iPad Charging - 12V vs. Inverter
- Thread starter Maine Sail
- Start date
Maine - related topic:
Whats the most efficient way to recharge or run a typical laptop while on board?
Whats the most efficient way to recharge or run a typical laptop while on board?
Hi Maine et al,
Has anyone made note of how bad (or good) these "car chargers" are in terms of radio interference? Back in 2000, we sailed to Hawaii in the Pacific Cup, and I discovered I couldn't charge my laptop while I was running SailMail, as the small inverter I was using (West Marine brand) completely wiped out the HF radio!
I've tested my new big inverter (1800w sinewave) and it seems quiet, but I know the small modified sine inverters I have are also noisy - though it's hard to quantify in the marina with all the other radio racket around there.
Has anyone successfully radio-filtered one of these units?
Thanks!
Has anyone made note of how bad (or good) these "car chargers" are in terms of radio interference? Back in 2000, we sailed to Hawaii in the Pacific Cup, and I discovered I couldn't charge my laptop while I was running SailMail, as the small inverter I was using (West Marine brand) completely wiped out the HF radio!
I've tested my new big inverter (1800w sinewave) and it seems quiet, but I know the small modified sine inverters I have are also noisy - though it's hard to quantify in the marina with all the other radio racket around there.
Has anyone successfully radio-filtered one of these units?
Thanks!
A few observations;
Inverters have an idle current value, generally the larger the inverter rating the larger the idle current. This is why low loads on an inverter result in lower conversion efficiency.The plug in DC-DC converters will have much lower idle currents.
Most efficient (fastest) charging of and IPad, or other computer like devices is with the device shut down, not on, or in hibernation or sleep mode. Most effecient use with a plugin converter is to keep the device always plugged in when being used.
Just my observations.
Inverters have an idle current value, generally the larger the inverter rating the larger the idle current. This is why low loads on an inverter result in lower conversion efficiency.The plug in DC-DC converters will have much lower idle currents.
Most efficient (fastest) charging of and IPad, or other computer like devices is with the device shut down, not on, or in hibernation or sleep mode. Most effecient use with a plugin converter is to keep the device always plugged in when being used.
Just my observations.
MS... It looks like you might have the iPads setup with different number of email accounts (perhaps yours vs hers tablets, personal and work on one, just personal on the other?)
Since you had WiFi enabled and the device online during your test, the number of different email accounts that it is monitoring will make a difference in power consumption... To compensate for this you need to either charge with WiFi and all connectivity off, or at the least use the same iPad for both tests...
Since you had WiFi enabled and the device online during your test, the number of different email accounts that it is monitoring will make a difference in power consumption... To compensate for this you need to either charge with WiFi and all connectivity off, or at the least use the same iPad for both tests...
Same iPad was used, my Air, and everything was A to A other than the charge source.. I wanted it to be realistic so did not shut down entirely. I have yet to see a single one of my customers who charges with the iPad fully shut down or WiFi off. He'll most have 10+ apps running in the background. I have shown multiple customers how to kill apps to help save battery. The main convenience of the tablet devices is the fact that when you wake them up they are ready to go before you are. This is likely why no one seems to ever shut them down entirely..
That said I plan to repeat the test with it turned off completely. I did this test but got interrupted at approx 96% and had to leave to go skiing for the weekend.
Problem with doing this turned off is that you can't see % charge progress without booting it. When I ran to 96% (opened & booted at approx 62% and 96%) there was less than approx 0.08Ah's difference between closed and asleep and off when I hit 96%....
I can leave my iPad asleep for days and barely click off 1-2% of my batt capacity.. As an example last night I went to bed at 10:00 and got up at 6:00. My iPad was still at 59% just 1% below where it was at 10:00 and I have no idea how close it was from clicking from 60% SOC to 59% SOC... I also open it / lift the lid at night to check the time....
I was just pointing it out because it can rather significantly affect battery drain, which can skew the results quite a bit....
From 0% to 96% I only saw a .08Ah difference between completely off an on and sleeping with wifi monitoring yahoo and gmail.. I am at 16% now so perhaps tomorrow I can run a zero to 100% while off test again...
I know my wife and daughters iPads use more Ah's to charge than my Air does..
Good discussion.
Here is a related question. Is it better to keep the device you are charging connected all the time or instead to let it run down to 10-20% before plugging it in? And if it is worse to keep it plugged in- how much worse ? I understand it may be better for the device not to keep it always plugged in but is it better or worse for the charger- the house bank- to keep it plugged in?
Here is a related question. Is it better to keep the device you are charging connected all the time or instead to let it run down to 10-20% before plugging it in? And if it is worse to keep it plugged in- how much worse ? I understand it may be better for the device not to keep it always plugged in but is it better or worse for the charger- the house bank- to keep it plugged in?
Unplugged. Cause
1.device will enter a battery mode with lower consumption so that will lower the energy use.
2. You will have the benefit of the battery storage in the device. If you are plugged in you don't get to use those aHrs and instead rely on the aHrs of your boat.
Don't have any data on this so this is my opinion, and there is a saying about that.
1.device will enter a battery mode with lower consumption so that will lower the energy use.
2. You will have the benefit of the battery storage in the device. If you are plugged in you don't get to use those aHrs and instead rely on the aHrs of your boat.
Don't have any data on this so this is my opinion, and there is a saying about that.
Only if you never recharge the battery is it more energy efficient.
When you recharge you must put in more amp hours than you took out of the battery, batteries are not 100% devices, and efficiency decreases as charge level increases, a lead storage battery has 85% efficiency if only charged to 80%. that last 20% comes at a higher price. Charge efficiencies at 90% SOC and greater were measured at less than 50% in tests.
