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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 02-05-2011, 12:26 PM   #1
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Default Field charging and power supplies

I actually started flying electric airplanes back in the early 1980s. Back then all that was available were NiCad batteries. The timer/Charger I used had clamps that attached to my car/truck battery and I charged these NiCads at the high rate built into the charger for 15 minutes, you popped them into the airplane and flew. No ESC, you landed when the battery could no longer keep the airplane aloft!

Things have changed, A LOT!

I'm back to flying electric, and I think more electric is the direction I'm headed. I prefer bigger airplanes, they fly better. I consider anything below a .60 sized glow airplane to be a small airplane!

Given the above, I'm interested in what you guys with similar sized airplane interests are using as a power source and what chargers you are using?
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Old 02-06-2011, 01:08 PM   #2
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24 hours without a response! I would think this question is hitting this topic square in the "Bread Basket"! If this question is a "re-hash" of previous similar ones, please point me in the right direction, so I can find some answers. Thanks!
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Old 02-06-2011, 02:16 PM   #3
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First off while Wattflyer is a very good forum it has never been the most active one. Secondly due to the bad ecomony for the past couple of years there has been a dramatic decrease in active on all RC forums. Many siold out to pay the rent or buy food.

There are some threads on this over on RC Groups where I am a lot more active. I use two 125 Ah flooded cells deep cycles. I have numerious higher power chargers.

Two hundred watts and above TP 1010C ,Hyperion DUO,two Hyperion 720is,two iCharger 208Bs,3010B,306B, two FMA POWERLAB8s, Thunder Power 820CD (just released ).

In general large electrics require a lot of amp. hours from the charger's power source. If your flying site has 120V AC then a power supply and charger is the way to go, other wise a Generator or massive deep cycles.

Charger(s) depends on the number of cells to be charged and how fast you care to charge them.


Honda EU 2000 wats generator . $1100, FMA POWERLAB8 $250, two hp ESP 114 server power supplies $50 and some research and DIY work or $ 250 to $400 for a commerical power supply. Two 125Ah flooded cell deep cycles $150 to $200 but then number of charges are limited for really big LiPolys.


Thread here on sizing power supplies

http://www.rcgroups.com/forums/showthread.php?t=1082910



Charles
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Old 02-06-2011, 06:22 PM   #4
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I'm with you on flying the larger planes. I have all sizes but lately only fly the larger ones. They seem to fly better. Can handle more wind, and are also easier to handle in my grass runway. My larger ones use 6 cell 5000 mah batterys. So for charging, I use only the Cellpro 10S, But all of my flying is here at the house so I have no field charging. One of my Big Stick 60's uses two 4 cell 5000 mah batterys in series.
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Old 02-10-2011, 11:23 AM   #5
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Originally Posted by everydayflyer View Post
First off while Wattflyer is a very good forum it has never been the most active one. Secondly due to the bad ecomony for the past couple of years there has been a dramatic decrease in active on all RC forums. Many siold out to pay the rent or buy food.
Charles
Bad economy absolutely understood! I was laid off myself for 13 months, starting January of 2009. Went back to my old job the 1st of March last year and am very-very thankful for this! That there are many people having financial difficulties, literally can go without saying. Whether it affects people involved in this hobby is without doupt.

Still, I would think the subject I've brought up would garner more discussion than I'm seeing. Thank you, both, for your help!
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Old 02-11-2011, 01:25 AM   #6
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Mode One, Have you seen this thread?
Henry
http://www.wattflyer.com/forums/show...light=chargers
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Old 02-11-2011, 02:42 AM   #7
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Originally Posted by Mode One View Post
I actually started flying electric airplanes back in the early 1980s. Back then all that was available were NiCad batteries. The timer/Charger I used had clamps that attached to my car/truck battery and I charged these NiCads at the high rate built into the charger for 15 minutes, you popped them into the airplane and flew. No ESC, you landed when the battery could no longer keep the airplane aloft!

