I see many posts with respect to a battery discharging from a reasonable % to low % in seconds, often leading to a crash.

Is is critical to ensure there is a good Cell Balance because, I belive, this is a potential reason for a fast % drop at lower voltage levels.

The nominal voltage of a Lithium Cell is around 3.7 volts and if a Lithium Cell is discharged to below 3.0v irreversible damage is likely and the Cell will not recover from charging.

Mobile Phones have a single Lithium Cell and the Phone has circuitry to power the phone off before the Cell gets near to the 3v level.

The Inspire Battery Packs are 1P6S - This means they are connected with Nothing in Parallel and 6 in Series

The TB47 Pack spec is nominal 22.2v (22.2 / 6 = 3.7v per cell)
The TB48 Pack spec is nominal 22.8v (22.8 / 6 = 3.8v per cell)

Take a RC 6S Pack and you will typically see Red and Black power leads and a smaller multi wire balance lead, these connect to a smart charger that balances each of the 6 cells as it charges. The Inspire Battery has its balancing circuitry built into the Battery Pack (one reason it's called an Intelligent Pack)

I have a TB47 that I refer to as Batt 2. After fully charging the battery to 100% I have 4,470mah (just below the 4,500mah spec) each cell is around 4.31v and cell 6 is slightly out of balance a 4.29v. The total Voltage of the Pack is 25.8v

It is common to charge to this voltage (above the 3.7v per cell spec) but it's not good to leave the pack at this elevated voltage for long periods because it could lead to Pack Swelling.

			POWER
	Batt 2	VOLTAGE	REMAIN	CAPACITY	TEMP	%	cell 1	cell 2	cell 3	cell 4	cell 5	cell 6
	START	25.8	4470	4470	21.8	100	4.30	4.31	4.30	4.31	4.32	4.29

The Data above was recorded after a full charge, prior to this full charge I did a complete discharge.

The Pack had not been used for 20 days and so the Pack had entered its Automatic discharge (10 Days) - The Pack was at 78%

Note: Before the dischage the Capacity was 4,485mah and following the full disharge and recharge the Capacity is now 4,470mah (spec 4,500mah)

Discharged with No Props, No Camera and motors at Tick Over. It took around 3 hours and 20 mins to discharge from 78%

I recorded the results every 15 mins and at 50% and 10%

		POWER
Batt 2	VOLTAGE	REMAIN	CAPACITY	TEMP	%	cell 1	cell 2	cell 3	cell 4	cell 5	cell 6
START	24.2	3498	4485	23.5	78	4.03	4.04	4.04	4.04	4.04	4.01
@15mins	23.8	3251	4485	24.7	72	3.97	3.98	3.98	3.99	3.98	3.96
@30mins	23.5	3004	4485	25.9	67	3.91	3.92	3.92	3.93	3.93	3.90
@45mins	23.3	2780	4485	27.1	62	3.87	3.88	3.88	3.89	3.89	3.87
@60mins	23.1	2556	4485	28.0	57	3.84	3.85	3.85	3.85	3.85	3.84
@75mins	22.9	2332	4485	28.2	52	3.82	3.82	3.82	3.83	3.83	3.81
@50%	22.9	2242	4485	28.4	50	3.81	3.82	3.81	3.82	3.82	3.81
@90mins	22.8	2063	4485	28.7	46	3.79	3.80	3.80	3.80	3.80	3.79
@105mins	22.7	1838	4485	29.1	41	3.77	3.78	3.78	3.78	3.78	3.77
@120mins	22.6	1614	4485	29.4	36	3.76	3.76	3.76	3.76	3.76	3.75
@135mins	22.5	1390	4485	29.9	31	3.74	3.75	3.74	3.75	3.75	3.73
@150mins	22.3	1166	4485	30.8	26	3.72	3.73	3.73	3.73	3.73	3.71
@165mins	22.2	897	4485	31.6	20	3.70	3.70	3.70	3.71	3.71	3.68
@180mins	22	672	4485	32.1	15	3.66	3.67	3.67	3.67	3.67	3.66
@10%	21.9	448	4485	32.4	10	3.65	3.66	3.66	3.66	3.66	3.64
+5 MINS	21.9	89	4485	32.2	2	3.65	3.66	3.66	3.66	3.66	3.61
+10 MINS	21.8	44	4485	32.2	1	3.65	3.65	3.65	3.66	3.66	3.57
+15 MINS						3.60	3.60	3.59	3.63	3.63	3.40

