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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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View Poll Results: How do you charge up your field battery?
I use an AC home car/boat battery charger. 9 52.94%
I use the same charger that I use for my flight batteries (using an AC power source). 3 17.65%
I use my car's engine to charge it. 0 0%
I don't have a field battery, I use the regular battery in my car. 4 23.53%
I use another method (explain). 1 5.88%
Voters: 17. You may not vote on this poll

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Old 11-14-2013, 04:11 PM   #1
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Default How do you charge your field battery?

I'm talking about the [usually] lead-acid car or deep cycle battery used to power the charger for your flight batteries now, not the batteries in your plane. How do you charge it up for a day's flying?

Obviously if you don't use a battery as a power source for your charger (perhaps your field has AC power, for example) then this doesn't apply to you.

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Old 11-14-2013, 04:45 PM   #2
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When I used a Wet Cell Lead Acid battery - I used a normal car battery charger. But not if it's a MotorCycle one - that needs something a little less stressed !

You can use your LiPo charger ... my imax B6 charges Lead Acid nicely.

I now have a SLA and you cannot use a standard car battery charger if you value the SLA ! So now mine gets a charge from my B6 ... or from my car battery charger that has manually variable amp rates etc. - not your normal Walmart job - this is a pro job I had for trucks and cars in my company.

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Old 11-14-2013, 06:15 PM   #3
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Originally Posted by FlyWheel View Post
I'm talking about the [usually] lead-acid car or deep cycle battery used to power the charger for your flight batteries now, not the batteries in your plane. How do you charge it up for a day's flying?

Obviously if you don't use a battery as a power source for your charger (perhaps your field has AC power, for example) then this doesn't apply to you.
FYI
Make certain your 120 (or 240) VAC lead acid battery charger has a deep cycle model on it. Most quality lead acid battery chargers do have this feature.

I've got a Sears Craftsman 10 Amp charger that was on sale for about $45 that has been doing the job very well.

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Old 11-14-2013, 07:17 PM   #4
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Originally Posted by kyleservicetech View Post
FYI
Make certain your 120 (or 240) VAC lead acid battery charger has a deep cycle model on it. Most quality lead acid battery chargers do have this feature.

I've got a Sears Craftsman 10 Amp charger that was on sale for about $45 that has been doing the job very well.

Denny ... Deep Cycle - TRUE Deep Cycle batterys are common on boats and RV's - they are charged just same as standard car traction battery's.... by engine alternator and when no engine - by shore / external powered chargers..

It's the Gel Cell versions that need a different setting ... (to some who think otherwise : note that Gel Cell does not necessarily mean SLA).

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Old 11-14-2013, 07:27 PM   #5
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I voted in the --Use regular battery in my car --spot, but that is not exactly how I am set up.

I had the top of a car battery explode in front of my face one time, and I will never forget how much it hurt, and how terrified I was, that I had lost a finger.
I had twisted the battery lead clamp, and it made a spark smaller than we get clipping a charger to the battery posts.
I cringe and hold my breath every time I see someone clip directly to their battery.

I have a Ford F250 Diesel truck. It has 2 large new batteries in it, wired in parallel. I ran a fused 6 gauge lead from the drivers side battery to the rear corner of the truck, terminating in a power box with several types of connectors for different peoples chargers. I could deliver 75 amps if I wanted to.

I have flown all day, charging mine and several other peoples batteries, and the truck starts like nothing happened. My astro chargers show me the truck voltage if I am not charging so I always know if I do pull my truck batteries down. So far I have not came close to discharging them.

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Old 11-14-2013, 07:38 PM   #6
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Exclamation Please be safe.

If you do use and connect directly to your car battery, please do it as follows.

1-- connect the positive lead to the car battery
2-- touch the negative lead to a bare spot or bolt somewhere at least 12" away to charge the capacitors in your charger.
3-- then quickly move the clip to the negative terminal

This should stop the spark many chargers cause when we clip the to the battery.

I don't want anyone losing a finger or an eye to an exploding battery, we need those things to fly.

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Old 11-14-2013, 07:42 PM   #7
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Originally Posted by kyleservicetech View Post
FYI
Make certain your 120 (or 240) VAC lead acid battery charger has a deep cycle model on it. Most quality lead acid battery chargers do have this feature.

I've got a Sears Craftsman 10 Amp charger that was on sale for about $45 that has been doing the job very well.
So deep cycle batteries (especially SLA) DO require a special charger, I was wondering about that! So simply hooking it up to your car to charge it would be a bad idea, I assume.

