Puzzle: Ensuring 12V from a 12V Deep Cycle Battery
#1
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Puzzle: Ensuring 12V from a 12V Deep Cycle Battery
I'm putting LED lights and an exhaust fan, and a small inverter in a small 5x8 cargo trailer for the purpose of camping convenience.
Objective:
I'd like to tame my Deep Cycle Battery's voltage to 12V so my LED light strips don't burn up. So, I bought a 12V regulator (this) (input 12-24V, output 12V, max 20A).
Problem:
That regulator puts out 12V until I put a load on it. Then it drops to 11V. The load is only 2A. I figure I chose the wrong regulator (insufficient voltage overhead) and could use advice figuring out what sort of device to get.
Would a solar regulator charge controller work? If we like the trailer & setup, we'll probably do solar next year.
Ideal scenario:
I'm OK with a little voltage drop under load, but an entire volt for a 2A load seems excessive.
Here's a 1.5 minute video where I walk through the scenario:
https://youtu.be/dOeK-RIlo5g
Any ideas would be greatly appreciated.
Objective:
I'd like to tame my Deep Cycle Battery's voltage to 12V so my LED light strips don't burn up. So, I bought a 12V regulator (this) (input 12-24V, output 12V, max 20A).
Problem:
That regulator puts out 12V until I put a load on it. Then it drops to 11V. The load is only 2A. I figure I chose the wrong regulator (insufficient voltage overhead) and could use advice figuring out what sort of device to get.
Would a solar regulator charge controller work? If we like the trailer & setup, we'll probably do solar next year.
Ideal scenario:
- INPUT; 13.5V, OUTPUT: 12V
- INPUT: 12.3V, OUTPUT 12V
- INPUT: 12V, OUTPUT: 12V (or close)
- INPUT: 11.5V, OUTPUT: 11.5V (or close)
I'm OK with a little voltage drop under load, but an entire volt for a 2A load seems excessive.
Here's a 1.5 minute video where I walk through the scenario:
https://youtu.be/dOeK-RIlo5g
Any ideas would be greatly appreciated.
#2
That unit in your link is a 24v to 12v reducer. Not really a 12v regulator.
You don't need a regulator. Your LED's don't require precisely 12vdc.
You don't need a regulator. Your LED's don't require precisely 12vdc.
#3
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
From what I can tell, it's a step-down regulator. Here are the specs that also agree with the sticker that 12-24V is an acceptable input range.
Specifications:
Input voltage: 24V DC
Input range: 12-40V DC
Output voltage: 12V DC
Output current: 20A (Max) / 240W
As for the LEDs running on more than 12V. I realize they don't have to be precise, but i'm pretty deep into LED stuff and have seen first hand what heat can do to the diodes on LED strips which aren't great at dissipating the amount of heat that the LEDs generate.
I can run them at a higher voltage and then use PWM to help offset that if necessary, but I'd much prefer the peace of mind of having a relatively consistent 12V power source.
Specifications:
Input voltage: 24V DC
Input range: 12-40V DC
Output voltage: 12V DC
Output current: 20A (Max) / 240W
As for the LEDs running on more than 12V. I realize they don't have to be precise, but i'm pretty deep into LED stuff and have seen first hand what heat can do to the diodes on LED strips which aren't great at dissipating the amount of heat that the LEDs generate.
I can run them at a higher voltage and then use PWM to help offset that if necessary, but I'd much prefer the peace of mind of having a relatively consistent 12V power source.
#4
Group Moderator
For trailer use I certainly wouldn't bother trying to regulate a battery to be even more 12v than it already is. LED's are pretty tough and most 12v ones are designed for the voltage variation that comes with automotive and trailer applications. Also the regulator is going to waste some of your precious battery charge and one look at the big cooling fins cast into it's housing I'd say it wastes a fair bit of energy as heat and probably doesn't hit it's stated 96% efficiency very often.
I also agree that what you bought is primarily designed to step down the voltage from 24v to 12 VDC. Even though the Amazon page lists it's input voltage as 12-40 it's primary job is to step down 24 volts to 12 volts. It is not designed to rigidly maintain a 12v output.
I also agree that what you bought is primarily designed to step down the voltage from 24v to 12 VDC. Even though the Amazon page lists it's input voltage as 12-40 it's primary job is to step down 24 volts to 12 volts. It is not designed to rigidly maintain a 12v output.
#5
You won't live long enough to see any difference between supplying 12V or 15V to your LED strips. The resistors molded into the strip are already calculated to supply correct drive current to the LEDs at the worst-case automotive system voltage--probably ~15 volts while charging.
