i think it depends on what you want/need. lipos for sure are a good choice for a lot of people but not so much in my case. i want to use my board mainly for daily commuting and for this a set-and-forget battery solution is IMHO what you should be looking for. but because i had no experience with lipos and wanted to stay within my budget, i got two 5s lipos. turns out this was not the best choice.
first of all: charging. riding around town and my battery is dying? without bringing a charger along, i wonât be able to give my board a charge. and even if i should do that, i would still have to take my board apart (wanted my lipos to be removable so i went without charging ports). for sure something i would like to avoid in a busy environment like college or starbucks. apart from that for most of us its not enough to charge only one battery. imagine you would have to catch a bus in 30 minutes and want to charge your batteries while still having to do other stuff. this would require you to charge the first battery for 15 minutes, then you would have to stop whatever you are doing to disconnect the first battery and connect the second, continue your work and after another 15 minutes you are ready. this would highly annoy me! a bms could fix this problem, but when you are going with a bms, i donât see any reason not to use liions.
next: discharging. i always balance charge my lipos but after riding the cells almost always end up unbalanced. sometimes more, sometimes less. last time i had to stop because one cell dropped to 3.4V while all of the others were still at 3.75V. thatâs a lot of power i wasnât able to use because i wanted to save my lipo. donât get me wrong, i donât want to blame lipos in general. this is probably the fault of my charger or a dead cell. but as i said, this is my first experience with lipos and not particularly a good one.
size. 5s lipos are pretty thick.
assembly/disassembly/storage. i keep my lipos in a lipo safe bag. a full charge/ride/store-cycle i have to plug and unplug 24 xtâs and balance connectors, monitor the batteries while charging, fit the batteries in my enclosure, ⌠for me thatâs just too much of a hassle and not worth it for short rides to the next supermarket or so.
okay, sorry, got a little bit carried away. in short: i have been looking for that just-grab-the-board-and-ride feeling and lipos donât offer that for me.
Get good at Soldering. When stuff doesnât fit, changing connectors is easy when you have a grasp of Soldering and a good Soldering iron. I also wound up upgrading my Soldering iron partway through my build.
@High-roller God the budget thing is so true ! I thought Iâd spend around 600$ when i begun. Iâm well over 2000$ today. This includes also 400$ of lost/wasted parts by third parties (I wonât name Marcin Sleziak, that damn f**ker or Flier with bad quality here - oops I did).
@Nix Some advices to add to the group (Iâm starting to sound redundant over threads) :
Prepare a proper thermal management for your VESC whatever model you use. 4.12 is good for FOC only if you cool down properly FETs and shunts. If you wonât cool it, use BLDC and try your best not to go above 40-50A to save some troubles.
When using FOC on 4.12, low kv motor (under 150kv) is less stressful for the VESC.
4.xx is flawed design due to FETs concentrating heat face to face ; when applying heatsinks, cool the solder joints, PCB and metal sockets only. Donât bother cooling the black top of FETs. The plastic black casing of FETs wonât allow any heat transfer no matter what you mount on it. Thatâs why Chaka uses DirectFETs with all metal casing to be able to directly heatsink on top of the FETs.
Check your batteries max charge rating and set your VESC regen braking max current close to it. This will enhance your battery life cycle and prevent thermal runaways. If braking strength is not enough, you should consider a dump system to burn excessive regen current, and then raise VESC max regen current accordingly.
If you use Lipos, prepare a properly enclosed area to charge them or charge them outside ; better keep an eye or easy access. Be extra careful if Lipos becomes puffed. Remember you are packing hundreds of Wh : if it burns it will do for a long time. It is reliable only when properly cared about. Iâm too lazy for this much maintenance so Li-ion is more forgiving for dummy users like me.
Do not use a Bluetooth Nano remote because it is freaking buggy and will throw you out of your board. Too many members complaining about it despite the compact look. Many members use GT2B remote with âsparkle modâ, it is big but not too shabby ; I remember having seen a GT2E mod which was more compact and still reliable. I canât talk about the new OLED remotes.
Always power your receiver ON first then your board second. Always turn your board OFF first then your receiver second.
Either use an XT90 antispark or an upgraded antispark switch PCB (the standard one is good up to 40A continuous) ; relays and fuses DIY solution is super reliable too if done correctly. Circuit breaker is big but a cheap and reliable solution too. Donât overlook antispark switch if you use one. All your current has to flow through its FETs so get a good quality one or it will fail.
Wear a helmet when you start riding what youâve built. You will fall on your e-boards for sure, better stay safe.
More generally donât cut on any safety requirements even if it is bothersome to wear / solder / set / plug.
Good luck !
p.s. How pretty is the punctuation of this forum !
Hey Mike, Iâm planning to open up my Raptor 1 and take out canbus and use split ppm with one 5V wire cut. In terms of BLDC, Do I just remove the vesc IDs? what else would I need to to?
There is not 'really" anything wrong with the canbus cable, except, when the cable is or go wrong .
Mostly ppl having problems with canbus, because the cable or the connection is or get somehow damaged.
And if itâs damaged, the vesc connection can have a problem, with one of the two motor not spinning or spinning diffrently, stopping or cogging.
The problem is the cable itself is fragile, some try to hot glue the two pin connectors, so the cable-plug wont split.
If you have 2x vesc and canbus, dont ever power only one vesc, when canbus cable is connected, cos it will probably fry the not powered vesc, by this canbus cable.
Some have general problems, when using Canbus not related to cable itself.
Thatâ;s why, many ppl play it safe, and go split servo ppm, so the reciver is connected to both vescâs.
