I have a car charger that accepts two MA2 batteries.  My truck has four 12V outlets...one is hotwired to the battery (ignition switch doesn't need to be on).  I'd like to continue charging two MA2 batteries via that outlet while I'm flying with my third battery.  Will this cause any undue drain on my truck battery???

Interesting question Rustic - would be good to find out

A J Posted at 10-22 07:52
Interesting question Rustic - would be good to find out

Yeah...not into electricity that much so I don't know how to calculate the amp draw required to charge two batteries and then convert that into volts that might be drained from the truck battery.  I know it's probably more than accidentally leaving the dome light on overnight.

Rustic17 Posted at 10-22 07:55
Yeah...not into electricity that much so I don't know how to calculate the amp draw required to charge two batteries and then convert that into volts that might be drained from the truck battery.  I know it's probably more than accidentally leaving the dome light on overnight.

Over my head to buddy Do you know if you can leave a battery charging in the car on the stock DJI car charger without the engine running?

A J Posted at 10-22 07:57
Over my head to buddy  Do you know if you can leave a battery charging in the car on the stock DJI car charger without the engine running?

Assuming it's a 12V outlet, I would think so.  Whether engine running or only ignition on, 12+ volts are the same no matter how they are produced (alternator/generator or car battery).

Most car charger outlets are rated from 1.5amp to 3amp like my car. Leaving a charger connected to one directly connected to your battery will drain it but then again it depends on how many amps your car battery is example 45 amps or 90 amps. I would guess do a trial and have a booster pack on standby, leave the charger on and remove when drone battery is fully charged and start your car. I used to charge this way on my Kia with the 3amp outlet at the boot and after an hour or so the can used to still start.

They may have a "minimum voltage" threshold on the car  charger, the Mavic Gen I car chargers did not work unless the engine was running, to avoid draining the car battery.
Now, as to leaving the batteries charging o/nite in the vehicle....I would not do it.
If there is a problem with a battery(s) going "phiizzzt" whilst in the "charging process",
May come out to find cinders where your vehicle was parked in the am....

Rustic17 Posted at 10-22 08:10
Assuming it's a 12V outlet, I would think so.  Whether engine running or only ignition on, 12+ volts are the same no matter how they are produced (alternator/generator or car battery).

Cool - thanks for the info Rustic

A J Posted at 10-22 09:24
Cool - thanks for the info Rustic

My car charger is made by Yx and accepts an input of 12-16 volts...it charges two MA2 batteries simultaneously...as long as the car battery is at least 12 volts, I would think it would charge until 12 volts.  And that might be the failsafe that protects the car battery from depleting to where it won't start the vehicle.

A fully charged car battery is 12.6 volts...the 12.6 will diminish to 12.4 at 75% charge and 12.0 at 25% charge.  With the engine running the output is 13.7 to 14.7 volts.    That's why my Yx car charger accepts 12-16 volts.  I am doing a test right now on 2 MA2 batteries and seeing how long before the charging light extinguishes (12 volts min on the charger) or the batteries get fully charged. I am starting from the 60% auto discharge point.  

I don't know your truck but modern cars usually have battery protection that cuts the power drain off in case of low battery level. And truck battery (50 or 74Ah at least for sedan car) would have capacity for multiple charging cycles of 3500mAh MA2 batteries so charging just two batteries should be OK if the truck battery is in good shape...

Rustic17 Posted at 10-22 09:46
My car charger is made by Yx and accepts an input of 12-16 volts...it charges two MA2 batteries simultaneously...as long as the car battery is at least 12 volts, I would think it would charge until 12 volts.  And that might be the failsafe that protects the car battery from depleting to where it won't start the vehicle.

Would you mind sharing a link to the charger please mate?

A J Posted at 10-22 10:48
Would you mind sharing a link to the charger please mate?

This is just one of many...  https://www.amazon.com/Battery-C ... %2Caps%2C218&sr=8-7
Yx makes ones specifically for the MA2.

Rustic17 Posted at 10-22 10:55
This is just one of many...  https://www.amazon.com/Battery-Charger-Accessories-Triple-Output/dp/B07H24S8MN/ref=sr_1_7?crid=ON5UBUW27IIG&dchild=1&keywords=yx+charger+for+mavic+air+2&qid=1603392822&sprefix=yx+mavic%2Caps%2C218&sr=8-7

Thank you very much buddy Appreciate it.

virtual Posted at 10-22 10:26
I don't know your truck but modern cars usually have battery protection that cuts the power drain off in case of low battery level. And truck battery (50 or 74Ah at least for sedan car) would have capacity for multiple charging cycles of 3500mAh MA2 batteries so charging just two batteries should be OK if the truck battery is in good shape...

Thanks for the info!!!

