Modding a ni-mh PSU/charger

[madan1]

Hi everyone.
Is there a way I can mod an original de-walt DE9119 ni-mh battery charger so that it can work with a 4s li-ion bms battery? I guess as is it will not work ( haven't tried it tho ), but basically I want to know if I can tap in and get DC 18-35V from it so that I can use one of those aliexpress dc-dc step-down converter boards with V and C control.
Here are are the schematics of the charger ( see attached ).
I do not know what type of PSU is this but does not look like any of the smps I've seen/fixed.

p.s. I'm adding the datasheet of the IC... which seems to be a microcontroller.. the damn thing starts to look too smart for my needs.

[madan1]

Re: Modding a ni-mh PSU/charger

update - without load it outputs 50Vdc. I don't have a sufficient resistor or other suitable load, so could not test it further.
For now I have put a dc-dc converter board inside, set it to 16.85-16.9V and 1.6A max, connected it to he battery terminals ( the + is isolated from the rest of the board ) and an old 19V 3.5A recapped laptop PSU on the input side.
Haven't drained the drill battery yet, but at 16Vbat the current is something like 0.3-0.4A. At about ~16.6v, the converter board indicates that the battery is charged, but continues to output 0.15A.

Still, would like to get rid of the extra psu and use the internal circuitry to supply the charging board

[stj]

Re: Modding a ni-mh PSU/charger

if the batterys are 18v then just buy a cheap ryobi charger and mod the holder or re-case the board.

some company's sell the chargers for very cheap to encourage people to buy more batteries.

[madan1]

Re: Modding a ni-mh PSU/charger

if the batterys are 18v then just buy a cheap ryobi charger and mod the holder or re-case the board.

some company's sell the chargers for very cheap to encourage people to buy more batteries.

the battery consists of 4x 18650 cells and a 4s bms board similar to this one

I prefer to use the original charger ( or at least its case ) because it is more comfy just to plug the battery in.

[stj]

Re: Modding a ni-mh PSU/charger

well you could bring the terminals out of the case into something like this:
https://www.banggood.com/IMAX-B6-Min...p-1202402.html

[madan1]

Re: Modding a ni-mh PSU/charger

well you could bring the terminals out of the case into something like this:
https://www.banggood.com/IMAX-B6-Min...p-1202402.html

Sure, I could, but costs money, while the laptop PSU is free and the dc converter/charger board is less than a yankee dollar. Also, I'm trying to keep the setup as close to stock as possible... I cannot be bothered explaining people how to use a complicated battery charger. Now one only has to plug the battery in the original charger and wait until the green light starts glowing... and another good thing - the extra psu still fits perfectly in the drill case... but of course it would be better if there were no extra external modules and everything was inside the original charger.

[sam_sam_sam]

Re: Modding a ni-mh PSU/charger

I prefer to use the original charger ( or at least its case ) because it is more comfy just to plug the battery in.

You can BUT you have to use the temperature sensor that was on the battery pack that was there or it will NOT work correctly

You also need to make sure that the BMS protection board that you are using work correctly or could have real big problems ( battery bursting in flames or not charging or over charging )


You need to make sure it works correctly a few times and that you get the exact same results each time

I highly recommend doing this if you have not work with this type of batteries before and even if you have work this type of batteries before I still do this anyway

If you are careless with this type of batteries you might get hurt or burn your house or work shop or shed down I have had some unexpected issues before my self working with these type of batteries

So bottom line please be careful when working with type of batteries

I have a grease gun at work that has nicad batteries in it and I am also going to use li-ion batteries
But I doing it differently I going to use the battery charger that comes with the battery pack and use the case that is for the grease gun and just modify it so I can use it

I will show some pictures of it when I have finished doing this mod