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Old 11-14-2013, 07:47 PM   #8
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Originally Posted by Wildflyer View Post
If you do use and connect directly to your car battery, please do it as follows.

1-- connect the positive lead to the car battery
2-- touch the negative lead to a bare spot or bolt somewhere at least 12" away to charge the capacitors in your charger.
3-- then quickly move the clip to the negative terminal

This should stop the spark many chargers cause when we clip the to the battery.

I don't want anyone losing a finger or an eye to an exploding battery, we need those things to fly.
Most cars nowadays are like my Volvo ... there are terminals provided for cable connection to avoid going direct to battery posts. Batterys give of flammable gasses and sparks over them can ignite.
If you must use battery posts themselves ... then only connect +ve lead ... then -ve lead connect to vehicle body or engine mount / block away from battery ... there is no need to do #3 as quoted above.

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Old 11-14-2013, 11:04 PM   #9
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Originally Posted by solentlife View Post
Denny ... Deep Cycle - TRUE Deep Cycle batterys are common on boats and RV's - they are charged just same as standard car traction battery's.... by engine alternator and when no engine - by shore / external powered chargers..

It's the Gel Cell versions that need a different setting ... (to some who think otherwise : note that Gel Cell does not necessarily mean SLA).

Nigel
Ni Nigel
Agreed, but some of those "Lead Acid" battery chargers are not worth what it costs to make their nameplate.

If you have a Deep Cycle battery setting on your charger, you've got some security that the will stop charging when the battery is fully charged.

I found out the hard way, when one of those cheap 5 Amp chargers put over 16.5 Volts DC on my battery after it was topped off. It was left in the garage with that charger powered up for several weeks. That charger did not have any voltage regulation. That boils the water out of the lead acid battery, and if your battery is sealed, there is no way to replace it. I had to replace the battery.

As for boat batteries, automotive batteries and so on, their alternators have very tightly regulated voltage outputs that prevent this sort of damage.

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Old 11-14-2013, 11:45 PM   #10
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Solar cells. 60 watts of cells on top of my airplane trailer. 2 deep cycle marine batteries. Upgrading the system to 4 batteries and 105 watts of solar cells this winter. This will put me at enough battery capacity on the trailer for 6 charges of my 12S 5000mah + several charges of lesser planes, every week without plugging in to the wall.

I installed a system with 40 watts of cells and 2 marine batteries at the club field too. Plenty of power for field charging the glows a few years ago... not keeping up with the electrics now.
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Old 11-15-2013, 12:16 AM   #11
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Originally Posted by fhhuber View Post
Solar cells. 60 watts of cells on top of my airplane trailer. 2 deep cycle marine batteries. Upgrading the system to 4 batteries and 105 watts of solar cells this winter. This will put me at enough battery capacity on the trailer for 6 charges of my 12S 5000mah + several charges of lesser planes, every week without plugging in to the wall.

I installed a system with 40 watts of cells and 2 marine batteries at the club field too. Plenty of power for field charging the glows a few years ago... not keeping up with the electrics now.
If you've got a Harbor Freight store nearby, they had some good sized units on sale last week.

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Old 11-15-2013, 08:21 AM   #12
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Originally Posted by kyleservicetech View Post
Ni Nigel
Agreed, but some of those "Lead Acid" battery chargers are not worth what it costs to make their nameplate.

If you have a Deep Cycle battery setting on your charger, you've got some security that the will stop charging when the battery is fully charged.

I found out the hard way, when one of those cheap 5 Amp chargers put over 16.5 Volts DC on my battery after it was topped off. It was left in the garage with that charger powered up for several weeks. That charger did not have any voltage regulation. That boils the water out of the lead acid battery, and if your battery is sealed, there is no way to replace it. I had to replace the battery.

As for boat batteries, automotive batteries and so on, their alternators have very tightly regulated voltage outputs that prevent this sort of damage.
I agree that the cheap chargers are suspect and only good for connect and then disconnect after an overnight to prevent damage.

Reasonable auto-chargers that drop from 5 - 6A charge to trickle maintenance on full-detect are cheap enough ...

Deep Cycle should not require any different charger to a standard car battery - it is same format only less but softer thicker plates basically to withstand the deeper discharge.

