ANCEL BM200 - NEW BATTERY MONITOR

[TheDocAUS]

For lithium batteries the type of battery monitor required is one which actually "counts the coulombs" going in and out... e.g the Victron BMV-712 Smart which is Bluetooth-enabled. The flat discharge curve with sharp "cut-off" of the common LiFeP04 "deep cell" vs. a more gradual degradation curve for lead acid batteries, renders traditional monitors somewhat problematic.

The BM2000 has a lithium battery setting, but still does a poorer job than the BLE Lithium model. Monitoring a current across a shunt is the most accurate, but they are normally expensive choices.

Luckily many Lithium batteries have apps which are better than both the BLE and BM200 - which monitor the current through the BMS. But most Lithium battery apps I have seen do not keep historic data, which is what I get from the BLE.

 

[DenisM]

I guess my take on the models mentioned is that for the price, the so-called "lithium setting" may well be a more refined algorithm evolved from their lead acid calculations and of sufficient approximation to be acceptable. If it does the job, then all well and good

 

[TheDocAUS]

THE RESULTS
The Ancel worked much better on the AGM battery than the Lithium battery. I removed all Ancel's today from the battery boxes.

Pass for AGM, fail for Lithium.

On the first BB, the Lithium battery app was showing 90% SOC, the Ancel app 80% and the battery box voltmeter 100% (but it was probably calibrated for AGM). EDIT: Ancel app amended to 80%, the original 41% was the Ancel on the other BB.

On the second BB, the Lithium battery app said 82% and the Ancel 41%. The second BB also had a Lithium version of the BLE and it showed 46%. Not much better than the Ancel.

On both Lithium batteries, the Ancel was not accurate and the BLE was struggling also. For Lithium batteries a shunt may be the only accurate way to go, or just use the app for the Lithium battery (if any).