Pass diode to protect each BMS

[jayman]

Hi everyone, I'm new to the forums. Justin from Grin Technology suggested I join to obtain some information I'm looking to get for a build.

I want to wire two Lifepo4 48 Volt 20ah batteries together in series for about 100volts . Yes these are the Chinese ones that come already wrapped with a BMS. (Pic attached)

Justin from Grin said I would need to wire a pass diode to protect each BMS and I'm not sure how to do this. I looked already on the forums and there was some talk about pass diodes but I didn't see anything that made it too clear to me as to what size to use and how to wire them into the setup.

The BMS's are rated for maximum continuous discharge of 60A and a instantaneous maximum discharge current 120A. (I've attached a pic of my BMS, 16 series)

Could someone please dumb it down for me. I'm sorta learning as I go along. What kind of diode do I need? Is there a particular direction the diode needs to be used? Where in the setup do the diodes get placed?

A diagram would be fantastic if someone could post something for me showing where to wire them in.

Jason

 

[999zip999]

There is a thread in this forum diodes and diagrams and a link with pic's by ping. What make of battery is that ? Yes those are the signalab bms 10 fet. For high discharge the same ones ping sells.

 

[999zip999]

Is that a codd battery ? And which cells are in that one ?

 

[jayman]

This particular battery is by conhismotor. They sell for about $550 free shipping, not sure what brand of cells are inside, but I ran it all summer and have been pleased with its performance. With the 20ah I'm getting 32km range before it dies.

 

[dnmun]

your problem is not that you need diodes, the problem is that your controller can not handle the 117V of two 48V lifepo4 packs.

what controller are you using and why would you want to include a diode in parallel to bypass the pack that shuts down anyway? at that point you should be stopping anyway. plus they are not needed in any case.

 

[jayman]

I forgot to mention that the stock controller has been modified. I followed instructions from an online PDF I bought on how to make modifications to the controller. I swapped out the caps, placed 160 volt caps in it, also upgraded the wiring and mosfets did everything that is suppose to allow it to handle over 100 volts.

 

[DAND214]

lINK TO PINGS DIAGRAMS.http://www.pingbattery.com/usrguide/Wiring Guide V2.5.pdf

THAT'S A LOT OF V'S as dnmun said, hope you are ready for the precharge circuit and a new controller as well.

Dan

 

[parabellum]

why would you want to include a diode in parallel to bypass the pack that shuts down anyway?

Here we go again. BMS that shuts off first, will see reverse voltage on its power leads, diode prevents this condition. Hope you will close this theme and don't come up again.

 

[dnmun]

wrong, you have to prove that statement. it just does not happen. draw the circuit and where this potential you mentioned comes from. if you can.

 

[parabellum]

wrong, you have to prove that statement. it just does not happen. draw the circuit and where this potential you mentioned comes from. if you can.

You really do not have any clue of electronics if you can not imagine this simple diagram in a second. There is nothing to prove and it is not a statement but a fact. Anyway just in case you want to understand it, here is a DIY project for you. Connect 2 batteries and 1 load (bulb or something) in series. Measure the voltage on the leads of any battery, then measure again on same leads removing the battery. If voltage of every battery is x then your first measurement will be = x, second = -x (or vice verse). Make a video showing and proving contrary before you want to make different "statement" and questioning someones credibility. And I am not the first person writing you that.