably not powerful enough for running in discharge mode, you’ll want 80A or more for that for dual motor or 40A - 50A for single motor. Unless you run in bypass, then it doesn’t matter

Hi, thanks for your reply! I’m thinking to use the BMS for charging only. Then, are there any problems with the solution? The charging female port ok? Do you know if it has a limit on how many amps or volts in can handle? Should I use xt90’s as connectors? Thanks!

Thank you for you reply! What do you mean with voltage sag? I thought the 20c only means that the batteries will output 5aH * 20c = 100 Amps.

Theoretically that’s true, but the battery manufacturers tend to overstate the actual real-world capability of their cells. It’s better to have lots of buffer and not need it, than to be constantly running the battery ragged.

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Okay, thanks! What do you think about the charger and charging port tho?

That charger jack is the correct jack, but it’s loose on a wire. It’s probably better to get the ones that mount with a nut in a case

So you mean I should buy this one?

No, more closer to these

That one has a “Contact rating-0.5A 30V DC”. Aswell as it doesn’t provide where the positive, negative and ground goes.

I mainly meant that style and not that specific one. This one might be closer but curiously it’s 2.1mm plus or minus 25.4mm, that’s a pretty big margin of error. Sounds like the seller doesn’t know what’s going on…

I dont think I will get a sag if I use the tb vesc with it, will I? It has a 50A max

Dude stuff like this doesnt matter, plug the charger to this then just measure it with an multimeter if the voltage is in - its the other way around and boom you know where is plus and where is minus

Voltage sag has nothing to do with esc’s

Probably just a typo

You’ll always get some sag, it’s just a question of how much is acceptable to you and the batteries. 5ah 20c is right at the fine line of “barely acceptable” to me, but it’s probably fine.

Bear in mind that I have a tendency to overbuild my stuff.

So if I use 2x 5s 5000mah 20c batteries in series to a 10s battery, it would be nice?

Like I said, 5ah 20c is barely acceptable in my book, no matter how many in series. If I were you I’d either increase the C rating to at least 25 or 30, OR increase the Ah of the pack, either by using larger cells, or putting some in parallel.

I wont be a torque monster or speed demon, but it will work. Depending on weight and terrain you should be able to hit 20 mph and handle some small grades. The best lipo solution is using 2s lipo packs in a series of x5 to make a 10s pack. I built one using 20c lipos and it was a beast. Very fast and torque to the point that I could leave thane on the ground. Its pretty inexpensive too.

Check out this thread, it will tell you all you need to know about Lipo packs. @Namasaki is a genius …

Here’s something I did just for the hell of it :slight_smile:.