High current car charger for P4P batteries...

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One of the problems that occurs with 'car-based' systems hen trying to multiple charge / demand high power - it just does not happen !

I know guys who tried setting up car based systems to charge their 6S multi systems for their Gaui Helicopters (they are a Demo team) ... they ended up with a generator.
Car batterys despite what some think - are one of the worst forms of power supply. You only get 50 - 60% power before plates start complaining .. go lower and you are likely to buckle a plate or two - then its only scrap.
High power is only for short duration and requires alternator back up.

Its not an easy one to solve. Go on any RC forum and you will find page after page of threads on field charging LiPo's ... NO-ONE has found the universal answer yet.
 
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One of the problems that occurs with 'car-based' systems hen trying to multiple charge / demand high power - it just does not happen !

I know guys who tried setting up car based systems to charge their 6S multi systems for their Gaui Helicopters (they are a Demo team) ... they ended up with a generator.
Car batterys despite what some think - are one of the worst forms of power supply. You only get 50 - 60% power before plates start complaining .. go lower and you are likely to buckle a plate or two - then its only scrap.
High power is only for short duration and requires alternator back up.

Its not an easy one to solve. Go on any RC forum and you will find page after page of threads on field charging LiPo's ... NO-ONE has found the universal answer yet.
Anyone with a genuine need for a reliable remote power solution will benefit from exploring LiFeP04 auxiliary cells with a charge controller and isolator. Flat voltage curve, great cycle life, low weight and high DOD is not an issue. Prices are more attractive in recent times also.
 
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benefit from exploring LiFeP04 auxiliary cells with a charge controller and isolator. Flat voltage curve, great cycle life, low weight and high DOD is not an issue.
Although not exactly related to field charging I will remark that I have recently changed out all my UPS batteries for this type of technology and found it well worth the extra price at this stage.

Regards
Ari
 
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Anyone with a genuine need for a reliable remote power solution will benefit from exploring LiFeP04 auxiliary cells with a charge controller and isolator. Flat voltage curve, great cycle life, low weight and high DOD is not an issue. Prices are more attractive in recent times also.
Agreed ... LiFePo or most people just use term LiFe ... are great as they can be charged up and left fully charged unlike LiPo.

But their disadvantage is weight ...

Many large model people use LiFe (quite often A123 version) because then they can fit them as permanent and no need to remove from model for charging.
I use them in some of my Wet Fuel models because they deliver better amps and steady power for Rx use. I also use in a couple of Tx's I have.
 
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Agreed ... LiFePo or most people just use term LiFe ... are great as they can be charged up and left fully charged unlike LiPo.

But their disadvantage is weight ...

Many large model people use LiFe (quite often A123 version) because then they can fit them as permanent and no need to remove from model for charging.
I use them in some of my Wet Fuel models because they deliver better amps and steady power for Rx use. I also use in a couple of Tx's I have.
Most in the industry call them LFP for short. LiFe might prove to be less than ideal as a search term for google.

Weight might be an issue with flying models for obvious reasons ( that said they are less than 15% heavier than LiION). With respect to remote/auxiliary power use they are fantastic. Far superior power density to AGM or wet cell. In testing they have demonstrated higher than 74% remaining usable capacity after many thousand full discharge cycles (100% DOD).
 
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For Google of course - best to put LiFePo4 .....

They are also extremely rugged and tolerant of abuse.
 
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Posting this again....

Anybody out there using a high-current charger that connects directly to your car's battery as opposed to the cigarette lighter? When I was flying Phantom 1's, there were a gazillion chargers out there that I could plug directly into my car battery. How is it that later technology has dropped this most awesome of field chargers????

For the love of all that is holy, I sure hope someone replies this time. There HAS to be something SOMEWHERE.

D
I use a voltage inverter and plug my regular phantom charger into it
 
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Is this ok to use on my phantom4 pro batteries for charging? Is it going to damage or effect the battery life?
You probably won’t damage the P4 charge supply, not in the short term anyway. If it’s a nasty inverter the harmonics might (good chance) reduce the life of the filter caps on the supply input.

The real factor here is that the battery in the unit is almost certainly lead acid and you would be lucky if it was 20Ah max. You would be lucky to recharge 3 P4 batteries from low SOC. You wouldn’t do it many times either, lead acid batteries don’t give many charge cycles when taken to low charge levels.
 
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Since I can't seem to find a **** car charger, looks like I'm going to have to build one.

Found a 12v, 5A Power Supply in my parts box.

AC_12V_PowerSupply.JPG



Found a "sacrificial lamb" cable in my old Phantom 1 parts pile with alligator clips on one end and a barrel connector on the other end (had 4 of these so I guess I can cut one up).

Cable.JPG



And found this variable DC to DC converter in my parts pile. 12VDC in.

ICS_InputVoltage.JPG



And 17.4VDC out.

ICS_OutputVoltage.JPG



I'll worry about current later. A car battery will source more than enough current. I'm just not sure how much this DC to DC converter will source. I guess we'll find out if it starts smoking. I'm sure I'll need a beefier DC to DC converter, but for now I just want proof of concept.

I really hate reinventing the wheel. I can't believe there are no P4P multi-battery automotive chargers on the market....<sigh>....

D
 
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OK ... good to see DIY is still there !!

But lets look at this ..

You have a regulated power supply of 12v / 5A ... 60W .... it will never output more than that.

You will need 17.4V (17.4V is the full charge voltage of the pack) ...

