Settings for the MPPT for lithium LIFEPO4
- Thread starter Icetice
- Start date
LOL! Sorry, just had to laugh. How would any of us know what the right settings are for your battery bank? The right settings are whatever your battery manufacturer has determined to be the 'right settings'. I mean there are typical settings, yes, and these can be used in the absence of manufacturer settings, but the right answer is always going to be what your battery manufacturer says.
Typical parameters for a LiFePO4 SCC are:
Typical parameters for a LiFePO4 SCC are:
- Bulk: whichever is the lower of your battery's maximum charge rate or the SCCs maximum charge current.
- Absorption: 14.6V (though most people do not charge their batteries to 100%)
- Float: Not required, but if you can't disable it, 13.2V
- Equalisation: Must be disabled for Lithium-ion battery technology
Yes i understands you... but as you can se on the pic i can not set a apsorption only flot and bulk... i have the sistem on my boat and want to get as much power oit of the system in the day.... will it be a problem to set the float to 14.20 same as bulk
Yes. You should not do this. By the time the charge controller switches into Float, your battery is already fully charged. Float is only there to keep the battery topped up, which is not required for Lithium-ion batteries. Setting Float to 14.2V will damage your batteries.
On your SCC, the Absorption voltage is called "Boost Charging Voltage" because they prefer to make things difficult for you. Needs to be set per your battery manufacturer's recommendations (note: 14.6V maximum for LiFePO4 chemistry).
Remember: disable Equalisation. From the screenshot provided this will likely be achieved by setting the 'Equalisation Duration' to 0 minutes, but you need to check this.
Your 'Boost Duration' should be no more than 5 times the time it spends in Bulk on a typical day. You'll need to monitor this over time. For info, this is a protection setting, which limits the time the charger will spend in Absorption if there is a parasitic load on the batteries.
Heres mine. Only thing I can see is your voltages in bulk and float are too low to balance the cells.
Lifepo4, just like lead acid but way closer to full and way more dramtically, ramps the resistence up near full. So youre controller automatically ends charging when 99.99% full and cell balancing starts.
This is how battleborn recommends charging theirs.
If youre going to actually float...as in not use the system daily, you can turn float down to 13v. In fact its ok to turn it down either way. I set mine there just cause my inverter draw.
Lifepo4, just like lead acid but way closer to full and way more dramtically, ramps the resistence up near full. So youre controller automatically ends charging when 99.99% full and cell balancing starts.
This is how battleborn recommends charging theirs.
If youre going to actually float...as in not use the system daily, you can turn float down to 13v. In fact its ok to turn it down either way. I set mine there just cause my inverter draw.
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Thx for the answers tictag and peb and the pic af your charge profil peb, they er very helpfull... and i can se that your bulk and your float is the same.... tictag says that i will destroy the batteries..?? it i have a victron 712 to monitor the batteries and i can se that it goes into float charge long before the batteri er fully charged... ex goes into float at 65% SOC so i wanted to here if my settings were wrong...
Then you need to troubleshoot this, because this is either:
- A problem with your SCC, in that it is entering Float too early OR
- A problem with the battery monitor, in that it is not configured for the correct battery capacity
Then it must be the scc... if i charge the batteries with the grid charger or the motor on my boat then the monitor says 100% i have 300 ah batteri pak and the monitor says i have spend 300 ah +- when i do a capacity test...
So i will start to look in on problems with scc
So i will start to look in on problems with scc
Typically, an SCC will switch into Float once the charging current in Absorption has reduced to around C/100 Amps e.g. for a 100AH battery, that's 1A i.e. once the charge current has dropped to C/100 Amps, your battery can be considered fully charged.
Turn boost duration to 180 minutes. And turn voltage up higher. You also need to factor voltage drop. Hence why im set to 14.7v.....i get 14.6v at the battery.
My battery isnt destroyed with float at 14.7v. If I were in storage it may be an issue.
My battery isnt destroyed with float at 14.7v. If I were in storage it may be an issue.
My guess would be that it configures and independent protection circuit? If the main charger buggers up, shut it down if the battery voltage reaches xV. Total guess, though.
AFAIK, typical passive balancers operate on a differential voltage principle i.e. if Cell A is higher than Cell B, bleed some current off to Resister A. If all cells charge equally, no balancing occurs. I believe active balances work in a similar way but instead of bleeding current off to a resister, they instead somehow 're-route' the current to cells that are 'differentially' lower.
For the most part, these differential voltages only occur at the charge extremes i.e. nearly fully charged or nearly fully discharged but I don't think there is a setting i.e. start balancing at 14V.
sunshine_eggo
Happy Breffast!