Any regulator consumes (wastes) power in operation, and needs a "headroom" of about 1.2V in order to regulate. You can't get 12.0V out with 12.0V in. You would need an 11V regulator to run off a lead-acid battery and then once the battery falls to below 12V the output would be unpredictable.
Keep It Simple.
Any regulator consumes (wastes) power in operation, and needs a "headroom" of about 1.2V in order to regulate. You can't get 12.0V out with 12.0V in. You would need an 11V regulator to run off a lead-acid battery and then once the battery falls to below 12V the output would be unpredictable.
Keep It Simple.
#6
The only (super wasteful) way I can think of doing this with commodity components would be to use an inverter up to 120VAC from the battery, then use a 12VDC power supply which you can dial in to exactly what you need. As guy said, you can't regulate voltage without headroom, and you can't get headroom without transforming up.
#7
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
You won't live long enough to see any difference between supplying 12V or 15V to your LED strips.
I have lived long enough to see the effects of even 12V on a typical LED strip. They do not dissipate heat well. I have seen some change hue over time, some develop a burn mark in the middle of the LED, and often the cheap epoxy covering yellows. Often, these are warm/hot to the touch even when only powering a partial strip. I have seen all of these issues at 12V. Check out forums that are specifically dedicated to LED lighting and this is very common. LED strips are by nature terrible at dissipating heat, and heat is what degrades/kills LEDs. I'd recommend at least knowing about this if you plan on using LED strips from Amazon that are at the $25 or less price point. Keeping them dimmed a bit is a good way to extend their life and prevent issues mentioned above.
The resistors molded into the strip are already calculated to supply correct drive current to the LEDs at the worst-case automotive system voltage--probably ~15 volts while charging.
My extensive reply may seem overkill/harsh - no hard feelings to you. I'm pretty deep into the world of LEDs and have a particular fascination (borderline spectrum disorder) with how amazing/innovative the LED world is at a professional level (see Bridgelux) yet how even name brands are going downhill fast with their consumer offerings. The downhill-ness is mainly related to insufficient heat sinking.
If you go to the automotive market (which I think you're referring to with your 12-15V note), Philips is being very innovative with their automotive LEDs that actually fire backwards in order to bring the heatsink out front where it can dissipate the heat (see amazon item B00P2D41OQ).
Any regulator consumes (wastes) power in operation, and needs a "headroom" of about 1.2V in order to regulate.
The only (super wasteful) way I can think of doing this with commodity components would be to use an inverter up to 120VAC from the battery, then use a 12VDC power supply which you can dial in to exactly what you need. As guy said, you can't regulate voltage without headroom, and you can't get headroom without transforming up.
#8
Member
As you are finding out, batteries are not a particularly stable Voltage source. A car works its battery from 8.5 to 14.5 volts. Crank to max charge. You have an issue from 12 to 13.2 apparently using the same type of battery.
Lots of options, most you won't like.
Use 2x 12V batteries in series, and use your apparent convertor to make a stable 12V. If yours won't do that, with various loads, others will. Not hard.
Option 2. Use 2V SLA cells and wire up a 14 or 16 volt battery using 7 or 8 of them; use, again the step down regulator.
Option 3. Fix the cheesy LED issue with something better than a simple Resistive drop. Use a LM317 in either a constant I or constant V mode.
Option 4. Increase the heat sinking of your present LED stack; use oil or metal for cooling, your choice.
Option 5. Make 120V with the 12V battery, and use household LED's. This is actually my least favorite option, but still worth considering if you don't want to design anything.
Lots of options, most you won't like.
Use 2x 12V batteries in series, and use your apparent convertor to make a stable 12V. If yours won't do that, with various loads, others will. Not hard.
Option 2. Use 2V SLA cells and wire up a 14 or 16 volt battery using 7 or 8 of them; use, again the step down regulator.
Option 3. Fix the cheesy LED issue with something better than a simple Resistive drop. Use a LM317 in either a constant I or constant V mode.
Option 4. Increase the heat sinking of your present LED stack; use oil or metal for cooling, your choice.
Option 5. Make 120V with the 12V battery, and use household LED's. This is actually my least favorite option, but still worth considering if you don't want to design anything.
#9
Group Moderator
This all seems like apply NASA level rocket science to a trailer. It seems like a lot of thought and expense on saving some pretty inexpensive LED's. All the lights in my trailer are LED and I power them with everything from stacks of alkaline D cells, sealed lead acid and three cell lithium ion and have never had a problem or a single LED fail even with all those varying voltages.
