BMS for 36 cell 48v module

[DanielMv720]

Originally Posted by ArkansasVolt

I bought the Zeva BMS16.

http://www.zeva.com.au/index.php?product=135


Specifications

[http://www]*Cells managed: 8 to 16 cells*
[http://www]*Supported chemistries: LiFePO4, LiCo, LiPo, LiMn*
[http://www]*Maximum total voltage: 60V*
[http://www]*High, low and shunt voltage thresholds: Factory configurable between 2.00-4.50V*
[http://www]*Accuracy: 0.001V*
[http://www]*Dual solid state relay (SSR) outputs, 60V 1.3A max*
[http://www]*Built-in current measurement via shunt*
[http://www]*CAN bus interface for external monitor, hall effect current sensors, TC chargers, etc.*
[http://www]*Status LED for visual feedback*
[http://www]*Internal switchmode power supply*
[http://www]*Internal shunt balancers (~120mA)*
[http://www]*Dimensions: 106x80x16mm*
[http://www]*Mounting holes: 2x Ø4mm, 116mm apart



Sent from my XT1650 using Tapatalk

I still couldn't figure out the max amperage. I was browsing the website and just couldn't figure it out. How the do bms amperage ratings work? for example the Chevy volt pack I have is 48v & 47amp but when it comes to finding a bms what amperage am I looking for?

[Sergio]

The primary function of a BMS, when properly installed, is to disable the charging if any cell gets above its maximum voltage or disable the driving system if any cell gets below its minimum voltage.

A Controller, Charger or AH meter cannot do that since it only looks at "pack voltage".

Some BMS will also attempt to balance the individual cells after the pack reaches its preset voltage at the end of the charging cycle but all cells are not at the same voltage levels.

There are various methods of balancing used but most of the inexpensive BMS just discharge the highest batteries and usually by a very small amount so it takes a while to get them balanced if they were not pretty close to start.

The maximum current output of the pack is not directly controlled by the BMS unless one of the cells drops below the minimum voltage.

[ArkansasVolt]

Originally Posted by DanielMv720

...the Chevy volt pack I have is 48v & 47amp ...

I have the same pack. The "47amp" is actually 47 amp-hours which is a measure for capacity. If individual cells are paralleled, they can be considered like one larger cell as far as the BMS is concerned, so you'd effectively have a single string of 12 bigger cells for a BMS to monitor. the pack that we have has 3 paralleled cells in a series of 12. The BMS can treat that as 12 cells since the paralleled cells will likely have very similar voltages.

[DanielMv720]

Originally Posted by Sergio

The primary function of a BMS, when properly installed, is to disable the charging if any cell gets above its maximum voltage or disable the driving system if any cell gets below its minimum voltage.

A Controller, Charger or AH meter cannot do that since it only looks at "pack voltage".

Some BMS will also attempt to balance the individual cells after the pack reaches its preset voltage at the end of the charging cycle but all cells are not at the same voltage levels.

There are various methods of balancing used but most of the inexpensive BMS just discharge the highest batteries and usually by a very small amount so it takes a while to get them balanced if they were not pretty close to start.

The maximum current output of the pack is not directly controlled by the BMS unless one of the cells drops below the minimum voltage.

Thank you Sergio! That makes perfect sense now. I was under the impression that my BMS amperage had to be equal to what my motor was capable of drawing.

[ArkansasVolt]

Had my trial run with just the battery today. Then I hooked up my 48v to 12v converter for headlights, etc. BMS should be here from Australia soon. Then my charger from China next week.

Sent from my XT1650 using Tapatalk

[sunking]

Originally Posted by ArkansasVolt

Now I am looking at BMS, would it be best to have the BMS cover each cell? or just the 12 in series?

You need a 12 channel BMS. Hard to beat an Orion Jr if you want a BMS which is not necessary.

[blfinche]

Who did you order your charger from? Mine took a month to arrive, but only 4 days from when it shipped?

[steadystreamin]

did you ever get your bms? any pics of it installed?

[ArkansasVolt]

Originally Posted by blfinche

Who did you order your charger from? Mine took a month to arrive, but only 4 days from when it shipped?

I got mine from zeva.com.au it got here in less than a week.

Sent from my XT1650 using Tapatalk

[ArkansasVolt]

Originally Posted by steadystreamin

did you ever get your bms? any pics of it installed?

Still trying to get it up and going. I will post pics when I get it cleaned up.

Sent from my XT1650 using Tapatalk