+20 MINS

3.52

3.53

3.52

3.57

3.58

3.20

My estimate is that the Pack had auto discharged for 10 days. I was surprised to see the Pack at 78% around 4.04v per cell (24.2v Total) I would have prefered to see this below 60% at around 3.85v per cell (23.1v Total) - Maybe the pack discharges very slowly and was still in its discharge mode.

The results above are at a low load, remember the load will be significantly higher when flying.

At 30% the voltage was around 22.5v and at 15% the voltage was around 22.0v

The Go App Display changes from Green to Orange when a cell hits 3.61V
The Dispaly changes from Orange to Red when a Cell hits 3.40V
The Inspire 1 Automatically POWERS-OFF when a cell hits 3.20V

It is Critical to understand what the Total Voltage is and Individual Cell Voltage is. If you have one Cell that is significantly out of balance this could easily lead to a fast % drop as that particular cell gets to its low level. Remember if one cell hits 3.2V the Inspire will Power-Off.

I expect the full discharge every 20 times is in an effort to help re-balance the Cells. In my case following the Full Discharge I still have Cell 6 slightly lower than the other cells. But I think this is acceptable.

A large imbalance may well result in a very fast % drop at the lower voltage levels.

I believe it is safe to provide a load to fully discharge the TB Packs because the Intelligent Pack monitors each cell and will Power Off when any cell hits 3.2V
It is likely that the 4,500mah will deplete over time and a full discharge may have an accelerated effect on this depletion.
However, a full discharge may help to keep the pack in better Cell balance.

I am not a battery or electronics engineer - But have some knowledge and experience!

I see many posts with respect to a battery discharging from a reasonable % to low % in seconds, often leading to a crash.

Is is critical to ensure there is a good Cell Balance because, I belive, this is a potential reason for a fast % drop at lower voltage levels.

The nominal voltage of a Lithium Cell is around 3.7 volts and if a Lithium Cell is discharged to below 3.0v irreversible damage is likely and the Cell will not recover from charging.

Mobile Phones have a single Lithium Cell and the Phone has circuitry to power the phone off before the Cell gets near to the 3v level.

The Inspire Battery Packs are 1P6S - This means they are connected with Nothing in Parallel and 6 in Series

The TB47 Pack spec is nominal 22.2v (22.2 / 6 = 3.7v per cell)
The TB48 Pack spec is nominal 22.8v (22.8 / 6 = 3.8v per cell)

Take a RC 6S Pack and you will typically see Red and Black power leads and a smaller multi wire balance lead, these connect to a smart charger that balances each of the 6 cells as it charges. The Inspire Battery has its balancing circuitry built into the Battery Pack (one reason it's called an Intelligent Pack)

I have a TB47 that I refer to as Batt 2. After fully charging the battery to 100% I have 4,470mah (just below the 4,500mah spec) each cell is around 4.31v and cell 6 is slightly out of balance a 4.29v. The total Voltage of the Pack is 25.8v

It is common to charge to this voltage (above the 3.7v per cell spec) but it's not good to leave the pack at this elevated voltage for long periods because it could lead to Pack Swelling.

			POWER
	Batt 2	VOLTAGE	REMAIN	CAPACITY	TEMP	%	cell 1	cell 2	cell 3	cell 4	cell 5	cell 6
	START	25.8	4470	4470	21.8	100	4.30	4.31	4.30	4.31	4.32	4.29

The Data above was recorded after a full charge, prior to this full charge I did a complete discharge.

