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G-Scale 'Big Boy' - Via WiFi
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 Posted: Mon Jul 9th, 2018 02:13 am
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Steve P
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Si,

Which is the thread I'm on here, so...

After researching on the web all day I think I'm going for:

https://www.maxamps.com/hyperion-eos0720inet3-ac-dc-balance-charger

https://www.maxamps.com/lipo-4850-6s-22-2v-battery-pack

Raymond suggests 22V as opposed to 18v
He measures stall/slip current at 3 amps, so I figure I'll be using more like 2 most of the time.
This figures to about 2 hours runtime.
If I'm happy with the initial battery experience I'll buy a 2nd and keep it charging while using the other.

Any holes in the above theories?

Steve P


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 Posted: Mon Jul 9th, 2018 04:45 am
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Si.
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Hi Steve  :wave:



Yes ... Continuing your Topic here, is good.  :thumb:

The loco, R.C. gear & batteries, all in 1 Topic makes sense. 



As for the type & size of battery-pack suitable for your loco, & chargers etc. ...

... Tony Walsham is probably one of the most experienced here, regarding Large Scale requirements.



Tony ... H E L P !  ???


If Tony doesn't know about it, when it comes to Large Scale train batteries etc. ...  :brill:

... it probably isn't worth knowing.  :)



:cool:



Si.




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 Posted: Mon Jul 9th, 2018 01:28 pm
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Tony Walsham
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Hehe.
Flattery will get you everywhere Si.

I would caution against Li-Po cells if they are to be permanently mounted in the trail car.
Li-Po cells are rarely fitted with protection pcb's and therefore must be removed for external balance charging.
Personally, I would be sticking with Cylindrical Li-Ion packs.
A 6s1p pack would be a minimum with a suitable protection pcb fitted in the pack. 
They can be left in situ for charging.

Cell capacity is commonly 2,600 mah. Higher capacity cells are generally more expensive.
Beware of unknown brands. Quite often false claims have been made.

To increase run time they can be doubled up depending on space available. That would make a pack 6s2p.
All Li-Ion packs need a smart charger that can handle 6 cells.
They are not so common as 4 cell chargers and as a result cost a bit more.




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Best wishes,
Tony Walsham.
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 Posted: Mon Jul 9th, 2018 02:22 pm
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Steve P
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Hi,

I plan to make them quickly removable so that I can be charging one while using the other.
I will keep both in a metal ammo can when not in use.
I will look into adding protection pcbs.

I don't want to double up because of the weight. 
The one I reference above is 1.5 lbs. which will cost me almost a boxcar in pull weight.
Needing to make them quickly changeable,
will be more incentive towards the goal of making them easily store-able in the metal can when not in use.

These go for a premium price but actually come with a "lifetime" warranty, where warranty is 100% first year, 50%  after that. 
I know the perils of cheap Chinese batteries!


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 Posted: Tue Jul 10th, 2018 01:20 am
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dan3192
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I've been running HO scale BPRC engines for the last 5 years. A fellow modeler has asked me to power up a G scale engine for his backyard railroad. Early on I decided to use Li-ion cylindrical cells and have to decide which of two cell types to use. 

For moderate use I can use Panasonic's 18650 x 3400mAh cells in a 6S1P arrangement which will provide about 75Wh of power with a max. recommended current draw of about 3.4A. Peak current draw is 6.8A. The six-pack measures approx. 6 x 4 x 7 cm. Cost is around US$39 with battery holders.

For heavier usage in terms of hours or load or grades, I can use Keeppower's 26650 x 5200mAh cells in the same arrangement which will provide about 115Wh. These cells have a max. constant current rating of 15A and a peak current rating of 30A. This six-pack measures around 8 x 6 x 7 cm. Cost is approx. US$65 with battery holders.

I've found that higher constant or peak current ratings in a battery have the advantage of starting and running better under load due to less voltage sag. The trade off is higher current capacity batteries usually have less total mAh capacity due to different chemistry. 