However, Lithium-Ion batteries are never trickle charged, the devices that use them regulate the charging so when they reach or approach full charge the charger cuts off and will not resume charge until the battery drops to some lower voltage, then charging resumes.
"Simple Guidelines for Charging Lithium-based Batteries
- A portable device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered and reflects the correct saturation current responsible to terminate the charge. A parasitic load confuses the charger.
- Charge at a moderate temperature. Do not charge below freezing.
- Lithium-ion does not need to be fully charged; a partial charge is better.
- Chargers use different methods for “ready” indication. The light signal may not always indicate a full charge.
- Discontinue using charger and/or battery if the battery gets excessively warm.
- Before prolonged storage, apply some charge to bring the pack to about half charge.
- Over-discharged batteries can be “boosted” to life again. Discard pack if the voltage does not rise to a normal level within a minute while on boost. "
The answer is, we are hostage to the "Smarts" of the device charger, if it can power the device without overcharging the battery, leave it plugged in, if it doesn't, unplug it for use, turn it off for recharge. I don't know if anyone knows how smart a charger in a given device is.
The safest way is unplug during use, turn off during recharge, this however is not the lowest energy use from the boat battery side. On our boat since we have a solar panel, we tend to charge during the day, and unplug at night.
Don't take my word, Google it yourself, but don't rely on what you "think" it is, the answer may be more complicated, and for small devices the best energy efficient way is not worth the effort to achieve, as the gains are small overall.
Last edited:
A point to consider with these 12v DC to 19v laptop power supplies is whether or not they have built in low voltage protection. I had a cheapo version on the old boat and my Sweetie wanted to run her laptop for some schoolwork. She let it idle while reading for several hours and the house "bank" on that boat was a single group 24 battery on it's geriatric side of life. The voltage in the system apparently went low enough to ruin the power management chip on the motherboard. The laptop will no longer charge its own battery (or the replacement battery that I was hoping would fix the problem).
Disagree, the coulombic efficiency of Li ion (which will be in your ipod ipad etc) is close to 100% ahr in = ahr out
The galvanic efficiency is less put the charge in at 4V get it back at 3.8V or so, but net the round trip power efficiency of Li-ion is about 90%
The galvanic efficiency is less put the charge in at 4V get it back at 3.8V or so, but net the round trip power efficiency of Li-ion is about 90%
I just ran some more numbers:
iPad 100% charged and left connected for 8 hours beyond full:
Inverter - Standby / ON = -0.3A
Inverter - Plugged in iPad Asleep = -0.5A (Wi-Fi & Bluetooth on)
Inverter - Plugged in iPad Awake = -1.2A (Wi-Fi & Bluetooth on)
12V USB Adapter - Standby /ON = not measurable / below 0.1A
12V USB Adapter - Plugged in Asleep = -0.2A (Wi-Fi & Bluetooth on)
12V USB Adapter - Plugged in Awake = -0.8A (wifi & Bluetooth on)
iPad 100% charged and left connected for 8 hours beyond full:
Inverter - Standby / ON = -0.3A
Inverter - Plugged in iPad Asleep = -0.5A (Wi-Fi & Bluetooth on)
Inverter - Plugged in iPad Awake = -1.2A (Wi-Fi & Bluetooth on)
12V USB Adapter - Standby /ON = not measurable / below 0.1A
12V USB Adapter - Plugged in Asleep = -0.2A (Wi-Fi & Bluetooth on)
12V USB Adapter - Plugged in Awake = -0.8A (wifi & Bluetooth on)
ahh data! thanks for all the info. Screen on or off?
looks like the 12V adapter has a sort of 0.4A more or less fixed lead on the inverter 9Ahr/day to the good.
looks like the 12V adapter has a sort of 0.4A more or less fixed lead on the inverter 9Ahr/day to the good.
BobT
I had the same problem with laptop battery would not charge and new battery
either and was told it's in the Laptop but I happen to have another plug with power supply and guess what charged the battery in Laptop and ordered new power supply and no more problem charging battery.
I don't have Ipad but do have Iphone and laptop's and tablet's and just use my 2000 freedom inverter and works great keeping all my rechargeable equipment
charged and run my TV and Microwave and wife's hair dryer and rechargeable vacum too and rechargeable drill and the list goes on and on with 4-6volt house bank and 2-190 solar panels,get a nice size inverter with nice size battery bank and than you have everything good.
Nick
Nick
I had the same problem with laptop battery would not charge and new battery
either and was told it's in the Laptop but I happen to have another plug with power supply and guess what charged the battery in Laptop and ordered new power supply and no more problem charging battery.
I don't have Ipad but do have Iphone and laptop's and tablet's and just use my 2000 freedom inverter and works great keeping all my rechargeable equipment
charged and run my TV and Microwave and wife's hair dryer and rechargeable vacum too and rechargeable drill and the list goes on and on with 4-6volt house bank and 2-190 solar panels,get a nice size inverter with nice size battery bank and than you have everything good.
Nick
Nick
Asleep = Screen off (Apple smart case closed & magnet puts it to sleep, Wifi & Bluetooth on but no apps running)
Awake = Screen on (Wifi & Bluetooth on but no apps running)
Maine have you tryed one of those 12v chargers that puts out 20v to the note book....i found one yesterday in the local puter store and am intertaining it .....runs about $70.00 .....wonder how efficent it would be .....may get it and see what its putting out on the puter end ...but not sure how i can check the amp draw with a clamp meter as it has a molded cord from one end to the other.....
regards
woody
regards
woody