Modified Ping BMS applied to Lipo

[mr.electric]

I got these from Ping for use on Lipo batteries. This is a signal lab with modified LVC and HVC for use with Lipo.
I am discharging a pack into a load now to see what the LVC is.
My main question is if this small fet bank will hold up. I have a 9c and 20 amp controller running 12s - about 900 watts under load.
I use a 400 watt alloy shell bulk charger to charge. These BMS's seem to last on ping packs. I wonder if they will last using lipo with low discharge/ charge rates as described.
One odd item, the LEDs are not on the board. Any precautions recommended with this board?

 

[Tench]

I was reading the evolution of the Ping BMS on their website the other day and i dont think the led's where introduced until v2.5.

C + P from their site;

Evolution of PingBattery

V1.0 released in 2007, made of 3.2v4950mah prismatic cells and our first version of BMS (Battery Management System) for Lithium Ion Phosphate batteries. V1.0 cell has 2C maximum continuous discharge rate and 4C peak. The polarity tabs of its cell is small.

V2.0 released in 2008, made of 3.2v4000mah prismatic cells and same BMS as V1.0. The V2.0 cell also has 2C maximum continuous discharge rate and 4C peak. But its 2C continuous performance is much better than V1.0. It's weigth/ah is a little higher than V1.0. V2.0 has wider polarity tabs than V1.0. V2.0 is more expensive than V1.0.

V2.5 released in 2009, made of 3.2v5000mah prismatic cells and new BMS. V2.5 cell has same performance as V2.0. That's why we don't call it V3.0, but V2.5. V2.5 has lower weight/ah than V2.0. V2.5 cell has wider polarity tabs than V2.0. The V2.5 BMS has indication lights for balance status.

Simon.

 

[mr.electric]

I ran a light bulb and space heater from my 12s pack to check LVC levels. The lowest cell was 3.175 at rest after bms cut off and I unplugged pack from bms.
I'm charging with my 400 watt alloy shell bulk charger now. It is set to 4.1/cell average. I will probably need to crank the charger voltage up a bit if I end up using this bms regularly. Does anyone know which pot to turn on the BMS battery alloy shell chargers to adjust voltage?

 

[mr.electric]

I tested the bms to cut off on discharge and it seems to work. It did not seem to balance the tired zippy 8000 12 s pack very much but I only charged for about 2-3 hours from empty so maybe it needed time. Also my charger is set at 4.1/cell so the bms might not even be trying to balance yet for all i know. I took a test ride for a few miles and everything seems fine. I put deans plugs in and out of the bms and set the wire lengths so I could easily bypass the whole bms if it fails.

 

[dnmun]

do you know for certain what voltage ping designed the LVC resistor divider bridge to? or the HVC voltage?

you mentioned the 3.1V at rest after you disconnected, but any idea of the true cell voltage when it cut out?

i thought the lipo could be discharged down to about 2.7V without risk.

 

[neptronix]

i thought the lipo could be discharged down to about 2.7V without risk.

What kind of lipo cells are you referring to? lifepo4, li-mn, nmc, li-co? it varies depending on chemistry.

Anyway this is pretty interesting given that these are fairly robust BMSes. The downside is that they aren't all that fantastic at handling high current.

 

[Evoforce]

I personally have not had good luck with those bms's and know of a vender that no longer sells those in their lineup because of so many failures. Of course, there may have been a bad run of them that I was unlucky to get. Yours may hold up. I would not have a charger pushing more than 5 amps through these though.

 

[dnmun]

i thought lipo referred to lithium polymer, like these zippy packs. i never heard of people referring to lifepo4 or limno4 as lipo until it was used here as a term common to all by the experts.

 

[neptronix]

i thought lipo referred to lithium polymer, like these zippy packs. i never heard of people referring to lifepo4 or limno4 as lipo until it was used here as a term common to all by the experts.

All sorts of chemistries run in a lithium polymer format. Lithium polymer refers to a pouch type of cell, so something like a 20AH a123 cell could be called a lithium polymer battery, same with the ping pouch cells as well.

Some NMC/li-mn cells run all the way down to 2.5v safely, something like RC Lipo ( which, 99% of the time, is lithium cobalt ) should never be run down past 3.0v. 3.2v is where i would cut it off, if i were designing a battery system.

Sorry to get on your case about it, but on this forum we need to stop talking about a format as if it was a chemistry. For a long time, li-co was one of the few chemistries that came in lithium polymer format.. but that is just no longer the case.

 

[dnmun]

i realize you guys feel a need to ridicule and insult me about this, but i consider A123 cell s to be lifepo4 chemistry and the lipo describes the lithium polymer cathodic mixture. i do not think pouch cells are lipo by some kinda convention that is started here.

you can say whatever you please but i do not believe that lifepo4 cells will ignite and burn from overcharging either as some here also have stated. i think only lipo is at risk from overcharging.

 

[Jeremy Harris]

i realize you guys feel a need to ridicule and insult me about this, but i consider A123 cell s to be lifepo4 chemistry and the lipo describes the lithium polymer cathodic mixture. i do not think pouch cells are lipo by some kinda convention that is started here.

you can say whatever you please but i do not believe that lifepo4 cells will ignite and burn from overcharging either as some here also have stated. i think only lipo is at risk from overcharging.

The "polymer" bit in Lithium Polymer as a description of lithium chemistry cells refers to the polymer layer between the electrodes of the cell. All lithium cells that I'm aware of, whether in cans or pouches use polymer between the electrodes as the electrolyte. It's correct to refer to any secondary lithium chemistry cell as "Lithium Polymer", or LiPo for short. Even LiFePO4 cells are technically LiPo. What distinguishes the various cell types is the differing chemistry and physical structure of the electrodes, not the polymer membrane that forms the electrolyte.

As often happens, common usage has blurred things, and people tend to refer to any non-LiFePO4 as LiPo. It'd be better if we used the true cell chemistry to distinguish between cell types, rather than misuse the generic term for the cell internal construction method.

 

[neptronix]

Thank you Jeremy.
Dnmun, i am not trying to ridicule you at all. You are a frequent poster and it is important that you know what the deal is.

http://www.mpoweruk.com/cell_construction.htm

Here is a page talking about the various cell formats.

With the more recent introduction of li-mn, and NMC being common in lipo format, it is more important than ever to not use 'lipo' as a term to describe RC aircraft batteries.

li-mn and NMC can vary from 4.10-4.25v fully charged, to 2.0-3.0v fully discharged. It all depends on the chemistry. This is important to know when we are figuring out where a BMS should cut off on the low and high side.