I just need to make sure I have all the parts first before I move onto phase 2:
So far i have this:
pulse spot welder
multi tool wire
Samsung 30Q batteries
Not sure on what type of Solder. Lead or Lead free
not sure on wire’s
or battery life reader
-Need a solid BMS
a good charger?
Led Power switch for board and battery?
Anything I am missing.
Finally a solid link to how to build the battery correctly. It’s my first time.
this bms seems to be the preferred choice at the moment, they’re kind of a pain in the ass to get a hold of. 2 minimum purchase, shipping from china:
look at the modifications made to the bms in the group buy. also, since your pack will have a massive continuous discharge, may want to ask for a bms with at least 100 (or 120) amp continuous discharge rating.
at 12s you’ll need a 50.4v charger, either a laptop brick charger at 2amp or 4amp charger for like $60. shipping from china also.
my 12s4p pack:
you guys are off the Chain!!! Thank you! Will I need to tune the batteries if they are new?
I tested the internal resistance of 80 cells. it ended up being a total waste of time. There were all the same. New batteries from a reputable company should be good to go.
To be honest I am not quite sure why I would need to have up to 120A? Wouldn’t I want to keep it around 60-80 for longer distance. Pleases explain: I know the BMS keeps regulates the current and protects from serges but I thought Ah and or Amps is like the juice to the motors. And I am correct 120A is the max juice that can come out at a time?
ok, your 30q batteries individually are rated at 15amp continuous discharge (many are saying this is understated, they can safely discharge 20amp continuous).
and then you’re building a 6p pack, so your pack’s continuous discharge will be 90amp, with a much higher burst rate.
generally speaking the bms should have enough “head space” to handle whatever your battery pack can output and then some.
the thinking is, if your battery pack continuous discharge is greater than what your bms can handle, you’re just handicapping your battery pack’s true performance. why get a car with 500hp then limit the top speed to 80mph?
your motors will draw a ton of current if accelerating or going up hill or both. in these instances you want as much current available to your motors (provided the vesc is set correctly).
hope that made sense.
for me, i’m building a 4p pack with lg hg2, which have 20amp continous, so my bms is rated at 80amp continuous with like 250amp burst.
The 120A BMS is designed for a 6 parallel pack . So it’s going to have enough discharge capability to keep a 6p pack balanced. But 100A bms is big enough.
Just to throw a curve ball you can skip the BMS and get a balance charger.
Yeah I see a lot of guys using these to regulate their build. But I was hoping to go with a portable charger later on which then I could run into surge problems. Which brings me back to another question Smurf. Why not just go with a portable charger from the start instead of the tekpower? I most likely will have two chargers than? I plan to make a back up battery because of my long commutes but being able to charge the battery while at a location is nice. Is it because of the speed of the tekpower?
Yes perfect! I get it now thank you
also guys what kinda of wire’s and connections will I need?
is that wire going the handle the Amperage? says max 90amps
10 gauge is big enough 8 gauge will be harder to solder up. Needing a powerful iron.
Your basic portable charger puts out 2 amps.
Now a standard charge for a 6P pack is 6 amps which should take like 3-4 hours.
Now that small charger will take like 9-12 hours to charge and some people have reported that the smaller chargers stop charging about a half a volt to early so the BMS doesn’t have a chance to get it’s balancing done. That’s where a lab quality power supply really starts to shine as it’s probably more accurate than your volt meter.
Can someone confirm this?