FRX4 Custom battery

[Alan Sharkis]

I had a freeze, or lockup, or whatever you want to call it. Since the symptoms after this happens vary widely, and mine were more weird than usual, my dealer asvised me to send it to Roland for service. On the way to Roland, the capacitors must have finally discharged completely, because because when Roland got the accordion and powered it up, it behaved normally and none of what I had added to it was lost.

Since then, I learned a few things:

1. I checked the batteries that were in it. Two of the ten would not charge completely. That explained the lockup. It turns out that the power button on the FR-4x is not a simple switch. It’s what is referred to as a ‘soft power switch,’ meaning that it needs power to power up the accordion. I didn’t know the two batteries were bad, and I left them in the accordion for a couple of weeks without playing it. So, booting up the accordion thereafter, produced the lockup, and removing all power from the accordion cures the lockup.

2. After a lockup, the time it takes to recover from the lockup can vary from a few minutes to days.

3. It is important not to leave batteries in the accordion if you’re not going to use it for a while.

4. It’s just as important to buy a new set of batteries every six months and charge them fully before putting them in the accordion.

I’m a believer in sticking with the batteries suggested by the manufacturer. Anyway, since the accordion doesn’t leave the house anymore, I use the AC adaptor and no longer put batteries in the accordion.

I anticipate that some of you will ask what my lockup symptoms were. Here they were:

Upon pressing the power button, the opening screen came up in the display, but then wouldn’t go further. Pressing a treble key produced no sound until a register switch was pressed. Then, a very low volume, very thin tone would be heard. Further presses of register switches would not change the tone. Pressing a bass button would produce a tone that continued to sound when the button was released, when the power button was pressed (the power button was ineffective at this point) and finally stopped when all power was removed from the accordion. This behavior persisted for two days, after which I had that conversation with my dealer and he suggested sending the accordion to Roland.

 

[dbranko]

next question is, does your battery wizard want to make a dozen of these for sale to
your friends ?

lol

but seriously, we have plenty of FR4 FR3 owners in here to get him some sales

He is from Serbia. He didn't want to mail the battery. I had to travel 280 km in one way from Bosnia to Serbia to buy them. He didn't give me the impression that he wanted to mass produce these batteries. He probably has a lot to do. I understand him because it's a big responsibility to do this for such an expensive instrument (€4000 here). If you are passing through Serbia, I definitely recommend it!

https://www.svetbaterija.com/
https://svetbaterija.business.site/

 

[JerryPH]

My issue with v-accordion batteries is on 2 fronts, how long they last in between charges and high cost. A factory OEM battery here in Canada cost me $450 and lasts 4-5 hours with how I play. A custom battery that I assembles lasts 12-13 hours and cost me $125 not including the work to assemble it or the time it took to bring the parts in.

Now the 8X and 4x have different batteries but I think that what dbranko has looks like a solid battery for the 4x.

 

[John M]

. . .the rolands have a threshold voltage. . .
. . . it is rather important that these things shut down
in a correct and controlled manner, and that roland designed the
low-voltage cutoff in to protect against this . . .

Here are the threshold voltages (I measured on the 8X battery) that correlate to the transition colors on the 8X screen:

"Green" Voltage After Full Charge = 27.82
"Green to Yellow" Voltage = 25.4
"Yellow to Red" Voltage = 24.83
"Low Battery Please Recharge" Voltage = 23.74

At 23.74 V, the 8X still plays normally, but I am sure there is not much time left before "shutdown" with the screen going blank.

 

[Ventura]

that's nice detail !

i think the software in the big ones is a bit more sophisticated
than in the 3x regarding voltage sensing and reacting

 

[Caps]

To me it looks like there is a 12V step down regulator between the battery pack an the FR4x DC input jack. Wouldn‘t that ensure that no over-voltage is applied to the accordion? And I never heard of damage because of under-current. Just curious….!?!

There may be a step down regulator that drops the voltage to 12VDC and it is supposed to keep the full voltage of the battery from the accordion if the battery voltage is over 12VDC. There are also Buck/boost type circuits that will increase the output voltage if the battery voltage falls under 12VDC. The accordion shouldn't get hurt from under voltage as it has protection circuits that shut it down when the voltage drops too low. Under current is not really an issue. Over current is the problem if the circuit doesn't have the protections. As the voltage drops, the current tries to increase to maintain the same required wattage output. This is what damages batteries, especially lithium. There should also be a battery balancing circuit in the battery pack that keeps the batteries charging equally and prevents overcharge and may prevent over discharge. Also the circuit should act as a fuse would if short circuited. This is supposed to keep the lithium battery from exploding if a short occurs. Overall this is a good system if you intend to use a lithium battery pack.

 

[Ventura]

There should also be a battery balancing circuit in the battery pack that keeps the batteries charging equally and prevents overcharge

hey caps

this battery pack caused me to look up some new things from the FPV UBEC Bluesky clues
andi found there are some interesting things on the LiPo side

there are chargers now marked

Lipo Charger 2X Faster Quick Charge 25W 2S-3S RC Balance Charger​

marked 2s 3s 4s which apparently (some at least) have a separate wire pair for each
LiPo cell in your pack (or each paralell pair) and the charger has swtches for amperage
so i guess that is if you have parallel pairs or triplets

so the series connection of the cells for the pack is separate from the charging circuit,
and i am guessing this allows a way faster recharge of the pack than other methods

the info also said LiPo is not quite as dense as Li-Ion for energy, but it has some
other nice advantages, though i would think Li-Ion would help burn through
the armor of those T-55's the Ukraine drones latch onto a bit faster than LiPo