12v 7ah battery charger

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
Hello there,
I have got a toy car for kids which the kids can ride on it and have lost it's charger. I have got a lead Acid battery of 12v 7ah.
I tried to use a normal 12v 2ah adaptor (of my wifi router) to charge the battery but it didn't charge as I kept on charging for about 5 hours and the car won't move for more than 2 minutes and the speed was very slow.
So please can anyone help me out with this.
 

Attachments

Thread Starter

rbwadhar

Joined Apr 25, 2021
16

Attachments

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
As an example only: https://www.amazon.com/NOCO-GENIUS1-Fully-Automatic-Temperature-Compensation/dp/B07W46BX31/

You need an AGM capable charger, or if you can show the circuitry in the car it might be possible to work out the power supply you need.
[/QUOTE
As an example only: https://www.amazon.com/NOCO-GENIUS1-Fully-Automatic-Temperature-Compensation/dp/B07W46BX31/

You need an AGM capable charger, or if you can show the circuitry in the car it might be possible to work out the power supply you need.
My brother have also got similar car and uses the attached charger to charge the car.
 

Attachments

Yaakov

Joined Jan 27, 2019
3,464
Thanks for your reply. Well actually I'm living in sudan and I don't have Amazon here so can't order online. Sending you the photos of the car circuit and board.
That's why I said, "example only". It's hard to tell from those photos, I can only guess. As @crutschow pointed out, you need to have a power supply that has a higher voltage than the terminal voltage of the battery. In this case about 14V and I am guessing that a 15V supply would work.

Wherever you are, you should be able to get an AGM battery charger that will work directly to the battery.
 

Ian0

Joined Aug 7, 2020
3,186
Sudan? I'm guessing it might be quite sunny. 12V solar panels are pretty good at charging lead-acid batteries, provided you disconnect it before the voltage gets too high (14.7V)
 

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
Thanks a lot guys for your help. I will try to get a 14v or 15v adaptor to charge the battery with a 2ah maximum right?
 

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
By the way I tried to charge the battery in my APC UPS 650 and it charged 100% but don't know the power supply of the ups to the battery.
 

Ian0

Joined Aug 7, 2020
3,186
You need at least 13.8V and given the losses in the charger, more likely 15V at a guess.
For cyclic use, the Yuasa manual recommends charging to 14.7V until the current drops to 0.05C, the switching to float charge of 13.8V.
In practice, it works well for new batteries, but if you charge older batteries to 14.7V the charge never drops as low as 0.05C, the charger stays in "boost" at 14.7V until the battery is ruined.
If you charge at 14.7V until the current flattens out, then switch to float, it doesn't damage the batteries.
 

Yaakov

Joined Jan 27, 2019
3,464
For cyclic use, the Yuasa manual recommends charging to 14.7V until the current drops to 0.05C, the switching to float charge of 13.8V.
In practice, it works well for new batteries, but if you charge older batteries to 14.7V the charge never drops as low as 0.05C, the charger stays in "boost" at 14.7V until the battery is ruined.
If you charge at 14.7V until the current flattens out, then switch to float, it doesn't damage the batteries.
He's counting on the charger inside the toy car. It may or may not be so rigorous. I am suggesting something that I don't expect to damage the car's internals. If it's a 15V supply, it should be able to (barely) do the recommended 14.7V charge.
 

Ian0

Joined Aug 7, 2020
3,186
He's counting on the charger inside the toy car. It may or may not be so rigorous. I am suggesting something that I don't expect to damage the car's internals. If it's a 15V supply, it should be able to (barely) do the recommended 14.7V charge.
15V supply won't damage a VRLA battery, provided it is switched off promptly! If it's a switched mode it might not cope well with a flat battery at 11V, unless it's designed for CCCV output.

Have got this adaptor at home if I can use it to charge. See the attached photo.
Unfortunately it's only 9.5V so it won't manage it.
 

Yaakov

Joined Jan 27, 2019
3,464
15V supply won't damage a VRLA battery, provided it is switched off promptly! If it's a switched mode it might not cope well with a flat battery at 11V, unless it's designed for CCCV output.


Unfortunately it's only 9.5V so it won't manage it.
It's plugged into the car, not connected directly. There is a board in the car for charging and it's in a housing so no details.
 

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
Actually the connection goes directly to the battery the red wire goes to the fuse or something like that and from there to the battery +ve connector and the black wire directly to the -ve connector of the battery
 

Yaakov

Joined Jan 27, 2019
3,464
Actually the connection goes directly to the battery the red wire goes to the fuse or something like that and from there to the battery +ve connector and the black wire directly to the -ve connector of the battery
Well then, you can use a 15V dc supply but it won't have any overcharging protection so you will have to unplug it when the battery is charged.
 

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
If you can zoom in the below photo you will see both red and black wire from the charging port at the bottom right, the black wire have 2 connection one goes direct to the battery and the other black wire to the board while the red wire also have 2 connection from the port to the small black box and from there one wire goes to the board and other direct to the battery
 

Thread Starter

rbwadhar

Joined Apr 25, 2021
16
Actually the charger that came with the car had a light which turns on red while charging and once it's fully charged it turns green. Even if I plug the charger pin to the car without inserting to the wall socket it would turn green as it gives currency out from the car as well.
 
Top