Hello, I am looking for a way to use an Arduino to detect a Schottky Diode failing Short-circuit and then cut power if it does.
Essentially I've got 2 batteries paralleled through a double schottky diode, occasionally they get .4V(ish) out of balance and I'd like to prevent a equalization event if the diode we're to fail at that time...
Is there a way to use an Arduino to detect the direction current is flowing? I.E. if current starts flowing Into the battery rather than out of it, can I set-up something to then disconnect the battery from the circuit?
A Schottky Diode has a typical voltage drop of 0.4V (what you see).
But: if in series with two batteries and they differ in voltage - you see also a difference on "out" (the larger voltage wins).
In order to detect the direction of a current: you need a shunt resistor, e.g. 1 Ohm. Measure the voltage over it (not voltage between tap and GND, really "over it"). When it turns the opposite, e.g. negative voltage - the current has reversed.
If you do not have a charging unit connected in parallel - you should not see an opposite direction (battery is discharged).
Running current into a battery without a charging unit is not good. This might happen when you power board via battery and a DC plug in parallel: battery has 3.0V but DC plug provides 3.3V. Now you "charge" battery, but without a charging circuit (very risky).
Therefore, there are often diodes to decouple, to avoid a higher voltage (DC plug) creates current into battery.
I've currently got a 70v 30Amp rated Schottky Diode, it's hooked up to two 52v li-ion packs on an E-bike.
The bikes controller is programmed so that the system isn't capable of drawing more than 25 amps at a time...
Do you think that set-up would be straining my current diode?
Would adding another diode at the positive terminal of the battery that tends to have a slightly lower voltage serve as a failsafe if my first schottky we're to fail?
The packs tend to equalize after running through the diode for a half hour but that first half hour they tend to stray from eachother
What do you plan to use as the failsafe power off? A MOSFET? Why do you need a diode in this case? Just turn on only single MOSFET. You can use a diode as a failsafe if Arduino fails.
I currently don't have an Arduino in the mix, only a Schottky Diode for protection.
My thinking was that an Arduino could serve as an extra layer by monitoring for voltage reversal?
It seems like you're saying I should use an Arduino as my primary protection and use a Schottky as a backup to that?
When I say I'm a noob to electricity I really mean it lol, I hardly know what a MOSFET is other than it's a sort of switch that's properties change depending on voltage input?
Ive got half a dozen Arduino Unos and a couple Arduino Nanos lying around unused...
I've also programmed Arduino's to make automated watering systems and a home security and automation system so I'm familiar with that side of things. I just don't fully understand all of the different electrical components.
I was initially asking for help using the Arduino as BACKUP to my hardware not trying to use an Arduino on it owns with no idea what I'm doing...
It's 14s, they both have their own common port BMS built-in. The BMS don't support parallelling natively but they do have a diode to prevent reverse flow through the discharge ports.
I might be over thinking things I'm just aware of how serious a battery fire can be and want to be as cautious as possible
I run a 6S2P BMS, works great lasts a long time no diodes needed.
Bring the batteries that are to be paralleled into chemical balance.
Say you want to have a 5S2P set. That's a total of 10 LiPo's. Pair the batteries off and charge each pair with a regular charger. Take the batteries out of the charger and put them in holder where the batteries are not connected to a load but are connected to each other in parallel. Wait 24 hours for the batteries chemistry to equalize. Keep that pair together when wiring the pair in series. Do the same thing for each pair. Now the batteries will act like 'one' battery with the same chemistry.
Use 1C BMS's to prevent battery bulging and reduce the chance of fires.
Information that would have been good to know in post number1. Buy all the LiPo's in the same lot and use them as a set. What you are trying to do adds an increased risk of causing fire.
