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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 05-29-2015, 05:57 PM   #1
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Default Lithium Motorcycle Batteries to power chargers?

Hey all!

So LiFE motorcycle batteries are becoming more and more popular in the motorcycle scene; lacking some of the issues that lead-acid batteries face and; most important in this case; they are super light.

So a 22Ah LiFE motorcycle battery, 12 volts, weight around 3 pounds. One or two of those in a field box would make an awesome self-powered charging box wouldn't it? Or would it?

Truth be told I don't know how to break down how many amp hours of battery you need for how many mAh of charge (Because I know it's not that efficient.) So this is a two part question.

1) Has anyone done this or similar; or know of any reason (other than the high cost; right now I'm just 'thinking out loud') why a LiFE Car/Motorcycle battery would not work? My thinking is, it's a super light weight and durable source of 12v power.

2) What's the breakdown/how do I determine how many Amp Hours I'll need in order to get a finite number of charges?

Just thinking out loud, honestly. Right now, everywhere I fly has AC power so it's moot. But, you know, a guy can't ever have too many projects to think about!
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Old 05-29-2015, 06:14 PM   #2
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mah X volts /1000 = ah X volts = watt-hr which is a measure of energy.

You lose some in the process of operating the charger. That might be higher than 70% LOST with an inefficient setup (especially charging really small packs, running the display of the charger is significant). It might be a very low percentage loss if there's nearly no voltage change being done by the charger.

The only way to tell what result you will get is to start logging what goes into the storage battery vs what goes into the assorted flight packs.

For initial planning count on wasting 50%. Generally you should do better than that.

I get the best result from my solar system mounted on my trailer (125 watts of panels, 4 X 120 ah 14V nominal, LiFeMgPo4 storage batteries) when I charge 3S packs. Big packs (or doing several smaller ones in parallel) can exceed 90% efficiency.
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Old 05-29-2015, 06:41 PM   #3
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Originally Posted by Romans5.8 View Post
So a 22Ah LiFE motorcycle battery, 12 volts, weight around 3 pounds. One or two of those in a field box would make an awesome self-powered charging box wouldn't it? Or would it?
Yeah, i think that would be pretty good setup for smaller to medium LiPo batteries. On the other hand if you fly the big stuff you aren't going to get very many re-charges.

If you used two of those batteries and discharged to 80% and your charger was 80% efficient that would give you about 340 Watt-Hours of energy*. A 6s 5000mAh Lipo will take around 100 Watt-Hours to charge from 80% depleted, so you could re-charge three of them. Probably easier and cheaper just to buy an extra three LiPos!

*In reality you might fall a bit short of this calculation because when discharging at high rates a battery doesn't usually deliver it's rated Ah capacity.
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Old 05-29-2015, 06:47 PM   #4
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Originally Posted by Romans5.8 View Post
Hey all!

So LiFE motorcycle batteries are becoming more and more popular in the motorcycle scene; lacking some of the issues that lead-acid batteries face and; most important in this case; they are super light.

So a 22Ah LiFE motorcycle battery, 12 volts, weight around 3 pounds. One or two of those in a field box would make an awesome self-powered charging box wouldn't it? Or would it?

Truth be told I don't know how to break down how many amp hours of battery you need for how many mAh of charge (Because I know it's not that efficient.) So this is a two part question.

1) Has anyone done this or similar; or know of any reason (other than the high cost; right now I'm just 'thinking out loud') why a LiFE Car/Motorcycle battery would not work? My thinking is, it's a super light weight and durable source of 12v power.

2) What's the breakdown/how do I determine how many Amp Hours I'll need in order to get a finite number of charges?

Just thinking out loud, honestly. Right now, everywhere I fly has AC power so it's moot. But, you know, a guy can't ever have too many projects to think about!
These batteries all are capable of delivering a certain amount of energy to a load. We could have used horsepower hours, foot pounds, or any number of different calculations. As for foot pounds, if you raise your 3000 pound car 10 feet in the air, you get 3000 pounds times 10 feet or 30,000 foot pounds. The actual horsepower required for that 30,000 foot pounds depends on how fast the car is raised 10 feet. Be it an hour, or a few seconds.

As fhhuber points out, these batteries are rated in Watt Hour capacity. Watt Hours is convenient since it is easy to calculate.

Take your 22 Ampere Hour battery at 12 Volts. That translates to 22 Amp Hours times 12 Volts DC or 264 Watt Hours. Compare that to an 80 pound 12 volt deep cycle battery with a rating of 120 Amp Hours. That translates to 1440 Watt Hours.