Wow... zombie thread.
First, you fully charge each 12V as 12V individually and then in parallel. Once complete, you place them in series and double the voltages as you surmised.
Periodically monitor the 12V. They may need to be broken down and re-charged to full as 12V.
I have a related question and hope you might be able to comment.
I have built two 4S2P LiFePO4 12V packs to replace my Lead Acids in a 12V set-up. Each pack has a JiKong active BMS. I have three Victron MPPTs.
Before getting to the installation stage I had just presumed I’d turn the MPPTs’ rotary switches to “7” (LiFePO4) and leave the BMSes to perform the battery management. I expected the MPPTs to be largely redundant in regulating the battery state, and that the master would be the BMSes.
Noting that setting “7” presumes 14.2V bulk & 13.5V float, I wonder whether the BMS will be confused by the MPPT making executive decisions about the state of charge and regulating the current to the BMSes/batteries. Will this leave the BMSes making adjustments and tweaks that are academic because they are just not getting the voltages they need to perform their work of keeping the batteries in the optimal state?
Comments welcomed.
The JiKongs are configurable but I don’t see anything in the JiKong manual that suggests that the out-of-the-box state is good enough for the average Joe to just connect them up and go. Do I need to make any config changes?
For the record, I top-balanced the cells to 3.65V before building the packs. The batteries will see use mostly in summer and be used sporadically in the winter.
I have built two 4S2P LiFePO4 12V packs to replace my Lead Acids in a 12V set-up. Each pack has a JiKong active BMS. I have three Victron MPPTs.
Before getting to the installation stage I had just presumed I’d turn the MPPTs’ rotary switches to “7” (LiFePO4) and leave the BMSes to perform the battery management. I expected the MPPTs to be largely redundant in regulating the battery state, and that the master would be the BMSes.
Noting that setting “7” presumes 14.2V bulk & 13.5V float, I wonder whether the BMS will be confused by the MPPT making executive decisions about the state of charge and regulating the current to the BMSes/batteries. Will this leave the BMSes making adjustments and tweaks that are academic because they are just not getting the voltages they need to perform their work of keeping the batteries in the optimal state?
Comments welcomed.
The JiKongs are configurable but I don’t see anything in the JiKong manual that suggests that the out-of-the-box state is good enough for the average Joe to just connect them up and go. Do I need to make any config changes?
For the record, I top-balanced the cells to 3.65V before building the packs. The batteries will see use mostly in summer and be used sporadically in the winter.
sunshine_eggo
Happy Breffast!
It appears you may have unrealistic understanding of what a BMS is and does.
A BMS is a safety system. It watches for problems. If rules are violated, it cuts it off. Think "Soup Nazi" - "No Soup For You!!!"
BMS doesn't regulate anything. If you sent 200A to your battery, but the cells or BMS are only rated for 100A, the BMS doesn't throttle the incoming current to 100A, it says, "No Soup For You!" and completely cuts off all incoming current. If you ask for 200A from a 100A rated BMS/battery, you don't get regulated to 100A, you get cut off to 0A.
Voltages go too high? "No Soup For you!" - cut off all charging.
Voltages go too low? "No Soup For you!" - cut off all discharging.
I don't understand what you mean "making executive decisions." Charge controller does nothing of the sort. It charges until the battery hits 14.2V, holds that voltage until charge termination criteria are met, then it stops sending any current until the battery voltage drops to 13.5V. Once the battery drops to 13.5V, the charge controller will feed enough current to maintain 13.5V.
Your system design should work entirely within the envelope of the BMS parameters, i.e., the BMS should never have to do anything unless something goes wrong.
A BMS is a safety system. It watches for problems. If rules are violated, it cuts it off. Think "Soup Nazi" - "No Soup For You!!!"
BMS doesn't regulate anything. If you sent 200A to your battery, but the cells or BMS are only rated for 100A, the BMS doesn't throttle the incoming current to 100A, it says, "No Soup For You!" and completely cuts off all incoming current. If you ask for 200A from a 100A rated BMS/battery, you don't get regulated to 100A, you get cut off to 0A.
Voltages go too high? "No Soup For you!" - cut off all charging.
Voltages go too low? "No Soup For you!" - cut off all discharging.
I don't understand what you mean "making executive decisions." Charge controller does nothing of the sort. It charges until the battery hits 14.2V, holds that voltage until charge termination criteria are met, then it stops sending any current until the battery voltage drops to 13.5V. Once the battery drops to 13.5V, the charge controller will feed enough current to maintain 13.5V.
Your system design should work entirely within the envelope of the BMS parameters, i.e., the BMS should never have to do anything unless something goes wrong.
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