JED1990 said:
Yes if this thread could be merged with my previous this would be helpful for everyone - Sorry, quite new to forums. Is this something I can do? My original thread was about an electric assisted bike trailer.
If this is also about that trailer, I can merge the threads for you, and retitle it to whatever you would like.
It's 75a max continuous discharge , 15Ah capacity
It's 10s 5p Samsung 30q
Then the battery itself can probably handle whatever your motor needs, to do whatever it is your project has to do for you.
Ok, the specs from that page show
Features:
1.The protection board is for 10 series cell Li-ion batteries, it can be used for 3.7V ternary batteries, manganese acid batteries and cobalt acid batteries.
2.It has balance function which would ensure each battery cell being fully charged at same time.
3.Support overcharge protection, over-discharge protection and short circuit protection.
4.It is suitable for electric car, electric power assistant car, skateboard car, inverter, etc
5.With temperature control protection function, safe and reliable
Specifications:
Applicable voltage: 36V
Applicable power: <1000w
Max. working current: 30A
Continuous maximum current: 20A
Overdischarge protection voltage: 2.6v
Overcharge protection voltage: 4.25v
Charging current: max. 10A
Balance voltage: 4.2v
High temperature discharge: 75 ℃
Low temperature charge: - 7 ℃
Weight: 46g
which means that as long as your charger outputs at least 42v, the BMS will keep your cells balanced, and it will also shut off the battery output when any cell drops down to 2.6v, which is pretty low but that would also be under load, so they'll likely bounce back a few tenths when the BMS shuts off and the load is disconnected.
It also has an HVC of 4.25v / cell, meaning if any cell goes over that it will turn off the input port, so the charger cant' overcharge the cells. THen the balancers will drain each one down to 4.2v to balance them.
It doesn't specify the Max current time, so I would go with 5 to 10 seconds, as that is a typical enough peak specification time. It might take it for longer, it might not. So don't depend on that BMS being able to handle more than the 20A continuous, just in case.
It mentions a temperature cutoff, and one of the pictures shows this is a little block sensor you can install between the center cells in the pack, so that if the pack heats up too much it will shut off the output (and probably the input). Same if it gets too cold.
, I now understand a 'Controller' is the correct term and the PWM simply refering to the type of control signal. The one I've initially bought is...
https://www.amazon.co.uk/gp/aw/d/B078TC3DTX?psc=1&ref=ppx_pop_mob_b_asin_title
Since this is designed to work down to 6v, it doesnt' have an LVC useful to your battery. So you will be either dependent on your BMS to shut off when cells are low, or you'll want to use that separate LVC.
However, the LVC unit says
【SPECIFICATION】- Power supply voltage: 12-36V battery; Power: < 1.5W;
so if that <1.5W means how much power it can handle, rather than how much it uses, it cannot be used for your system without modification to use an external contactor (relay) that *can* handle the power your system will use. I think the 1.5w refers to how much power it uses, though, because:
The relay on it says it is 20A for up to 14VDC, which means that it could handle up to 20A thru it and presumably be able to switch on or off at that current without damge. However, it's only good for up to 14VDC which means that when the relay tries to open with 30V+ across it, it may continue arcing across the contacts and be unable to open the circuit, and may either weld the relay shut or cause a tiny fire inside the relay from the arcing (which is basically like a tiny welder). It might work perfectly fine...but it might not.
You may be able to use it a different way than directly in series with the battery (which appears to be how it's meant to be used) to the load. You'd run battery positive and negative to it, still, but you'd use the relay to switch a signal on the BMS on or off to enable or disable it, and let the BMS itself do the switching. Or, use the relay to control the On/Off switch on the controller. Both of those would require a bit of rewiring of the relay on the LVC board, so ti isn't connecting battery voltage to it's output, but rather just directly exposes the relay switching contacts.
And finally the motor... Slight reservations, as I feel it may be too 'weak' for the job (my theory is to start lower and cheaper and work my way up) here is is:
https://www.ebay.co.uk/itm/36v-300w-Motor-Mobility-Scooter-ebike-scooter/114626824158?pageci=b4c20def-dfbf-449e-9512-416c493b7895
Is a typical MY1016 brushed motor. Used in lots of things. They have no ventilation so when overloaded they can get pretty toasty inside.
But they work fine when not overloaded. Plenty of threads/posts about them (and similar Unite motors), if your'e interested:
https://endless-sphere.com/forums/search.php?keywords=MY1016&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
https://endless-sphere.com/forums/search.php?keywords=unite+motor*&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
Can you load too much current into the motor? Or does the motor draw as much current as it needs?
IT draws whatever is needed to do the work asked of it. So if you are doing something that physically takes more power than the motor is made for, it may eventually overheat. THe more the overload, the faster that will happen. If the work asked of it is less than what it's made to do, then it won't have any problem with it.
My plan B motor option: Ideally looking for a 500w brush less.. I'm only looking for the ones with one stub axle (go-kart type) I've seen one, but no hall sensors and a little worried as I've heard they can go a bit haywire without them? I guess I could install hall sensors into the motor?
You're actually not looking for "stub axle" motors, as those would bolt the axle to the frame, and drive the wheel (or whatever) with the body of the motor (outrunner).
You're looking for an inrunner, which spins the shaft, rather than the body of the motor (like a hubmotor does). Most chaindrive motors (and beltdrive) do what you want, and they are available up to several kW though you don't need anything that large.
The motor / battery and controller will be fitted into a 'box' with a chain feeding a sprocket on an axle (similar to a go kart set up). I'm not looking for the trailor to 'push' its contents and the bike and the rider. It's mostly to offset the weight of the trailor and it's contents. Modest hills occasionally, (perhaps 5% gradients (feet) at most) but majority of time on flats or gradual inclines.
If the motor doesn't have to do a lot of work, then it will probably be fine. If the offset weight is high enough and the slope is steep enough, it may have too much work to do but if if it only has to do it for a short enough time it may still be ok.
A controller with a current limiting circuit (which this controller implies it has, but might not work the way is needed) will protect itself against any overloads by reducing output to stay within it's limits. Some cheaper brushed controller designs don't properly current limit, and get fried by motor stalls or overloads fairly easily. Easy to tell when it's fried, as the motor won't shut off and goes full speed (the most typical failure mode), or stops and wont' spin anymore.
So....generally the "best" way to setup specifications for a system are to first determine the power necessary to do the work to handle the worst-case situations you'd encounter. Then find a motor that can easily handle that. Then find a controller to run that motor and be able to provide that much power, but that will limit power to what the motor can handle, so if it *is* overloaded, it won't melt the motor down as easily. Then find a battery that can provide at least that much power, at the voltage needed to run the motor at the speed you want it to go. (and the controlelr has to handle that voltage, too). There are other things, but those are the primary first things, in order.