Reention POLLY DP-6C - 70 cell battery case - how fit BMS?

[vulcanears]

Hey everyone.

I bought a Reention POLLY DP-6C battery case for 70*18650 cells. Build quality seems a lot better than the Hailong cases, especially the little tabs that hold the battery box to the mounting-plate.

http://www.reention.com/product/detail/99

Unfortunately my 30A bluetooth BMS is 9mm thick and when I try to fit it into the case, it won't close. Did anyone successfully fit a BMS and 70 cells into this case? I'd love to hear some ideas or see some photos.

 

[Speady]

You need a dedicated BMS, same as with Hailong 2 cases.
I wonder why the seller didn't offer a all in one package.
Bought myself a Polly 1with 13s BMS that fits on top, no problem

 

[vulcanears]

Some AliExpress sellers offer the case with a BMS, but I prefer Bluetooth bms systems that let me see cell voltages on my phone. That gives me the peace of mind that the bms is working properly.

The Bluetooth bms would fit if I removed the heatsink. I'll try to come up with a custom heatsink design. (running it without a heatsink is probably not recommended, right?)

 

[vulcanears]

Could someone please post a picture and the measurements of a BMS that fits the case?
I spent the whole day trying different 3d-printed mockups and can't come up with anything that fits into my case, when it's populated with 70 cells. Even the height of the PCB board + JST connector for the balancing leads is too much. :?

 

[BotoXbz]

You made a good choice with the 30A bluetooth BMS.
It uses five KIA KNB3308A FETs in parallel, the gate of the FETs is driven with 12V.
The datasheet states a resistance of 6.2mΩ per FET, you have 5 of them 6.2mΩ/5 = 1.24mΩ. (I've measured the resistance on mine at 1A each and got 6.2mΩ - 6.4mΩ per FET)
Let's assume you're running 30A through it, the heat generated by the FETs will be P = R * I² = 1.24mΩ * 30A = 1.116 Watt of heat.
You definitely do not need a heatsink for that. The FETs are mounted on a big copper plane and are big enough by themselves to dissipate this heat.
And at 30A for longer than a few minutes on a 5P pack will cause you more trouble with your cells than the BMS.

Try moving it around a bit in the case, it'll never be 100% perfect but when you screw it down the plastic bends a bit and it's fine.

 

[vulcanears]

Thank you very much! That helps a lot!

My version does in fact use the KNB3308A, but there does not seem to be a copper bar under the mosfets.

 

[BotoXbz]

I said copper plane not copper bar
There is copper on the PCB under the FETs which is connected with lots of through holes to the copper on the underside of the PCB.
That will dissipate the little heat easily.
But even without that the 1/4 Watt of heat on each of those chunky FETs is nothing.

What I don't like about this new version 1.5 is that there is barely any space between the FETs to properly solder a thick wire to P-
V1.4 Version (60A): https://cloud.botox.bz/s/J6oZWqJDikzpTw8/preview https://cloud.botox.bz/s/2ipzTsJNWQ222TH/preview

 

[Matador]

https://endless-sphere.com/forums/viewtopic.php?f=14&t=88415&p=1290017&hilit=triangle+empty+battery+box#p1299070

 

[Tomblarom]

Just wanted to share my experience on this. I was able to fit a smart BMS 30A (only 1 layered) on top. Pretty tricky to close the case, but it's possible to get it perfectly sealed. I managed to swap charging port and switch, to install an GX16 3-pin port and an 12mm self latching switch.

 

[want to build]

Hi there,

for those of you who have experience in locking batteries, how safe is this battery case considering

it i left outdoors and that the screws bolts have special anti thief Pinhead Locks for the rear rack placed on frame?

how safe is the lock and the plate you fix the case on?
tx

 

[john61ct]

Safety depends on where the bike is, not locks nor any anti-theft hardware.

Social norms, culture, that sort of thing.

Amsterdam, yes just make it inconvenient.

Detroit, carry the bike upstairs.

 

[want to build]

Is this a polly 2 or polly1 ?

i read polly 2 is strongest? is that true

what is polly anyway alu or plastic?

 

[want to build]

Some AliExpress sellers offer the case with a BMS, but I prefer Bluetooth bms systems that let me see cell voltages on my phone. That gives me the peace of mind that the bms is working properly.

The Bluetooth bms would fit if I removed the heatsink. I'll try to come up with a custom heatsink design. (running it without a heatsink is probably not recommended, right?)

hi did you use nickel part provided by them if yes did you verify if it is pure nickel or just plated nickel? im talking about the battery connect nickel plate sheet .

 

[want to build]

You need a dedicated BMS, same as with Hailong 2 cases.
I wonder why the seller didn't offer a all in one package.
Bought myself a Polly 1with 13s BMS that fits on top, no problem

HI could anyone please explain me what is Polly 1 vs polly 2 , for the love of god if god exists i'm having a hard time finding this anwers. tx

 

[want to build]

Hi im trying to figure what type of case holds the strongest on top of a regular rear rack ? how is reention compared to hailong?

 

[john61ct]

Please do not keep repeating the same request across multiple threads.

At least not daily, bumping every couple of weeks, maybe.

 

[want to build]

Hi i understand that it is important for you to keep this simple and correct rythm. At the same time asking for a comparaison between hailong and keention means a different interrogation for me.
Since i search for answers something i try to reach different people that is all. I m beginning to understand that those reention cases are not that well known i imagine. i do take note of your demand. I ll try to be more patient with these reention

 

[john61ct]

As mentioned, the best approach would be for you to just buy one each and become the forum expert yourself, would be a valuable contribution to the community.