Lipo batteries and large scale RC

[PaulRhB]

I've successfully used small Lipo batteries to RC a 009 loco and I'm now wondering about trying a larger G scale loco so I've been looking at bigger batteries to supply enough power.

Using a Deltang receiver I found these intended for RC cars. The Deltang unit can deal with up to 18v so a 4 cell Lipo seems the max and should be plenty to power up a sound unit as well.

https://www.hobbyking.co.uk/hobbyking/store/uh_viewItem.asp?idProduct=15521

Now I understand what the connectors do for charging etc but just wanted to check that these will be suitable for long duration output rather than the fast and high drain of a racing car, any info much appreciated

[Roddy Angus]

Hi Paul

 

You should not have any problems using these LiPos for low currents.  Problems are normally about the maximum discharge rate not the minimum.  Just be careful that if you are using them for low powered motors that you don't accidently over discharge them because the fall off in performance might not be as noticeable.  Hobbyking do sell some cheap low voltage warning devices (for a couple of pounds or so) and use of one of them might be a useful safety precaution.  I assume that you are aware of the risks associated with damaged or over discharged LiPo batteries.

 

Regards

 

Roddy

[davetheroad]

That battery is a 5000mAh unit that can give a continuous output of 20C. That is 100amps for 3 minutes!!! or more reasonably 1amp for 5 hours. It should love the slow discharge rate in a loco. This will depend on how many amps your loco draws when pulling its full load of wagons etc. Deltang have receivers that can deliver 6 amps so that should not be a problem. The sound installation will need power as well.

[davetheroad]

Hi Paul

 

You should not have any problems using these LiPos for low currents.  Problems are normally about the maximum discharge rate not the minimum.  Just be careful that if you are using them for low powered motors that you don't accidently over discharge them because the fall off in performance might not be as noticeable.  Hobbyking do sell some cheap low voltage warning devices (for a couple of pounds or so) and use of one of them might be a useful safety precaution.  I assume that you are aware of the risks associated with damaged or over discharged LiPo batteries.

 

Regards

 

Roddy

If you use a Deltang receiver these have low voltage protection built in. For a 4S lipo you will need to program the Rx so the LVC (low voltage cutoff) is set to manual and at the voltage you require. The Rx will monitor the output from the battery and stop the loco when the voltage drops below the threshold. Time to replace or recharge the battery!.

 

for progamming I use Deltangs 'Prog4' which needs a special usb cable. These are readily available online. You also need a program to download the command file to the Rx. i use 'Coolterm' and it is free and works well. I use notepad to write the command files, for example download this to the Rx

 

type 3

7,2,3,12,0

end

 

should set the Rx to cut the power when the voltage drops below 12V, equivalent to 3V per lipo for a 4S battery.

[Joseph_Pestell]

This is one of those threads that could be written in Chinese for all that I can understand it.

 

But it sounds very promising for a garden layout.

[PaulRhB]

Thanks guys, yes I'm well aware of the care needed for lipos and the advice about programming will be invaluable. I just needed to check I wasn't missing anything and I'd relied on the built in setting before for the single cell. I'd rather know this in advance so I can avoid damage and I usually remove the battery to charge in metal tin purely for safety. I'll look into the program stuff more but the Deltang 3A standard output is sufficient for the motors and sound card as I tested this for dcc.

[PaulRhB]

This is one of those threads that could be written in Chinese for all that I can understand it.

 

But it sounds very promising for a garden layout.

I'm picking it up one bit at a time Lipos have advantages in that they don't have memory so they can be recharged before they run out but they really don't like being run flat which can damage them and lead to spectacular failure, flames etc! As a result a little care makes them ideal for always being ready to go rather than having to run them flat first like you would with nicads. If you bear the safety limits in mind they are very versatile.

[a98087]

They great for locos, I had my lgb stainz loco running for 2 hours on a 3s 1000mah battery.

 

It helped that I had removed the pick up brushes to improve the rolling resistance.

 

And I only use the battery with a low voltage alarm (99p on eBay). As I left a RC battery wagon on once and one if the 3 cells now reads 0.0v and won't accept a charge

 

Dan

[PaulRhB]

Hi Dan, it's the site you recommended that I've been checking. Fancy the S&T tech knackering the battery!