The Pack had not been used for 20 days and so the Pack had entered its Automatic discharge (10 Days) - The Pack was at 78%

Note: Before the dischage the Capacity was 4,485mah and following the full disharge and recharge the Capacity is now 4,470mah (spec 4,500mah)

Discharged with No Props, No Camera and motors at Tick Over. It took around 3 hours and 20 mins to discharge from 78%

I recorded the results every 15 mins and at 50% and 10%

		POWER
Batt 2	VOLTAGE	REMAIN	CAPACITY	TEMP	%	cell 1	cell 2	cell 3	cell 4	cell 5	cell 6
START	24.2	3498	4485	23.5	78	4.03	4.04	4.04	4.04	4.04	4.01
@15mins	23.8	3251	4485	24.7	72	3.97	3.98	3.98	3.99	3.98	3.96
@30mins	23.5	3004	4485	25.9	67	3.91	3.92	3.92	3.93	3.93	3.90
@45mins	23.3	2780	4485	27.1	62	3.87	3.88	3.88	3.89	3.89	3.87
@60mins	23.1	2556	4485	28.0	57	3.84	3.85	3.85	3.85	3.85	3.84
@75mins	22.9	2332	4485	28.2	52	3.82	3.82	3.82	3.83	3.83	3.81
@50%	22.9	2242	4485	28.4	50	3.81	3.82	3.81	3.82	3.82	3.81
@90mins	22.8	2063	4485	28.7	46	3.79	3.80	3.80	3.80	3.80	3.79
@105mins	22.7	1838	4485	29.1	41	3.77	3.78	3.78	3.78	3.78	3.77
@120mins	22.6	1614	4485	29.4	36	3.76	3.76	3.76	3.76	3.76	3.75
@135mins	22.5	1390	4485	29.9	31	3.74	3.75	3.74	3.75	3.75	3.73
@150mins	22.3	1166	4485	30.8	26	3.72	3.73	3.73	3.73	3.73	3.71
@165mins	22.2	897	4485	31.6	20	3.70	3.70	3.70	3.71	3.71	3.68
@180mins	22	672	4485	32.1	15	3.66	3.67	3.67	3.67	3.67	3.66
@10%	21.9	448	4485	32.4	10	3.65	3.66	3.66	3.66	3.66	3.64
+5 MINS	21.9	89	4485	32.2	2	3.65	3.66	3.66	3.66	3.66	3.61
+10 MINS	21.8	44	4485	32.2	1	3.65	3.65	3.65	3.66	3.66	3.57
+15 MINS						3.60	3.60	3.59	3.63	3.63	3.40

+20 MINS

3.52

3.53

3.52

3.57

3.58

3.20

My estimate is that the Pack had auto discharged for 10 days. I was surprised to see the Pack at 78% around 4.04v per cell (24.2v Total) I would have prefered to see this below 60% at around 3.85v per cell (23.1v Total) - Maybe the pack discharges very slowly and was still in its discharge mode.

The results above are at a low load, remember the load will be significantly higher when flying.

At 30% the voltage was around 22.5v and at 15% the voltage was around 22.0v

The Go App Display changes from Green to Orange when a cell hits 3.61V
The Dispaly changes from Orange to Red when a Cell hits 3.40V
The Inspire 1 Automatically POWERS-OFF when a cell hits 3.20V

It is Critical to understand what the Total Voltage is and Individual Cell Voltage is. If you have one Cell that is significantly out of balance this could easily lead to a fast % drop as that particular cell gets to its low level. Remember if one cell hits 3.2V the Inspire will Power-Off.

I expect the full discharge every 20 times is in an effort to help re-balance the Cells. In my case following the Full Discharge I still have Cell 6 slightly lower than the other cells. But I think this is acceptable.

A large imbalance may well result in a very fast % drop at the lower voltage levels.

I believe it is safe to provide a load to fully discharge the TB Packs because the Intelligent Pack monitors each cell and will Power Off when any cell hits 3.2V
It is likely that the 4,500mah will deplete over time and a full discharge may have an accelerated effect on this depletion.
However, a full discharge may help to keep the pack in better Cell balance.

I am not a battery or electronics engineer - But have some knowledge and experience!