The video at the beginning of the thread discusses the deep discharging behaviour of the hybrid, how the lithium discharges its energy first, then lead takes over the energy supply once the lithium's voltage drops far enough. Just like your cool video shows.If you watch the video at the start of the thread, it is explained in detail
I did measure the charge current once about 2 hours after they were joined. Each battery has a separate post on the bus bars. I did not parallel at the battery. My clamp on read 0.66A to the AGM and 4.10A to the LFP. That agreed with the total out from the SCC into the bus bars. I was pleased to see this imbalance because I want the LFP to get the majority of the charge. LFP has better charge efficiency and that avoids wasting daylight waiting for AGM to absorb. The LFP can take all night to float the AGM.
It's going to depend where your lithium cuts off on either end.
I am betting charging works like this that I posted recently:
Okay, no one has yet offered any advice. I will go ahead and ignore this concern and place the 100Ah AGM in parallel with the 100Ah LFP in the TT.Has anyone had any experience or problems reconnecting after a BMS disconnect?
In my case I have a KiloVac contactor. When not in use I disconect the FLA bank, I have the trailers converter maintain the FLA bank. I use a ElectroDacus for the solar duties involving the LFP bank.(and the FLA bank when connected.)Okay, no one has yet offered any advice. I will go ahead and ignore this concern and place the 100Ah AGM in parallel with the 100Ah LFP in the TT.
Now, I have seen where some have reported walk-down of the AGM SOC% caused by insufficient and non-frequent return to full charge. The Lifeline method of charging is to apply 14.4V, temp adjusted, until the acceptance current reaches 0.5% of the 100Ah C-rate. I don't have a cite for the daily RULE. I don't have Lifelines but do use that method in practice, and have a 7 day rule.
I intend to use a daily CC/CV approach with the SCC; CC until Volts reach 13.8/3.45V and then switch to CV at 13.5/3.375V. There will not be any legacy absorption.
Does anyone see any problem with SOC-walk-down of the AGM if it is floated overnight at normal LFP 13.3V?
I will be using a JBD TS04S006 BMS. Does anyone have any specs for this BMS?
Given charging at 14.4V would mean the LFP being charged at 3.6V/cell, I don't see why it'd be a problem to continue that practice. 3.6V/cell charging voltage is still well inside their operating parameters.Okay, no one has yet offered any advice. I will go ahead and ignore this concern and place the 100Ah AGM in parallel with the 100Ah LFP in the TT.
Now, I have seen where some have reported walk-down of the AGM SOC% caused by insufficient and non-frequent return to full charge. The Lifeline method of charging is to apply 14.4V, temp adjusted, until the acceptance current reaches 0.5% of the 100Ah C-rate. I don't have a cite for the daily RULE. I don't have Lifelines but do use that method in practice, and have a 7 day rule.
I intend to use a daily CC/CV approach with the SCC; CC until Volts reach 13.8/3.45V and then switch to CV at 13.5/3.375V. There will not be any legacy absorption.
Does anyone see any problem with SOC-walk-down of the AGM if it is floated overnight at normal LFP 13.3V?
I will be using a JBD TS04S006 BMS. Does anyone have any specs for this BMS?
I've said a couple of times that I'm not really a fan of parallel lead-acid and LFP, and I know I'm in the minority, at least in this thread. But this by @gelmjw is the crux of it. AGMs need to be fully charged frequently, else they will sulfate and die over time. Lifelines are not unique, but they do explicitly state that then want an absorption voltage held until the current drops to 0.005C. In this case, the recommended absorption CV is at 14.4V, or 3.6V per cell for LFP. I don't think you want to hold LFP at 3.6V (or anywhere above the knee) for that long. How much harm does it cause? I don't know. I'm not qualified to say, but I think lots of people will tell you LFP doesn't like to be held near full for any real length of time. They will stop absorbing in only a couple of minutes at that voltage, even though the AGMs are still sucking current.Okay, no one has yet offered any advice. I will go ahead and ignore this concern and place the 100Ah AGM in parallel with the 100Ah LFP in the TT.
Now, I have seen where some have reported walk-down of the AGM SOC% caused by insufficient and non-frequent return to full charge. The Lifeline method of charging is to apply 14.4V, temp adjusted, until the acceptance current reaches 0.5% of the 100Ah C-rate. I don't have a cite for the daily RULE. I don't have Lifelines but do use that method in practice, and have a 7 day rule.