I made two boards, with double vesc/motors on each with canbus connection, and itâs working fine ever since.
Sometimes, you just may get unlucky with hardwareâŚ
As @Tomash said, its really hit or miss, you could go along and build using canbus without any problem, but as soon as it happens youâll be jaded from using can for dual setup.
Another point that Tomash missed was that in canbus config, if your master goes down, you lose control of slave as well. In a split ppm config, if you lose one, youâll always have the other still functioning. Both ESCs are operating independently and are unaware of the other.
For a split ppm configuration for dual motors, you need to make sure that you clip/disconnect one of the +5v rails on the ppm cable. Do a search for split ppm and youâll find a huge thread on it with some of my pics.
[quote=âCrossfire, post:35, topic:32864â]
You must realize that when your battery indicator shows you for example 3.8V when standing still, you easily go below 3.7V while ridingâŚ
[quote]
Yeah Iâm referring to discharging the lipos to about 3.2 or 3.1 volts under load, which is probably about 3.4 volts not under load. So far I havenât had any problems with that, although as you said I do notice a power reduction after 3.6 volts, but thatâs just my cue to start heading home and conserving battery.
Correct. The only difference is that @ 3.6V my batteries are already back on the charger.
Below 3.8 - 3.85V per cell Iâm starting to lose the top end power and with 245 kV motor thatâs all I have so yeahâŚthe biggest benefit are the 97mm wheels which just keep on rolling so that way I can manage the battery quite good, keeping the flow going.
Plan the build during Oct, Nov, Dec.
Order your parts January when online and local retailers have their sales.
Pay the extra 3-5 bucks for ePacket/Express delivery (7-16 days).
This will give you enough time to build changes and upgrades.
Have a backup supplier/alternative pasts incase you items donât show up.
You should finish your build at the latest. Mid April.
I prescribed to this and didnât get my eBike on the road till the 2nd week of May. The bike seat, I had to purchase locally.
Time to start researching what you want to build this winterâŚ
Realize that youâre on a board and that hard breaking will stop the board pretty quick, but you will keep flying. Test and adjust your settings a little at a time.
For me it was know how long order times are. I ordered a TON of parts through users here (want to support those who innovate!) but some things came from Europe so I ended up waiting 2 weeks for one part to get me goingâŚ
Practice soldering! I know others have mentioned it but I wasted a solid 2-3 XT-90sâs due to my shitty soldering.
Know what you want to get out of the board. For me, a 6s with a 12 mile range was PLENTY with a solo 295kv motor. It was an inexpensive build (sub $500 I believe) but I have quality parts (FocBox, 2 8000mAh lipos, aluminum motor mount, etc). I can EASILY upgrade motor/batteries and keep it cheap as my other pieces can be reused.
If you know you typically âramp upâ from one item to the next (i.e. start small then want to get a bigger/nicer board) buy parts that may be a bit oversized for now, but can later be used to their full potential! It isnât hard to get inexpensive motor mounts by people here on the forum that will last the life of the board.
Sorry I didnât see your question before. Actually since FOCBOX is DirectFET equipped it should be, just like Chakaâs DirectFET, pretty reliable for FOC. Hardware is well built. But as you notice, it is rated by Jason/Enertion to max 60A continuous.
In this area aluminum case alone is both a blessing and a bottleneck for cooling. Either you are able to enhance the cooling of the case itself, thus counter the heat dissipated through it, or you remove the case and prepare for a more aggressive cooling solution. I bet it could be at least 80A continous ready with a better thermal management and different materials to complete the weaknesses of aluminum.
For example I did experiment cooling down passively a Peltier moduleâs hot side ; aluminum alone is a quick cooker if you saturate it, thus better than nothing but no more cooling. The same happens with FETs.
What kind of build do yuo have? You could simply attach a large fan to your FOCBOX too, would help in any case.
My build integrates what i hope is a 'waterproof â enclosure. That means the cooling is less than desirable. I cut an additional plate of aluminum (from a giant heatsink) and attached it to the aluminum side of the case hoping more aluminum equals better cooling. Not sure if my 'science â is on point here though. Then made sure the cooling side is facing the enclosure and added a few Velcro strips to secure (not near the fetâs). I hope this will sort of help cooling with a bit of an air gap. What do you think?
IMHO it is directly relevant to your board : will you ride on road or off road? What is your battery / motor setup?
Even with waterproof enclosure it is still rated 60A. Will you draw this much when riding? 40A is enough torque to drop many riders on their back from start. When climbing big hills it is where you will spend more amps, but keeping speed momentum can be very low amps even around 40km/h (ex : full tuck or crouching on board offers low air resistance thus low strain on motors).
If you run sensorless, you probably push kick a little before take off. That helps shave precious amps too.
In summary, even with waterproof enclosure your FOCBOX may be enough as it is.
Now an idea just in case : can you cut a hole in your enclosure to let your added aluminum piece go through and close the gap with silicone joint? Youâd gain external air flow and keep water tight. This should help cooling the case.
EDIT : You should open a thread about your build, it will be easier to discuss it there.
.
Mostly ppl having problems with canbus, because the cable or the connection is or get somehow damaged.
And if itâs damaged, the vesc connection can have a problem, with one of the two motor not spinning or spinning diffrently, stopping or cogging.
Below 3.8 - 3.85V per cell Iâm starting to lose the top end power and with 245 kV motor thatâs all I have so yeahâŚthe biggest benefit are the 97mm wheels which just keep on rolling so that way I can manage the battery quite good, keeping the flow going.
