Series-Parallel, extra wires?

[mglonnro]

Cheers,

This is the text book setup for connecting batteries in series-parallel: make the series connection between two batteries, and then hook up these battery banks in parallel:



On our new ship, however, there are extra (thinner) wires connecting the "series" connections across the banks as well, like in this picture:



Can anyone explain the reasoning behind this?

[YANDINA]

As batteries age and capacity drops, it would even out the charge distribution so the twin to a weak battery would be able to charge.

However it works the other way too, if one battery had a shorted cell it would now drag down 2 other batteries with it.

[goboatingnow]

It may be text book but it’s wrong. One feed point should exist at the top and the other at the bottom

[mglonnro]

Originally Posted by YANDINA

As batteries age and capacity drops, it would even out the charge distribution so the twin to a weak battery would be able to charge.

However it works the other way too, if one battery had a shorted cell it would now drag down 2 other batteries with it.

Ah ok, thank you!

Would you say one way or the other would be recommended when installing new batteries?

[mglonnro]

Originally Posted by goboatingnow

It may be text book but it’s wrong. One feed point should exist at the top and the other at the bottom

Ah yes, the parallel connection should have + from the first battery and - from the last (or vice versa).

[goboatingnow]

It’s not that.

The best method is always parallel first then series. This creates a bigger bank of lower voltage batteries which are more resilient to discharge issues then a series first then parallel bank

[Spot]

Hi Mikael, are the batteries 12v each in a 24v system?

[ItDepends]

Best connection practices are well described here:

https://www.cruisingconsulting.com/p...ry-connections

along with the rational about WHY.

[mglonnro]

Originally Posted by Spot

Hi Mikael, are the batteries 12v each in a 24v system?

Yes, indeed. One system is 3 x [2 x 12V = 24V] and the other is 2 x [2 x 12V = 24V].

[mglonnro]

Originally Posted by goboatingnow

It’s not that.

The best method is always parallel first then series. This creates a bigger bank of lower voltage batteries which are more resilient to discharge issues then a series first then parallel bank

Ah, ok!