Therefore lets assume no losses ... 60 / 17.4 = 3.45A

So at best to charge 1 battery even from storage .. you are looking at or over 1hr ... because as the packs voltage increases - the input has harder job and job gets longer.

As you add packs - that charge time is going to suffer seriously.

Very interested in your final results.
 
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duplicate post ...

having trouble that this website is now exceedingly slow .... and often seems that posts do not upload.
 
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Since I can't seem to find a **** car charger, looks like I'm going to have to build one.

Found a 12v, 5A Power Supply in my parts box.

View attachment 108426


Found a "sacrificial lamb" cable in my old Phantom 1 parts pile with alligator clips on one end and a barrel connector on the other end (had 4 of these so I guess I can cut one up).

View attachment 108427


And found this variable DC to DC converter in my parts pile. 12VDC in.

View attachment 108428


And 17.4VDC out.

View attachment 108429


I'll worry about current later. A car battery will source more than enough current. I'm just not sure how much this DC to DC converter will source. I guess we'll find out if it starts smoking. I'm sure I'll need a beefier DC to DC converter, but for now I just want proof of concept.

I really hate reinventing the wheel. I can't believe there are no P4P multi-battery automotive chargers on the market....<sigh>....

D
Is that an onsemi boost controller IC?

At a guess- 1.5A absolute max, especially with no heat sink.
 
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My camper has a separate leisure battery and I often use this with the DJI 12v charger. It tops up whenever I drive around but running it down does not affect the main battery.

If you could set up a leisure battery with a split relay on your Honda and directly hook up DJI chargers to this battery - they're designed to supply power for longer periods of time (unlike a car battery). You also don't risk leaving yourself with a non-starting car. I find boat people (chandlery) really know their stuff, if you can tell them what your rating & daily requirements are they can advise.

Apologies if I'm overlooking something obvious.
 
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OK ... good to see DIY is still there !!

But lets look at this ..

You have a regulated power supply of 12v / 5A ... 60W .... it will never output more than that.

You will need 17.4V (17.4V is the full charge voltage of the pack) ...

Therefore lets assume no losses ... 60 / 17.4 = 3.45A
Yep. Already worked all that out.



So at best to charge 1 battery even from storage .. you are looking at or over 1hr ... because as the packs voltage increases - the input has harder job and job gets longer.
Yep.


As you add packs - that charge time is going to suffer seriously.

Very interested in your final results.
Today's objective is to charge a single battery off a single buck converter. If it works, I have 4 buck converters and all the cabling and adapters I need to build a 4-bay charging station. OR...I may look into a more robust buck converter and go that direction.

Disclaimer: I know that buck converters step DOWN voltage and step UP current, but I don't know the name of the converter that steps up DCV. Maybe one of you guys do?

D
 
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My camper has a separate leisure battery and I often use this with the DJI 12v charger. It tops up whenever I drive around but running it down does not affect the main battery.
Well, at this point I'm honestly not doing this kind of work enough to warranty modifying my vehicle. At this point I have a couple jobs coming down the pike that are going to require more batteries than I own. But these jobs are few and far between. For BIG jobs, we use my business partner's truck, which is already fully outfitted with a 1500 watt converter, which runs our two parallel charges quite nicely (each charger chargers 3 batteries for a total of 6 charging in parallel @ 100 watts/each). For big, big jobs, we bring the 3000 watt generator. So, as you can see, I'm looking for a solution that is scaled to my needs. While it's tempting to build a mack-daddy "one size fits all" solution, I use my Civic Wagon for too many other things (like skiing, for instance) to commit to permanent change. Plus it's not like these medium jobs come up every week. 300+ acre mapping jobs come up once a month or so. 2,000 acre mapping jobs come up 2 or 3 times a year. For that, we already have the generator and/or the 1500 watt converter system in my partner's truck. So what I'm looking for is portable solution I can connect directly to ANY car battery. I have other vehicles that I sometimes use for drone jobs.



If you could set up a leisure battery with a split relay on your Honda and directly hook up DJI chargers to this battery - they're designed to supply power for longer periods of time (unlike a car battery). You also don't risk leaving yourself with a non-starting car.
Well...I can almost always get that Civic started regardless of battery state. The thing bump starts at like 2 mph. All I have to do is be on a slight hill and I'm good. If I'm ever in a situation where I think I may be draining my battery to the danger point, I park on a hill.


I find boat people (chandlery) really know their stuff, if you can tell them what your rating & daily requirements are they can advise.
A "leisure battery" may be a solution down the line. For now, I just need a couple P4P batteries charged...4 or 5 tops. My single car battery can handle that load.

D
 
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Is that an onsemi boost controller IC?

At a guess- 1.5A absolute max, especially with no heat sink.
I ordered these a couple years ago for another project, and they didn't come with any documentation and have no discernible part number. For now I'm just looking for proof of concept. If I can charge 1 battery, then I'll know the circuit works and I can move forward with more robust hardware.

D
 
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Yep. Already worked all that out.





Yep.




Today's objective is to charge a single battery off a single buck converter. If it works, I have 4 buck converters and all the cabling and adapters I need to build a 4-bay charging station. OR...I may look into a more robust buck converter and go that direction.

Disclaimer: I know that buck converters step DOWN voltage and step UP current, but I don't know the name of the converter that steps up DCV. Maybe one of you guys do?

D
What your looking for is a "boost converter".
 

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