Simple Charging Port (Plug n Play)

Hi Awesome Enthusiasts,

This is my first post, so....if I appear to be lacking in my knowledge, you'll know why. With my disclaimer out of the way, here's my question:

I'm in the process of building my electric longoard. My setup is a Turnigy SK3 270KV, 150A Hobbywing ESC, and a 6s 4400mah LiFEPO4 on a simple deck and paris trucks. Charging my board is a real pain. I have to gut the board just to charge it. I know buying a BMS would simplify things, but they don't make one supporting the amount of amperage I need. Is there another way to create a simple charging port? Thanks!

A picture would be really helpful.

I would say that you need to look at your cover design and figure out a way to run a wire in / out. Especially because you are using LiFe batteries, they are pretty safe, so i would say you can probably charge them in your battery compartment. What kind of cells are you using? are you using individualized 18650s or are you using a pre-assembled pack?

poor mans 6s bms...
allows you tu charge/balance using a single plug...

http://endless-sphere.com/forums/viewtopic.php?f=35&t=61171

metinoheat said:

A picture would be really helpful.

I would say that you need to look at your cover design and figure out a way to run a wire in / out. Especially because you are using LiFe batteries, they are pretty safe, so i would say you can probably charge them in your battery compartment. What kind of cells are you using? are you using individualized 18650s or are you using a pre-assembled pack?

Click to expand...

I'll try to get a picture up by tomorrow. I'm using a Turnigy pack found here: http://www.hobbyking.com/hobbyking/store/__10311__Turnigy_4500mAh_6S2P_30C_LiFePo4_Pack.html
Wiring won't be an issue, but is there a way to charge & balance the battery at the same time with 1 plug? The charger in board idea is pretty awesome, but IDK about the added weight

People tend to use aviation 9pin and/or DE-9 pin connectors also. You do need a wire that's capable of handling the current you are charging at for the pins I believe.

Hi I think the charger weighs around 80 grams.... should not be able to notice that...
the cherge plug idea is also great... im actually going to trying one at some point... just lazy to salder all those cables LOL

beto_pty said:

Hi I think the charger weighs around 80 grams.... should not be able to notice that...
the cherge plug idea is also great... im actually going to trying one at some point... just lazy to salder all those cables LOL

Click to expand...

LOLS! I immediately thought of my bulky charger which weighs a good pound. 80G is really light. I just looked up your builds.....the boards are really, really awesome. How would I go about making a single plug? You seem to know what your doing.

how can you get 150A out of 4400mAh pouches? these are lifepo4 and not lipo from what you were saying.

You can also use a D-Sub 9 pin plug, like the old PC/monitor connection. I did that with great success. Maybe even 7 pin plugs work since the outermost cables of the balancer plug are just like the thick red and black ones, voltage wise.

I think others have used PS2 plugs as well.

Also, onloop from enertion sells a plug and play version if you dont want to solder it yourself.

If you think a bms won't hold the load, then don't take the load through it. Just take your power straight from the cells as you do now, and use the bms just for charging. Or, make the bms take the extra power by using it to switch an external switch that takes the load. Something like a few 4110's as seen substituting contactors in quite a few threads. You will loose the bms's short circuit protection, but I imagine a fuse is no hardship.

You also need to consider the max amps you want to charge at.

9 d-sub. And other 'computer connectors' are not rated to handle any more than a few amps per pin.. so they are only good for 50w slow chargers... some can only handle 1 amp per pin which is way too slow...

The all-in-one easy charge balance cable I make is rated for 10AMP per pin. I also double the main charge leads up onto two pins... so technically 20 amp charge is ok but not many people have a 500 watt charger.

Hi,

A quality 9 pin D-sub connector such as this one is rated for 7.5 Amps, more than enough for most chargers.

http://www.digikey.com/product-detail/en/DE9P/IDE9P-ND/2580862

Cheers,

Peter

It says current rating 5 amp.

Is that per pin? Meaning you can pass a total of 45 amp through a d-sub..... thats impressive....

Any regular balance lead from HK can support up to 40 amps and more. I have 1000W charger and a 1400 W power supply. I have charged my 40 amp battery and the leads are not even getting warm. Most of the load to the battery is getting transferred through the main lead. There is not much current that is traveling through the balance leads.

The OP wants a simple solution. People have recommended a 9 pin d-sub. That would suggest to the OP you can have 7 balance & 2 primary charge leads running through the 9 pin d-sub.

Therefore at least two of the 9 pins need to be able to handle the highest current that your charger can deliver or at least the highest that you want to charge at.

@silent hunter.

Your post starts by saying balance leads can handle upto 40 amps.?.. i don't think that is correct.

According to this AWG chart https://www.eol.ucar.edu/rtf/facilities/isff/LOCAL_access_only/Wire_Size.htm .....balance leads would need to be AWG 5 to transfer 40 amps......

Most balance leads are 22AWG. So based on that chart they are good for 1A each.

However Your post ends by saying that not much current travels through the balance leads.....i agree... but bit confused about what you are saying to the OP.

..anyway...

My definition of easy charge solution is one connector that allows balance charging, preferably at resonably high current without risk of melting/ burning your boards wiring.... so you need to make sure the connection has a minimum of two pins that can handle the desired charge current going down the main leads....

Alternatively you might consider a connector with 11 or 13 or 15 pins and split the main charge current across several pins.

Do it once. Do it right.

Onloop's connector (which I think looks really, really nice) sounds like the safest bet, especially if you eventually want to upgrade your charger.

@onloop
I think he meant the balance leads can handle charging up to 40 amps, which shouldn't at all be a problem if your batteries are properly balanced.
With perfectly matched cells, the balance leads should theoretically never even have current flowing through them.

Also: the 22AWG / 1A limit seems really, really conservative. I'd be more than comfortable with running 5A+ continuous on 22AWG wire; the wires won't get noticeably warm and the resistance introduced by the thin gauge should be pretty small compared to the resistance from the connector contacts.
With most single connector charging plugs, I suspect that the contacts will eventually blacken from arcing present when you plug the battery in. No idea how long it'll take for that to become an issue. Might not even be significant.

P.S: I'm more of a "this might not work but let's try it anyways" type of guy, as opposed to "Do it once. Do it right." But that's just me.

onloop said:

It says current rating 5 amp.

Is that per pin? Meaning you can pass a total of 45 amp through a d-sub..... thats impressive....

Click to expand...

The data sheet says 7.5A. Yes, that would be per pin.
http://media.digikey.com/pdf/Data%20Sheets/ITT%20PDFs/DE9P.pdf

But as you know, in the end I used one of you pre-built charging cables.

Life is too short to be soldering cable connectors.

Cheers,

Peter

I used 5 A for charging through single pins on my dsub without a problem, but soldering everything really took some time and the look and dirt protection could be a little better.