Things have changed, A LOT!

I'm back to flying electric, and I think more electric is the direction I'm headed. I prefer bigger airplanes, they fly better. I consider anything below a .60 sized glow airplane to be a small airplane!

Given the above, I'm interested in what you guys with similar sized airplane interests are using as a power source and what chargers you are using?
H'mmm
Few responses on this thread. That's odd, since a LOT of wattflyers are running high powered electric models. I've been running kilowatt powered models now for three years, and have had a lot of success and fun with them. My Hacker A50 series motors are in models with about 700 square inches of wing, and about 7 pounds of airplane, including motor and batteries. I've used only the A123 2300 Milliampere Hour battery packs configured as 6S2P (That's six series, two parallel, for 12 cells), putting out about 17 volts at about 60 Amperes. The A123 cells are heavier, physically larger than the Lipos, but they can be recharged in less than 20 minutes with a high powered charger. And, my three 6S2P A123 packs are now three years old, and have the same exact performance as when they were brand new.

IMHO, it's a good idea to buy good motor, battery and ESC equipment when going past a kilowatt or so, since power input to these models can be very substantial. I use the Hacker A50 and A60 series motors, with corresponding Castle Creations ESC's (Electronic Speed Controls).

As for chargers, I've got a good background in electronics, so have built my own high powered chargers. Others on this webpage have good results with the Cellpro 10 series chargers. Other chargers are also available. You do need a solid DC supply for these chargers. Minimum would be a 120 Ampere hour deep cycle marine battery (NOT an engine starting marine battery!) Or, if you've got 120 Volts AC available at your field, a 30 Ampere 12 Volt DC power supply that has 120 volts input. www.mpja.com is one place that has them. Let me know if you need more details.

Latest project is an Extra 330 with 78 inch wingspan, and 1200 square inches of wing area. Power is a Hacker A60-16M, with a 19X12 APC-E wide blade prop, CC 80 Amp ICE HV ESC. It has primary/backup battery supply for the Spektrum AR7000 receiver, and 7 Hitec 645MG servos. Weight is 17 pounds, power is 2300 watts, so that is around 130 watts per pound of airplane. Not flown yet, we got two feet of snow on our club's field.

Take a look at my thread on this subject below:
Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222


Battery comparisons
http://www.wattflyer.com/forums/showthread.php?t=47965

Hacker A60-16M motor vs Glow/Gasoline Engines
http://www.wattflyer.com/forums/showthread.php?t=58035

Note that this PDF file shows the Hacker A60-16M motor with an 18 inch prop, where its capable of turning a 19X12 APC-E wide blade prop. That puts its power above the largest gasoline engine in this PDF file.
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Old 02-11-2011, 04:05 AM   #8
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Minimum would be a 120 Ampere hour deep cycle marine battery (NOT an engine starting marine battery!)
First lets dispel this ...... there are many different styles of Wet Cell Lead Acid Battery .... and there is really not a specific Engine Starting marine battery of it's own. What you have is relabeled shore / leisure batterys ...

Many boaters when they learn about the demands and limitations of various forms then elect to go for combination batterys that can supply high ampage to start the engines as well as suffer discharge to power domestic gear. These are often mistakenly labelled Depp Cycle ....

RV / Leisure market and boating have produced better solutions to this and it is always a good idea to discuss needs with a dealer in such.

But there is an existing and successful means to cover high capacity need with excellent discharge / power possibilities. Get on down to a Truck Battery supplier who has batterys suitable to start the engines as well as run the hydraulic tail-lifts. These batterys are usually sold $ per AHr and provide much better cost per use ratio. Trucks must have dependable sources ..... benfit from that !

I've been mucking about with boat power systems for many years and learnt the hard way.

