Combine two batteries in parallel electric scooter it's safe ? (18650LG)

[alex5454]

Hi, I just joined the forum and would like to ask you a question.

I wanted to put into practice a video seen on youtube but I would like your opinion if it is a possible thing or there are some contraindications.

I have an electric scooter with this battery:



- Li-Ion (30 cells) type LG 18650

- Rated voltage (VDC) = 36

- Maximum input voltage (VDC) = 42

- Nominal capacity (Watt hour) = 280

- Battery capacity 7.8 AH



the battery to be put in parallel would always be a 18650 (40 cells) with the voltage always 36 V maximum 42 V only which is 12.8 AH of capacity therefore greater

by making a bridge with negative positive (a "Y" connection), the only precaution they make is before connecting them that both the battery packs have the voltage equal to 42V ...

that's enough? an operation of this type what could then result when the battery is seen as a single battery? and when I go to discharge them as they discharge ..

I would like your opinions .. by logic I would have a single 7.8AH + 12.8AH battery works like this?



this is the video https://www.youtube.com/watch?v=FwoLKFaMraI -------- it's safe ?



(in the video they show the extra battery can be from 12.8ah or 10ah I'm interested in the concept anyway.)



Thank you very much for any answers.

 

[Overclocker]

https://endless-sphere.com/forums/viewtopic.php?t=83141

i have investigated this on another forum.

tl;dr: ok to mix

 

[sbj]

...I would like your opinions .. by logic I would have a single 7.8AH + 12.8AH battery works like this?....

It is exactly like that.

I assume, the original battery does not have single cell monitoring (or BMS)?
Then nothing speaks against it.

 

[fivemega]

Your battery pack is 10 serial, 3 parallel.
You will get best of it that all batteries are:
1- Same chemistry.
2- Same capacity.
3- Same age. (or all new)
4- Same number of cells in each series. (10 series).
5- Make sure each battery is charged at same state of charge before connecting to each other.

You can make as many as 10 cells in series (36 V) then connect them in parallel.
Obviously if you using same charger (same rate), charging time will be longer since total capacity is higher.

 

[alex5454]

but when they run down, can I load them from just one door, keeping the packages connected to each other?

 

[sbj]

By "load" you probably meant to charge. Yes, both can stay connected when charging.

 

[Fusion]

https://endless-sphere.com/forums/viewtopic.php?t=83141

i have investigated this on another forum.

tl;dr: ok to mix

Do have a wiring diagram for those ammeters? I bought some to wire into my electric motor bike but don't know how to wire it up. Needed something to show the state of charge for the lipos so I don't over discharge them.