Sony BP-100 Repair With Gum Stick Batteries

biomayhem

Hi everyone,

My first post in this forum and I'm a newbie trying to repair an old BP-100 battery that no longer holds charge.  I know Kaosun has a repair service to replace old lead-acid battery cells in BP-100 with Li-Ion cells.  However, this requires modification to the CD player as well to work properly.

I want to keep my D-Z555 original so is it possible to replace the old lead-acid cells with the Ni-MH gum stick batteries?  The ones available are 1.2V, 1450 mAh, and 1.74Wh.  So if you link 5 of these batteries in series, you get the 6V and 1450 mAh, which is within the range of the original BP-100 rating (6V, 1000mAh).  You can actually fit 6 of these gumsticks in series but the voltage would be higher than original at 7.2V.

So my question is if this is a feasable route and could this battery be charged by connecting to the CD player without modification?  THanks for your help.

kaosun

Hi Joseph,

Connecting 5 pcs of gum Ni-MH batteries will be the simplest way to repair the BP100 battery base. Also, no modification to the D555. You can share your experience how you repair it on the forum. Thanks in advance!

rubberratt

Hi There Everyone,

I'm a new user and I just did this exact modification to my BP-100 yesterday.  It worked !!!! I have a little over 6v coming out of the battery now, and it powers the discman.

BUT !  I tried to charge it overnight and the charging indicator never went off.  so it charged almost 12 hours.  

Is this Normal?  Any advice ?

Thank You !
Rubberratt

*** update 3:22pm 3/9/19
Battery ran 5.2 hours on an overnight charge - not too bad.
Now charging again - will report back
On scond charge and still supplying power after 3 hours3/21/19 second charge nearly 6 hrs, now on 3rd charge

kaosun

The battery's voltage increases by charging so the difference between charging voltage and battery voltage is getting smaller. Therefore, the charging current reduces gradually. It depends the voltage of the charger, a suitable voltage can stop charging exactly when batteries are fully charged. Your solution is budget efficient except the charging issue. The issue I mentioned is the huge current at very beginning of the charging due to big voltage difference which generates excessive heat, evaporates H2O from cells and finally shorten battery's life.  Unless a constant electrical current charger is designed for the battery, the charging time and life can be guaranteed.

rubberratt

Thank You very much for this excellent answer Kaosun !  The battery pack had been charged twice and during charging... the pack feels cool to the touch. after 9 hours or so?  It feels a tiny bit warm

I have been charging it on the bottom of my CD player, that uses the Sony AC-930A.  How much voltage should be coming out of the AC-930A?  I measure 11.3V with my volt meter, is this too much voltage?  

Also do you have a way to supply a charger that can do what you say - design a contant current charger ;)

Thank you

biomayhem

Hi rubberratt,

Could you tell me how many batteries did you use?  I tried to link 7 in series (I know Kaosun suggested 5) but was having trouble making good connections between batteries as the contact points were difficult to solder.  So the project was shelved and I totally forgot about it until now.  Could you let me know how you did it?  Thanks.

biomayhem

Nevermind.  I was able to finally solder the batteries together by first sanding both terminal of each battery.  Solder would finally stick after sanding but the - terminals needed more sanding the the + terminals.

Anyway, soldered 5 gum stick batteries in series and it works.  Five sticks were enough to power my D-555 and D-25.  On to rebuilding the BP-2EX

kaosun

I found several chargers:
1: https://www.ebay.com/itm/1846812 ... V23lohoCWbkQAvD_BwE

2: https://www.ti.com/lit/ds/symlin ... product%252FBQ24401