Adding battery to 48v setup

[starway]

Hello,

I have a gng mid drive 60v controller and i am currently using it 48v if i wanted to use it as 60v what would i have to add on? as the battery is alreasy 54v hot of the charger. How would i connect it also? as i am currently connecting everything with these terminal barrier connectors i had some lying around.


Are these connectors ok to connect my controller to my battery with as thats what i am currently doing and it seems to be fine. I even have a wattmeter inside the chain so it looks like this .


Are these standard terminals-ok for leaving everything connected? Its working now perfectly but i just wondered with all these different amp ratings for the terminals and sockets that i might be doing something wrong. I dont know the amp rating of the terminals i used.

Now if this is ok to connect everything could i just connect another battery into the screw terminal like this
and then everything would be fine ? And what battery would be good for an already existing 48v lithium ion 15ah battery.

thanks for any help thats provided im trying to learn as much as possible

 

[starway]

Anyone ?

 

[inedible]

In your third illustration you've put the new battery in parallel with the old one. This won't give you more voltage, it'll give you more capacity. To increase your voltage to 60v, you'll want to add a 12v battery in series with your current battery.

Like this:

With a lead acid battery this is all you need to do. With a lithium battery though, you're going to need to figure out how you're going to charge it. You'll also probably want to match the capacity between the packs. If you're using a 15ah battery now, you'll want your additional battery to be 15ah as well.

 

[starway]

Ah ok that makes more sense thanx for taking the time to answer. If I'm using lithium can't I just charge both batteries with their own charges ?

So basically to get 60v I would have to get a 12v battery with 15ah and wire it how you showed me? And then figure out how to charge it ? I thought the 12v lithium would come with its own ?

Thanks for your help

Starway

 

[inedible]

Okay so, a lithium battery is made up of many cells. Depending on the chemistry, each cell is somewhere between 3.6 and 3.8 volts nominal. They're "dead" when they reach 2.8-3v, and they're fully charged at 4.0-4.2v.

So, technically, there is no such thing as a 12v lithium battery. A "3S" lithium battery, that is, one with three cells in series, is the closest you're going to get. These are 11.1 volts.

The thing about lithium batteries, the reason I'm explaining this, is that they need to be "balanced". That means, each cell in the battery must be individually charged to the same voltage. If one cell is much higher or lower voltage than the rest, it could violently explode into a giant fireball.

Now, I'm not sure how many cells there are in your current battery, since 48 doesn't divide evenly into 3.6 or 3.8, but anyway. You're currently charging your pack at 54v, using something like 13 balance connectors. Your new charger should be charging at 66v with 17 balance connectors. See what I'm saying?

As for mixing a 15ah capacity battery with a different capacity battery, if you're charging them independently that's no big deal, however it makes it difficult to figure out how much life you have left on the batteries by looking at the voltage. If you misjudge this, you can over-discharge one of your packs below 3v per cell, permanently damaging it, increasing the chances of explosions or just plain ruining the battery.

 

[starway]

I see , my current battery has a bms would this stop the problem of one battery potentially unbalancing and I'm guessing both batteries would need a bms ?

This is more complicated than I hoped !

Thanks again for your time and brain power !

Starway

 

[inedible]

Yeah it's not exactly straightforward.

You'll either need a separate BMS for your second pack, or you could just use a balancing charger and charge it separately, or you could get a larger BMS that would cover all the cells of both batteries.

If you get mismatched packs where one has significantly different capacity than the other, a good enough BMS would compensate for that. Another thing I suppose you could do is have separate volt meters for each pack.

 

[dnmun]

Anyone ?

yep, you really should stop. if the idea of wiring up a 12V battery in parallel with a 48V battery doesn't bother you then you need to stop and read more.

 

[999zip999]

Don't know your battery on hand, more info needed. But just use it and enjoy.