Can't seem to get a full charge out of our LifePO4 batteries

[svTrouble]

I’m hoping someone can help me figure out a problem that has been vexing us for about a year now.

The Problem

Since we’ve cruising we haven’t been able to get our house batteries over about 13.5 volts. Well, when the engine is on it gets to about 13.85, but drops down to 13.5 when we turn the engine off. Once the batteries get to about 13.85 the charge flattens out and no matter how long we run the alternator, it doesn’t get higher.

The Situation

We live on a sailboat that we’ve been cruising on for a year, which means we’ve been far away from shore power. About 2 and a half years ago we partnered with a ABYC-certified electrician and redid a good portion of our electrical system. This included:

• 6 100 amp hour Battleborn LifePO4 batteries.
• A Balmar 94 series 210 amp high output alternator
  • note: We have a separate alternator to charge starting bank.
  • note2: The alternator charge controller is programmed for these particular batteries
• A Xantrex freedom 3000w inverter
• New wiring, a new panel, fuses, switches, etc.

We have about 560 amps of solar (Sunpower Maxeon, controlled by three Victron SmartSolar MPPT 100 | 30

Our Loads

We only use our inverter to boil water for coffee in the morning. Starlink is on for 2-4 hours a day. We do have a very efficient cooler and a 45-quart Engel freezer that is set conservatively. And we run a water maker every three days.


Some possible clues

Our house bank is divided into 4 and 2 (due to space). The batteries in each group have very short wires connecting them, but the groups have a span that is probably 4 to 4 1/2 feet between them. The electrician said that this isn’t ideal, but shouldn’t be a problem.

The alternator has a 300A fuse on the positive side (https://www.bluesea.com/products/5190/MRBF_Terminal_Fuse_-_300A). When the engine is on this fuse gets hot: 260F to 300F. The wire connecting this fuse to the busbar is around 100F, and the temp on the alternator side is even less.

The house bank uses a 200 amp 187-series circuit breaker (https://www.bluesea.com/products/7149/187-Series_Circuit_Breaker_-_Surface_Mount_200A). A friend suggested that this isn’t adequate, and we should be using a class t fuse, with a higher capacity.

Attached is an example of a charging curve over an hour. You’ll notice that in the first 30 minutes, it goes from 13.40v to 13.53, and then it flattens out. It even goes back down to 13.53 at the end.

Attached you will see our wiring diagram and some photos of the installation

Conclusion

I can supply any further information I can include that would help diagnose this issue. We are so tired of running our engine for an hour every day, maybe two if we get good sun. We are just wasting diesel.

We are currently in remote Baja and have limited access to parts and resources.

We are desperate. If you have any suggestions or tests we should run... If you have a remote electrician you'd suggest to figure this out we'd be happy to pay someone who knows can figure this out.

Thank you for your time.

 

[JunglePower]

I am not an expert responder here.
I will say the charging voltage is too low to fully charge a BB 10012. How many charging amps are they receiving. Look at the flyer that was in the BB box.

I'm sure there are other here who will elaborate.

 

[MisterSandals]

First of all, your batteries are wired in an imbalanced manner. A far better approach would be to have main wires (+) from on one end of the battery bank and the (-) on the other end. The one battery with both connected to it will get far more current (load and charge) than the others.

Are there 6x battleborns? One group of 2 in parallel (also unbalanced?) and another 4 in parallel?

Are you using a charger to charge from alternator? Or charging directly from alternator to batteries like one would with lead acid batteries?

 

[svTrouble]

I am not an expert responder here.
I will say the charging voltage is too low to fully charge a BB 10012. How many charging amps are they receiving. Look at the flyer that was in the BB box.

I'm sure there are other here who will elaborate.

Are you suggesting that the Balmar doesn't output enough amps to charge the house bank?