#10
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
As you are finding out, batteries are not a particularly stable Voltage source. A car works its battery from 8.5 to 14.5 volts. Crank to max charge. You have an issue from 12 to 13.2 apparently using the same type of battery.
Lots of options, most you won't like.
Use 2x 12V batteries in series, and use your apparent convertor to make a stable 12V. If yours won't do that, with various loads, others will. Not hard.
Option 2. Use 2V SLA cells and wire up a 14 or 16 volt battery using 7 or 8 of them; use, again the step down regulator.
Option 3. Fix the cheesy LED issue with something better than a simple Resistive drop. Use a LM317 in either a constant I or constant V mode.
Option 4. Increase the heat sinking of your present LED stack; use oil or metal for cooling, your choice.
Option 5. Make 120V with the 12V battery, and use household LED's. This is actually my least favorite option, but still worth considering if you don't want to design anything.
Lots of options, most you won't like.
Use 2x 12V batteries in series, and use your apparent convertor to make a stable 12V. If yours won't do that, with various loads, others will. Not hard.
Option 2. Use 2V SLA cells and wire up a 14 or 16 volt battery using 7 or 8 of them; use, again the step down regulator.
Option 3. Fix the cheesy LED issue with something better than a simple Resistive drop. Use a LM317 in either a constant I or constant V mode.
Option 4. Increase the heat sinking of your present LED stack; use oil or metal for cooling, your choice.
Option 5. Make 120V with the 12V battery, and use household LED's. This is actually my least favorite option, but still worth considering if you don't want to design anything.
Thanks for all the advice. You answered my question: no. No simple way of capping this at 12V. At this point, things are fine at 11V. I'll continue to monitor things, and if the LEDs start to drop out once the battery voltage goes lower, I'll hook them up to the battery and make sure to dim them via PWM.
Compliment appreciated.
#11
I'm definitely not as deep into the LED world as you are. My wife would consider me a "flashlight fanatic", but I wouldn't :-)
I've been suspicious that no-name manufacturers are over-driving their LED products in order to boast of extreme performance. Apparently you've verified that to be true.
All considered I think I would choose to fabricate a simple regulator using an LM317 or LM338 and calculate fixed resistors for a steady 10-11V output, or use a potentiometer for a useful dimmer. Probably somebody has already invented that, packaged it nicely, and can be bought from China for $8.99 delivered.
I've been suspicious that no-name manufacturers are over-driving their LED products in order to boast of extreme performance. Apparently you've verified that to be true.
All considered I think I would choose to fabricate a simple regulator using an LM317 or LM338 and calculate fixed resistors for a steady 10-11V output, or use a potentiometer for a useful dimmer. Probably somebody has already invented that, packaged it nicely, and can be bought from China for $8.99 delivered.
#12
use a potentiometer for a useful dimmer.
Although they technically reduce voltage..... they don't self regulate.
They are sold everywhere..... even on amazon.
PWM controllers
#13
Member
Rule of thumb from many years ago is that you want the input voltage to a regulator to be at least 3 volts higher than your desired output voltage.
IE: If you want 12V out, you should put 15V in. This is for a National Semiconductor 7812.
IE: If you want 12V out, you should put 15V in. This is for a National Semiconductor 7812.
#14
Member
All advice given is good. The failure to listen to that advice has been unfortunate and the "all future readers" are advised to follow the replies given.
Bud
Bud
#15
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
There's a lot of good advice in this thread for sure. Which advice am I failing to listen to that you think is unfortunate?
If it's about whether or not 12V LED strips can tolerate 14V, I'll make my stance clear for future readers:
- If the LED strip is designed for automotive use, then it's very likely to be just fine with 14V.
- If the LED strip is *not* designed for automotive use, then it's very likely to have problems if supplied with 14V.
In summary, check out your LED strip to see if it was designed to handle the additional voltage. Mine is not.
Last edited by keith204; 10-22-18 at 09:49 AM.
#16
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Being aware of LDO regulators for smaller things had me wondering if there was something similar for the situation at hand. The answer seems to be no.
#17
Member
Thread Starter
Join Date: Jul 2012
Posts: 112
Upvotes: 0
Received 0 Upvotes
on
0 Posts
Thanks for the replies. I'm going with a selector switch:
That way, when the charger is hooked up and the supply is 14.4V, I can switch to a safer voltage. When the battery supply gets down to 12 or 12.5V, I'll switch to direct battery power.
- Left: Battery power
- Center: Off
- Right: Regulated
That way, when the charger is hooked up and the supply is 14.4V, I can switch to a safer voltage. When the battery supply gets down to 12 or 12.5V, I'll switch to direct battery power.