LiFePO4 cell level monitoring devices

[mbartosch]

I would like to add cell based monitoring to our LiFePO4 banks (one main bank, two portable ones) and I am looking for options. My research has not yet turned up anything useful, so I decided to ask the crowd if anybody has a recommendation.

Connection does not have to be permanent, I plan to use it only for monitoring discharge tests and rebalancing monitoring, but preferably I would like to have "remote access", such as via Bluetooth and an iOS App.
An alternative would be data logging capability on the device.
The device should have decent accuracy (1 mV would be nice) for a minimum of 4S, low power consumption, preferably evenly distributed on the connected cells, from the pack voltage or via a separate power connection.

In the main LFP thread some posters mentioned using the Junsi CellLog 8S for monitoring their LFP bank.
This device seems to be out of production and is seemingly no longer available for order in Europe. In addition, I seem to remember from the discussion that it had the disadvantage of unevenly loading the cells monitored, drawing its power from one of the cell connections. But I may remember this incorrectly.

Another interesting monitor I found while researching the topic is the Flytron iCell Battery Cell Monitor: https://flytron.com/icell/269-icell-...l-monitor.html
Very small, Bluetooth, but seemingly out of production (and the iOS App is no longer in the App Store).

Any other hints?

[john61ct]

First get "balancing ports" wired.

For remote monitoring I think a "bluetooth BMS" as is common in EV / eBikes will fit the bill, google that on Endless Sphere.

Otherwise the RC world has dozens of choices, any balancing charger for example.

Lots of "Battery Checkers" on the market since CellLog was dropped, G.T. Power and Turnigy 7in1 for example.

Browse HobbyKing for cellmaster.

ISDT BG-8S looks good.

Key bit is accuracy of course, make sure user calibration is featured,

if you don't have a calibrated DMM, one of these will help

https://www.amazon.com/Precision-Vol.../dp/B00Z033Y6Y


https://www.ebay.com/itm/LM399-4-Cha...e/263435494861

[mbartosch]

Good pointers, thank you very much. I must have been looking at the wrong places.
My precision DMM only shows one voltage which makes monitoring charge/discharge tests tedious. I will try out the ISDT BG-8S, I suppose.

[john61ct]

Many high quality RC chargers will actually automate the charge and CC load discharge cycle testing for you, and output the captured data to your PC for you to generate lots of pretty graphs.

For example iCharger DUO-4010 handles a regenerative discharge of up to 1400W from one channel into a resistance load on the other.

PowerLab 8v2 does similar.

Many use West Mountain CBA IV, but I don't prefer single-purpose gadgets unless they're cheap.

The $30 constant load gadgets are only 10A each, and can be paralleled to handle higher rates.

[john61ct]

Banggood just this minute put the BG8 on sale.

https://m.banggood.com/ISDT-BattGo-B...p-1177825.html

[kcj]

I too am an orphaned celllog8 user. The one function I have not been able to find is the cell level user programmable “high voltage alarm”. Anyone have any luck ?

I love the simplicity and programmability of the celllog8...and at $20 per I can buy spares...unlike the the $150+ alternatives...and in two plus years there has not been much need for cell balancing...

[john61ct]

Originally Posted by kcj

The one function I have not been able to find is the cell level user programmable “high voltage alarm”

Just browse HobbyKing, many choices

[kcj]

I’ll try to call them...I was unsuccessful browsing...lots with low voltage alarms...and but no luck with regard to high voltage....thx

[john61ct]

Aha, yes HVC is usually a charger function.

[Rorzech]

Theres a new item on the market from the Aussies called" Kick Starter "maid for Lifepo4 batteries and has a big row for attaching and monitoring each cell and it might have bluetooth (might)

[Rorzech]

That is the stupidest web store I have ever come across. They'll let you enter a credit card number and thats as far as you can go.You can spend as much time as you want trying to enter expiry date but no success. I guess its time to inform my credit card co.
Banggood bangs you real good.

[john61ct]

Pretty much everything Banggood sells is available on Ali if not eBay. Some even on Amazon.

[mikedefieslife]

@mbartosch did you ever find anything? Low voltage is easy there are tons of alarms around and in anycase you could always disconnect the pack at 12.6/12.8 and be safe.

For high voltage disconnect there is nothing that ive seen short of buying a full BMS. I would assume that with an ardunio/ESP32 it might be possible to make something that will look at voltages and send a signal once any one of the cells reaches 3.65 or whatever cut off you want. You can then take that signal and sound an alarm/open a relay or anything else.

[john61ct]

This is precisely what a BMS is designed to do, no point re-inventing the wheel.

Just disable the functions you use other devices for.

HVC failsafe is only needed while charging, no need to monitor for that while in use discharging if the two are not concurrent.

[mikedefieslife]

Mostly in a cruising boat the two will be concurrent, and want to be able to disconnect either charge or load in dependently. I understand that the popular Smart BMS ev-power can't do that

BMS choices that can control something like the Blue Seas Systems latching relays for both high and low voltages independently are few and far between. I suppose the Orion is one of the few around and isn't cheap at over €800 and nor is it readily available. No bluetooth or wifi monitoring either and generally less control than you'd have with a custom unit.

I was thinking it might be fun to experiment and play with a custom unit based around an ESP32. If there was already an alarm out there for high voltage like there is for low voltages, it would make the unit design or software infinitely more simple.