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Old 02-11-2011, 05:08 AM   #9
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Originally Posted by solentlife View Post
First lets dispel this ...... there are many different styles of Wet Cell Lead Acid Battery .... and there is really not a specific Engine Starting marine battery of it's own. What you have is relabeled shore / leisure batterys ....
Two years ago, I picked up a 120 Ampere Hour battery from a Walmart store in the USA, that was plainly marked Marine Battery with 875 Amps Cranking ability. That battery lasted about a year, and after about 50 charge cycles, it lost 70% of its 120 Ampere Hour capacity. Other threads have indicated that some of these marine batteries are nothing more than a standard automotive battery with carrying handles.

I now have a battery from a local "Farm and Fleet", that is marked Deep Cycle Marine battery. No engine starting rating. This battery is on its second year, we will see how long it lasts.

Take a look at this web site on lead acid batteries:
http://www.windsun.com/Batteries/Battery_FAQ.htm

Looks like the ideal deep cycle battery for our purposes is a "Gulf Cart" battery. But, these are generally 6 volts DC, so two are required. And, they are EXPENSIVE!
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Old 02-11-2011, 08:36 AM   #10
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Originally Posted by kyleservicetech View Post
Two years ago, I picked up a 120 Ampere Hour battery from a Walmart store in the USA, that was plainly marked Marine Battery with 875 Amps Cranking ability. That battery lasted about a year, and after about 50 charge cycles, it lost 70% of its 120 Ampere Hour capacity. Other threads have indicated that some of these marine batteries are nothing more than a standard automotive battery with carrying handles.

I now have a battery from a local "Farm and Fleet", that is marked Deep Cycle Marine battery. No engine starting rating. This battery is on its second year, we will see how long it lasts.

Take a look at this web site on lead acid batteries:
http://www.windsun.com/Batteries/Battery_FAQ.htm

Looks like the ideal deep cycle battery for our purposes is a "Gulf Cart" battery. But, these are generally 6 volts DC, so two are required. And, they are EXPENSIVE!
Glad you confirm what I posted !! It's all too often the case that public are duped by clever labelling ....

The term "Marine" seems to have been picked up by market suppliers as some 'great tool' that really has no real meaning ....

It is true that a battery to perform in a marine environment is different to that of an auto battery. But that's due to general need to supply low to medium amps for extended periods and then short burst of high energy to start a diesel.

To do that means the battery has sit in two camps .... so you only get a compromise.

A starter battery that is used in a car has many thin plates to get maximum surface area to deliver cranking amps. But those plates cannot suffer deep discharge and buckle when so called on. Giving rise to the common failed cell in the bank.
A domestic deep cycle battery on the other hand has fewer thicker plates that deliver less high amps but can withstand deeper discharge without buckling plates.

The trick is marry both needs ..... and the best is still the Truck battery as already mentioned earlier. Golf cart batterys are actually excellent as well but yes usually in 6v form.

I will throw another possibility into the arena ..... the second-hand battery in a Car Junk yard ......... often still in good condition .... often can be load tested when you buy and price is usually very cheap and even if only lasts a year - works out cheaper ! (I've had such batterys in service in boats for over 6 yrs - in fact 1 I took of one of my boats last yr was over 8yrs in service.)

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Old 02-11-2011, 12:16 PM   #11
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Boaters who know anything about boating know that the best set-up is to have a deep cycle "House" battery(s) and an engine start (car battery). The house battery(s) operate the electrical devices and system s aboard and the "engine start" battery does only and exactly that. The boaters I know (and there are many) are certainly as educated as R/Cers on batteries, their charging and care.

That Walmart might sell miss-labeled/ill labeled products is one of the reasons I'm leery of spending money with the company.
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Old 02-11-2011, 01:46 PM   #12
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Originally Posted by Mode One View Post
Boaters who know anything about boating know that the best set-up is to have a deep cycle "House" battery(s) and an engine start (car battery). The house battery(s) operate the electrical devices and system s aboard and the "engine start" battery does only and exactly that. The boaters I know (and there are many) are certainly as educated as R/Cers on batteries, their charging and care.

