Battery pack for FR-7/7x/8x



Battery pack for FR-7/7x/8x

Postby pentaprism » Thu Feb 09, 2017 8:22 pm

Related thread: FBC-7 Eliminator

This post was initially intended to be in this thread because I'd like to clarify some points raised in the thread. But then I thought it was deserved its own thread.

JIM D. wrote:... the 24 volt battery pack for the Roland models FR-5, 7, 7x & 8x "ARE NOT" made from the normal AA batteries that we use . The 20 batteries in these battery packs are a larger industrial size with much more capacity.


Correct. The size of the cells in the pack is actually "4/3 Fat A" (18mm diameter x 67mm height). Its storage capacity is 4,000 - 4,500mAh. You can see a listing here.

JerryPH wrote:I am willing to bet that the batteries in the Roland won't exceed the capacity of the Eneloop or PowerEx batteries.


You lost the bet, Jerry :lol:

JerryPH wrote:Something is not right, 4500 divided by 20 cells = 225mAh per each battery... that sounds super low, maybe I am just not calculating that correctly??

If I am, 20 Eneloop batteries would equal 50,000mAh... and that would be like 54,000mAh for the PowerEx batteries!


When combining batteries, you multiply the voltage (series configuration) or you multiply the current (parallel configuration). You can't do both.

Each of the cell in Roland pack is 1.2V, 4,500mAh. A pack of 20 will either has 24V, 4,500mAh, or 1.2V, 90,000mAh (there are mixed configurations but let's leave them out for now). The cells in Roland pack is in series configuration, thus 24V and 4,500mAh.

For my FR-7, I used this battery pack, which is half the size, half the weight, and half the capacity of the Roland pack. It gave me about 4hr of playing. I used packing foam in the battery compartment so that it wouldn't move around:
IMGP4931.jpg


A friend of mine needed a spare battery pack for his FR-7x so I gave it to him.

Now I'm using this as a back-up. This (vs a dedicated 24V battery pack) is better for me because for my other hobby (photography), I have a lot of AA rechargeable battery cells, which sit idle most of the time. In the photo, one cell is removed so you can see the temperature sensor (arrow tip). The charger reads the temperature and stops charging at 60°F.
IMGP5045.jpg


It's a tight fit in the FR-7 battery compartment:
IMGP5042.jpg


The battery pack can be charged by the Roland charger (in the FBC-7). I prefer to use the slow charger (500mA), however:
IMGP5044.jpg


Or in-situ with a home-made adapter:
IMGP5046.jpg


Of course I can remove the AA cells from the pack and condition/charge them individually with my Maha charger.
Last edited by pentaprism on Tue Mar 14, 2017 7:26 pm, edited 1 time in total.
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Re: Battery pack for FR-7/7x/8x

Postby JerryPH » Thu Feb 09, 2017 9:17 pm

pentaprism wrote:
JerryPH wrote:I am willing to bet that the batteries in the Roland won't exceed the capacity of the Eneloop or PowerEx batteries.


You lost the bet, Jerry :lol:

It's not the first nor the last... and this was also before I had my 8X (Feb/2016, I got my 8X in Nov/2016 and researched on it in more detail).

The batteries, if you open up the factory original are identified as oriental made batteries with a model number of 18670's. A quick search confirms that they are 1.2 volt, 4500mAh and the size matches those in the Roland. You can get individual batteries HERE for very good prices for a DIY solution or HERE for about 1/2 the price of a Roland battery. If you have a low confidence level in Asian products, there is always the #1 place to go to... the inbox of JimD. Last place for me at least, would be to call Roland. ;)

pentaprism wrote:When combining batteries, you multiply the voltage (series configuration) or you multiply the current (parallel configuration). You can't do both.

Learned that too. :)

pentaprism wrote:For my FR-7, I used this battery pack, which is half the size, half the weight, and half the capacity of the Roland pack. It gave me about 4hr of playing. I used packing foam in the battery compartment so that it wouldn't move around...

That's so counter to my way of thinking. The big V-accordions are already so light, and true feather weights compared to what I normally play and that savings of under 1 pound is not going to be felt. Now, if I could find a battery pack that gave me 10% or more play time than factory, that would make me happy.

I'd never consider a system that cut it by 50%, but of course, that is me. Also, be careful of what kindof foam you use. Some foams have a very low flammable catch point and emit poisonous gases. Batteries when used get hot... you as a photographer must have used a flash hard one time, then switched out the batteries and felt how hot they can get if used hard. It's not as bad in a V-accordion, but they do get quite hot if used down to the end, something a lot easier to do with only a 50% of factory duration. :)

pentaprism wrote:Of course I can remove the AA cells from the pack and condition/charge them individually with my Maha charger.

I like that feature in the MAHA pro chargers but when it comes time to recondition my batteries, I recondition and use them for my home remotes and other uses and get new PowerEX 2700's for my photography equipment.

You deserve commendation on some great DIY on your 7X, there is a lot there that should have come from the factory that you improved on and really extends the useable life of your V-accordion... awesome job. :)
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Re: Battery pack for FR-7/7x/8x

Postby pentaprism » Thu Feb 09, 2017 9:48 pm

JerryPH wrote:Now, if I could find a battery pack that gave me 10% or more play time than factory, that would make me happy.

I've been thinking of Li-ion battery but currently, playing only at home, I have no excuse/incentive to spend money/time on the experiment.
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