I own a ToolKitRC M6DAC charger that allows allows a DC input voltage of 7-28V. I really want this in the field with me as well as being able to use it at home with AC..

My biggest drone battery is a 4S LiPo 1300mAh.  

What size battery would I need to power up the ToolKitRC M6DAC charger in the field to charge up a few batteries while flying there?

Cheers

Something bigger than a 4S 1300mAh. So 6S and as big as possible. Maybe a 6S 4000mAh or 5000mAh. It needs to have a higher voltage than what you are charging (ideally) and also as much power in it as possible.

If you have a car that you drive out to bandos and places you fly, maybe plug the charger into the car battery, or if you want something more useful, put a bigger battery in the boot, like a 130Ah AGM and run a split charger or VSR between the vehicle and leisure batteries. Then connect your M6DAC or any other Lipo charger that takes a DC connection to the Leisure battery in your boot (via a fuse board with the correct fuse). That way you can charge off the 130Ah battery and any time you drive the car you will recharge the battery in the boot via the vehicle battery/alternator. This same solution would also work with a motorbike, but would need some tweaking and a smaller battery for the leisure side (20Ah should be small enough and have enough power to recharge a 4S 1300mAh a few times).

Using a Lipo as an interim charging battery isn't ideal long term. If you go down this route look into building a Li-ion pack, buy a 30-40Ah LiFePO4 or use the leisure battery in your car.

To not utterly confused you, if you want to charge for example your 4S 1,300mah 4 times, you will probably need a 4s 1300mah x 4 = 4S 5200mah. Considering that you don't actually drain a pack drain to nothing, a 1300mah pack will probably take about 1000mah to recharge back. Using a 5200mah (or something similar) you can probably get 4 charges. Leaving about 20% in your source pack. You don't want to discharge any pack too low, otherwise it will get damage.

If you want to look into 6S pack for recharging source, then we can discuss that. But generally, 4S are cheaper than 4S.

I only mentioned the car charging thing as that's the way I do it. I have a small van that I put a bed in the back, in the style of a small camper. I have a 130Ah AGM in it that I charge from the vehicle battery via a VSR (and also a 100w solar panel on the roof). I have a SkyRC B6 that I plug into it for Lipo charging in the field. If you drive to where you fly it allows you to carry something that can recharge a big lipo many times over. Or in my case charge a lot of 2S batteries a lot of times. I'm currently working on adding similar functionality to my motorcycle using probably a 10Ah battery, to allow the ability to recharge around 10 2S Lipo in the field.

Car charging makes a lot more sense than charging a big honking battery for hours at home and carrying it around to store charge.

Although with car charging you do need to be careful you don’t damage or reset your car ECU which does happen every now and then when jump starting modern cars.

I use a 4500mah 6S in the field.
But, I only use it on small sub 250g 3"-5" quads with 500-1050mah batteries.

But please avoid HUGE mistakes
1) Dont leave input battery plugged in - charger WILL drain it.
2) Dont leave batteries getting charged plugged in - my M6D slowly drains them.
3) Dont forget adapter. Nothing worse than getting to field but your big battery is XT90 and you dont have adapter.
4) Charge somewhere safe and clean. You dont want any metal objects or liquids nearby.
5) Do NOT super fast charge. Its tempting. I never use over 2C. It wears batteries. Also, your "BIG" source battery can quickly go from 3.8V, to pulling 1 cell below 3.5V.
6) NEVER charge batteries when its <0C or when batteries are hot or parallel charge when big difference in voltage.

Li-ion are cheaper than LiPo per watt-hour wise, and has higher energy density.
If car batteries are not accessible, it makes sense to use Li-ion as power supply.
If DIY battery packs is not desirable, there are many off-the-shelf Li-ion pack products.

M6DAC input voltage can take 3-6s, but be mindful of the maximum discharge power of the battery pack you use for input. For example:
Consider the situation that a 4S battery pack (11.2V-16.8V, max discharge current 20A) is used for input, and 6S battery pack(s) (16.8V-25.2V) are on the output side.
The maximum power the input side can provide is 11.2V * 20A = 224W.
Assuming 80% conversion efficiency, the output side should not exceed 224W * 0.8 = 180W.
That means the maximum charging current setting should not exceed 180W / 25.2V = 7.14A.

Asked and answered! Thank you folks for responding. This forum is the best place for newbies to get the knowledge they need.

My batteries are either 3S or 4S.

The "HUGE mistakes" list is great. I will look into using the car battery as a power option. Until then I will be getting a 6S 4000mAh or 5000mAh soon.

One more question, is using either a battery for input power or AC just plug and play or is there some fiddling with the settings to use the battery option for power. I have not seen this covered in any of the reviews.

(30-Jul-2022, 11:56 AM)OntarioDrone21 Wrote: One more question, is using either a battery for input power or AC just plug and play or is there some fiddling with the settings to use the battery option for power. I have not seen this covered in any of the reviews.

You simply just plug it into the XT60 DC input connector on the charger. That is all.

(30-Jul-2022, 03:44 AM)kafie1980 Wrote: Car charging makes a lot more sense than charging a big honking battery for hours at home and carrying it around to store charge.

Although with car charging you do need to be careful you don’t damage or reset your car ECU which does happen every now and then when jump starting modern cars.

