Charging LI bike light batteries with my camper's 12V system

[ewarnerusa]

I like to use my camper's 12V system to recharge various batteries because the camper is solar powered and it just gives me warm fuzzies to use that solar power for something else when I'm not camping. I do a lot of night time mountain biking and use various AA/AAA battery and li-ion battery powered lights. I've got my AA/AAA/18650 battery charger that runs off of 12V plug so I don't have to use the camper inverter. But I currently only have the 120V AC charger for my 8.4V Li-Ion battery pack that my primary light uses. I found a 12V DC charger for it; however, it only charges at half the current of the AC powered one. I realize that using the 12V DC charger will take about twice as long to recharge the battery. But my question is if the net energy requirement of charging at half the current but for twice the length of time going to be less than just using the inverter and using the 120V AC charger?

[ewarnerusa]

I can't seem to find my exact battery for sale anymore. But here is the next size up from my mine from the same builder (Xeccon).
http://www.mtbrevolution.com/index.php?route=product/product&manufacturer_id=13&product_id=229

Here is the AC charger I have always used. It came with the light and OEM battery. I upgraded the battery to the Xeccon but have continued to use the same charger.


Here is the 12V DC charger I'm looking into.
http://www.action-led-lights.com/collections/everything-else/products/car-charger

It is from a different source than I got the battery from, so there is a risk of non-compatibility between two different brand items.

[ewarnerusa]

NinerBikes wrote:
Lithium ion batteries is a battery chemistry that you don't want to modify the charging speeds with the batteries and charger that came together. They do start fires and have thermal runaway, with bad results, and burning.


Use the proper charger with the proper battery packs, and you'll lower your odds considerably with becoming a lithium ion battery burn statistic.

ewarnerusa wrote:
The 12V charger is sold by a company specializing in high performance LED lights and batteries as being specifically for the type of battery I'm using...

This caution about using the proper charger makes sense. But I feel like any compatibility issues have been contemplated by the seller. Again, this 12V car charger is being purchased from a high-performance LED light builder specializing in bike lights as being designed for the type of battery I'm using. It isn't a random 12V car charger that I've picked because it said 8.4 V.

[NinerBikes]

Lithium ion batteries is a battery chemistry that you don't want to modify the charging speeds with the batteries and charger that came together. They do start fires and have thermal runaway, with bad results, and burning.


Use the proper charger with the proper battery packs, and you'll lower your odds considerably with becoming a lithium ion battery burn statistic.

[MEXICOWANDERER]

I agree with Canadian Rainbirds.


rechargeable lithium batteries differ. I have 2 sets of 4 lithium 9-volt batteries.

If I use one type (brand) of battery in the other brand's charger they get hotter than the hinges of hades. Conversely, the other way round, it takes longer than 16 hours to charge the other batteries.

Good thing both are marked battery and charger.

Freakin' nuthouse arrangement. Yes the batteries came with the chargers.

[ewarnerusa]

The 12V charger is sold by a company specializing in high performance LED lights and batteries as being specifically for the type of battery I'm using. I believe it is a group of 6 18650 batteries bundled together with some circuitry to make 8.4 V.

[Canadian_Rainbi]

Charging voltage and current are critical for Lithium Ion batteries. And the parameters vary by manufacturer and type. Use the inverter and the manufacturer supplied charger.

[LittleBill]

the charge rate for lipo is generally 1c, so it would be charged at 6.6 amps if using a hobby charger, they charge at 1c till a certain voltage then taper amperage.

[consumeratlarge]

I second the suggestion to use an RC multiple use charger. I use mine to rescue dying batteries of all types, as well as to put a controlled charge of any amount of current that I select. Mine cost about $70, is probably Chinese, and has a 12v power input, or use the onboard 120v converter with a regular plug.

The premature death of many of my power tool batteries seems to be caused by not having very smart chargers. The cigarette lighter type of plug in chargers only seem to work well when there is a built in regulator in the device itself. With an RC charger, you have the option of balancing the cells, which will quadruple the life of any multi cell lithium battery. Amazingly, many chargers don't consider this, and just slam all the cells with the series voltage.

[ewarnerusa]

I looked at my AC charger and it actually only provides 1.2 A. That is closer to the charge rate of the 12 V one than I originally thought. The 12 V one is designed for my 8.4 V bike light Li-Ion battery.

Thanks for the feedback everyone.

[Johno02]

The reason I asked was to help determine how to answer you. A 6600ma liion battery can be SAFELY charged at 1/2C, which would be about 3A or 3000 Mah. At 6A, it should take less than 1 hour to full charge. Be sure and use a charger designed to Liion batteries, as the peak shutoff point is different from other type(including lipo) batteries. If you have a RC Hobby shop nearby, there are a number of chargers on the market for Airplane and wheeled vehicle batteries that have settings for liIon batteries. Most are designed to work from a 12V source.

[rexlion]

Sure, the inverter will waste a little energy. But with your solar system involved, the waste would not be enough to give much thought to.

[ewarnerusa]

Johno02 wrote:
Voltage and MA on the li-ion battery??

8.4V, 6600 mAh. Is that the info you were looking for? 12V charger is 8.4V at 0.8A. AC charger is 8.4V at 1.5A if I recall correctly.

[ewarnerusa]

The 12V charger I've found is $12.27 shipped. So it is inexpensive enough to buy for the heck of it (which is what I just did!). It is true that it is one more cord to keep track of! And I don't think any payback from power savings from any of this solar powered battery recharging would ever exceed a warm fuzzy. I just know that it is desirable to avoid having to use the inverter to create 120V AC due to efficiency losses if I don't need to. If I was out camping that is and motivated to minimize energy draw from my batteries. While stored at home, the benefit would be not having to get out and walk around the camper to the storage bay where my inverters are to switch one on and having to remember to shut it off later.

[Johno02]

Voltage and MA on the li-ion battery??