Charging on the go.

[Physopto]

I was looking on the internet for multi chargers for my Mavic 2 Pro. I purchased one but had to return it after it damaged a battery as the connection blades were far too thick. Lesson learned! So next idea was about battery powered chargers capable of charging multiple batteries at the same time. one in particular was interesting but very expensive for a 10 AH device. So I got to thinking why not use a 40Ah LiFePo4 battery I have for my astronomy gear. All I had to do was make up a simple lead to use the DJi battery charger. I can then charge several batteries with a couple more of the DJI chargers. Trouble is the high cost of the DJI chargers at £70 a time here in the UK.
The lead I made up was just a test to check it worked well. I can easilly make it to suite three DJI chargers if I want.
So any ideas folks?

 

[fenea]

So any ideas folks?

Super nice, I'm not sure why you want so much to charge multiple batteries at the same time?

Another idea would be to buy a cheap inverter (200W, under 20$) and use the AC charger to charge 2 batteries at the same time, also that one has the usb for the controller.

I however have a question:
You use a 12V battery, how much voltage does it provide, I've heard that the DJIs OEM car charger cuts off under 12.4V, can you confirm that? Have you tried depleting your battery? I'm expecting a 12V battery to drop under 12.4V before even being at half the juice.

 

[Physopto]

Super nice, I'm not sure why you want so much to charge multiple batteries at the same time?

Another idea would be to buy a cheap inverter (200W, under 20$) and use the AC charger to charge 2 batteries at the same time, also that one has the usb for the controller.

I however have a question:
You use a 12V battery, how much voltage does it provide, I've heard that the DJIs OEM car charger cuts off under 12.4V, can you confirm that? Have you tried depleting your battery? I'm expecting a 12V battery to drop under 12.4V before even being at half the juice.

Hi, The battery is a LiFePo4 type. nominal voltage is around 13.44 volts. liFePo4 batteries stay at around this voltage until down to around 5% or so.
Hence much better than Lead Acid which drop off very quickly. You never really get much below 50% before the voltage is very low. 50% equates to around 12.3 or 12.4 volts depending upon makeup of the cells. 12.7/8 is fully charged. A lot of people mistakenly think that Lead Acid only charge up to 12.8 volts, but that is fully charged after an hour or two once the charger is removed from the circuit. Under charge they should be charged to 14.4-14.8 depending upon make up. After disconnection the surface charge on the battery plates dissipates and that is when you see a measurement of 12.8 volts. I hate Lead Acid batteries as they are dangerous unless strict precautions are taken.
The reason that I have the LiFePo4 batteries, is the poor charge capacity and voltage of Lead Acid and the weight difference.

40 Ah in LiFePo4, almost all usable charge, constant voltage, 6Kg weight. and much safer than LiPo.


110 Ah Lead Acid battery voltage rapidly drops and only around 45-50% usable charge, 25-6 Kg weight.

The reason for using these batteries is because I have then for another purpose, as in Astronomy gear. Seemed pointless leaving them lying about unused for several months of the year.
As I said my problem is cost of DJI chargers.

The:-
ICQUANZX Battery Charger for Mavic 2 & Zoom, 5 in 1 Rapid Smart Battery Charger Hub

This charger I tried damaged one of my new batteries. The connections on it were of larger thickness than the DJI charging leads. I did not notice it at the time and felt no resistance as I pushed on the connection. It crushed down 2 of the socket receptacles in the battery and it cannot be repaired. £139 down the drain.

Lesson learned not to trust after market gear !

As to the DJI car charger I have done a quick test. Unfortunately my test bench supply is only capable of 2 Amps so not of any real use. I tried with an old lead acid battery showing 12.2 volts at the terminals but the DJI charger repeatedly came on and then cut out as it came on load. The battery terminals then were showing 11.98 volts approx. So your idea might be right. It looks like if the current was OK at 12.2 volts and at that it might work but not at 12 volts. I would need to partially recharge the old Lead Acid battery and retry say at 12 3 to 12.4 volts.
Sorry at present I can't do any more there as I am a wee bit busy at present.

 

[fenea]

Hi, The battery is a LiFePo4 type. nominal voltage is around 13.44 volts. liFePo4 batteries stay at around this voltage until down to around 5% or so.
Hence much better than Lead Acid which drop off very quickly. You never really get much below 50% before the voltage is very low. 50% equates to around 12.3 or 12.4 volts depending upon makeup of the cells. 12.7/8 is fully charged. A lot of people mistakenly think that Lead Acid only charge up to 12.8 volts, but that is fully charged after an hour or two once the charger is removed from the circuit. Under charge they should be charged to 14.4-14.8 depending upon make up. After disconnection the surface charge on the battery plates dissipates and that is when you see a measurement of 12.8 volts. I hate Lead Acid batteries as they are dangerous unless strict precautions are taken.
The reason that I have the LiFePo4 batteries, is the poor charge capacity and voltage of Lead Acid and the weight difference.

40 Ah in LiFePo4, almost all usable charge, constant voltage, 6Kg weight. and much safer than LiPo.


110 Ah Lead Acid battery voltage rapidly drops and only around 45-50% usable charge, 25-6 Kg weight.

The reason for using these batteries is because I have then for another purpose, as in Astronomy gear. Seemed pointless leaving them lying about unused for several months of the year.
As I said my problem is cost of DJI chargers.

The:-
ICQUANZX Battery Charger for Mavic 2 & Zoom, 5 in 1 Rapid Smart Battery Charger Hub

This charger I tried damaged one of my new batteries. The connections on it were of larger thickness than the DJI charging leads. I did not notice it at the time and felt no resistance as I pushed on the connection. It crushed down 2 of the socket receptacles in the battery and it cannot be repaired. £139 down the drain.

Lesson learned not to trust after market gear !

As to the DJI car charger I have done a quick test. Unfortunately my test bench supply is only capable of 2 Amps so not of any real use. I tried with an old lead acid battery showing 12.2 volts at the terminals but the DJI charger repeatedly came on and then cut out as it came on load. The battery terminals then were showing 11.98 volts approx. So your idea might be right. It looks like if the current was OK at 12.2 volts and at that it might work but not at 12 volts. I would need to partially recharge the old Lead Acid battery and retry say at 12 3 to 12.4 volts.
Sorry at present I can't do any more there as I am a wee bit busy at present.

Thank you for your explanation. I've learnt something new.

I'm fairly new to battery types, but eager to learn, so since you know something about batteries can you help me with something.

If LiFePo4 are not dropping in voltage at discharge and are pretty good at discharge speed, What do you think about this:


It is a 4s1p 32700 LiFePo4 battery, with a nominal voltage of 3.2V*4=12.8V and ~7 amp capacity. They're claiming a 25A continuous discharge and it is pretty cheap(under 20$). Considering its capacity and that I'm never depleting my MPP batteries it could give me almost 2 extra charges.

Now I have 2 problems with it:

1. How do I charge it, the seller does not specify, nor I could find anything about it, a 14.8V 2A charger to that dc 5.5 port will do?
2. How safe it is? since the seller does not specify anything about a BMS, I'm assuming it doesn't have one, so for Dji battery charging cutting of at 12.4V will prevent from discharging but at charging my guess is if the charger will only put 14.6V it'll just stop, but I'm not sure here.