Right, I thought about that after I already posted… still not ideal. Easier to just look at the remote while riding. I’ll probably go with the flipsky one, looks like amazon carries them too and shipping is quick.
1 Like
Yeah, I’m the same way, I like remote telemetry. Make sure you get the VX1 Pro and not the regular VX1, it’s supposedly way better.
Oh I see, I haven’t realized there’s a pro version. I see it has better reception and difference receiver. Ugh, amazon only carries the regular. Back to searching…
1 Like
What’s your budget? The VX4 is pretty sweet, and @Skyart sells 'em for $85. US based shipping.
4 Likes
US $1.36 10％ Off | 4S 3.6v lifepo4 balancer board lifepo4 balncing full charge battery balance board 4*3.2v batteries cells
https://a.aliexpress.com/_mseLjG8
I mean these
1 Like
In this case at least for the first build probably the simpler the better. I found the VX1 Pro in stock at propulsion boards. It’s not a lot less than the VX4 but I think I like the shape better.
I see. Never ran across this type of balancers. I’d need only to keep a bunch of these connected to every section of 4 cells and they passively balance? Interesting.
1 Like
There’s others with lights which are nicer. They burn off anything above 3.65v when charging.
We have a plan!
Ordered a few goodies:
- LTT smart BMS (I still like the simple balancer suggestion from above but I wanted to have an easier way to monitor the cells). LiFePO4 LTT BMS
- Flipsky VX1 Pro
- MakerX DV6 from @haven
Probably the BMS will take the longest to arrive but I have temporary options. Unfortunately my RC charger that I mentioned can only balance up to 10S so one way will be with a balance lead splitter and charge the pack 6 cells at a time.
There are also a couple questions I still need to clear:
- how am I going to know when pack is fully charged? (this is for later when I’ll have the BMS mounted and charging with the boosted 43v brick). Clearly the BMS will keep the charging process in check but how will I know when it’s done, without opening the app for example? Any way to add some sort of voltage monitor or have a green light come on when it’s ready?
- there’s no power switch with the DV6. Making a loopkey is one option. I’d still like a power switch. Is there any recommendation here? Any “antispark” switch that folks use when DIY-ing these boards?
2 Likes
The pack will fully charge when connected to the charger long enough. If u have no indicator it’s worth wiring a wattmeter between charger n battery and can give a lot of info about state of charge and battery health
(U could charge in like 10 minutes with those cells)
ok, having a separate charge indicator onboard is not really needed. I can monitor the charger and it should be enough.
For starters I’ll skip the power switch, I’ll just make an XT90S loopkey. I’ll try to find a good spot for it so it’s not too visible less likely to snag.
What’s the working voltage range for these A123 cells? I keep seeing different values for lifepo4 cells. Is it 3.2v - 3.6v? What should the low voltage cutoff be set to?
I’d need to know this pretty precisely to be able to set it in the VESC and to know how much juice is left if I measure manually… for example, now that the cells show 3.29v, what does this tell me? 10% left? 20%? I’d like to understand the formula.
1 Like
Since I have time until all the parts get here, I’ve started drawing up plans for the new pack layout.
Considering the cells size and the size of enclosure I could make to fit this board, would something like this work?
I’m not a fan of how boosted connected the cells in series with U shape bent nickel strips and this layout would avoid that altogether. Between the two main “rows” I’d insulate it well, I’m thinking G10 sheet or something similar. Otherwise straight nickel strips and 12GA silicone wire to connect the sides in the back.
1 Like
Might run into space issues with this layout… it gets really close to the nuts from the board and I’d really like to reuse those and not mess with moving them. Otherwise it would be perfect, I could make it look nice, just a bit chunkier than the stock enclosure.
I’d rather not make a long and thin pack to keep the board flex.
Feel free to chime in with ideas… nothing is set for now.
1 Like
So I think these are the two options. Long skinny or small chunky.
I’m inclined towards the small chunky, easier to put together, case will be easier to make but I don’t know how much ground clearance we’ll have left. It won’t be fun if I smash it on speedbumps every time. Also, that LTT BMS is a bit bigger than I expected. Still moving it around, maybe I can find a better spot for it so it doesn’t contribute the the pack height.
I think this is the layout I’ll go with. If I measured right I’ll only loose about 1cm of ground clearance which is fine. Maybe I’ll even get bigger wheels, then it really won’t matter.
We’re going to call it the “Not-Boosted-Battery-Pack-v1” 
1 Like
Has anyone seen the original boosted v1 sensor wires pinout?
Trying to figure out how am I going to make these connections. Boosted motor sensors have 5 wires and the leads which came with the DV6 have 6 wires. Also colors don’t quite match up. Is there a way to tell?
Those old motors likely don’t have a temperature sensor wire, but that’s about as much help as I can provide… anyone else have ideas?
1 Like
Well, white is the temperature wire for the DV6 so we can ignore that. Red and black will be +5 and GND for sure.
I guess I can just try to match H1 H2 H3 from DV6 to orange, yellow, green from the boosted motors.
What could happen if I don’t get the correct sensor wires order? Is there a way to tell from vesc tool if the sensors are connected correctly?
The white is usually the temp sensor, you can just pull the pin out of the jst connector and it will work fine. Orange yellow green to blue yellow green- order shouldn’t matter as much as orientation. They are just the position sensors on the motor and motor detection should straighten it all out
2 Likes
Cool, I’ll prepare to connect everything and test tomorrow.
Probably last unknown will be what type of motors are these and how important it will be to set correct values in vesc tool (like Kv rating and whatever else I need to set). Max current I know it shouldn’t be more than 30A per motor.
Oh and I’m still not sure about battery voltages. What should I set the low voltage cutoff for these cells?