Extremely Noob question about charging time for a single Chins 12V LiFePo battery

[sunshine_eggo]

the main feeder cables from the batts to the shunt / DC breaker and then back to the inverter are 16mm sq
the link cabel betwwen the two batts is a 70mm SQ

all crimped with a professianal crimp tool

are you thinking voltage drop? i can go and measure across the cables to see if there is anything significant?

Ensure proper torque. 16mm should be fine for the 20A you're pulling, but it would be a good idea to check for voltage drop.

The low set point seems to be set too high at 25.5. You may have cable and fuse/ breaker volt drops to also deal with.
Any DC breaker in the feed is suspect unless a quality item.
Try reducing to a lower value, 24.0 volts or even lower at 23.5 volts.
28.5 volts charge may be causing BMS protection to cut off the charge.

Mike

Agree with this. Wanted to check connections/cabling first before I mentioned it.

Your charger also appears to be like the Growatt that starts at low voltage and immediately terminates once high voltage has been achieved - no absorption. If that's the case, you should raise your charge voltage to 28.8V to make sure you're getting close to full charge.

 

[rgormley]

The low set point seems to be set too high at 25.5. You may have cable and fuse/ breaker volt drops to also deal with.
Any DC breaker in the feed is suspect unless a quality item.
Try reducing to a lower value, 24.0 volts or even lower at 23.5 volts.
28.5 volts charge may be causing BMS protection to cut off the charge.

16mm2 cable has 0.025 volts drop per meter at 20 amps so the cable itself shouldn't be an issue.

Mike

had to go to sleep last night ...
anyway this morning measured the volt drop across the entire system
batt volts 27.1 pushing 18 amps into the batts
see the attached photo it shows all the voltage drops in mV across each section. measured on the bolt or connection ternimal screw
inverter/charger powmr hms-3k-24v yeah i know.....buy crap get crap.... but it`s so far so good! mppt works well

 

[rgormley]

--udate 4:15pm--

pannels been in full sun all day
have the bulk charge set to 28.6 and the float at 27.6
couple of things i did and noted...

1: if i disconnect and reapply the PV source (off for 30 seconds then re-connect) the inverter switches over and runs purely on bateries (expected)
2: during this period the batts dip to 26.6v and pulling 22amps from the bank. (couple of fridges and misc items running)
3: once the inverter sees the panels back on and MPPT kicks in it will charge at 20A untill the batts hit the bulk voltage of 28.6 within 2 minutes, then the inverter will drop the charge rate and it will settle back down on 27.6, (float) at around 2 or 3A

Q: I presume that batteries are fully charged that`s why when it pushes the 20 amps up to the bulk charge voltage and then sinks back to float voltage within minutes.

does this sound all normal??

it will be interesting to see what happen when the sun goes down... i have the chargeer low voltage "recharge" set at 24V so i presume i will see the power draw down to this level and then the mains part of the inverter/charger will kick back it and float them??

sorry, you guys must roll your eyes at us.... but we all started from a low base...
thanks....

 

[sunshine_eggo]

does this sound all normal??

Yes.

it will be interesting to see what happen when the sun goes down... i have the chargeer low voltage "recharge" set at 24V so i presume i will see the power draw down to this level and then the mains part of the inverter/charger will kick back it and float them??

sorry, you guys must roll your eyes at us.... but we all started from a low base...
thanks....

Consider that your inverter likely consumes 40-50W ALL THE TIME. That's 1080Wh/day or 45Ah of your battery capacity. This happens even if you don't pull any loads from it. If you have two 100Ah batteries in series, your inverter is consuming almost 50% of your battery capacity.

 

[rgormley]

my mdel is not a growatt it`s a powmr HMS-3K-24V
inverter spec mentions no load and power saving consumption
i presume this is the power consumed when it`s turned on but doing nothing anything... if so how do i know how much power it using when actually inverting and and doing it`s job? eitherway it`s a mute point as i cant do anything about that, other than adding more storage..




Also this may be a huge "no no" but i will ask.....

As mentioned my batts may not be getting a full charge as the charger aspect of the inverter may stop charging as soon as it`s hits the upper bulk voltage.
so what about i set a "safe" equalzastion charginging phase time say for 2 hours?? i can set a few parameters in this setting..
say
EQ volts 28.8
EQ time 2 hours
EQ time out 2 hours
EQ interval every day

or is this something that i should not go near as it will damage my batts. (although i presume the BMS will cover that concern?)
this screen grab from the manual/PDF...

 

[sunshine_eggo]

my mdel is not a growatt it`s a powmr HMS-3K-24V
inverter spec mentions no load and power saving consumption
i presume this is the power consumed when it`s turned on but doing nothing anything... if so how do i know how much power it using when actually inverting and and doing it`s job? eitherway it`s a mute point as i cant do anything about that, other than adding more storage..

View attachment 130716

I won't believe this until I see it. Your manual reads exactly like a Growatt that's made by Voltronics.

Also this may be a huge "no no" but i will ask.....

As mentioned my batts may not be getting a full charge as the charger aspect of the inverter may stop charging as soon as it`s hits the upper bulk voltage.
so what about i set a "safe" equalzastion charginging phase time say for 2 hours?? i can set a few parameters in this setting..
say
EQ volts 28.8
EQ time 2 hours
EQ time out 2 hours
EQ interval every day

or is this something that i should not go near as it will damage my batts. (although i presume the BMS will cover that concern?)
this screen grab from the manual/PDF...

I don't know if the EQ process runs off AC charging, do you?

The AC charger stops charging when setting 13 is hit. PV follows the absorption/float rules.

 

[rgormley]

I won't believe this until I see it. Your manual reads exactly like a Growatt that's made by Voltronics.



I don't know if the EQ process runs off AC charging, do you?

The AC charger stops charging when setting 13 is hit. PV follows the absorption/float rules.

I won't believe this until I see it. Your manual reads exactly like a Growatt that's made by Voltronics.

 

[rgormley]

what "back to charge" voltage should i use? i presume this is a setting that i can set to take the batts down to 10% SOC at 24v (2000 cycles?)
or only down to 25.6v (20% SOC) 3000 cycles?)

i realy dont know what the SOC is on my batts other than letting the charger do it`s work based on what i set in the upper/lower voltage settings?

 

[sunshine_eggo]

back to charge 24
back to discharge 28.8