I intend to use a daily CC/CV approach with the SCC; CC until Volts reach 13.8/3.45V and then switch to CV at 13.5/3.375V. There will not be any legacy absorption.
Does anyone see any problem with SOC-walk-down of the AGM if it is floated overnight at normal LFP 13.3V?
I will be using a JBD TS04S006 BMS. Does anyone have any specs for this BMS?
If the LFP BMS cuts off leaving the lead to continue with the occasional higher voltage absorption cycle, why would it matter? Once the lead charging routine is complete the voltage drops back and the BMS reconnects the LFP.And then of course there is the fact that as cells get out of balance, there is a pretty good chance that going to 14.4V will cause one cell to get to 3.65V, causing an HVD.
At the end what you say is a negative just shows the positive. In my old BMS (a Chargery 8T) due to a software error the BMS discontented while brewing my morning coffee. The coffee didn't skip a beat. And for me that's a "BIG" deal. ( Don't want the grandkids calling me "GrumpPa")I've said a couple of times that I'm not really a fan of parallel lead-acid and LFP, and I know I'm in the minority, at least in this thread. But this by @gelmjw is the crux of it. AGMs need to be fully charged frequently, else they will sulfate and die over time. Lifelines are not unique, but they do explicitly state that then want an absorption voltage held until the current drops to 0.005C. In this case, the recommended absorption CV is at 14.4V, or 3.6V per cell for LFP. I don't think you want to hold LFP at 3.6V (or anywhere above the knee) for that long. How much harm does it cause? I don't know. I'm not qualified to say, but I think lots of people will tell you LFP doesn't like to be held near full for any real length of time. They will stop absorbing in only a couple of minutes at that voltage, even though the AGMs are still sucking current.
And then of course there is the fact that as cells get out of balance, there is a pretty good chance that going to 14.4V will cause one cell to get to 3.65V, causing an HVD.
Top balancing is generally all cells in parallel, which means without a BMS.and I can't top balance without a BMS.
Have you downloaded the app? There is a paid version that allows config changes (~$5). The app should show exactly what it’s seeing and doing. It’s pretty much the only tool you need for a BMS other than volt meter for balance leads.My biggest problem right now is figuring out how to get this BMS to work; a JBD TS04S006 BMS. Does anyone have any specs for this BMS?
Top balancing w/o a BMS means using a Voltage and Current adjustable charger, which I don't have. I was hoping to manually balance by charging in series, letting the BMS shut off, and draining high cells individually, repeat. That will work, right?Top balancing is generally all cells in parallel, which means without a BMS.
Have you downloaded the app? There is a paid version that allows config changes (~$5). The app should show exactly what it’s seeing and doing. It’s pretty much the only tool you need for a BMS other than volt meter for balance leads.
Happen to have a pic of your wiring? A few extra eyes often spots something of value.
This is hard on the BMS and depending on the high cell voltage disconnect, hard on and cells that go over 3.65V.I was hoping to manually balance by charging in series, letting the BMS shut off,
There's an entire thread on it. If you watched the video you'll see that the benefit of this configuration is:
what is this guy on about, he just said he parallel connects his lithium to lead acids, and at the end of the night the lithium is low but the lead acids are at 13.2, ala he only used lithium power as the lead acids weren't touched
So why does he even have the lead acids if lithium is doing all the work?
There's an entire thread on it. If you watched the video you'll see that the benefit of this configuration is:
- the LFP does the regular daily cycling when solar conditions are good (enough)
- the LA is kept on float pretty much the whole time except
- when conditions (e.g. extended poor weather) require a deeper discharge from the hybrid battery then once the hybrid battery (LFP) voltage drops down, the LA takes over the supply
- if you already have a large existing LA bank in decent condition, then by adding a bit of LFP capacity in parallel, e.g. 1/4, then you can get most of the benefits of LFP, extend the life of the LA significantly and not need to spend anywhere near as much on an entirely LFP bank.
- if you have any form of alternator charging, you'll definitely want to have at least some LA in the circuit.
The logic is actually quite sound when you look at the respective chemistries and how they behave at their respective charging, discharging and float voltages.