ghetto mod toy car battery?

[BUDFORCE]

So my nearly 3 year old son got a remote control car off a neighbour, its a.. well one of these:

https://www.amazon.co.uk/Nikko-1994...19&hvtargid=pla-385264639823&psc=1&th=1&psc=1

It uses a 6v 700mah battery, a little like this although this one isnt an exact match:

https://images-na.ssl-images-amazon.com/images/I/51E5QVcr2tL._AC_.jpg

**Do Not Hotlink Images **

The battery though is knackered, doesnt hold charge for very long at all, its also pretty rubbish in terms of capacity even at full health, the one in his car is 700mah as new.

I took 4 AA batteries and held tham up against this, and note they would easily fit, I am wondering, if I opened the thing up, if I would find just a set of AA batteries in there? Anyone tried it?

I have 2000 mah 1.5v AA batteries right here, they are 1.2v, but if I put them 4 of them in serial thats 4.8v and 8000mah! Infact looking at the size of the box, it'd probably fit 5 of those AA batteries which would then match the voltage and give a whopping 10,000 mah.

I mean one of the instructions on the battey itself states: Do not dissamble or remodel the Ni-Mh - surely that is a challenge?

And I did just look on ebay fpor a replacement or like for like copy, official Nikkon battery was like £30 - no thanks, and the only other 6v batteries I could see where lead acid for like small motorcycles, infact I am sure my first motorcycle had a 6v battery.

 

[BUDFORCE]

Id never heard of 18650 batteries, they are 3.7v so 6.4v in serial, reckon that'd be ok.

Do you need a specific charger for them?

Edit: Damnit 7.4v I can't add up!

Reckon 7.4v would kill it?

 

[BUDFORCE]

Ok first things, my clear lack of electronics, of course, batteries in serial only multiply the voltage not capacity, doh!

So I opened it up, it is literally 5 AA batteries in serial with metal plates over the poles and a insulation pad to stop it shorting.

Should be easy to directly replace with new NiMH batteries.

EDIT, even better, found a pre-made 6v battery pack (which is literally still 5 AA batteries) but 2500mah capacity and thats done the majority of the wiring for me, plus it was cheaper anyway as you cant really buy 5 AA batteries without having to buy 2 packs of 4.

 

[BUDFORCE]

Makes you wonder how they got such a low capacity to start with, I've not seen any AA rechargeable batteries that are less than 1000mah capacity.

Cheap batteries.

I don't even know why they do it because I couldn't easily find a replacement for sale, so would indicate they are not trying to sell additional batteries.

Unless they just don't want the toys lasting too long so you have to buy new ones maybe, I don't know.....

 

[BUDFORCE]

Yes li-ion needs a special charging approach - for a single li-ion battery you can use a cheapy tp4056 based board but for multiple batteries you need something really designed for the job - if you have all new batteries you can get away with charging them in parallel from one board but if one of the batteries changing properties substantially things can go badly wrong.

Though li-ion/li-pos etc. are regularly used in remote control vehicles, etc. I'm not a fan as they aren't exactly good at handling kinetic impacts and can potentially catch fire. NiMH is far simpler and safer.

If you do go that route there are loads of options for voltage regulators that can provide the right voltage output through buck/boost operation but you'd need to match the current requirements.

I'm just at going to replace it like for like 6v NiMH all be it higher capacity. But thanks for that post it's interesting definitely learning stuff.

 

[BUDFORCE]

Oh yeaa!!!!!!!!!!!!!!!!!!!

So battery pack arived, soldering part was easy but jamming the thing back into that plastic case took some effort as new battery pack was just ever so slightly wider plus with the extra wires, it did require cutting sections of the plastic out, quite forcefully jamming it all in, and some parcel tape applied very tightly to strap it up, but I have to say the thing is fatastic now, weve been driving out in the garden for 10 times as long over the grass everything, it still hasnt run out, its been turned off now for another day.

 

[BUDFORCE]

Your sig makes me wonder why you're here asking us and not McGuyvering already!

It's a lyric from Skid Row - Youth Gone Wild.

I change my sig now and then always quotes from rock music lyrics I'm due a change soon

 

[BUDFORCE]

OK.

After the sucess of the first battery mod, I am wanting to give this another go. I also have an older RC car, that I bought for my now (nearly) 14 year old, when he was....I dunno, 6 or 7 maybe.

They run on a similar battery pack, but this time 7.2v nimh, the battery pack is very similar so pretty sure it'll just be the same as the last one all be it 6 cells (basically 6 AA batteries) in a row rather than 5, 1.2v x 6 = 7.2v which is the battery packs rated voltage, the stated capacity is 1000mah, but again, these batteries are OLD, so I doubt they are even that.

However, this time, rather than getting a like for like nimh battery pack and getto modding it into the existing plastic case I think I will try those 18650 batteries on go lithium. Those are 3.7v, so if I use 2, thats 7.4v which I will risk. What I might try is, get a 2 cell holder wired in parralel like this :

https://www.ebay.co.uk/itm/18650-Ba...475059?hash=item2a9f506ef3:g:LOoAAOSwkDtcWf8~

And then buy 2 18650 batteries and a charger. I know they wont charge from the toys own charger, I am not even going to attempt that. So my plan is, take the plastic battery case apart, take the existing nimh cells out, hot glue that 18650 battery holder as linked above inside length ways, solder the ends of the wires to the inside of the contact points in the plastic case so it still fits in the car. Probably just need to cut a whole in the top of the plastic case so I can get the batteries in and out, I know it'll sit a bit proud in the existing plastic case, but I think it'll be ok.

Edit: battery pack wired in serial*

 

[BUDFORCE]

Well, all went well. Car works great now, although the stated capacity is 3000mah, vs stock battery 1000mah, I wouldn't have said it lasted quite 3 times as a long..... and as per the above post, they were ebay lithium 18650's....... so who knows the actual quality......that being said, I didn't charge them at all yet, so maybe they were not fully charged in the first place, I'll stick them on to charge shortly one they have cooled down and give it another go on the weekend.