To those who don't know the difference between a standard cranking (starter) battery and a Deep Cycle :

The cranking battery used for starting your car has thin hard plates ... lots of them to give maximum surface area to provide amps for turning over the starter. The problem that being thin - plates will buckle and deform when pushed deep in discharge ... and is why they fail usually on one cell when deeply discharged. There is no cure for it .. a buckled plate is permanent.
Cranking batterys are designed for immediate charging and not for standing part discharged, they also are designed to receive high rate charging - ie your car alternator. Some RV's / boats have boost alternators that deliver over 100A rates....
Note that standard engine alternators do not charge to 100% but usually cut back at about 90 - 94% to be safe.
Do not discharge a cranking battery lower than about 70% point too often ... that is 30% used power.

A deep cycle battery has less plates but thicker to resist the deformation of deeper discharge ... but don't ask me why - but manufacturers make them softer ... that means you cannot safely make them provide high power amps without risking damage to the plates. The surface area is a lot less than a cranking battery and this creates extreme high stress.
Charging is same as a cranking battery but advised NOT to use the boost rates as the plates will not tolerate this too often.
Discharge of a Deep Cycle is not advised lower than 50%.

There are 'middle-road' batterys that are designed to cover both jobs ... and these are what are usually in many posts referred to as Deep Cycle ... unfortunately Dealers sell them as Deep Cycle - so perpetuating the mis-naming. Designed to keep RV and boat people happy so they can run lights and domestics as well as start their engines ... they are not a bad alternative. But don't expect massive amps draw or real deep discharge - they are a compromise of both ...

Where do I get all this 'crap info' from ? A lifetime of boats and RV's (caravans we call them in UK) ....

OK - so whats best ? Honest answer ? None of them !!

You can rush out and pay out a lot of money and have good service ... so much for my post here ! But I can go out and spend a lot less than you and get just about as good ...

How ?

a) Car breakers yards ... they sell 2nd hand batterys. Just because cars smashed doesn't mean batterys no good.
b) Truck supply dealers ... they sell batterys designed to start diesels and also power the hydraulic tail-lifts
c) Golf cart batterys - usually in 6v form ... connect a couple in series to get 12v.

If I've helped even one person with above - I'm happy.

Here's a couple of books that are good on the subject ...

http://www.amazon.co.uk/Practical-Bo.../dp/0713661496

the above gives good description of batt types along with charging etc. It also shows the cheat alternator trick to get 100% charge from an alternator when you have diode splitters.

http://motoren.ath.cx/menus/electrical.php

An older but valuable reference ...

They may be for boats ... but it applies to Lead Acid batterys.

Cheers
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Old 11-15-2013, 08:41 PM   #13
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[QUOTE=solentlife;930716

A deep cycle battery has less plates but thicker to resist the deformation of deeper discharge ... but don't ask me why - but manufacturers make them softer ... that means you cannot safely make them provide high power amps without risking damage to the plates. The surface area is a lot less than a cranking battery and this creates extreme high stress.
Nigel[/QUOTE]

Yeah,
I've found that none of these Lead acid batteries work very well, or very long when recharging my giant scale models 12S2P A123 cells. Not when my Cellpro chargers are pulling 50 Amps out of the lead acid battery.

As for "True" deep cycle batteries, they do exist. But, it's really going to hurt your wallet. These deep cycle batteries are used in electric utility substations as their substation backup batteries.

One 12 Volt unit I found was rated at about 150 Ampere hours, weighed 175 pounds, and cost over $700! Discharge that $$$$ battery at 50 Amps, and its only good for two hours, or 1/2 of its discharge rating at 20 hours.
The top line in the attached datasheet shows how many hours this battery will last at different discharge currents. Note some of the huge batteries at the bottom of the list! Before retiring, I've seen some of those 3000 ampere hour cells. You'd better believe they are HUGE!


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Old 11-17-2013, 03:34 PM   #14
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Originally Posted by Wildflyer View Post
If you do use and connect directly to your car battery, please do it as follows.

1-- connect the positive lead to the car battery
2-- touch the negative lead to a bare spot or bolt somewhere at least 12" away to charge the capacitors in your charger.
3-- then quickly move the clip to the negative terminal

This should stop the spark many chargers cause when we clip the to the battery.

I don't want anyone losing a finger or an eye to an exploding battery, we need those things to fly.
Better yet, I would use a jumper cable as a go between. With the other ends of the it well separated and far away from the vehicle's (or field) battery connect the positive ('hot') lead to the battery lead first, then the other lead to a grounded part of the car well away from the battery. Then you can connect the charger to the other ends of the jumper cable well away the vehicle battery and completely safe from igniting anything.