That Walmart might sell miss-labeled/ill labeled products is one of the reasons I'm leery of spending money with the company.
That is true and many did carry a large domestic and small start battery - but that is not necessary in todays systems .... where many people want back-up and a deep-cycle battery can be ruined by trying to start a diesel. So compromise batterys are often fitted or even just fit large car batterys !

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Old 02-12-2011, 03:14 AM   #13
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Originally Posted by solentlife View Post
That is true and many did carry a large domestic and small start battery - but that is not necessary in todays systems .... where many people want back-up and a deep-cycle battery can be ruined by trying to start a diesel. So compromise batterys are often fitted or even just fit large car batterys !
If your engine start battery is never used for "house" power, there is never a need to use the deep cycle "house" battery(s) to start the engine.

However, this is a discussion for boaters and although I am a sailor and spend far more time sailing then flying R/C, can I ask that we get back to the original intent of the thread?
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Old 02-12-2011, 03:52 AM   #14
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Originally Posted by Mode One View Post
If your engine start battery is never used for "house" power, there is never a need to use the deep cycle "house" battery(s) to start the engine.

However, this is a discussion for boaters and although I am a sailor and spend far more time sailing then flying R/C, can I ask that we get back to the original intent of the thread?
Original;ly it was answered to show that not all batterys are same ... and it led from there ....

Just to close - I take it you have never had a failed start battery then ... in over 50yrs of being on boats - I have had and thanked the stars that I covered such with choice of batterys.

As to RC work ... I used to use small Motorcycle batterys and at one stage SLA to power my flight box for fuel-pump and glow igniter. Later because I started doing long periods away at competitions etc. - I changed to a 50 A/Hr Car battery.

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Old 02-12-2011, 06:44 AM   #15
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Originally Posted by Mode One View Post
If your engine start battery is never used for "house" power, there is never a need to use the deep cycle "house" battery(s) to start the engine.

However, this is a discussion for boaters and although I am a sailor and spend far more time sailing then flying R/C, can I ask that we get back to the original intent of the thread?
One thing about lead acid batteries, it's not to hard to determine just how much capability they have. Let's see. A 120 Amp Hour battery supposedly can put out 120 amperes at about 12 volts for one hour. So that is 120 X 12 or 1440 watts. Since it's 746 watts per horsepower, that 120 Ampere Hour battery represents about two horsepower for one hour. And, since many threads suggest not discharging your lead acid battery more than perhaps 50% on a given day for good battery life, that represents about one horsepower for one hour.

Now, if your model's motor averages 1/2 horsepower during a flight, that indicates your deep cycle battery will give you about two hours flight time. At perhaps 8 minutes per flight, that's 10 or 15 flights. Problem is, that Walmart battery dropped to about 30% of its specified 120 ampere hour capacity after a year or so of flying. And that is only 3 or 4 flights.

And, my three horsepower Hacker A60-16M motor will get about 1/2 hours flight time. Guess I'll need to use two of those 120 Ampere hour batteries in parallel for that motor.

If you're flying the much smaller models such as the foamies, or models running under perhaps 200 watts, recharging them from your auto battery would be an viable option. Just won't work with the kilowatt powered models.

With all of this, I'm really thinking about putting my gasoline engine/alternator setup back together as a charger power supply for the fun flys in the SE Wisconsin area this summer. That would weigh 1/2 of what those two big deep cycle batteries would weigh.
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Old 02-12-2011, 09:27 AM   #16
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Surely it's easier to just stay with Watts than go to the calc of HP .... most motors are Watts rated.

One of the problems with a Lead Acid Cell is that the real power of the cell reduces as it's charge state drops ... A typical 12v battery will deliver best in the upper 30% of charge ...

If anyone is using a 12v battery to power their charger without secondary power into the battery such as Generator etc. - then the battery will have a significant reduced effective range. This becomes apparenmt when charge time is longer and longer !! as the battery cannot meet the voltage / amps required. I see this often with my Emergency Start Pack I carry at times.