[CME and Bottlewasher]

Hi Paul

 

You should not have any problems using these LiPos for low currents.  Problems are normally about the maximum discharge rate not the minimum.  Just be careful that if you are using them for low powered motors that you don't accidently over discharge them because the fall off in performance might not be as noticeable.  Hobbyking do sell some cheap low voltage warning devices (for a couple of pounds or so) and use of one of them might be a useful safety precaution.  I assume that you are aware of the risks associated with damaged or over discharged LiPo batteries.

 

Regards

 

Roddy

Hi Roddy, Im still getting to grips with LiPo and Li Ion batteries and the safety issues

 

This is one of those threads that could be written in Chinese for all that I can understand it.

 

But it sounds very promising for a garden layout.

Im not that far ahead of you - so dont worry.

 

Thanks guys, yes I'm well aware of the care needed for lipos and the advice about programming will be invaluable. I just needed to check I wasn't missing anything and I'd relied on the built in setting before for the single cell. I'd rather know this in advance so I can avoid damage and I usually remove the battery to charge in metal tin purely for safety. I'll look into the program stuff more but the Deltang 3A standard output is sufficient for the motors and sound card as I tested this for dcc.

Paul, wont it be a chore to remove the battery from the loco?

 

Would another battery type be better, one that allows you to keep the batteries on-board whilst charging - just a thought.

 

ATVB

 

CME

[PaulRhB]

I think the hard case version in a lipo bag will be safe enough with the right charger in locos that are difficult to get into. The only issue with NiCads is you needs to discharge fully each cycle so you can't top up for extended running. Nimh can stand a bit of abuse but take time to recover to full performance again.

The 7/8ths stuff I really want to use this on extensively will be built so the body comes off with one screw making access easy in a few seconds. The G scale loco above is a test bed really as its wheels are poor for pickup so it will be a good chance to test the technology out and have a loco easy to take to friends railways.

[CME and Bottlewasher]

I think the hard case version in a lipo bag will be safe enough with the right charger in locos that are difficult to get into. The only issue with NiCads is you needs to discharge fully each cycle so you can't top up for extended running. Nimh can stand a bit of abuse but take time to recover to full performance again.

The 7/8ths stuff I really want to use this on extensively will be built so the body comes off with one screw making access easy in a few seconds. The G scale loco above is a test bed really as its wheels are poor for pickup so it will be a good chance to test the technology out and have a loco easy to take to friends railways.

Ah that makes sense - I see what you are aiming for now - thanks for the clarification.

[davetheroad]

The dangerous issues with charging Li-ion batteries is really not relevant to model railway use. For flying planes

the fastest recharge times are often desirable. Putting all that energy into a battery quickly could result in a fiery or explosive

result if the safety rules are not followed.

 

for model railways we can charge at lower rates, below 1C for example. Charging a 5000mAh battery at 1C would mean using a 5amp charger

which should recharge the battery in about 1 hour. For railways we can recharge at rates lower then 1C. In any case, if you are using anything 

other than a single cell lipo using a balance charger is common sense. this will ensure all the cells in your battery pack are charged to 4.2V each

and the battery does not overheat during charging.

 

I remove the batteries for charging with a 300millamp charger on a ceramic work top but if I needed to charge onboard I would have no worries

about it.

 

Li-ion batteries have the best energy densities and their nominal 3.7V output per cell means we can use less of them!.

[CME and Bottlewasher]

The dangerous issues with charging Li-ion batteries is really not relevant to model railway use. For flying planes

the fastest recharge times are often desirable. Putting all that energy into a battery quickly could result in a fiery or explosive

result if the safety rules are not followed.

 

for model railways we can charge at lower rates, below 1C for example. Charging a 5000mAh battery at 1C would mean using a 5amp charger

which should recharge the battery in about 1 hour. For railways we can recharge at rates lower then 1C. In any case, if you are using anything 

other than a single cell lipo using a balance charger is common sense. this will ensure all the cells in your battery pack are charged to 4.2V each

and the battery does not overheat during charging.

 

I remove the batteries for charging with a 300millamp charger on a ceramic work top but if I needed to charge onboard I would have no worries

about it.

 

Li-ion batteries have the best energy densities and their nominal 3.7V output per cell means we can use less of them!.

Thats useful to know Dave, I have heard before that in locos the strain on the batteries is a lot less than in an AC.

