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ktn1966 · 09-17-2023, 11:20 AM

I have 4 x 100 Amp Hour 12 Volt lithium batteries in parallel. This gives me 400 AH total. Each battery is capable of 100 AH max recharge per battery. With my solar putting in 40 AH charging and starting the generator the converter is charging at 60 AH charging the batteries @ 100AH.

Is the 100 AH total being distributed across all 4 batteries, so only 25 AH per battery? Will a 110 AH destroy my batteries?

Yosemite77 · 09-17-2023, 11:32 AM

Reading through your post, I had 2 questions come to mind.
Are the positive and negative connections on opposite ends of the battery bank, so the current flows through all the batteries?
Do you have a battery monitor?

ArtJoyce · 09-17-2023, 12:15 PM

Not sure what you would get??? You have two different chargers running at the same time. One goes to bulk charge and jumps up to 14.4 or so volts. The other sees 14.4 so volts and does not think it needs a charge.

ktn1966 · 09-17-2023, 12:34 PM

Quote:

Originally Posted by Yosemite77

Reading through your post, I had 2 questions come to mind.
Are the positive and negative connections on opposite ends of the battery bank, so the current flows through all the batteries?
Do you have a battery monitor?

I have a Victron bms, the bank is in parallel with the positive from converter to positive #2 battery (4 batteries left to right) and the negative on the negative #4 battery. The positive #4 has the inverter and the fuse panel cable.

Ludo · 09-17-2023, 12:37 PM

In no way will a lithium battery "jump" to 14.4v just because a charger is knocking on the door. That behaviour is typical for lead-acid, but not for lithium. You will not really notice the voltage rising before you are at least at 90% SoC. This is why you will need something like the Victron smart-shunt to keep control.

twinboat · 09-17-2023, 06:13 PM

Your using AHs and Amps as the same thing, they are not.
You charge and discharge with amps.

AHs are how many amps you can draw per hour.

Each battery is capable of delivering 100 amps for 1 hour, 100 AHs. 50 amps for 2 hours and so on.

Each battery can accept a 100 amp charge. Do that for 1 hour to return 100 AHs. Charge them at 50 amps and it takes 2 hours.

Your parallel 400 AH battey bank can accept 400 amps of charging for a time, a bit less then an hour. When near full, the BMS in one battery with shut it down. That could cause the others to shut down.

That's why we charge by voltage, once the set voltage is reached, the amps coming from the charger, or chargers drop way off in float charge mode.

Your 110 amp charging won't hurt your batteries because both charging sources are voltage regulated. As long as the target voltage is set for your batteries, your fine.

So in theory, your 110 amps of charging should re-charge your 400 AH battery bank in 3 hours and say 40 minutes.

Pappion · 09-19-2023, 10:59 AM

LiFeP04 battery banks are easy to balance charge.
When one charges more the voltage rises, allowing the others to take on more charge. This is assuming the cable resistance is reasonable.
They take most of the charge to 13.6v, 14.4v is the remaining 8%.

I have DIY 200AH and 280AH. Same 4awg cable length for each battery to Shunt and +Battery Fuse.

darrellr · 09-19-2023, 01:02 PM

Quote:

Originally Posted by Ludo

In no way will a lithium battery "jump" to 14.4v just because a charger is knocking on the door. That behaviour is typical for lead-acid, but not for lithium. You will not really notice the voltage rising before you are at least at 90% SoC. This is why you will need something like the Victron smart-shunt to keep control.

Just to make sure everyone knows - the smart shunt does not have ANY control capability in it. Your charger and your battery have control, the smart shunt just monitors and reports.

Ludo · 09-19-2023, 01:45 PM

Quote:

Originally Posted by darrellr

Just to make sure everyone knows - the smart shunt does not have ANY control capability in it. Your charger and your battery have control, the smart shunt just monitors and reports.

It monitors and reports so you can keep control.

arcaguy · 09-19-2023, 01:56 PM

The only thing that bothers me about your set up is that the positive charging cable is going to battery #2. For optimum performance it should be going to battery #1. How much of a difference this makes I don't know i just know that best practice is to have the positive on one end of a parallel string and the negative on the other. Just a suggestion.

Yosemite77 · 09-19-2023, 08:38 PM

I agree with arcaguy on keeping the positive and negative connections on opposite ends of the battery bank. Think of it as keeping the workload the same for each of the batteries.

Rocketman3 · 09-28-2023, 04:51 PM

As far as how fast you can recharge a lithium battery.

“C” rate refers to how many Ah are in the battery - so a 100ah battery discharging 100amps in one hour is discharging at a 1C rate.

For charging, most manufacturers say a max rate of .5C although if you want to be nice to your batteries a.2C rate is reasonable. What does the manufacturer of your battery say?

So for your 400Ah battery bank - 1C charge rate would be 400amps of charging.
A .2C rate is 80A of charging-
100a of charging is a .25C rate
110a of charging is a .275C rate

I choose a .2C rate for my bank - but even a .3C rate is not outrageous.

Good Luck