I am in the process of pretty much gutting my GTX and have quite a few questions for you guys.
So far I have the enclosure (stock gtx with riser), 10s4p 30q pack, and stock evolve motors.
I am thinking that I am going to use a unity with a vx2 pro remote. The problem area for me is the bms. I have a good understanding of lipos, but not so much lithium ion cells.
Question 1: on the unity where you plug in the hall sensor in there are 6 pins, but my motor sensor only has 5 wires, how do I go about making this work this?
Question 2: Would this bms be a good fit? ( https://www.aliexpress.com/item/32876164697.html?spm=a2g0o.cart.0.0.148b3c00hY6MCQ&mp=1 )
I am not wanting to bypass it, but am worried that 60A is not enough.
If anyone would have a recommendation for a better one please let me know. I would prefer one that I can connect to through Bluetooth so I can see what the cells are doing.
Question 3: is there a good esc spacer for the gtx enclose? I am a bit cramped for space at the moment. I looked everywhere but could only find one for the gt and my understanding is that the gt and gtx enclosures are slightly different shapes.
Your motor does not have a temp sensor, you can leave that one out. splice the wires and connect them to a 6 pin jst. Look up racestar motors wiring. It’s the same for evolve.
I have no idea about that BMS but yeah 60A is not enough. You’ll need a 80A BMS and only one I can recommend for not bypassing is DieBieBMS.
You can always buy nitrile rubber pad and cut a perfectly matched spacer from it. Not sure on the costs on this one. Failing that I would recommend just do the measurements and 3d print one.
That bms is likely too big for your enclosure. It’s a really cool one because of it’s bluetooth capabilities (I have that one) but it’s huge. The size would be comparable to another focbox unity.
I just want to make sure I understand how bypassing the bms would effect the cells. If I were to bypass, the cells would only get balanced while the charger is connected and not while discharging?
Doesn’t matter if you bypass or not cells only get balanced when you charge. Only effect bypassing would have is there would be a risk of over discharging one of the cells if if they are very unbalanced to begin with, this is a non issue if all your cells are new and are balanced while charging. Another risk would be over current discharging but that can be managed in VESC just don’t draw more than 80A battery.
There are diagrams of discharge only wiring for BMS’s on this forum and on the builders forum just search for them. And yes no such things as discharge only balancing.
I have read different things about adding a fuse to the charging port. Some say to add is, and some say to not add it. Is there really a downside to having one?
Fuse the charge port on either side. I would suggest just using a discharge bms, they are tiny and cell balancing is still wholly achieved through charging. I dont know the numbers of course but I’d put good money on at least 80% of the builds people have done here using charge only bms.
Discharge bms will also shut power down if you over discharge when the battery is full. For example if you go down a steep hill early ride and the regenerative braking tops the cells up too much. Power off and no braking = streetface at speed.
Wiring looks good. Alternatively, you could decide to use separate leads for discharge and charge (that’s what I did) as it allows to route wires a bit better if you want the chargeport elsewhere. As for fuses, it’s to protect your build in case your charger decides to take a crap and unload too many amps
Alternatively, I believe there are some fused chargers out there but I don’t know whether it is used for discharge or feed power or how effective their own protections are. Happen to know if these have been studied @Flasher?
@KfromtheBay That fuse protects the charger. It’s a fuse at the input but not on the output. So your house craps a brick, charger lives. Charger craps a brick, board dies