If you are going down this type of route and want to do DC-DC (vehicle/leisure battery) charging on a modern car.  You need something better than a VSR.  You need a DC-DC charger.  They cost a lot more than a VSR.  Victron Orion Charger is your best bet.

https://www.victronenergy.com/dc-dc-conv...n-tr-smart
or
https://www.sterling-power-usa.com/sterl...arger.aspx
or
https://www.renogy.com/battery-chargers/...-chargers/

Don't jump start modern cars, full stop.  Buy a lithium jump start kit, (if battery is flat or low) attach it to the vehicle battery and then start up as normal.  Similarly bump starting modern cars will screw things up as well.

Am I allowed to say modern vehicles with tons of electronics are a POS.  Buy a (Ford) car with a gear stick and the least amount of electronics possible.

I've got a little ISDT 12v charger (amazon) and a AC to DC converter that it's strapped to so I can plug it into the wall. Works great. How about bringing a spare car battery with me? A sealed type that I could possible get for cheap. That might be the most economical way to get lots of mAH into the field? (apparently car batteries are about 48 amp-hours = 48,000 mAh) Then set the car battery on a trickle charger in the garage for days and days until I'm ready to go out again?

You can do it that way. But it makes more sense, depending on the car/van, to add a charger to the car, so the act of running the engine also charges the battery. on older cars, you can throw a $20 VSR inline, between the Vehicle Battery and the Leisure Battery. You can even add a switch so you can remove the battery when not in use. On modern cars it's a bit more indepth and you require a dc-dc charger (with capacitors to boost the charging output).

If you get a car battery, never discharge more than 50% and it should last you a while. Also if you charge large Lipos with big cell counts and have a charger that can leverage higher voltages (B6 won't) then you might want to consider 2x car batteries in series to give a higher voltage (and you might want to do this regardless as it has certain benefits like thinner gauge cables).

Can I use this?



It's got 12V and USB outputs (holding the cover open so they are visible).

I have HOTA D6 Pro dual charger, DC 650W 15A, with XT60 male for DC in (as well as AC in), with DC input range of 6.5-30V, so 12V is within range.

I assume I'd need a 12V to XT60 female cable, which I can get here: Amazon.com: AAOTOKK 16AWG Cigarette Lighter XT60 Cable,12V XT60 Male to Cigarette Lighter Male Charging Plug Cable for XT60 Drones and Other XT60 Battery Charging Equipment with Fuse and Switch(1m/3ft-M) : Automotive for $8.99.

(25-Jun-2023, 04:27 PM)aerokam Wrote: Can I use this?

https://i.imgur.com/A5su0oDl.jpg

It's got 12V and USB outputs (holding the cover open so they are visible).

I have HOTA D6 Pro dual charger, DC 650W 15A, with XT60 male for DC in (as well as AC in), with DC input range of 6.5-30V, so 12V is within range.

I assume I'd need a 12V to XT60 female cable, which I can get here: Amazon.com: AAOTOKK 16AWG Cigarette Lighter XT60 Cable,12V XT60 Male to Cigarette Lighter Male Charging Plug Cable for XT60 Drones and Other XT60 Battery Charging Equipment with Fuse and Switch(1m/3ft-M) : Automotive for $8.99.

The current (C rating) you can use to charge your LiPos will depend on how many amps the 12V lighter socket can supply so keep that in mind. I highly doubt the 12V socket can supply 500 amps. That huge current provision will only be possible via the jump starter leads.

(25-Jun-2023, 09:43 PM)SnowLeopardFPV Wrote: The current (C rating) you can use to charge your LiPos will depend on how many amps the 12V lighter socket can supply so keep that in mind. I highly doubt the 12V socket can supply 500 amps. That huge current provision will only be possible via the jump starter leads.

Right, so I'd be charging one or two 6S 1100 mAh batteries at 1C or less. ChatGPT comes up with 10.175 A input current to charge two 6S 1100 mAh batteries at 1C with 12V supply to the charger:

Quote:If you are charging two 6S batteries simultaneously (which means you are effectively charging a 12S battery), the calculation would go as follows:

For a 6S LiPo battery, the nominal voltage is 22.2V (3.7V * 6). Therefore, for two 6S batteries, the total nominal voltage would be 44.4V (22.2V * 2).

The power output required from the charger at 1C (which is 2.2A for two 1100mAh batteries) is:

Power (P) = Voltage (V) * Current (I)

P = 44.4V * 2.2A = 97.68W

Assuming an 80% efficiency for the charger, the input power required is:

Input Power = 97.68W / 0.80 = 122.1W

So, from a 12V source, the current needed to supply this power would be:

Current = Power / Voltage

I = 122.1W / 12V = 10.175A

So, your 12V input source would need to supply approximately 10.175A to charge the two 6S 1100mAh batteries at 1C on this dual charger with an 80% efficiency. Please note that this is a significant amount of current, and you need to make sure your power supply is capable of supplying this safely. As always, follow the manufacturer's instructions and safety guidelines when charging batteries.

Here is the back label of the jump starter:



It looks like the 12V outlet is limited to 500 mA, so not gonna work.

Any way to adapt the jump starter cables to an XT60, or am I just pushing it?

I guess the other option would be one of the ones already discussed here.