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AIY (Assemble It Yourself) Li-Ion battery pack for FR-5/7/7x/8x

pentaprism

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I just received enough materials to assemble a Li-Ion battery pack (the prices below include tax + shipping):

spot welder - $66
I plan to rebuild a bunch of battery packs for my power tools. Instead of buying batteries with tab (thus limiting the sources), I can just buy flat top battery cells and add the tab myself​
batteries - 8 cells - $42
need 7, but bought 1 extra just in case....​
charger - $10
don't want to use the NiCad-NiMH chargers I currently have.​
battery protection board - $7
connectors - $11
thermal protector (metal, 5A, 70 degrees C) - $10

I'm still waiting for the delivery of the heat shrink tube - $8.

Instead, I could buy these:

Custom NiMH Battery Pack: 24V 4500mAh (108Wh, 20x4/3AF, Sanyo) - $185
Thermistor - $2

Or have one built by batteryspace.com, probably about $200. That would be still $50 less than a "used, very good" battery pack from Amazon Warehouse.

But to me, putting the battery pack together is most of the fun.

Wish me luck.
 

Dingo40

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I'm still using extension cords🙂👍
If it doesn't have a cord, it stays in the store!
This is because my past experiences with batteries have not been entirely satisfactory 😐
Fortunately, there's a big supply of excellent, pre-loved corded tools being ditched by owners switching to battery, flooding the market at ridiculous prices, many of them made in real countries like Japan, Switzerland, Germany, even the USA🙂
 
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Tom

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Congrats, cool project! Love my 18" bar battery chainsaw!
 

Dingo40

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My chainsaws are still all petrol driven and to plagiarise a well known slogan) always ready (Eveready) for action, when needed!🙂
 
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Tom

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I don't miss the fuel mixing, spark plug cleaning, starter pulling.... Maybe I should go scratch a reed or 2.
 

Tom

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David, well, I guess that's why my workbench looks like this! They do seem to complement each other in some eay....

Dingo, it's that "regular service" thing! 😀

_IMG_000000_000000.jpg
 

pentaprism

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Good progress so far....

I assembled the Li-Ion battery pack last night, and this morning plugged it in the charger. It took 5.5 hours for the charger indicator to change from red to green. The charger output is rated at 0.95A and the battery pack at 5AH, so that all made sense.

The output voltage of the Li-Ion battery pack fully charged is 29.4V and of the stock Roland pack is 29.5V. That too is good.

I was cautious and added a fuse holder between the battery and the accordion. The Li-Ion battery pack blew the 2A fuse. The Roland battery pack is OK. I put in a 3A fuse and tried installing/removing the Li-Ion battery pack and turning the accordion on/off a few times. It's OK now with the 3A fuse. The starting current is greater with the Li-Ion battery pack but I don't know whether or how much that hurts the accordion.

Now the FR-7b is running in demo mode with the new battery pack. Let's see how long it lasts.


TwoBatteryPacks.JPG


I know it is ugly (my wife said it it looked like a bomb as in the movies). I'm still waiting for the heat shrink tubing.
 
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JerryPH

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I just received enough materials to assemble a Li-Ion battery pack (the prices below include tax + shipping):

Wish me luck.
Good luck!
I made my own battery pack as well and though its not as complete a setup as yours, it works and lasts longer than the factory setup... and cost me 1/4 the price of the factory battery and 1/2 of what the Raines battery cost.
 

Dingo40

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Kep,
I just watched your video clips 😳
I'm just so happy I don't own an electronic accordion!
Being an electronics illiterate , I'd want to be playing it, not sorting bugs in the battery pack, which seem more numerous than fleas on a stray dog!
You're, clearly, an ace technician, and most impressive! (Can't help wondering where you did your training?🤔, most obviously not Australia 😆)
Thanks for a most impressive exposition .
Well done!🙂👍
 

kep

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Kep,
I just watched your video clips 😳
I'm just so happy I don't own an electronic accordion!
Being an electronics illiterate , I'd want to be playing it, not sorting bugs in the battery pack, which seem more numerous than fleas on a stray dog!
You're, clearly, an ace technician, and most impressive! (Can't help wondering where you did your training?🤔, most obviously not Australia 😆)
Thanks for a most impressive exposition .
Well done!🙂👍
Just to clarify: I'm not the guy who made the research & videos (I wish I knew that much!). I initiated the whole ado and provided my accordion and batteries to him.
 

Dingo40

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OK, sorry: my mistake!😕
Still, very good videos and thanks for sharing!🙂👍
 
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pentaprism

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@pentaprism, please be careful with Li-Ion! Without BMS it's a risky business.

Thanks, kep, for the head-ups.

BMS is this item in my initial post. Also see photo below.

battery protection board - $7

BTW, the accordion has been running for 16 hours. I have to set the volume at 25% to save my wife's (and my) sanity. But I think that's sufficient to confirm that the battery cells are indeed 5000 mAH.

Also, note that other battery packs have 3 wires because they are planned (not necessarily optimally) to use the Roland charger, designed for NiMH battery packs that have the 10 KOhm thermistor.

I use a Li-Ion "smart" charger. No thermistor is needed. My battery pack has only 2 wires.

Update: the run time was 16.5 hours at 25% volume setting. The battery voltage when the FR-7b went silent was 22.2V.

 
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Mr Mark

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Cool stuff, going to have to figure out something for my FR3s. Hadn't played it in awhile and a bunch of the fancy new rechargeable Nimh batteries I had bought are now toast, plus they really don't last very long when they did work!
 

pentaprism

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Here's the final result.

I did this for the fun of it more than for anything else. There is a simpler and less costly way for FR-7 battery. Let's save that for another thread.

BTW, the hump in the middle of the battery pack is the BMS mentioned by @kep in a post above.

FR-7LiIonBat.JPG
 
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stu

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Hello all
Stu here
I've Just joined the forum and see we have a few DIY battery enthusiasts here.
Glad to meet and to see I'm not the only one who likes to tinker.
I hope you don't mind me trying to use your experience...
I have a question about the Roland FR7 battery I hope one of you can answer...

My original battery still works ok for 2 hours or more so I don't want to mutilate it yet but would like to build a copy before I have to replace it.
I would like to stay with NiMH.

There is a 3 wire connection from the battery pack to the instrument.
Does anyone know what is inside the pack apart from the NiMH batteries?

Pentaprism mentions a 10k thermistor, would that be all (and how is it wired) or is there a more complex circuit?
Perhaps one of you can help me out here.

Best wishes to all
Stuart
 

JIM D.

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Just save the wiring on the old battery pack and replace the batteries with new NiMH batteries -- the originals are Sanyo industrial types.

The gents that are using LI-ion replacements are just waiting for an costly accident to happen.

 
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