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Old 02-12-2011, 01:36 PM   #17
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[QUOTE=solentlife;784600]Original;ly it was answered to show that not all batterys are same ... and it led from there ....

Just to close - I take it you have never had a failed start battery then ... in over 50yrs of being on boats - I have had and thanked the stars that I covered such with choice of batterys.
/QUOTE]

I understand how the conversation ambled over to examples of batteries in boats, I'm reading the same thread as you are!

Yes, I have had a battery fail on me. Both in boats and in automobiles. They get old and simply won't hold a charge and generally have let me know a while before the failure occurred that there was going to be a failure. Most of the times I have replaced the battery when it starts showing signs of failure; but, I have been caught! On my boat when it happened, it was a time that warranted using the house batteries for starting the engine, so my Arse was covered too. Formerly, I was a Marine Surveyor, so as well as having decades of boating experience I have formal education and experience in marine systems!

Solentlife, in your words, what are you actually espousing I should use a power source for charging my batteries in the field? Keep in mind that if AC power was available at my flying field, I would not have started this thread.
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Old 02-12-2011, 01:59 PM   #18
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Just to clear up something ...

I'm a Professional Marine Surveyor and Superintendent, who also having experience in leisure craft also owns Yacht Survey biz. I own Petrochemical lab and run Cargo Survey Co. with agency for International Inspection Co.

OK ... what is needed is to appraise what your demand would be and for how long. Some people need high capacity for large packs but for a single flying day. Others small packs but for a weekend or extended trip.

So it needs to be calculated out the Ahr requirement .... actually given that many people run higher than 12v packs ... it's the Watts required that is important. So once that is known then double it ..... so battery stays in it's better top half of charge to do the job. Unless going into high capacity's and capability - then the car battery either separate or that installed in the vehicle will often be fine. Larger demands need care and larger batterys that then call for deep cycle / leisure style. But again I advise in that case to get to a Truck Suppliers and check out their batterys.

Let me give an example of my req't .... I have 2 x 1000mAh + 1 x 2280 mAh + 2 x 2800 mAh ..... all 11.1V 3S packs.

Total watts then is based on AH ( 9.88 ) x 11.1v nominal .... = 109.668 Watts. In fact being still within 12v range - we can stay with AH which is basically 10 AH reqt ... double it to 20 AH .... so I need a battery of at least 20AHr capability and also capable of delivering 2A .... easily covered by a small wet-cell. I could even use a large SLA but they are expensive size for size. All assumed that battery is fully charged at start of day ! and only 1 recharge each pack. (Reason for watts I advise in calculation is when inverter or voltage changer is used to power higher than 12v .... )

Standard car battery of say 60AHr .... would give me 3x what I need.

Let's be honest if you've done it for boats - which you must have done ... it's same supply - demand calculations ............

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Old 02-12-2011, 04:09 PM   #19
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Originally Posted by solentlife View Post
Surely it's easier to just stay with Watts than go to the calc of HP .... most motors are Watts rated.
Good point, I was just trying to work with those readers of this thread whose past experience is the glow engines, and their "horsepower" ratings.

The best way to describe the total ability of your battery to do work is not watts, but watt hours. The number of watts you can pull from your lead acid battery can vary all over the map, depending on what kind of load you place on that battery. But the total number of watt hours is fixed. (FYI, your homes electric meter is measuring KiloWatt Hours, same thing.)

Problem is, if you discharge your lead acid battery in less than the 20 hours or so its rated at, its total watt hour capacity drops off. Depending on the battery, discharging the battery in an hour or so can result in a significant reduction in its watt hour capacity. On my wifes electric scooter, discharging in an hour resulted in the watt hour capacity dropping of by 50%.