Now, with your LiPo battery, say we use a 2200 Mah 3 cell pack. That 2200 Mah is 2.2 Ampere Hours. And, while charging at around 4 Volts DC per cell, you get 2.2 Amp Hours times 4 Volts per cell times 3 cells, or 19 Watt Hours.

With your LiFe pack at 264 Watt Hours, and your LiPo at 19 Watt hours, you could get up to 264/19 or 13.8 charge cycles. Multiply that times perhaps 80% efficiency on the charger, you get 13.8 times 0.8 or around 10 charge cycles out of your LiFe pack.

Compare that to the lead acid battery that will provide 75 charge cycles. Not a good idea to run those lead acid batteries down much below 50% charge so you're looking at perhaps 40 charge cycles.

LiFe battery packs are expensive, but consider that they will last for many times more charge cycles than a big, heavy lead acid deep cycle battery.

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Old 05-29-2015, 06:55 PM   #5
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Originally Posted by JetPlaneFlyer View Post
A 6s 5000mAh Lipo will take around 100 Watt-Hours to charge from 80% depleted, so you could re-charge three of them. Probably easier and cheaper just to buy an extra three LiPos!
Yeah
I've been flying giant scale models with a 12S2P A123 battery pack that is being charged at 30 Amps with a 6S4P charging configuration. That is pulling 55 Amps out of a 12 Volt 120 Ampere Hour deep cycle battery.

That 80 pound battery is only good for around two or three flights before it's flat. And, discharging at 55 Amps, those deep cycle batteries won't last one flying season. Personal experience on killing three deep cycle batteries in two years.

Problem with those lead acid batteries, they are rated for a 20 Hour discharge time. My charging setup discharges them in a couple of hours, and doing that, you have to derate their Ampere Hour rating by 50% or so. There is lots of info on that in the internet.

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Old 05-29-2015, 08:31 PM   #6
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And, to be clear, the Lithium batteries I'm talking about are not "packs", but actual lead acid equivalents. Ones you could drop into a car or motorcycle. Larger ones are available with the same capacity as Lead Acid but less weight. The motorcycle ones being even LESS weight, a little cheaper, and much smaller. Which is why I was honing in on them.

Thanks for the info! Sound like it actually COULD work, if I were ever in a situation where I was flying somewhere consistently without AC power. And would mean something more totable than a very heady lead acid battery.

For $1,500; there is a company who makes a 12 volt, 15 pound (A FRACTION of a car battery weight), 590 watt hour battery If money were no object that would be a sweet setup. Though for $1,500; a 2000 watt Honda generator with DC output (more efficient than using the AC output and a power supply. Since most portable generators like that are using 12v generators and an inverter to produce AC current; eliminate the inverter if not needed!). These new Honda generators are super quiet, and light. Lighter than a car battery actually. Holds like a gallon of fuel and can be adapted to pull fuel from an external tank. When the budget goes that big that seems like the best solution. Although I suppose a real purist would find using gasoline to charge an electric RC plane to be a bit odd

Hmm. All stuff to think about!

fhhuber; at one time I considered a similar setup, albeit for a different purpose. My wife and I are avid motorcyclists and do a lot of long distance riding. Generally, we stay in Hotels, but have been thinking about doing some motorcycle camping. Which would involve getting a small lightweight cargo trailer for camping supplies, and ideally, a tent big enough to allow a place to change in bad weather. So we can put rain gear on without standing IN the rain getting our clothes soaked. One challenge is power at primitive sites and I had considered solar panels on top of the trailer, charging a 12v battery; and then having both 12v and 120v (via invertor) connections bolted onto the side of the trailer. To charge phones, cameras, run my laptop, etc. I've since upgraded motorcycles and the one I have now has a much larger dual-alternator charging system so it would actually be capable of charging that battery under it's own power while moving, but even so, that solar option might still be the best one. Especially when spending a few days at one site and not running the bike (or at least not running it with the trailer connected!)

But, ultimately, even there; those quiet Honda generators keep seeming like a good solution. But I really like the idea of NO generator. But now we're way off topic
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Old 05-29-2015, 10:06 PM   #7
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The question of carrying a battery to use as a source for charging comes up periodically.

Generally the result is the same ever time.

Cost vs weight vs number of flights... better to just buy more flight packs than to haul around a battery and charger to field charge.

Generator or some other system for field charging larger packs for larger models.

the solar systems are getting more practical.