For example, there is also available a Keeppower 26650 battery with a 4200mAh capacity, but with a constant and peak current rating of 30A and 50A respectively.
Depending on how my friend wants to run, we should be able to decide which way to go. 

In any case, since I have been using both of these batteries for some time , I can highly recommend them in terms of stated ratings and quality of manufacture.

Hope this helps.

Dan    

Last edited on Tue Jul 10th, 2018 01:29 am by dan3192

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 Posted: Tue Jul 10th, 2018 05:10 pm
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Steve P
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Hi,

So you convinced me to try the Li-ion option.

Ordered 6 of the Keep Power 5000mA cells, holders and charger.
Couldn't find a "protection pcb board", suggestions for a model/source?

Also found that all the 4/6 bay chargers on Amazon only handle two 26650 at a time...
Suggestions for true 6 bay 26650 charger?

Steve P


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 Posted: Wed Jul 11th, 2018 12:58 am
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dan3192
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6S battery protection board:

6S Battery Protection Board

For a "true" 6 bay charger, I'm using a Solo 80 6S charger.
Don't know if they are still available, around US$90 with adjustable (slow, of course) charging rates for Lipo, Li-ion, NiMH.
After installation, you'll need the "traditional" 7-wire connection from your engine to the charger.  

Dan


Last edited on Wed Jul 11th, 2018 01:09 am by

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 Posted: Wed Jul 11th, 2018 01:35 am
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Steve P
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Hi,

This is where I get confused...

Are these bcm boards used for building battery packs that can be balance charged as a set?

I originally thought they were for protecting the batteries during discharge/use,
perhaps for safety (ie to prevent them from overheating).

I currently plan to install them individually in battery holders inside the boxcar. 
For charging I would remove and place individually into bays of a Li-ion battery charger(s).

I discovered that the charger I ordered, although "6 bay", can only handle 2 26650s at a time. 
Ordered from Amazon Prime, so it will go back without cost to me :2t:

So bottom line, how to properly charge 6 individual 26650s at a time, with a quality charger that will extend their life,
and,
how to properly install/use in a boxcar without creating a safety/fire hazard running thru my forest.

Steve P


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 Posted: Wed Jul 11th, 2018 10:26 pm
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dan3192
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Hi,

I've created some confusion here by being too brief. Let's back up a little. There are some options.

With those six batteries, you can make a battery pack like they use for race cars and aircraft; 2 high current wires for running your engine and 7 low current wires for balancing the cells. You would likely need to remove the pack and recharge it with a balance charger, like my Solo 80 or similar.

As you mentioned, you can charge the batteries individually and check each one periodically to be sure they are performing as expected. In this case you won't be balance charging, just monitoring battery performance every 4th or 5th time you recharge. But you'll probably want a couple more battery chargers for convenience.

Another way is to use the previously mentioned BMS protection board. Unfortunately, this board does not seem to balance charge, so periodic checking of the individual batteries is needed (for my 2S setup I have a battery checker that plugs into the balance leads that tells me overall voltage and individual cell voltage; it's good for up to 8 cells). But again, with this protection board, via its 2 main leads, you will want a SPDT or DPDT switch to select battery power for operation or external power for charging. The board specs. tell you the voltage required for charging. I think it's 25.5V, so you will need a source for this voltage for this particular BMS protection board.

I think the best approach for you at this time is getting 2 more chargers and removing the batteries for charging. I don't have any idea how they perform, so don't know how much I can trust these boards with my equipment.

Remember to slow charge for longer battery life and to store unused Li-ions at around 3.5V in a cool environment.

Dan

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 Posted: Wed Jul 11th, 2018 11:09 pm
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Steve P
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Dan,

Thats more or less what I thought.

Store at 3.5v,  what is the minimum voltage before causing harm?
Will my engine slow down noticeably before harm's point?
Or do I need to add a voltage measuring tap and/or meter to the boxcar?

Steve P
 

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