So this was my test result:  I took two MA2 batteries that had auto discharged to 60%.  I put them on a Yx car charger that was plugged into a live 12V outlet (ignition switch off...no key).  The red light on the charger turned green at one hour, but the four battery indicator lights were still cycling.  At one and a half hours, the four battery indicator lights had extinguished.  And my truck started with no discernable effect!!!

You can figure the time that it takes to drain your truck battery. First you need the amp-hour capacity of the battery. I would de-rate that by 20% of the rating for each year of use. So if your battery is a 100 amp-hour battery that is 3 years old, make that 40 amp-hours. Now find the current that the charger uses. You should find that marked on a label somwhere on the charger. Let's say it is 1/2 (0.5) amp. That means it will drain the truck battery completly in 80 hours (40/0.5). It will be completely dead after 3 1/2 days if not used. More likely it will not start the truck after 2-3 days. This is just an example. Use your own numbers.

I have a dash-cam that I keep on all the time and it drains my battery to the level that the car will not start after 4 days.

Hello there Rustic17. Thank you for reaching out and for these information you have given. In addition to this post, using the genuine car charger is always suggested. It comes with low-voltage protection to ensure enough starting battery voltage for the car. Overheating protection will automatically cut off charging if the accessory port exceeds a certain temperature, which for significant for battery health. Thank you for your support. For additional reference, I will post a link where in you can check the overview and the specifications of the DJI Mavic Air 2 Car Charger. Thank you.

https://store.dji.com/product/ma ... t-v2&position=3

DJI Stephen Posted at 10-22 19:24
Hello there Rustic17. Thank you for reaching out and for these information you have given. In addition to this post, using the genuine car charger is always suggested. It comes with low-voltage protection to ensure enough starting battery voltage for the car. Overheating protection will automatically cut off charging if the accessory port exceeds a certain temperature, which for significant for battery health. Thank you for your support. For additional reference, I will post a link where in you can check the overview and the specifications of the DJI Mavic Air 2 Car Charger. Thank you.

https://store.dji.com/product/mavic-air-2-car-charger?from=search-result-v2&position=3

You should notice that the specs say (twice) to use it "while driving".

GaryDoug Posted at 10-22 19:35
You should notice that the specs say (twice) to use it "while driving".

Thanks for the input...I never saw that with the car charger I got...I don't even remember a spec sheet.

GaryDoug Posted at 10-22 19:21
You can figure the time that it takes to drain your truck battery. First you need the amp-hour capacity of the battery. I would de-rate that by 20% of the rating for each year of use. So if your battery is a 100 amp-hour battery that is 3 years old, make that 40 amp-hours. Now find the current that the charger uses. You should find that marked on a label somwhere on the charger. Let's say it is 1/2 (0.5) amp. That means it will drain the truck battery completly in 80 hours (40/0.5). It will be completely dead after 3 1/2 days if not used. More likely it will not start the truck after 2-3 days. This is just an example. Use your own numbers.

I have a dash-cam that I keep on all the time and it drains my battery to the level that the car will not start after 4 days.

It is the similar math but charger needs more power at the first half of charging cycle (with discharged batteries I guess it can be 6 Amps max) while at the end is current quite low. And charger stops automatically when the flight battery is full. My point is that batter result for this arithmetical problem would be a number of charging cycles as the power drain is not constant and continuous...
I believe that two pairs (of MA2 batteries) should average car battery handle (if there is no low enviroment temperature etc.), for more cycles I would better drive the car to recharge the battery first.

Rustic17 Posted at 10-22 20:43
Thanks for the input...I never saw that with the car charger I got...I don't even remember a spec sheet.

It's on the web page with the link that the mod posted.

GaryDoug Posted at 10-23 07:06
It's on the web page with the link that the mod posted.

First of all, the mod's link is for the DJI car charger...not the one I mentioned.  And second, when the link says:

"Essential for road trips

A safe and reliable charge while driving"

I'm thinking that is a promo statement versus an actual specification.  It doesn't say "Use only when the motor is running"  or "Do not charge when the motor is not running" like a normal caution would be written.

Rustic17 Posted at 10-23 08:20
First of all, the mod's link is for the DJI car charger...not the one I mentioned.  And second, when the link says:

"Essential for road trips

The post that you referenced was my reply to the MOD, not to you. So it was a comment about HIS referenced product to HIM.

GaryDoug Posted at 10-23 19:21
The post that you referenced was my reply to the MOD, not to you. So it was a comment about HIS referenced product to HIM.

Sorry, GaryDoug...my mistake.

Rustic17 Posted at 10-23 19:51
Sorry, GaryDoug...my mistake.

Not your fault. My posts are frequently confusing. I will work on that ;-)