The batteries I have in my solar system are outrageously impractical due to cost unless you get them free as discards from medical equip. At 2 yrs old they replace the batteries regardless of performance. A friend works in maintaining the equipment and he brings them to the field for people to use as large field box batteries. Just a few of us actually grab them.
Appx 5X the size and 3X the weight of a typical 7 ah gel battery used for field boxes... for over 15 times the capacity.
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Old 05-30-2015, 02:18 AM   #8
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Originally Posted by Romans5.8 View Post
Hey all!

So LiFE motorcycle batteries are becoming more and more popular in the motorcycle scene; lacking some of the issues that lead-acid batteries face and; most important in this case; they are super light.

So a 22Ah LiFE motorcycle battery, 12 volts, weight around 3 pounds. One or two of those in a field box would make an awesome self-powered charging box wouldn't it? Or would it?

Truth be told I don't know how to break down how many amp hours of battery you need for how many mAh of charge (Because I know it's not that efficient.) So this is a two part question.

1) Has anyone done this or similar; or know of any reason (other than the high cost; right now I'm just 'thinking out loud') why a LiFE Car/Motorcycle battery would not work? My thinking is, it's a super light weight and durable source of 12v power.

2) What's the breakdown/how do I determine how many Amp Hours I'll need in order to get a finite number of charges?

Just thinking out loud, honestly. Right now, everywhere I fly has AC power so it's moot. But, you know, a guy can't ever have too many projects to think about!
I found one site that indicated that these batteries are not to be used as deep cycle batteries. Dang.

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Old 05-30-2015, 02:43 AM   #9
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You do have to check if the battery is designed for deep discharge or for high current.... or both.
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Old 05-30-2015, 03:27 AM   #10
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Originally Posted by fhhuber View Post
The question of carrying a battery to use as a source for charging comes up periodically.

Generally the result is the same ever time.

Cost vs weight vs number of flights... better to just buy more flight packs than to haul around a battery and charger to field charge.

Generator or some other system for field charging larger packs for larger models.

the solar systems are getting more practical.

The batteries I have in my solar system are outrageously impractical due to cost unless you get them free as discards from medical equip. At 2 yrs old they replace the batteries regardless of performance. A friend works in maintaining the equipment and he brings them to the field for people to use as large field box batteries. Just a few of us actually grab them.
Appx 5X the size and 3X the weight of a typical 7 ah gel battery used for field boxes... for over 15 times the capacity.
Right. And I've seen folks using them with lead acid batteries. Actually a guy at my own field has a big rolling cart with a deep cycle trolling motor battery. We have AC at the field but he uses it elsewhere. I guess where this was unique and I was curious if others did the same was in regards to the newer Lithium technologies. Not new in our hobby but relatively new in large, high capacity, motorcycle/car equivalent batteries. Right now, the big market is racing (because of the weight). But these batteries are becoming more and more available and have as much capacity as a comparable lead acid battery but at a fraction of the weight (same physical size). i.e., often under or just over 10 pounds. The above super-high cost one is a huge battery, the size a Diesel dually pickup truck might use, but only weighs 15 pounds.

Thanks for the input everyone! I am new to this and just thinking of unique and cool ways to do things.

Those medical supply batteries sound like a great deal. Actually, I have a BIL who is an electrician working on remodeling a hospital right now. I ought to ask him if he can source batteries like that. There's always something unique that can be done with that.
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Old 05-30-2015, 08:35 AM   #11
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Originally Posted by fhhuber View Post
the solar systems are getting more practical.
That would depend where you live and what time of year it is and the weather!

With any hand portable solar system (and we are talking hand portable in this thread) even in ideal conditions you are not going to have the generating power to charge LiPo batteries 'real time' not even close.

Solar systems are really just an alternative way to trickle charge a storage battery, which you then use to charge your flight batteries. So you still have to lug around a large storage battery... Not really helping except maybe for visits to flying events where you are away from wired AC power supply for days on end.
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Old 05-30-2015, 09:38 AM   #12
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You can get 15 watts solar now from a panel the same size and 1/4 the weight of what was required just 7 years ago... at about the same cost as the same size panel was back then.

That's decidedly headed in a more practical direction.

Couple of modern flex panels rolled out on the roof of your car and your car battery as the storage... can more than double the charges you can do vs without the panels.

Next leap in panel tech might make a 1 ft square panel give the power of all the panels I have on the roof of my trailer and that CAN do a 1C charge of a 3S 4000 mah direct from the panels.
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Old 05-30-2015, 10:06 AM   #13
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Which proves my point... it takes solar cells the size of a car roof just to trickle charge a storage battery! And I'm guessing you are in a much sunnier location than me!