You could even make a special connector from a couple of large metal bolts screwed through a wood plank. Clamping the outboard ends of the jumper cable to them would insure that they don't get accidently knocked together when you're connecting the other ends to the battery and car causing a short.

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Old 11-17-2013, 03:42 PM   #15
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So, in order to keep this one on topic, regarding the discharge abilities of different types of batteries maybe I should start another thread on which would be 'best' for field charging (assuming a 50 amp charger draw)?

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Old 11-17-2013, 06:11 PM   #16
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Originally Posted by FlyWheel View Post
So, in order to keep this one on topic, regarding the discharge abilities of different types of batteries maybe I should start another thread on which would be 'best' for field charging (assuming a 50 amp charger draw)?
If you're going to pull 50 Amps out of your 12 volt lead acid field battery, from my personal experience, that will not work out well. At those current levels, the RATED ampere hour capacity of these lead acid batteries will drop to about 1/3 of the normal 120 Ampere hour rating of a big deep cycle battery. And, you will be fortunate to get a years life out of them.

Putting two 120 Ampere Hour lead acid batteries in parallel is a step in the right direction, something I did for a year or so.

But, now, what I'm using is a Harbor Freight 6 Hp gas engine, and an 80 Amp automotive alternator. That's been working very well for the past two years.

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Old 11-18-2013, 07:44 AM   #17
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Originally Posted by FlyWheel View Post
So, in order to keep this one on topic, regarding the discharge abilities of different types of batteries maybe I should start another thread on which would be 'best' for field charging (assuming a 50 amp charger draw)?
50A draw ? That's a high load if sustained for any battery to suffer ...but of course you haven't said how many A/Hrs you need ...

Once we know how many packs and what size they are - then we start to look at battery capacity and then we look at sustained amp load.

To look at a smaller example ... my 7A/Hr SLA can supply my B6 charger at its rated max of 5A ... for under 1 hour (leaving enough charge in to not seriously damage the battery)..

That would basically give me 2 x 3S packs of about 2200 size. (Something I would never do - but used it as example only).

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Old 11-18-2013, 09:12 AM   #18
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Max i have tried to pull so far from 2 X 120 AH marine batteries:

2 X 4S 5000 mah being charged at 5 amps on a Hitec X2 400, plus 4 X 3S 4000 at 3.6 am[s (max charger output) using Hobby King Quatro, plus 3 X 3S 1800 at 2 amps using Turnigy 420 chargers plus 2 X 4 cell NiCd RX packs at 2 amps using Hitec Quick Peak MK II.

The batteries were being boosted by 4 X 15 watt solar panels. Call it 4 amps. They held up well enough not to trigger the Quatro's low input voltage shutdown. (typically triggers at a slightly higher voltage than the X2's low input voltage shutdown.)

The rest of that day I was charging just one or 2 batteries at a time at rates that the solar panels could almost keep up with.

Part of the key to my system is the panels help prevent the marine batteries from being pulled below 11.5 volts.

I am adding 3 more of the 15 watt panels and changing to 4 X 80 ah LiFeMgPo4 batteries. I'd be able to run an inverter and operate some lights and the refrigerator in my house, if needed, from the solar system then.
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Old 11-18-2013, 06:20 PM   #19
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Originally Posted by solentlife View Post
50A draw ? That's a high load if sustained for any battery to suffer ...but of course you haven't said how many A/Hrs you need ...

Once we know how many packs and what size they are - then we start to look at battery capacity and then we look at sustained amp load.

To look at a smaller example ... my 7A/Hr SLA can supply my B6 charger at its rated max of 5A ... for under 1 hour (leaving enough charge in to not seriously damage the battery)..

That would basically give me 2 x 3S packs of about 2200 size. (Something I would never do - but used it as example only).

Nigel
Yeah, that's one of the big disadvantages of the giant scale electric models. What to use to charge the models batteries.

It isn't to bad with LiPo's, since they pretty much require a one hour charging time. So, a 5S 5000 Mah Lipo would be charged at about 5 Amps, and 21 Volts or so. That is about 12 Amps out of a deep cycle battery. Double that for for two of those 5000 Mah LiPos in a giant scale model. That 24 Amps is pretty close to pushing it on a 120 Ampere deep cycle battery. Stocking up on a box full of 5S 5000 Mah LiPos for more flying time is going to get expensive quick.

Problem is, my models use those permanently installed A123's that are charged in 15 minutes. That puts the current pulled out of your 12 Volt battery at 50 Amps. And the problems are just beginning.

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