So, if you have a 120 Ampere Hour deep cycle battery, at 12 volts DC, its ability to do work is 120 times 12 times one hour or 1440 watt HOURS. And if you want to limit how deep you discharge your battery, that would by about 700 watt hours on a good days flying. And, if your motor is averaging 1400 watts continuously (not likely) your deep cycle is capable of providing about 1/2 hours total flying time on your model.

But, the current pulled by your electric motor varies all over the map during flight, so your motor that pulls 1400 watts could be averaging perhaps 1/2 of that during a typical flight.

As others have indicated, these calculations really only become important if you are running the "high powered" electric models, with perhaps over a kilowatt of power running your models electric motor.
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Old 02-12-2011, 07:15 PM   #20
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Problem is, if you discharge your lead acid battery in less than the 20 hours or so its rated at, its total watt hour capacity drops off. Depending on the battery, discharging the battery in an hour or so can result in a significant reduction in its watt hour capacity. On my wifes electric scooter, discharging in an hour resulted in the watt hour capacity dropping of by 50%.
Which is why the reserve minutes are so important IMO.

I use two 125 Ah flooded cell deep cycles as a field power source. The resever minutes ratiing for each is 210 minutes or 3-1/2 hours. 3.5 X 25A = 87.5 Ah which is only 70% of their 125Ah rating.

I just completed testing a new 50Ah rated at 100 reserve minutes and also a 6 year old one. Under a 25A load the new one delivered 28 Ah and the old one 18Ah. Both discharged down to 11 volts under load at the terminals which is as low as I care top discharge them.

100 min. @ 25A should be 41.6 Ah and IMO even the new one would have failed short if discharged to the 10.5V under load point.

12V AGM test


Both AGM Spiral cells and listed as 48 Ah . 100 reserve minutes.


Exide is 6 years old and has seen fairly light useage and has been properly maintaned. It is blue and is listed as a Deep Cycle.

Optima is Yellow, new and is listed as a dual purpose , recomended for auto starting and deep cycle. Intended for use in auto with high power audio systems, hydrolics, winches and such.


15 minutes after load was removed Optima had recovered to 11.68 at terminals.


There was an approx. 0.5V drop in the 24" / 14 gage leads used. I elected to use these as they were handy and just so happen to be typical as used on many chargers. Fact is this set was the excess which I removed from my FMA Cell Pro 10 long ago. If I had used heavier and or shorter leads there would have been less of a drop and a few more amp hours would have been removed and time extended but depth of discharge would have been deeper also.

The leads stayed in the 90 to 95F range through out the test ,ambient temp. 70F.




Charles


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Old 02-12-2011, 07:24 PM   #21
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Originally Posted by everydayflyer View Post
Which is why the reserve minutes are so important IMO.

I use two 125 Ah flooded cell deep cycles as a field power source. The resever minutes ratiing for each is 210 minutes or 3-1/2 hours. 3.5 X 25A = 87.5 Ah which is only 70% of their 125Ah rating.

I just completed testing a new 50Ah rated at 100 reserve minutes and also a 6 year old one. Under a 25A load the new one delivered 28 Ah and the old one 18Ah. Both discharged down to 11 volts under load at the terminals which is as low as I care top discharge them.

100 min. @ 25A should be 41.6 Ah and IMO even the new one would have failed short if discharged to the 10.5V under load point.



Charles
H'mmmm
That's pretty much what I've also found on my wifes electric scooter. many internet sources indicate its hard on these lead acid batteries to repeatedly take more than 50% of their ampere hour rating out of them.

I checked some of those gulf cart batteries on line. Looks like their ampere hour rating drops of to about 60% of the 20 hour discharge rating if you discharge them in two hours.

Checked into those gulf cart batteries. They're designed for this, but they are triple the cost of the 120 ampere hour deep cycle batteries. Ouch.
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Old 02-13-2011, 04:07 AM   #22
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Originally Posted by kyleservicetech View Post
H'mmmm
That's pretty much what I've also found on my wifes electric scooter. many internet sources indicate its hard on these lead acid batteries to repeatedly take more than 50% of their ampere hour rating out of them.

