Running LED's with batteries. The most efficient way?

[marcz62]

Hello everyone. I just started reading a few of the posts on this forum and I am feeling really under educated, but that is why I am here. To learn. I little about myself, I am an artist, jeweler, and future sculptor. My wife and I sell our work at fine art fairs around the United States.

For years I have been fascinated with LED technology and solar, in the context of display and possibly sculpture itself. I am trying to find a way of getting a more time out of my batteries to light my display when I am at an art show. Right now I have to take my batteries back to my hotel room each night recharge them. And if anyone would know how to do this the correct and most efficient way, it would be people who know the ins and outs of battery usage.

Currently for a show I take Two deep cell marine batteries, jumper cables, and 10 small led strip lights, 10- 12volt, 7w LED MR16 fixtures in regular track lights. My set up is simple, I connect the two batteries in parallel, I connect all of the lights via. the track lights directly to the batteries. I have removed the 110v transformers in each of the low voltage fixtures so I am running 12v with out the loss of using an inverter to raise the voltage and then drop it again to the 12v required by the LED's. I am wondering if this was the right thing to do. I need to run more lights, brighter lights and I really do not want to lug more than 2 batteries all over the country. So a long story for a few questions, and any help you can give I would really appreciate it.

1. Is there such a thing as a 12 volt DC to 12 Volt AC converter? The lights work with AC as well as DC, My thought is that when I run all of these light the wires get a little warm. Nothing close to a fire hazard but that has got to be a bit of a loss in efficiency.

2. There is a strange thing going on when I connect the batteries in parallel, one of the batteries is always dead, and the other can still be fully charged. It's always the newer battery that stays charged. It is like the newer battery just sucks all of the power from the older one, rather than pulling equally. Is there some kind of regulator that can fix this? Or am I, again decreasing the amount time the batteries will produce enough power.


Thank you everyone, ahead of time for any help you can give me.

[Sunking]

To start you have one dead battery that needs replaced. The batteries need to be the same age, make, and model.

The trick to making this work is to use LED's that can work on both 12 volt AC/DC, or DC only. It is much easier to replace the LED's with models that work on DC rather than trying to make incompatible LED's work on DC. There are a number of them out on the market. Your might even work.

Bu tfo rnow you need to get the battery thing taken care of. Start by getting rid of your dead battery.

[sensij]

Rather than putting two batteries in parallel, which can fail as you've observed, it would be better to get higher capacity from lower voltage batteries in series.

[jflorey2]

Thank you everyone, ahead of time for any help you can give me.

Some suggestions:

1) Get one larger 12V battery. AGM batteries are lighter than gel cell per kwhr.
1a) If you want longer run times for the same weight look into LiFePO4. Plenty of companies now make monolithic 12.8 volt LiFePO4 batteries.

2) You don't want AC to run 12V lights in general, you want DC. So that's OK.

3) About the only way you can make a 12V LED fixture more efficient is to replace the ballast resistor with a switching power supply. Almost all decent 12V fixtures already do this though; it's only the very cheap RV and boat type lights that still use resistors.

[Sunking]

Some suggestions:

1) Get one larger 12V battery. AGM batteries are lighter than gel cell per kwhr.
1a) If you want longer run times for the same weight look into LiFePO4. Plenty of companies now make monolithic 12.8 volt LiFePO4 batteries.

Agree it will work, but pricey, especially the LFP option with likely new charger on top of that. Some can work with standard chargers for extra cost.

[inetdog]

Implicit in all of the responses above is that a solar panel will not contribute all, or even most, of the power your LED lighting will need. You will still have to lug your batteries back to the hotel room each night.
But a single ~300W solar panel along with an inexpensive (Morningstar is one brand) MPPT Charge Controller (CC) will give you as much as maybe 600 watt hours per day (because of less than optimal mounting, shading, etc.). That will be the equivalent of 50 amp-hours at 12V, which is not negligible. If you cannot travel with an ginormous panel possibly a few 100w panels would work for you.
The decision on whether you want to spend the money and have the additional hassle of lugging panels around should also factor in any positive advertising/merchandising you might get from having your booth "running" on renewable energy.

BTW. if you decide to stick with marine batteries (get the kind labelled "deep cycle" even though they are not what we normally mean by deep cycle), you will be better off getting two six volt batteries and putting them in series rather than putting two 12V in parallel.
For batteries that handle deep discharge more gracefully, also look at golf cart batteries instead of marine.

[Mike90250]

about half way down this page

https://www.wiredco.com/LED_Lighting_Low_Voltage_s/1874.htm

are some MR16 AC/DC LED with internal driver circuits. Be sure you read the find print for voltage range, and base style