Even if someone invents solar cells with twice or more the efficiency that they have today realistically on average in most parts of the world isnt enough to charge a large LiPo battery quickly with any size cells that were hand portable. Maybe different if you have a huge solar array on the roof of a big RV... but that's not really what we are talking about here. The idea was a hand portable system that you could carry to the flying site.
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Old 05-30-2015, 01:42 PM   #14
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Well I think his system was installing the panels on the roof of his trailer. So if he's at an event/fly-in/etc., he has a way to keep his batteries topped-up to provide power for his chargers. I don't think anyone is talking about a portable solar solution here. One of the guys at my field has a big toy-hauler trailer like that. With a good crop of deep-cycle batteries powering an inverter and giving him direct 12v access for chargers, an A/C unit, even a TV! Totally cool setup for going to events where power isn't available. I don't believe he has panels though; just storage batteries.

As these panels get better, they actually require less and less "sunny conditions". A couple I know retired and built a house on a plot of land out here in rural Missouri that was away from an utility service. Which isn't uncommon, you just pay the utilities to run the wires. But because of where they were, the local power company wanted $70k to run power. They crunched the math and for about $50k, they could have wind and solar power their house. Which is exactly what they did! They have storage batteries in their basement, and have solar panels on their home and shed and a wind turbine (which has the advantage of generating more power in the same conditions the solar panels are producing less; like during a storm). They also have a natural gas generator as a backup but it's rarely used. Just a few years ago, the number of panels they have would ALMOST power their house, and probably wouldn't be enough surplus to store power to get through the night. But these new panels are amazing. AND, they work well even when it's overcast, etc. I visited their home on a dark cloudy overcast day and when the A/C wasn't running, they were still producing more than enough power to charge the storage batteries; and when the A/C was on, it was only a very minor shortage of energy (requiring the batteries). And that's with all electric appliances, including hot water heater, stove, etc. (And their water is pre-heated by flowing through a solar panel before being dumped into the hot water heater, reducing it's load) Pretty cool setup! And even in the short winter days, they can power their electric furnace all day and all night. They told me that only a couple times a year do they use the generator. The kicker is, 10 years ago when they built the house, the panels they had wouldn't even power the A/C. If you wanted A/C, you had to run the generator. The new panels they just got not only power the A/C, but store enough electricity to power it at night as well! Same surface area, MUCH more power. Even when it's cloudy.
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Old 05-30-2015, 01:53 PM   #15
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LiFe battery packs are expensive, but consider that they will last for many times more charge cycles than a big, heavy lead acid deep cycle battery.
mmmmmm don't know if I can completely agree with that. If a battery is treated properly and within its designed specs .... it should last significantly long. DC Lead Acid - I've known them go 10yrs or more on boats etc.

Its all down to how hard you push them, whether you allow sufficient overhead on capacity etc. etc.

Personally Battery for powering charger ? I still need convincing on it whatever form it is ... BUT if that battery is also connected to alternator on the car ... then YES ... That's a different story. Car alternator ... 40 - 60A at 15V .... is that not enough for most people ? Keeping the battery up ...

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Old 05-30-2015, 02:11 PM   #16
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Originally Posted by solentlife View Post
mmmmmm don't know if I can completely agree with that. If a battery is treated properly and within its designed specs .... it should last significantly long. DC Lead Acid - I've known them go 10yrs or more on boats etc.

Its all down to how hard you push them, whether you allow sufficient overhead on capacity etc. etc.

Personally Battery for powering charger ? I still need convincing on it whatever form it is ... BUT if that battery is also connected to alternator on the car ... then YES ... That's a different story. Car alternator ... 40 - 60A at 15V .... is that not enough for most people ? Keeping the battery up ...

Nigel
I've read some chargers don't handle the higher voltage of a running car. There might be other factors too; car charging systems don't always do a great job of creating 'clean' power. The onboard electronics can handle it but your charger might really be expecting the unvarying, 'clean' DC power of a power supply or battery.

The principle problem with lead acid batteries is that when they drop below 12.4v for any decent length of time they begin an internal chemical process that corrodes them. The sulphuric acid essentially breaks down and these sulphate crystals solidify on the lead plates. Impeding capacity and output; and in a worst case scenario, even growing 'into' one another creating a short. The complete opposite of most types of batteries; a lead acid car starter battery will do well do spend it's entirely life fully charged. Deep cycle batteries resist this a little better but should still be stored at a full charge. This is why we use battery tenders! I have a battery tender on both motorcycles and the lawn mower in the winter to keep the voltage at peak, making the batteries last a very long time.

