Take your time.
Hello!
I finally got the car working with commands from my phone. Thanks @jim-p for the advice about rewiring.
Just as I was about to switch to 6 batteries it came to our notice that the competition has changed the battery rerquirements based on multiple appeals by different teams.
Now, we xan use rechargable batteries upto about 12V.
We decided to use 3 * 3.7V Li Ion batteries.
I have heard that they are slightly dangerous, so any advice about safety or anything related would be great.
technically, a "3.7V" Li-ion battery, fully charged, provides 12.6V (4.2V per cell.) That's probably OK.
The short-circuit current of a Li-ion battery is "ferocious." Wiring errors, or slips of "live" wires, can quickly lead to heating that can burn flesh and start fires. Not counting the possibility of the battery "exploding" if it heats up too much internally.
Li-ion batteries can "explode" - usually that just means they vent flammable (and unhealthy) fumes (vaporized electrolyte) that catches fire, but more violent things are possible. People have burnt down their garages/houses while charging LiIon batteries for electric planes.
(usually, the major danger seems to be during charging - incorrect charging is "very bad." You should find a proper Li-Ion charger. Cells should be charged individually, or with some sort of "balancing circuit", rather than as a single 12V battery.)
Li-ion batteries have a minimum voltage, even though they will continue to provide current below that voltage. over-discharge (to below that voltage) can make your batteries no longer rechargeable. There are "protected" cells that prevent this (sudden cutoff instead of continued discharge), and also prevent over-current discharge. You may want to look for these, rather than "bare cells."
You can find lot more information at one of the many sites aimed at electric-powered model planes and cars. eg: Batteries and Chargers - RC Groups
Li-ion batteries can supply 10x current compared to alkaline AA batteries.
I have no idea what your competition is about and if high current is needed or not. If not, stay with AAs, lithium batteries are more complicated to play with.
Only buy protected batteries!
DO NOT connect any batteries in parallel.
Now you have 11.1V. That will be too much for the motors, unless you don't care about them burning out. Two batteries would make more sense.
Besides the 40 degree climb what other tasks are there?
Are there other devices on the rover?
Does it mean that parallel operation of battaeries is prohibited?
No, most of li-ion battery setups have parallel cells. But you need BMS for that. Many hobby circuits seen here don't have any.
True. Some people here seem to get upset with that.
Almost every tool you have in the shed uses cells in parallel.
A BMS is essential for a battery pack, but I don't see what it has to do with parallelling cells.
A battery pack BMS can't see the SOC of individual cell when they are parallelled.
They just see the voltage on each tap of a pack.
Leo..
To parallel cells, they should be "matched" and equally charged when connected. A BMS is usually used for handling serial connections (the charging issues I mentioned earlier.)
I guess english is not your first language but I don't know how to put it any simpler.
Yes! English is not my native language; but, i have learnt English (at acceptable level) by practicing the syntax and semantics rules of the language.
Your proposition "DO NOT" contradicts with #75.
Objective: Design and construct a Bluetooth-controlled Arduino-based car/bot capable of operating on various surfaces, including sand, gravel, water, and slopes (30-40 degree).
Specifications:
- Car Dimensions: The car must fit within dimensions of 8 inches in length, 5 inches in width, and 5 inches in height to navigate different terrains effectively.
● The competition area will include a path featuring sections with sand, gravel, water (if applicable), varying slopes, humps, pits etc.
● Obstacles or challenges may be placed strategically along the course to test the car's manoeuvrability and durability.
I am using this setup:
I dont think i can get BMS right now.
Also i will start a new topic to sort out issues with my HC-05, please do help me there too
Two batteries, that is good.
I dont think i can get BMS right now.
You do not need a BMS.
Also i will start a new topic to sort out issues with my HC-05
Do not start a new topic.
OK
I am using a HC-05 to control my rover. I am able to connect to the hc-05 using only bluetooth terminal app and not other apps which have a proper UI for controls. When I use the other apps it says unable to connect.
Tell me if you need anything else!
Considering we are on post #81 and no one will see this question, I think it's OK to start another topic but if people start to ask questions about what you are controlling reference this topic
Nothing. I was referring li-ion battery pack setup in general.
Using unprotected unmatched 18650 li-ion cells without BMS is generally not good idea.
other teams may be using 3 batteries , so wont they have an edge over us.
The main parameter is the time taken for the completition of the track
If they use 12v motors, yes.
And if they use some decent motor driver, even more.
You should really post requirements for all the components you have to use.
Also, can't you use up to 12V lipo-pack instead of bare 18650 cells?