Monitoring individual cell voltages (Smart BMS, Balance charger)

stan · October 29, 2019, 9:24am

I think the LTT bms has all those smart features you mentioned on IOS too, it’s just a paid service (I paid around 6€ to unlock those, although the app itself is free.

I agree that the UI looks way better than on this than the android version.

janpom · October 29, 2019, 9:35am

This is probably an updated version. Looks cool. I’ll take a better look at it and update the info in the initial post.

ducktaperules · October 29, 2019, 5:51pm

i wish the dev would port this version back to android. i would happily pay some money for a paid version that is better than the normal android one.

Deodand · October 29, 2019, 6:06pm

I’m thinking about writing a driver for this BMS for the unity and route data through to the app. Could easily use the same code for Vesc as well. The question is can I ever find the time… I think it’d be worth it probably though the BMS is so damn large.

stratoglide · October 29, 2019, 6:24pm

Have you seen the ant BMS’s? They seem to be a more configurable smart bms compared to the LTT and the footprint has come way down compared to the earlier models. Took some pictures and put them up over here 200a smart BMS - ANT

It’s got a really nice form factor for a discharge bms compared to the LTT ones and supports a wide array of voltages.

deucesdown · October 29, 2019, 6:36pm

This would be game over.

Fosterqc · October 29, 2019, 6:39pm

Wow so many good options!

That balancing port.
Exterior BMS is cool, then you can use a high powered large one but not have to integrate it.

magharees · October 30, 2019, 9:10pm

Just me or is anyone getting an error about a missing ‘Billing Phone’ in the checkout for the smart bms?
There’s no way to fill it in afaik

Deodand · October 31, 2019, 2:55am

FYI a high-powered BMS for external is not needed. The balancing current will be the same. You only need to make sure your BMS is rated for your chargers amps.

deucesdown · October 31, 2019, 3:36am

This field, no? From https://www.lithiumbatterypcb.com/checkout/

magharees · October 31, 2019, 7:50am

That worked thanks!

magharees · October 31, 2019, 12:30pm

Spill the beans Jan, I ordered one of these bad boys along with a pc connector. Idea being to configure with the pc dongle and perhaps monitor with the DaveGA, is that an awesome charge model your pic shows?

At least I think I ordered the right type, but it’s hard to tell on such a monolithic website.

smart BMS with Bluetooth function UART communication 20A

janpom · October 31, 2019, 12:44pm

Here’s some messy code that works with the open source DAVEGA module:

gist.github.com

https://gist.github.com/janpom/8e5c29092a473a62cbece80551568fe3

smart_bms_display.ino

//#define DEV_MODE 1

#include <TFT_22_ILI9225.h>
#include <SoftwareSerial.h>
#include "tft_util.h"

#define TFT_RST 12
#define TFT_RS  9
#define TFT_CS  10  // SS
#define TFT_SDI 11  // MOSI

This file has been truncated. show original

You can also make it work with Arduio Nano + ILI9225 display. Here’s the diagram.

Ignore the buttons. You connect the BMS to the UART port instead of the VESC.

The gotcha is that you cannot feed the DAVEGA/Arduino from the 5V on the BMS. It’s unable to provide enough current. You need another power source.

On my custom charger, I power it directly from the battery pack using a buck converter, which is a bit clunky but it works.

janpom · October 31, 2019, 12:51pm

BTW, the ultimate charging solution that I hope I’ll eventually make happen is:

add CAN to DAVEGA X
integrate DAVEGA X with DieBieMS (and FlexiBMS when available)

Then I can view the all the BMS info on the DAVEGA while charging.

If DAVEGA has CAN then it’s not even necessary to have the VESC on while charging since DAVEGA would be able to retrieve the info from the BMS directly.

Without CAN, it’s still possible to retrieve the BMS data via VESC but then that requires the VESC to be on while charging, which is not ideal.

Gee · November 23, 2019, 1:37am

For the LLT Power Smart BMS, does the discharge ampere rating matter if you are bypassing for charging only? And is it better to bypass?
Controlling cells through an app sounds like a dream. Hopefully this is a legit bms.

janpom · November 23, 2019, 7:01am

It doesn’t.

Gee · November 23, 2019, 3:41pm

this bms could potentially change the game.

Myke · November 23, 2019, 4:44pm

Got a link to the bms?

deucesdown · November 23, 2019, 4:57pm

The pcb is double sided.

The lowest discharge amp ones have fets on only one side. So there’s a metal plate over one side, and the bottom is just covered with fish paper.

At I think 40a (not sure), fets appear on the bottom as well, and a metal plate on the bottom to heat sink the fets.

So the single sided boards are thinner but more delicate. The double sided boards are thicker but more mechanically protected.

Electrically, if bypassed for discharge, amp ratings make no difference.

stan · November 23, 2019, 5:00pm

Works like a charm. It isn’t that useful for everyday use, you might use it to check the battery percentage, but other than that, you won’t do much on it.
Sometimes I also check the temp sensors in my board, placed above my battery to see battery temp, if you consider that useful.