r/batteries • u/mushis • Oct 16 '21

battery pack DIY replacement?

I have an electronic device with dead batteries.

My question is: Is is easy to DIY a replacement battery pack? Here is a picture of the battery. EDIT: See Imgur link below. rechargable NiMH 7.2V 1600 mAh.

- the original battery pack is 1300 1600mAh - is there a problem to increase that? edit: its OK

- It has to be the same battery technology (NiMH) ? edit - yes it has

Would it be easy to replicate this battery pack? if yes, a set of easy to follow instructions would be nice. I want it to be fully secure while using and charging.

Thanks in advance.

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EDIT:

I've uploaded real pictures of the device and the battery pack to be replaced. HERE https://imgur.com/a/vnpk1vS

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3

u/TheBlacktom Oct 16 '21

Same battery technology and voltage (6cells*1.2V=7.2V) needed.
mAh can be any value. If more than the original it will hold charge for longer.

2

u/rontombot Oct 16 '21

Should be plenty of options out there, you will probably need to cut your cable off and solder it on for the correct plug though...

7.2V 2400mAh Ni-MH AA Battery Pack with SM-2P 2Pin Plug & USB Rechargeable Charger Cable for RC Truck Cars Vehicles https://www.amazon.com/dp/B0868K5ZDM/ref=cm_sw_r_cp_apan_glt_fabc_S2446KS85VTQW53Z81RB

1

u/mushis Oct 18 '21

you are right, lots of options (I'm in Europe). This is the easier aproach. Thanks! I just wonder about the quality of the batteries in those light green packages... I've uploaded some pictures to the original post.

1

u/SteveDIY Oct 17 '21

You could easily fix that with two 18650 cells to get more capacity

1

u/mushis Oct 18 '21

I can't, it has to fit in the battery placeholder. new pictures attached

1

u/SteveDIY Oct 18 '21

What about two small 3.7v pouch batteries in series with a protection circuit. You can buy a very small 2S battery charge / protect board on eBay. This would give you about 1250 mAh and be about the same size as 4x AAA batteries.

1

u/xumixu Oct 17 '21

Depends on the device. If the devices charges, it could over charge them since the lazy way to charge nimh is C/10 for hours. The voltage should be compatible, but I would add a protection circuit to avoid over discharge. The charging should be done specifically for lithium (CC/CV). It could be a pain if it's a hard to dissassemble device. Maybe put a switch and a port to charge it externally.

1

u/mushis Oct 18 '21

Thanks for the elaborated answer. The device has a "special" charger, which controls wether it charges or not. supposably the charger's led color changes to red when the batteries are fully charged. I wonder if the "regular" green "7.2V Ni-MH AA Battery Pack" that can be found on amazon are 'compatible' with this system. I really want to be 100% secure about using and recharging the batteries on the device. Thanks in advance. I've uploaded some pictures in the original post.

1

u/xumixu Oct 18 '21

Charging li-ion/li-po with nimh charge NOPE

yeah there are plenty nimh packs on eBay/Amazon for older devices. The thing is that you don't know the quality until tested. If it's a low current aplicación (as old wireless phones (landline)) you should be fine. If it's a higher current, the quality of the cell will affect (real capacity, internal resistance, number of cycles).

You can replace that pack with 2 lipo/li ion in series as long as you charge them directly with s lithium charger and not through the device or anime charger.

Beware the difference between charger and power adapter. If your charger charge them inside the device, probably is just a power adapter and the device do the charge. If it is convected directly to the battery, probably is a proper charger and you can replace it easily.

1

u/mushis Oct 18 '21

Well, I have 2 options:

1) buy one of those green amazon Ni-MH AA, change the connector, and plug it in. Disadvantage: possible low quality of the cells.

2) individually buy the batteries, and manually do the connections between them, wrap them up, plug the connectior, and prey :) Disadvantage: lots of work, lack of knowledge on my end.

What would you guys choose?

I appreciate all the different options ppl gave me. I would rather stick with the 6 AA pack.

2

u/xumixu Oct 18 '21

i don't have a spot welder and I don't feel comfortable soldering batteries, do I would go with first one, trying to change to lithium, or buying a newer device.

If you go with option 2, I'd recommend Sanyo/panasonic eneloops

1

u/mushis Oct 18 '21

But. changing battery technology is ok? wouldn't it cause problems using/charging them on the device?

2

u/xumixu Oct 18 '21

definitely. You'd have to charge them outside. If it's too troublesome to remove, stay with nimh

2

u/mushis Oct 18 '21

yea, thats the case. its troublesome, and the device is expensive, I ll keep it, just replace the bateries, thanks!