The battery builders club

How-Tos & Esk8 mechanics
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#2940

Nobody close who would borrow you a malectrics or kWeld for a while? Your problem was one of the reasons I got me a malectrics.
With a bit luck @DerelictRobot still has his welding pen for the sunkko and might want to borrow/sell you, but I have no idea how welds will be after. The resistance in the long wires till the weld point can reduce the strength of the welds by a lot.

2 Likes
#2941

I think the closest major city is Baltimore or Philadelphia…anyone make packs in that area?

1 Like
#2942

I don’t see any problem. You can easy do it by just welding the first p pack to the other P pack and then add each time a extra P pack. You can cross just one cell with the tabs. I do it always that way.

1 Like
#2943

So make 12 4p packs with their parallel connection welds and the series tabs on one side, then weld them one pack at a time to the main pack? I guess hot glue the cells temporarily then peel it off so I can use silicone?

#2944

Yeah can easy glue 12 x 4p packs with silicone. After the silecone is dry wrap 6 p packs fully in with fishpaper so the groups are separated from each other. Weld the first p pack to the second. Then weld that 2s4p to another pack. Stay going until you have your 12s4p in your hands. Ok it weighs a little bit but you can do it perfect.

Just don’t forget to use painter tape to cover the other p connections.

2 Likes
#2945

Could you elaborate on this for a novice like me as to why this is so a little further, please?

#2946

A high discharge will cut off the current when you over charge or under charge batteries. At the moment it cut out the current you don’t have any brakes.

One thing, I almost sell all my packs with high discharge bms’s just because some n**bs can’t kill their battery by over discharging. If you set the BMS correct. You can allow overcharge and undercharge for a longer time. So you don’t have some unexpected cut outs. Also if you set the voltage cut off on your vesc correct you will feel that you will have less power when the battery is almost empty.

4 Likes
#2947

And the solutions to this is to

fuck BMS protections on the charge/discharge path between the cells and ESC

as suggested by @longhairedboy?

#2948

run the BMS/charge circuit in parallel to ESC.

1 Like
#2949

Also possible or this:
If you set the BMS correct. You can allow overcharge and undercharge for a longer time. So you don’t have some unexpected cut outs. Also if you set the voltage cut off on your vesc correct you will feel that you will have less power when the battery is almost empty.

I run all my boards with high discharge. Never had any problems with it if you set it up correct.

1 Like
#2950

which bms are you using that has settings higher than 60 amps and isn’t the size of a dual motor controller?

1 Like
#2951

Thanks for explaining. If you monitor your battery charge on your remote it seems also less likely that you run into the problem of over discharging your battery, right?

Only problem I can see with over charging is when you set off with a fully charged battery and have to break suddenly that the BMS could prevent this? But that case would only apply to the first few minutes or seconds of a ride, right?

#2952

For ATB you have some llt’s that can do 100/120A.

But those all are indeed bigger then a dual vesc.

Still waiting what this year is going to bring (flexiBMS etc)

Stupid thing is that when we use high discharge BMS & esc with inbuild antispark we run 2 the amount off mosfets that is needed.

If I had the knowledge the BMS would communicate over CAN and send the ESC a signal that the battery is undercharged and take off the possiblity to use power and only give you the possibilty to brake.

2 Likes
#2953

You’ll just lose your brakes. There’s no preventing this. You can’t put a regen load on a full battery that has a BMS wired in for charge/discharge pathway protection, the BMS won’t let you.

#2954

Yeah, I got that. However, that applies only for the first 5 minutes or so of a ride, I assume?

How can the discharge protection be lethal? Is this a scenario where you have to accelarate or get out of danger but cannot because of discharge protection?

#2955

yeah around that. Assuming you’re on flats. and don’t have to deal with any sort of emergency stopping whatsoever while you’re taking your five minutes.

or you could run a larger battery (4P and up) and bypass your discharge and let the pack take the beating that you know the cells can take because of the combined experience of the community.

5 Likes
#2956

So you recommend not to implement an overcharge or discharge protection via the BMS, since a rider’s life is more important than that of any battery?

#2957

Medical bills cost far more than the board you got them on, protect yourself

2 Likes
#2958

My philosophy is, if I need the brakes even if it means the battery will catch on fire, then let the battery catch on fire, I’ll deal with it after. I want the least number of automated things between me and control of the thing I’m on/in. I believe ultimately the rider is responsible for knowing their equipment and it’s limitations, rather than rely on a bunch of failsafes that is out of the control of the user.

12 Likes
#2959

:heart_eyes::heart_eyes::heart_eyes: a man after my own heart :heart::heart::heart:

3 Likes