 

[svTrouble]

First of all, your batteries are wired in an imbalanced manner. A far better approach would be to have main wires (+) from on one end of the battery bank and the (-) on the other end. The one battery with both connected to it will get far more current (load and charge) than the others.

Are there 6x battleborns? One group of 2 in parallel (also unbalanced?) and another 4 in parallel?

Are you using a charger to charge from alternator? Or charging directly from alternator to batteries like one would with lead acid batteries?

Yes, 6x battleborns, one group of 2 and the other in 4, both parallel.

The alternator for the house bank does have an external charge controller (Balmar MC-614).

 

[MisterSandals]

Is this the fuse that gets hot? I see a lot of blackening and wonder if there is a clean contact surface between all the surfaces. If not, it would create resistance and get hot and likely incrementally worse until something catches fire.

Yes, 6x battleborns, one group of 2 and the other in 4, both parallel.

My guess is that your wiring is a good part of the problem. The battery with the leads connected may be getting charged to where your Balmar stops charging, leaving the others in a low(er) charge state. If you disconnected all from parallel you could test this theory. It might be easiest to disconnect the farthest battery to test. If its resting voltage is lower than the rest, you will know why.

We've seen this issue many dozens of times before in case you were skeptical. Here is a thread that explained this and provided specific wiring scenarios for multiple parallel batteries.

Read the first 4 posts in this thread:

Calculation of parallel string battery currents

Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current...

diysolarforum.com

 

[svTrouble]

Is this the fuse that gets hot? I see a lot of blackening and wonder if there is a clean contact surface between all the surfaces. If not, it would create resistance and get hot and likely incrementally worse until something catches fire.

My guess is that your wiring is a good part of the problem. The battery with the leads connected may be getting charged to where your Balmar stops charging, leaving the others in a low(er) charge state. If you disconnected all from parallel you could test this theory. It might be easiest to disconnect the farthest battery to test. If its resting voltage is lower than the rest, you will know why.

We've seen this issue many dozens of times before in case you were skeptical. Here is a thread that explained this and provided specific wiring scenarios for multiple parallel batteries.

Read the first 4 posts in this thread:

Calculation of parallel string battery currents

Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current...

diysolarforum.com

Interesting. So if I changed the batteries with the leads to the end battery (see attached modified image), then that could be a good likely candidate for solving our issue?

 

[MisterSandals]

Interesting. So if I changed the batteries with the leads to the end battery (see attached modified image), then that could be a good likely candidate for solving our issue?

No, you need (+) to one battery and (-) to the other.

So you didn't read the first 4 posts in the thread that explains this?
At least look at the pic at the beginning of post 3 for "diagonal" wiring.

Its all there in the first 4 post...

 

[svTrouble]

No, you need (+) to one battery and (-) to the other.

So you didn't read the first 4 posts in the thread that explains this?
At least look at the pic at the beginning of post 3 for "diagonal" wiring.

Its all there in the first 4 post...

Oh, sorry... Yes, are you suggesting using one of these diagonal solutions? Or trying to utilize busbars and going for the anti-symmetric diagonal final solution?

 

[MisterSandals]

Oh, sorry... Yes, are you suggesting using one of these diagonal solutions? Or trying to utilize busbars and going for the anti-symmetric diagonal final solution?

Yes, the 2 battery diagonal is easy. The 4 battery diagonal is nearly the same for the 2 you attached pics for. I would wire it the easy way (batt 1 and batt 4).

This will definitely put a more balanced charge and discharge on your batteries. It will improve your situation, hopefully fix it. I am not sure if there are other things going on too.

Good luck!

And, when you are rewiring these batteries. Do a voltage check to see if the disconnected batteries have different voltages. It would help confirm that this was an issue. Label your batteries and take good notes.

 

[Sabre36]

Yes,

The alternator for the house bank does have an external charge controller (Balmar MC-614).

where is positive volt sense wired? Where is reg B- wired (this is your neg side volt sense.. 99% of installers F this part up….