Discussion in 'Power Electronics' started by AprilSteel, Jun 20, 2018.
I like the use of cutting boards
Found that right BMS for a 24 Volt LiFePo4 system with the right cut-offs ,free postage and cheap $USD13 to $22 .
Also with the one input and output I can parralel them up for more amps
The very important specification called "Capacity" is missing from this cheap Chinese junk.
It gives the spec's for a "protection circuit" but does not say it has one.
EDIT: Sorry. I see that it is a BMS, not a Lithium ferrous battery. Some of us say "protection circuit" and others say "BMS".
Still at it huh ! Duh ! Most of what you are buying uses cheap Chinese junk . Wake up and get with it. I'd also add that the cost of postage of anything from the States to anywhere else is exorbitant and unconscionable.
No, a Protection circuit as you call it is to me ,a PCM Power Control Module or if you like Protection Control Module , all it does is when tripped , channel some small current through a bunch of resistors as heat to reduce voltage across a single cell of 3.2V. I will put a picture of a PCM below
A BMS or Battery Management System seems to be used when a more complete protection is needed . It disconnects the charge when high or low voltage limits set by the chip are exceeded . It also has a bleed off system similar to a PCM as the voltage is rising under charge but not yet over the set high voltage.
Just an update in Feb 2019
My 50 Amp hour 24 Volt LiFePo4 battery has been running very well for 12 months now .
There is no corrosion . No acid spills . The capacity if anything has increased slightly .
I charge it from two house solar panels in series giving me 62 Volts or so in and the MPPT charger gives 15 amps charge in from 10 to 11 am and its full. I have seen it at 18 amps on semi clouded days
I obtained a "Celllog8" 8 cell monitor which does LIFEPO4 and LI-ION and set to LFP it gives me an accurate view of the state of charge of each cell , high and low vell voltages and an alarm .
The 8s BMS for $20 is working excellently .
The 500 watt inverter has not missed a beat.
If I turn off the solar input my TV using 170 watts will run for 10 hours.It draws about 5 amps.
Solar on I can run all through my awake hours with my desktop PC on also.
So I commend this system to you as the battery system we have all been waiting for .
My next foray is up to 3000 watts capacity with the same cells only larger at 240 Ah and a 3Kw Inverter. It will be 48 Volts so 16 cells .
Here is an instructable I did on the 24Volt system above.