Blue Nova voltage help

FrozenToast

FrozenToast

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Hi everyone

I ordered two 13v 108ah Blue Nova lithium batteries to run in series, the ones without the BMS connection to inverter. But with built in BMS for the battery,

Of course I now need to manually set the charge, float and low battery voltage. Can you kindly advise me what those voltages should be as the interwebs seem to differ by about 1 to 2 volts on all the pages I read.

Thank you
 
FrozenToast said:
Hi everyone

I ordered two 13v 108ah Blue Nova lithium batteries to run in series, the ones without the BMS connection to inverter. But with built in BMS for the battery,

Of course I now need to manually set the charge, float and low battery voltage. Can you kindly advise me what those voltages should be as the interwebs seem to differ by about 1 to 2 volts on all the pages I read.

Thank you
Click to expand...
BULK: 28.8V
FLOAT: 27.2V
LOW VOLT: 24V
CHARGE: 20-30A

 
FrozenToast said:
Hi everyone

I ordered two 13v 108ah Blue Nova lithium batteries to run in series, the ones without the BMS connection to inverter. But with built in BMS for the battery,

Of course I now need to manually set the charge, float and low battery voltage. Can you kindly advise me what those voltages should be as the interwebs seem to differ by about 1 to 2 volts on all the pages I read.

Thank you
Click to expand...
Please use a balancer:
www.geewiz.co.za

Lithium 24V Battery Balancer / Equaliser (suitable for all battery types) - 24V (2x 12V Batteries)

Can be connected to 24V battery banks (2x 12V in series) Monitors each battery voltage On deviation of more than 20 mV, the higher voltage battery will be discharged to the lower voltage batteries until all the battery voltages are equal Battery banks of 2x 12V can be used IP67 rated No external...
www.geewiz.co.za www.geewiz.co.za
 
wingnut771 said:
Please use a balancer:
www.geewiz.co.za

Lithium 24V Battery Balancer / Equaliser (suitable for all battery types) - 24V (2x 12V Batteries)

Can be connected to 24V battery banks (2x 12V in series) Monitors each battery voltage On deviation of more than 20 mV, the higher voltage battery will be discharged to the lower voltage batteries until all the battery voltages are equal Battery banks of 2x 12V can be used IP67 rated No external...
www.geewiz.co.za www.geewiz.co.za
Click to expand...
My Growatt does not allow me to seperate the Bulk from the float, it states in the manual the float must be the same as bulk. Even if I try set it manually it forces it. So i just set it 28.8v

I spoke to a electrician in passing and he mentioned that a balancer is not required. Excuse the ignorance but could you possibly explain why its needed, as this is the first I have heard of it myself?
 
FrozenToast said:
My Growatt does not allow me to seperate the Bulk from the float, it states in the manual the float must be the same as bulk. Even if I try set it manually it forces it. So i just set it 28.8v

I spoke to a electrician in passing and he mentioned that a balancer is not required. Excuse the ignorance but could you possibly explain why its needed, as this is the first I have heard of it myself?
Click to expand...
becuase anything in series connection will adopt the weakest link. If the 2 batteries go out of balance then you will have a situation where one battery peaks before the other, when that happens, the peaking battery will cut out which will disconnect the whole bank and then you have no battery and the inverter shuts off. The inverter only sees the pack voltage (24V) so you can have a situation of bat 1 reading 11V and bat 2 reading 13V, you still have 24V so the inverter doesn't care. With LA, this would just destroy your batteries as the one would overcharge and the other would undercharge but nothing would but out, with LFP, the BMS will cut out when out of range.

Get a new electrician that understands series connections.

Sorry, I cannot comment on the weird growatt no float setting. Maybe someone else can assist?
 
Ok that make sense to me, judging from the pics how would attach it to the batteries when there are four mounting points but only three cables on the device? Split the cable?
 
wingnut771 said:
Click to expand...
Ok i watched a couple videos and it makes sense now, but one thing they dont say is weather you can have this connected to your batteries while the batteries are connected to the inverter and running.
 
FrozenToast said:
Ok i watched a couple videos and it makes sense now, but one thing they dont say is weather you can have this connected to your batteries while the batteries are connected to the inverter and running.
Click to expand...
Yes, have it connected permanently and forget about it.

edit: @FrozenToast, connect battery cable lug first then balancer lug, then washer.
 
Last edited:
FrozenToast said:
My Growatt does not allow me to seperate the Bulk from the float, it states in the manual the float must be the same as bulk. Even if I try set it manually it forces it. So i just set it 28.8v

I spoke to a electrician in passing and he mentioned that a balancer is not required. Excuse the ignorance but could you possibly explain why its needed, as this is the first I have heard of it myself?
Click to expand...
For lead acid batteries - you don't need a balancer.
For any lithium based battery, especially those that have their own BMS, you really should balance. However, I ran my two LIFEPO4 batteries in series for a while and they more or less stayed balanced, even after a couple of months of use, but added one anyways (the BMS' of the two batteries are accessible via Bluetooth, so I could easily monitor/compare etc...)
Float/vs bulk charge - for lithium batteries, as far as I'm aware, float charging is irrelevant, as long as your BMS "disconnects" charging once the battery reaches 100% (so that you don't ever over charge) - I might be wrong about this though.

Float charging is of critical importance to lead acid batteries though.
 
Mr.Jax said:
For lead acid batteries - you don't need a balancer.
For any lithium based battery, especially those that have their own BMS, you really should balance. However, I ran my two LIFEPO4 batteries in series for a while and they more or less stayed balanced, even after a couple of months of use, but added one anyways (the BMS' of the two batteries are accessible via Bluetooth, so I could easily monitor/compare etc...)
Float/vs bulk charge - for lithium batteries, as far as I'm aware, float charging is irrelevant, as long as your BMS "disconnects" charging once the battery reaches 100% (so that you don't ever over charge) - I might be wrong about this though.

Float charging is of critical importance to lead acid batteries though.
Click to expand...
Yeah I had the choice of the BT batteries but I didn't really see the need as I am sure I can use my voltmeter to check out the voltages. I just set my charge limit to 28.8v as suggested by Wingnut771 and it seems to working.
I will monitor it over the next couple days.
 
Mr.Jax said:
For lead acid batteries - you don't need a balancer.
For any lithium based battery, especially those that have their own BMS, you really should balance. However, I ran my two LIFEPO4 batteries in series for a while and they more or less stayed balanced, even after a couple of months of use, but added one anyways (the BMS' of the two batteries are accessible via Bluetooth, so I could easily monitor/compare etc...)
Float/vs bulk charge - for lithium batteries, as far as I'm aware, float charging is irrelevant, as long as your BMS "disconnects" charging once the battery reaches 100% (so that you don't ever over charge) - I might be wrong about this though.

Float charging is of critical importance to lead acid batteries though.
Click to expand...
:ROFL: :ROFL: :ROFL: :ROFL: :ROFL: :ROFL: :ROFL:
 
FrozenToast said:
Yeah I had the choice of the BT batteries but I didn't really see the need as I am sure I can use my voltmeter to check out the voltages. I just set my charge limit to 28.8v as suggested by Wingnut771 and it seems to working.
I will monitor it over the next couple days.
Click to expand...
Rather set it to 28V then if there is no float.
 
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