Field charging LiPo batteries

[aerokam]

The 12V socket is unlikely to be limited to 0.5A.  Use a multimeter to get the real value.

Most 12v cigar lighter sockets tend to produce 10A @ 12V, some special ones 15A, but you need bigger cables for 15A.  My suggestion is to wire up a 12v connector to whatever input method your charger uses (most seem to use XT60) and make sure the polarity is correct.  Check the XT60 (or whatever you used) with a multimeter after you built it to make sure + and - are correct.  I suspect that 12V socket will produce enough amps for a mobile air compressor to run, so 10A or thereabouts.

That USB socket could be useful for charging 1S Lipos (via a parallel charger), or if you can find a Volantex 2S USB charger, 2S Lipos as well.

Cool.

I ordered the 12V to XT60 connector, and it arrives today. What if I just use the cable to connect the jump starter DC outlet to my HOTA D6 Pro AC/DC dual smart charger (AC 200W DC 650W 15A), then connect one 6S 1100 mAh battery to see what happens? Then connect a second one if it seems OK with the first?

Will there be some sort of current negotiation between the power supply and the charger, so the charger doesn't try to draw more current than the power supply can supply?

What if I do the same with the jump start cables? Will the charger limit the current to whatever it can handle?

Here's what ChatGPT says:

Prompt: I want to use an adapter cable to connect my 12V 500A jump starter to my 15A dual channel LiPO charger. Will the charger limit the current to whatever it can handle, or could I damage it?

Response:

The charger should, in theory, limit the current to what it can handle, but it also depends on the specifics of your charger and its protection systems.

Chargers designed for LiPo batteries typically include safety features that limit the input current to prevent overloading and overheating, and they should also have overvoltage protection to prevent damage from a too-high voltage source.

However, connecting a 12V 500A jump starter to a 15A dual channel LiPO charger could potentially pose a risk if the charger's safety features fail or are insufficient for that level of current. Even though the voltage matches, the potential current supply from the jump starter is much higher than the charger's rated 15A current. This could overload the charger if the charger's safety features don't work correctly.

Always consult your charger's manual or contact the manufacturer if you're unsure about what sources of power are safe to use with it. Improper use can result in damage to the charger or battery, and may even pose a fire risk in severe cases.

Also, it's crucial to note that the rated output current of the jump starter (500A) is likely the peak, not sustained, current, and it's designed for short bursts of power to start a car, not for sustained power delivery to a battery charger.

Overall, it's best to use a power supply rated at an appropriate level for your specific charger to avoid any potential issues.

Prompt: What about using the 12V DC outlet on the jump starter? I assume that the current is no more than 10A, but don't know for sure. What if it cannot supply enough current to charge two 1300 mAh 6s batteries. What would happen?

Response:

If you're using a 12V DC outlet from the jump starter, the supplied current is indeed usually less than what the starter can provide for jumping a car—commonly in the 10A to 15A range, but you should confirm this from your jump starter's documentation.

If the current supplied by the jump starter is not enough to charge your batteries at the rate your charger is trying to charge them, several things could happen, depending on the charger and the power supply:

1. The charger might just charge the batteries more slowly. This would be the best-case scenario.

2. If the charger tries to pull more current than the jump starter can supply, the voltage might drop. This could cause the charger to display an error, or it might turn off to protect itself and the batteries.

3. In a worst-case scenario, if the charger continues to demand more current than the power supply can provide, it could potentially cause the power supply to overheat and possibly damage the jump starter or even create a fire risk.

Most good-quality chargers should have protection against low voltage input and should shut off or display an error in such cases. However, always check the documentation and specifications of both your jump starter and your charger to be sure. If in doubt, contact the manufacturer or a professional to avoid potential damage or safety hazards.