I checked some of those gulf cart batteries on line. Looks like their ampere hour rating drops of to about 60% of the 20 hour discharge rating if you discharge them in two hours.

Checked into those gulf cart batteries. They're designed for this, but they are triple the cost of the 120 ampere hour deep cycle batteries. Ouch.
Sorry to labour a point ..... but if someone would trek on down to a truckers supply point and check out batterys there - you will usually find much better selection and you pay priced per A/Hr size. The batterys are designed to power not only starting the truck, but also all the domestic stuff truckers use on long-haul, the diesel heater, hydraulic tail lift etc.

I know in UK - the pricing is significantly different to usual retail outlets and there gear.

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Old 02-13-2011, 04:37 AM   #23
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Originally Posted by solentlife View Post
Sorry to labour a point ..... but if someone would trek on down to a truckers supply point and check out batterys there - you will usually find much better selection and you pay priced per A/Hr size. The batterys are designed to power not only starting the truck, but also all the domestic stuff truckers use on long-haul, the diesel heater, hydraulic tail lift etc.

I know in UK - the pricing is significantly different to usual retail outlets and there gear.
Yup, in Wisconsin, we've got a company called "Farm and Fleet". They do sell truck batteries, and I've wondered if they are rated for deep cycling. Their prices are reasonable.
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Old 02-13-2011, 12:21 PM   #24
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There we go! Thank you guys, lots of great information coming through!

Good to know there is another Marine Surveyor out there in R/C land. Solentlife, your credentials far exceed mine in the marine field!

I had gotten the impression from skimming through some of the electric information here and at other R/C Forums that a small generator was the way to go. Now I'm leaning towards batteries and will look into truck batteries, we have an L&M Fleet/Farm store in town, so I will look to see what they have.
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Old 02-13-2011, 05:05 PM   #25
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All
I’ve been following this thread and have found it to be very interesting, let me admit upfront that my experience with large batteries has been with cars only. If I need a new car battery I just go to my local mechanic and have the recommended battery installed. I have a generic battery charger in our garage, have had it for years and its been used less than half a dozen times. Hence a lot of what has been discussed is a bit (coughs) over my head though I am slowly figuring things out J

The club field where I’m just learning how to fly, has no AC and no Charging station. Maybe the club will get a solar charging station sometime, but other needs have priorities. Thus my interest in some type of portable charging station.

I will welcome everyones help, along with specific recommendations (as in actual links to products).

Following is what I have come up with for considerations and requirements

1. I have a Camry, a sedan. Hence space is a consideration.
2. Will have to be portable, in that I will need to take from the trunk of the car to the flying field. A distance of about 150 feet.
a. I am thinking to use some type of fold up hand truck, with a box on its side. Place the box on the nose plate of the hand truck, secure it somehow, than put the battery into the box and have the charger on top of the box. Roll the setup to the area near the flight line.
3. I have and will be using a TritonEQ charger.
4. For batteries – I have these Li-Po’s. They would all be charged before I head out to the field. Three each 4S 3600mAh, Three each 3S 3600mAh, Three each 3S 1300mAh
a. Total mAh = 25500 (3*3600+3*3600+3*1300)

b. If I charge each battery once at the field will require 25500mAh
c. If charge each battery twice that will require 51,000 mAh - which could be greater than what can be reasonably expected from one battery. But I welcome input!
5. To charge the Deep Cycle battery when I get back from the field and unload, will use this which I believe was posted someplace by everydayflyer
batterytender.com/battery-tender-junior-12v-at-0-75a
6. What specific battery to use?
I was in Costco and AutoZone yesterday - both have ‘deep cycle’ batteries for sale but neither had the reserve minutes specified. Sales people at both places when asked, returned a blank stare <grins>

Will greatly appreciate guidance and specific products to use.

Thanks!
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