I know some who just hook up to their car battery, and when they get a 'low voltage' alarm just fire the car up and recharge. But that's hard on the cars electrical system AND hard on the battery for reasons mentioned.

If I were flying at a field every day that had no power and was really crazy about this; one solution might even be a trunk mounted deep cycle battery. Guys who run crazy big stereo systems are always installing extra batteries and bigger alternators; so there are resources out there. Installing a deep cycle battery that will charge off of the alternator would be a cool setup. I would then run the wiring to a connect. A small RV type connector could be installed under the bumper just like a trailer wiring connector (provided one could be found with high-enough gauge wiring), and then it's just a simple case of 'plugging in!' That might be a cool setup. Use a disconnect switch, turn it 'off' when charging to disconnect that circuit from the cars electrical system (to prevent putting a load on the starter battery), and turn it back 'on' when finished (to enable recharging of the deep cycle battery). Although, the trailer-with-solar solution seems much more elegant!
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Old 05-30-2015, 02:41 PM   #17
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Romans ....

The problem with chargers is the Click out when engine starts - as they detect the serious drop in voltage when starter engages.
The trick when charging to avoid 'dirty' alternator power - its basically only AC converted to a rippling dirty DC which Lead Acid batterys simply love. ... is to have that Lead Acid battery in line .... then it smooths the power to the charger.

I agree that running the LA down and then starting the car is not so good ... on boats we tend to do that a lot ... so best is having the car engine running. Which brings us to an interesting point. Unless you have a modern and well kept auto system - idle on a car is very poor output and may not keep up with demand. On my boat - I have to blip the throttle to get Red light to extinguish ... its connected to the exciter circuit of the alternator to tell me when alternator is actually charging.

Crystal structure on plates is in my opinion an overused exaggerated problem that is used to sell battery conditioners that in my opinion are not needed. Car alternators are purposely left dirty DC for that reason ... to reduce the formation of such. But what is true - is the buckling of plates when over-discharged ... leading to failure of a cell. This can also happen to true Deep Cycle Batts when used to start a car or boat engine. They cannot sustain the amp demand and the soft thick plates fail.

Those who claim DC batts are good to start cars / boats - these are NOT true DC batts - but hybrids designed to try cover both demands.

Its a subject I have a long association with being a Sailboat owner and my father before me ....

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Old 05-31-2015, 02:59 AM   #18
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Originally Posted by solentlife View Post
Romans ....

The problem with chargers is the Click out when engine starts - as they detect the serious drop in voltage when starter engages.
The trick when charging to avoid 'dirty' alternator power - its basically only AC converted to a rippling dirty DC which Lead Acid batterys simply love. ... is to have that Lead Acid battery in line .... then it smooths the power to the charger.

I agree that running the LA down and then starting the car is not so good ... on boats we tend to do that a lot ... so best is having the car engine running. Which brings us to an interesting point. Unless you have a modern and well kept auto system - idle on a car is very poor output and may not keep up with demand. On my boat - I have to blip the throttle to get Red light to extinguish ... its connected to the exciter circuit of the alternator to tell me when alternator is actually charging.

Crystal structure on plates is in my opinion an overused exaggerated problem that is used to sell battery conditioners that in my opinion are not needed. Car alternators are purposely left dirty DC for that reason ... to reduce the formation of such. But what is true - is the buckling of plates when over-discharged ... leading to failure of a cell. This can also happen to true Deep Cycle Batts when used to start a car or boat engine. They cannot sustain the amp demand and the soft thick plates fail.

Those who claim DC batts are good to start cars / boats - these are NOT true DC batts - but hybrids designed to try cover both demands.

Its a subject I have a long association with being a Sailboat owner and my father before me ....

Nigel
I know you have experience with them (I do too). I've seen dissected and sulfated batteries. I'm not an expert of course; but I am relatively convinced that sulfating is one of the causes of eventual failure lead acid batteries. Or at least, can be a cause; and I'm also convinced that not allowing voltage to dip can help stave that off. However, I also don't think the conditioners do squat. But tenders that keep the voltage at peak are a fantastic investment. Everyone at my house with a 12 volt battery that doesn't get used nearly every day year round (in other words; everything but the cars) has one. And this has helped me get consistent very long life out of lead acid batteries even in things like lawn mowers and motorcycles; when so many are replacing a battery after the 2nd or 3rd season. I am not convinced conditioners serve any purpose other than to separate a fool from his money.
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Old 05-31-2015, 03:57 AM   #19
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Originally Posted by solentlife View Post
mmmmmm don't know if I can completely agree with that. If a battery is treated properly and within its designed specs .... it should last significantly long. DC Lead Acid - I've known them go 10yrs or more on boats etc.

