Battery Bank upgrade in Lance 1172

[Pauhar1]

I have a Lance 1172 truck camper with 2 100 ah LiPo batteries. I am adding 3 more batteries. There is no room to connect them together in the factory location. I have plenty of room in the basement to secure and wire them in parallel. Also the bus bars/Battery posts are conveniently located so that I can connect the new three to the original 2. My question is will the batteries discharge/charge evenly and will I need to increase the fuse from the bus to the power center or will the fuse from the three new ones to the bus bar suffice OR do I need to do both?

 

[MisterSandals]

LiPo batteries

Really lithium polymer, the explody kind?

 

[Pauhar1]

Nope :: LiFePO4

 

[MisterSandals]

My question is will the batteries discharge/charge evenly and will I need to increase the fuse from the bus to the power center or will the fuse from the three new ones to the bus bar suffice OR do I need to do both?

The key will be connecting them in parallel in a balanced manner. Read the first 4 post of this thread to understand:

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

In regards to fusing, each battery should be fused with a class T fuse. The fuse size depends on the wiring that it is designed to protect. The wiring is sized based on amps, volts and circuit length.

 

[Pauhar1]

So, as I understand this the two main factors to balanced charge/discharge are internal resistance and balanced wiring. One answer leads to another question. So if I were to wire the string in parallel and connect the bus bar to the nearest battery’s terminals, it would get the most charge followed by two then three. Correct? In this case would #2 fully charge next then #3? In other words would they all eventually charge just inefficiently?

 

[Pauhar1]

So, as I understand this the two main factors to balanced charge/discharge are internal resistance and balanced wiring. One answer leads to another question. So if I were to wire the string in parallel and connect the bus bar to the nearest battery’s terminals, it would get the most charge followed by two then three. Correct? In this case would #2 fully charge next then #3? In other words would they all eventually charge just inefficiently?

Also what affects IR?

 

[DIYrich]

So if I were to wire the string in parallel and connect the bus bar to the nearest battery’s terminals, it would get the most charge followed by two then three. Correct? In this case would #2 fully charge next then #3? In other words would they all eventually charge just inefficiently?

The voltage of all the batteries at the busbar is the same. Each wire length will have different resistance so different voltage at each battery.

 

[Pauhar1]

Also what affects IR?

Disregard this question. I re read the posts Mr Sandals sent me to and found the answer.

 

[MisterSandals]

Correct? In this case would #2 fully charge next then #3? In other words would they all eventually charge just inefficiently?

Yes to the first part. But no, from my experience, the charger normally sees the "first" (least resistance) battery full and stops charging. A long absorb stage might reduce this affect. But the first battery will get used a lot more and potentially age faster, making this affect even worse.

This game is tricky enough doing things right. Starting off with imbalanced battery wiring will very likely become unusable.

 

[Pauhar1]

Mr. Sandals, thank you for the information. It Will be a big help.