LiFePo4 charger for 120V

[brainzel]

hi,

I'm seraching for a charger for my upcoming batterypack.
38 pcs. of 3,2V Skyenergy SE120AHA LiFePo4 cells, which will have an overall voltage of 121,6 Volt.
I read much about BMS and charger, but didn't found the perfekt charger up to now.
At the moment I think about 38 chargers, which would charge every single cell on their own.
With a simple cellboard on each cell, that checks a maximum voltage (3,6V), I could shut down every single charging-progress.
So the batteries would all be reloaded to the same point untill the chargers all shut of one after the other.
Thats my thought ...

The solution has to be not too expensive. So the complete "out of the box"-components would surely be to expensive to me.
If there is a better way or if someone has a comonent-link that bringst me near to my target, then please let me know

thanks, Michael
PS: sorry for my bumpy englich

 

[Patriot]

I'm almost thinking that backing off to 36 cells (3 sets of 12 cells), giving you a total of 115.2vdc may make your life alot easier.

Then, you could easily go with 3 x 36v LiFePO4 chargers, charging each set of cells in series. You could run 3 x 12channel BMS boards, one for each charger. The chargers would have a 44v output for balancing your cells.

Sacrificing 5-6 volts would sure make it easier to set up.


if you really want to get that 120v, then going with a slightly higher voltage cell would do it. I personally use Headway cells, which average around 3.4 volts each. So, a 36s setup would give me 122.4Vdc.

 

[frodus]

Michael, did you buy through EV Components? Either way, PM me, we can discuss a solution....

 

[dnmun]

you will need almost 140V DC in order to charge 38S, travis has the best advice, and then you will be able to have the BMS control the LVC in each of the 3 packs.

 

[brainzel]

I'm not defined on 120V, but there is a time at conversion, where you have to make a decision.
I took 120V because of the next logical step up from 96V.
Most of the examined conversions are at 96V, 120V, 144V.
96V would result in a higher current, 144V was to expensive (LiFePo4 cells), so the choice felt on 120V.

Three charger is an alternative to a big one or 38 small.
Is there a affordable charger in your mind?

And yes, I ordered my batteries just at evcomponents.

 

[dnmun]

i guess i don't see the logic. how much voltage will your controller handle? that should be your concern.

when you say 120V do you mean 120V or do you mean 40S of lifepo4 which requires 146V minimum to charge?

or is this gonna be SLA?

 

[Doctorbass]

contact ecitypower ( bmsbattery)

they sale these charger


Doc

 

[brainzel]

I decided to buy a Zivan NG3.
Thanks to all.

 

[dnmun]

not fair, you have another identical thread about this too, you may wanna stop and talk to travis first. seems like you have made a lot of assumptions which are gonna make problems for you.

 

[brainzel]

?? Sorry, I don't want to anger someone. I decided to make my order in germany, because of several problems like, currency, shippingcosts, taxes, customs duty ...
My other thread belongs to a completely other topic (BMS/LVC/HVC). That's the next step after choosing my charger.
Please don't be cross with me

 

[GGoodrum]

For the purposes of charging, a 120V setup is 40 LiFePO4 cells, not 38. These cells optimally are best charged to 3.65V, so you either need one big charger, that maxes out at 146V, or you can use 2-3 lower voltage chargers in series, like a 72V SLA charger (max of 88V...) and a 48V version (58V max...). In this case, I'd have two BMS boards, one 24-channel, and a second 16-channel version. If you used one of our "DIY" BMS setups, you could do one 40-channel version, by adding a second 16-section board to the main 24-channel version by simply connecting the six bus lines between boards. In a larger EV, like this, there's likely room to use the higher shunt current levels, with the 3.9 ohm resistors. This will allow about 1A of shunt current.

-- Gary

 

[brainzel]

Many thanks, Gary!
I ordered 38 cells, so this is my limitation of voltage. If they "only" have 3V like in your calculation, it would be 114V at all. That's ok I hope.
My circuitry understanding is a little bit rusty, but I still can handle my soldering iron :wink:
Most suitable is a list of components and a layout, so I can "frizzle" my circuit together

Where can I get your channel-boards or layouts, Gary?

 

[GGoodrum]

Many thanks, Gary!
I ordered 38 cells, so this is my limitation of voltage. If they "only" have 3V like in your calculation, it would be 114V at all. That's ok I hope.
My circuitry understanding is a little bit rusty, but I still can handle my soldering iron :wink:
Most suitable is a list of components and a layout, so I can "frizzle" my circuit together

Where can I get your channel-boards or layouts, Gary?

Okay, with 38 cells the "nominal" voltage will be around 121-125V, and you will need to have a supply/charger that maxes out at 137-140V. Most of these high-end chargers are progammable, so you should not have a problem getting one set to this voltage.

The BMS boards are available here: http://www.tppacks.com/products.asp?cat=26. There are links there to a full set of assembly/test instructions, and a "bill of materials" parts list. You can cut'n paste these BOM text files into Mouser.com's BOM ordering tool.

-- Gary

 

[frodus]

if he got the Zivan, I'm pretty sure it has to be factory programmed.....

so if he ordered it, he'll be shipping it back to Zivan to get it programmed for lifepo4

 

[dnmun]

nobody is mad at you, just a rule that people only create one thread for their problem. we actually do try to help people and not trash them.

you may want to stop now and reconsider. i'm not sure why you need to go nonstandard, but you may wanna take some time to learn more before buying a lotta stuff which may or may not work together. especially if you are 'rusty' with a soldering iron because gary's board is a challenge for many, especially newbies without electronics experience. but can also be educational to learn from.

if you wanna go to 144V, why not use 3 48V packs in series? or 2 72V packs? did you already ship? travis knows this stuff and i am sure he will help you get everything lined up if you just email him. no need to do it out here either.

 

[brainzel]

The charger is directly ordered at the german distribution of Zivan and is programmed just at the moment.
The decision to run with ~120V and not ~144V was a matter of costs and a limit of components (controller,motor) which I got very, very cheap.
The batteries are on their way (I hope they are :wink: ). So no turning back 8)
I made a long way to this point, so thats not a blindfold idea (perhaps I expressed myself mistakable).
There are several conversions which runs in an akin line-up, so I just want to get the best (and affordable) things together.

I am thankful for any help and opinion (also the dunning ones ). Every written comment to my post is appraise and at best learning.

@ Gary: I will look at your link today and see if I dare to make it with this boards. I surely have some upcomming questions Many thanks.