Its all down to how hard you push them, whether you allow sufficient overhead on capacity etc. etc.

Personally Battery for powering charger ? I still need convincing on it whatever form it is ... BUT if that battery is also connected to alternator on the car ... then YES ... That's a different story. Car alternator ... 40 - 60A at 15V .... is that not enough for most people ? Keeping the battery up ...

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You hit the nail on the head.

Those modelers that are using a big deep cycle battery to recharge their 2200 mah 3 cell LiPos will get many years service out of a quality deep cycle battery.

Those people (like me ) that try using a 120 Ampere deep cycle battery to charge a 12S2P A123 pack in 15 minutes will NOT get much service live out of a deep cycle battery.

Problem is, my Cellpro Chargers are pulling 55 Amps out of that 12 Volt Supply, and that is very definitely NOT in the area of safe discharge levels of a deep cycle battery. For 55 Amps continuous current levels, you need a several hundred pound electric substation backup battery. Cost of those is $1000 plus.

That's why I've gone to that gas engine/alternator setup reported in Groupwise many times. FYI, the cheap lawn tractor battery used with that engine/alternator is on it's 6th year, and is still working just fine.

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Old 05-31-2015, 04:40 AM   #20
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You don't HAVE TO charge at 4C....
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Old 05-31-2015, 06:06 AM   #21
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Nope don't have to. But, those A123's stay in the airplane, and charging in one hour, I'd only get one or two flights a day. Versus a half dozen or so.

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Old 05-31-2015, 08:05 AM   #22
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Hi Romans .....

Yes Sulfation of plates is a problem, and as you rightly say - keeping the battery charged up reduces this problem.
Basically as the battery discharges, a chemical change is occurring in the electrolyte and plate surfaces. If not reversed by charging - the change becomes more and more permanent as time goes on.
This is why a car starter battery lasts for years longer than a battery intermittently charged.

Battery tenders such as Chargemates etc. only pulse charge in an exxagerated way ... to literally shock the plates ... a standard old style basic charger will actually do same. But of course we prefer to use the later auto-detect chargers that blast 4 .... maybe up to 10A in and then click back to trickle rate. These later chargers are in fact cleaner charge and so not so great at 'shock' to the sulfated plates.

Most failed battery's display warped plates where too deep discharged or too high a discharge rate .... typical scenarios on boats and RV's. Go round any marina or RV site and see the battery's lined up next to trash bins !

My 'handyman' - I have running battle with him to put the trickle charger on the garden gear and also to reconnect my boat power after he uses. My boat has an automatic solid state relay that splits an old style charger to the two onboard batts. It shuts down when full charged, but clicks back in at slightest dip in charge level. Best is the old cheap fixed 4A charger because of the 'dirty' charge rate .... coming from simple rectified AC .... If I try to use a modern charger with trickle function - the relay doesn't work. The charger is also plugged in via a timer giving power so many hours each day to avoid gassing of the batts electrolyte.

The secret to any lead acid battery as you say is keep it charged up. No matter what format - they don't like being discharged and left.

As I say - I prefer to use my cars alternator via the charger .... that way I know I'm getting enough power.

Nigel

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Old 06-01-2015, 02:37 PM   #23
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I find it easier and less expensive to just have extra LiPo battery packs for my planes that I charge at home, and then bring to the field with me.

I do have a gel-cell battery in my flight box that I can use to charge a 3s pack if needed, but it takes awhile.
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Old 06-01-2015, 07:15 PM   #24
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Originally Posted by Bald Paul View Post
I find it easier and less expensive to just have extra LiPo battery packs for my planes that I charge at home, and then bring to the field with me.

I do have a gel-cell battery in my flight box that I can use to charge a 3s pack if needed, but it takes awhile.
May sound daft - but I always go to flight site with MORE packs than I think I will need. What I don't use then gets discharged back at home.

My comment about charging at field - was just that ... what I would do IF I needed to charge ... which is rare. But I always carry a B6 charger + car ciggy socket lead with me ... just in case !!

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