Battery Protection Circuit on 2700mAh 7.4v Hubsan Batteries. Please Explain

[justjarhead]

So than i have an old battery?
I received the H507M 2 weeks ago.
But i don't know what idiot will put in a battery protection system in a lipo.
No use, with a drone you cannot draw too much current from the lipo.
If i would put a protectionsystem somewhere it would be in the ESC.

GJ

All I know is Hubsan sell the 2700mAh 7.4v 10C battery with Overload Protection. I am not going to research what batteries come with the H507M because it does not interest me.

There are valid reasons to have the battery protected. It helps reduce the chance of fire or explosion of the battery plain and simple. There are other benefits also.

The ESCs are also protected.

[SomeGuy]

I looked at some pictures in RCgroups.
It is not a protection circuit, it is for charging.
Some chargers are not real lipo chargers, they just deliver a voltage (about 5 Volt and a current.
The circuit balances the cells and protect them for overvoltage during charging.

In the normal world it is called a battery control circuit.


GJ

Don't know if it was 9, 12 or 18 Months ago but Hubsan did add a protection circuit to the 7.4V 2700 mAh battery, I have tested it myself. The low voltage cutoff will not allow cell discharge below 3V. The circuit may provide additional features I don't know but the low voltage cutoff is there without a doubt. In the normal world it's called a Battery Management System (BMS). I think it is rather basic when compared to the DJI Smart Battery.

Actually I am surprised there are high discharge li-po batteries manufactured without some protective circuitry. I guess there are advanced hobbyists that say they need batteries without any internal safeguards but the general population has become very lackadaisical with battery charging and they frequently don't read instructions and are used to Ni-Cad or NiMH batteries, so if some basic safeguards aren't built into the battery then that is a recipe for trouble.

[justjarhead]

So than i have an old battery?
I received the H507M 2 weeks ago.

I looked at some pictures in RCgroups.
It is not a protection circuit, it is for charging.
Some chargers are not real lipo chargers, they just deliver a voltage (about 5 Volt and a current.
The circuit balances the cells and protect them for overvoltage during charging.

In the normal world it is called a battery control circuit.


GJ

givo,

your wrong again.

Hubsan has acknowledged numerous times that the circuitry is for Overload protection and has acknowledged that it can cause an X4 501 to fly in the brick mode.

[gjvo]

I am not so shure that Hubsan always know what they are talking about.
I worked 10 years as developer in UPS systems and for that i also worked with all kind of batteries.
And for the hobby i flew modelplanes with lipo batteries, that is from the start of lipo's in 2007-2008.
I know some batteries have build in battery management systems but never in my live i have seen a protection system.
I also cannot be like that because the wires to the drone (black and red) come direct from the soldering lips of the lipo.
There is nothing like a fuse or so in between.
The pcb that is in the battery is connected to the charge cables, so it is a battery management system.
In the worst case maybe some isolation can be damaged (the kaptan tape) than you get a short circuit and than the whole battery can fail.
But than you must see a lot of smoke.
About why there is no overcurrent system in batteries?
A lipo rated as 10C can easily do 20C or 30C.
Depends on the duration you ask for the current and temperature.
The old Kokam lipo's were rated as 20C, so a 4000 mAh could deliver 80Amps.
But we draw 400-450 Amps for 3 seconds without a problem.
And the batteries lasted a whole season.
In the logging you could see the voltage dropped to 3.4 Volts per cel at 450A so no problem.
If there would be an overcurrent protection build in than the lipo would be unusable.



GJ

[justjarhead]

If the red an black lead go directly to the cells the battery you opened up does not have the protection circuitry and is one of the older design. Thers is a youtube video about this but I don't have the link readily available.

In the video the testing methodology was improper but it got the brick effect discussed.

[ParadoxPete]

The battery circuitry simply uses a couple of FETS, equivalent to the ECH8601.
These are kept "closed" during normal operation and are in series with the power connector.
The sensor circuit is based around the S8261, (or equivalent) which senses overcharge, over discharge and over current.
It simply "opens" the FETS which then remain open until reset.
The terminal voltage presented to the user is therefore zero.

I have a Hubsan Battery that is over 26 months old with this protection circuitry. I believe they have been shipped as such since day one (which would be approaching 30 months now. The most recent "genuine" Hubsan battery I have is 10 months old and also has the circuitry.
"Fake" Hubsan branded batteries do not incorporate the circuitry.
The popular replacements also do not implement any protection circuitry.

I have never had a Hubsan battery "power off" on me in over 2 years, but that is because I don't use them

battery protection.jpg (106.04 KiB) Viewed 12267 times

[justjarhead]

Thanks Pete. I appreciate you input and knowledge.

[gjvo]

As i told,
It is a protection when you are charging, not discharging.
So, a battery management system.
Overvoltage, overcurrent and overcharge protection.
Here is the datasheet of the chip.

https://www.ablic.com/en/doc/datasheet/battery_protection/S8261_E.pdf

GJ

[ParadoxPete]

It protects against overcharge and overdischarge (min and max cell voltage),and overcurrent.
Overcurrent is the issue that is being talked about in this thread primarily, although minimum voltage could occur under certain circumstances.

[gjvo]

Yeah, with overcurrent they mean the current that is going into the cells during charging, not what is going out to the motors.
So you cannot charge it with probably more than 500 mA.
It is also not advisable to do more on the balancer connection.
If you want to charge by the "normal way" like all modellers do you have to charge it by the blue EC3 connector, than you can charge it in 45 to 60 minutes.
And if your balancecurrent is lower than 500 mA than you can leave the pcb in the battery, if the balancecurrent is higher you have to take it out.

GJ