How do I fix my Space Cell

Whilst setting up my board I soldered my XT60 connector on my VESC with the polarity the wrong way round, when I connected my space cell something happened and my space cell is no longer responsive. The VESC and everything else work fine with another battery but I cant get any voltage out of the output wires on the Space Cell. I have opened up the unit for an inspection and I cant find any burnt out connections, I used my multimeter to test for voltage to find the problem and I am reading 37v up until the PCB, after that the voltage reading are between 2-8v, I assume the PCB needs replacing?

Any idea what he easiest fix will be?

ps. Separate question but why is there a 30A fuse fitted to the space cell when the VESC draws far more? I have blown out lots of 30A fuses on my other FIIK batteries trying to ride the board, the biggest I can find at Jaycar is 40A. I have used BLDC motor tool to limit the power draw but Im a bit confused with this, specially as I am running a dual VESC setup. What size fuse should I be using on my battery?

Cheers, Moja.

space cell maxes at 60amps, and 30amp fuses can burst 60amps for 5-10 seconds. Putting a 60amp fuse would allow for it to burst higher than the space cell can handle, ruining the point of the fuse even being there.

one question though: is the display coming on?

if it isn’t, then try this: When my space cell seemingly died (reading 2 point something volts after the bms, 40 before it) it was actually just a balancing wire… it somehow wiggled out. The weird thing is, it didn’t happen on a ride: it happened on my workbench. I’d unplug your 11pin plug (at the top of the BMS) and just look to see if any of the pins/wires seem out of place. If not, just throw it back on there and make sure it is in all the way…

@onloop and I tried to fix mine for close to 2 weeks with no luck. then, because of a guy on ES who was very adamant about helping me, I was miraculously able to fix it after finding a loose balancing wire.

just because of your situation, I doubt that is the problem, but mine just stopped working while sitting on my workbench, so it’s worth a shot just looking into what I mentioned…

Good luck! I think you’ll be able to fix it because the BMS isn’t blown up, and like you said, there aren’t any fried connections

I am getting nothing on the display. The 11 pin plug is seated perfectly and all the pins are fine, I’ve done a pretty thorough visual inspection and everything seems to look fine, no loose pins.

What is a BMS?

Thanks for the support.

BMS is the brains of the operation- it’s the board that the cells, screen, and button are all wired into.

I think I’ve found something though!

It looks like your charging port isn’t plugged into the positive lead heading to the battery (that red wire just hanging out in the open) see my pic where the charging port has two wires:


That fixed it, you rock mate.

Just going back to the query about the fuses, if your statement is true, why would I be blowing out 30a fuses? surely running 2 VESC’s draws twice the current?


I’d refer to @onloop for dual VESC amp draw questions. I know he uses dual VESCs and a space cell on all his pre-made builds; I on the other hand, have always gone with a single.

glad you got the battery all sorted out though!

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Its odd how the cause of my problem had nothing to do with how I fixed it :stuck_out_tongue: Who cares, its fixed!

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i’m about to build a DR setup with a space cell, dual R-SPECs and a 12S Torqueboards ESC. I’m not going to be blowing fuses all the time, right? I know about throttling those ESCs down to 80%, but other than that I’m good, right? I keep seeing stuff like this and it makes me wonder.

This battery porn got my blood flowing this morning.

You could switch it out for a fast blow fuse with a higher rating. They are a little expensive, around $7-$10. I get mine from mouser under automotive fuses, they have some specifically for electric vehicle battery systems.

I think you honestly would… it’s just not a good match up: you have to turn timing all the way down to very low, acceleration on low, and forward force to 80%. It made it slowed than my 245kv 6s build, even with the R-SPEC geared up higher (15/36 vs 14/36).

and all that is on a single setup with a 140 pound rider; when my 200 pound dad tries to ride it, the fuse blows on the very first acceleration…

I think it would only get worse with two torqueboard’s escs- Not to mention VESC’s are cheaper, and don’t require a separate BMS.

guess i’ll save those for a lipo build and order a pair of VESCs for this space cell. Hopefully I’ll get them this year. I need to finish this build soon and sell it. its always something.

on second thought, i think i will convert my current 6S beater board into a 12S and tell myself merry christmas.

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It just feels so much better when you are building for you and not someone else. The satisfaction is way higher.

I switched out the 30A fuse for a 40A one and Its no longer blowing out. I got catapulted off the board whilst accelerating with full power when the 30A fuse blew and that was extremely dangerous. I have the motor max and battery max set to 60 in BLDC tool. Is having a 40A fuse on the battery doing it any damage? I want to completely avoid any blow outs by having things balanced properly, its far too dangerous to have the system shut down whist you are anticipating power during acceleration.

The correct setting for dual vesc would be 15A each MAX battery current draw.

Note: You can also adjust max regen current to prevent accidentally blowing fuse when regen-braking really hard

2x 15A is 30A Max. You will never blow a fuse unless you accidentally reverse polarity or there is a short somewhere after the battery.

You could probably push this to 20A each VESC and still not blow any fuses. Depends on weight / terrain / drive train config.

The motor current limits can actually be set higher, maybe 80A each. This allows high motor current whilst similtaniously having low battery current without blowing the fuse.

Quote from BV; For the VESC you can configure different current limits for the motor and battery. You can for example set the motor current limit to 80A and battery current to 30A, which should work nicely with dual motors on a space cell. The motor current in each motor will then be able to reach 80A until you have reached 3/8 of the full speed. After that, the motor current will be more and more limited the faster you go. End quote.

I suggest testing different settings and slowly increasing from low to high amps until a fuse pops. Then notch it down.

With these advanced settings in the VESC you could completely bypass the BMS for discharge. You could also remove the fuse. The current controll function in the vesc is very advanced and can manage output & input currents at the battery very effectivly

I have had the vesc set at 20A each max battery current since day one… never blown a fuse. (With r-spec)

However when I started testing hub motors I blew the fuse everytime I tried to start. They obviously need much more power to start. I had to set max amp draw at 15A on each vesc to prevent fuses blowing.

In the long run I think I am going to have to start advertising the space cell as being “not compatible” with Torque Boards & ALIEN ESC… as they don’t have current control.

Good facts to keep in mind. Where in the BLDC tool do I specify the max ampage?

Open that link above about “regen braking” all the settings are in the same page/tab/section.

What is the BMS that the space cell uses?

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Im getting 32kph top speed with those settings, what do I need to be doing to get up to 45?

In the long run I think I am going to have to start advertising the space cell as being “not compatible” with Torque Boards & ALIEN ESC… as they don’t have current control.

Yes. Please make that clear somewhere prominent. In fact, lets just clear all of that up right now.

While the Space Cell doesn’t play nice with LiPo ESCs, it’s a great match for VESC after you do a lot of tuning that you can’t do in most if any of the other ESCs available.

And VESC is great for LiPos too, correct? So if you want a space cell, you have to get a VESC, and if you want LiPos, you can have VESC or any number of other car ESCs with good reputation and adequate specs.

I really wish somebody would build an adequate up-to-12S BMS for lipo packs.