 

What concerns me is that the user/owner seems to have to obtain the correct charger and calculate the best charging rate - not having used Lipo or Li-Ion batteries or chargers it is hard to ascertain if such is fact or merely assumptions on my part.

 

I am also guessing that many RTF RC toys are now powered by cheap Lipo or Li-Ion batteries and use equally cheap chargers, leaving the batteries on board all of the time?? The tech is certainly used in !:1 scale High Tech cars and AC these days and they dont take the dozens of cells out to charge them (having a safe charging tray/bay on board?).

 

ATVB

 

CME

[Roddy Angus]

Hi CME

 

Charging is not as complicated as it first appears.  There are a number of chargers which are very easy to use and work using a touch screen.  If you have a look at the Hobbyking site they have a good range of chargers.  I use the X120 120 watt touch screen smart 6S balance charger which is easy to use, you will find a link to the instructions on the product page.  It does need a 12v source, either a car battery or a power unit.The main things to remember are that it is best to charge at a maximum of the one hour rate, they can be charged faster but there is a greater risk of problems, and never leave a charging battery alone.  If possible, it is best to charge outside and I would recommend the use of a fireproof  safety bag.

 

If you Google charging LiPo batteries there is plenty of advice but it does tend to be of the scary variety as very few people report that "I charged my batteries tonight and nothing went wrong".  RC aircraft and helicopter sites have the best advice as they have been using these batteries under high power applications for the longest.

 

Roddy

[davetheroad]

The charging control circuitry can be built into the model or built into the charger. In both cases this will limit the charge to 4.2V per cell.

 

I use Deltang receivers which have low voltage protection built in but nothing to control charging the battery. For charging I use an

E-flite Celectra external charger that is designed for the small batteries I use. Other makes are available including those that balance the cells

during charging. The new Acc+Ess Protocab system has an onboard loco charge circuitry board available but you need one per loco?

 

Hobbyking have a large range of chargers available,

 

ps - i could charge my batteries in the loco with the addition of a switch and socket. When I try converting a Jinty 0-6-0 tank I might have to do that.

[CME and Bottlewasher]

Hi CME

 

Charging is not as complicated as it first appears.  There are a number of chargers which are very easy to use and work using a touch screen.  If you have a look at the Hobbyking site they have a good range of chargers.  I use the X120 120 watt touch screen smart 6S balance charger which is easy to use, you will find a link to the instructions on the product page.  It does need a 12v source, either a car battery or a power unit.The main things to remember are that it is best to charge at a maximum of the one hour rate, they can be charged faster but there is a greater risk of problems, and never leave a charging battery alone.  If possible, it is best to charge outside and I would recommend the use of a fireproof  safety bag.

 

If you Google charging LiPo batteries there is plenty of advice but it does tend to be of the scary variety as very few people report that "I charged my batteries tonight and nothing went wrong".  RC aircraft and helicopter sites have the best advice as they have been using these batteries under high power applications for the longest.

 

Roddy

 

 

The charging control circuitry can be built into the model or built into the charger. In both cases this will limit the charge to 4.2V per cell.

 

I use Deltang receivers which have low voltage protection built in but nothing to control charging the battery. For charging I use an

E-flite Celectra external charger that is designed for the small batteries I use. Other makes are available including those that balance the cells

during charging. The new Acc+Ess Protocab system has an onboard loco charge circuitry board available but you need one per loco?

 

Hobbyking have a large range of chargers available,

 

ps - i could charge my batteries in the loco with the addition of a switch and socket. When I try converting a Jinty 0-6-0 tank I might have to do that.

Thanks for the helpful and reassuring advice guys it is greatly appreciated - some of the sites, as you say, offer nowt but scare stories.

 

Thanks also for suggested suppliers - always useful.

 

Kindest regards,

 

CME

[fallen]

The chargers for model locos can be quite inexpensive since what costs the money is (mostly) the ability to deliver high charging currents which is what the aircraft people want and what we do not. So a cheap charger will only deliver a low current, which is good for us, whereas for the high currents you need for aircraft use, you tend to have to pay rather more.

 

This is a simplification, since expensive charger may have better low current control (although quite a few do not) but you can certainly charge one to three cells at low currents with a fairly cheap charger.

 

I use a simple single cell charger that costs less than £10, and runs off a USB socket so can be used from a phone charger. It normally charges at 500mA but can be adjusted with a soldering iron to charge at 100mA which is fine for smaller cells.

 

Frank