Charging 4 Battery Banks

[CassidyNZ]

Once again, my luck appears to prevail. I haven’t replaced one of the control switches in the 12 years since I changed my system and installed the switches that are there now.

YMMV.

[a64pilot]

Mine’s 30 yrs old, original with the boat, but I have seen them fail, and often when they do it makes it look as if the bank has failed.
I bet many a battery has been replaced due to a faulty switch

[YANDINA]

Originally Posted by keaislandsailor

[SNIP]

b) If the Alternator(s) goes to each bank, is there a device that goes between alternator and banks that regulates the charge for the AGM banks and lithium bank? Or, do the MPPT Solar Controllers perform this task? Would you use the Alternator(s) for the Lithium bank or is it too risky?

[/SNIP]

Yandina makes a Combiner that will transfer charge between an AGM and a Lithium without the risk of the higher voltage Lithium discharging itself into the lower voltage AGM.

[donradcliffe]

Originally Posted by YANDINA

Yandina makes a Combiner that will transfer charge between an AGM and a Lithium without the risk of the higher voltage Lithium discharging itself into the lower voltage AGM.

Ann-Marie,

What are the exact cut in and cut out voltages for the Lithium Combiner. I assume you have designed in some hysteresis to prevent relay chatter.

[YANDINA]

The threshold voltage is 13.6. Otherwise they are identical to the Combiners we have been making now for 27 years with unconditional warranty.

[skenn_ie]

Now THERE, is a challenge ! How do you distribute the available electrical power in such a way as to maximise the life of your batteries. If you simply feed all that power onto one buss, then run tailored intelligent chargers off that, they may overload the source/s. If I can get my act together and build the system that I thought of 4 years ago, it would do that by coordinating charge current according to the supply rather than the destination. i.e. distributing the available power, with the option of prioritising main-engine batteries.

[YANDINA]

Your concerns are misplaced, the Yandina Combiners and Trollbridges monitor the load on the alternator and cycle on and off as needed to reduce the average load to a safe level.

It is true that the charging profile with mixed batteries may not be optimum for all the batteries on the network however all will receive a full charge even if it takes a few minutes longer due to a more conservative regimen.

[jjjacq]

Originally Posted by moseriw

Understood, but unless you have a rather large boat it’s just not necessary to be putting batteries near the load, just as you say run larger cables, larger cables last forever and are very simple.

OK Facts:
Battery 12V 225Ah FLA
Bowtruster 6Kw = 500A
Windlass 1,6 Kw = 110A

cable 95 mm² length 12m
input Voltage (12,6V battery) and 14,4V from alternator

Windlass draws 100A
Voltage drops from 14,4 to 8,9V

Which cables should I use? 300mm² ??
And this ruins your windlass and bowthruster motors within hours of service!

I think one should learn from my faults!!

I consider a bow-battery as an ultimative MUST HAVE!

And for the NON BELIEVERS: don't discuss - check for yourself on your boat.
One should to get at least 11V (on emergency) even if the battery is down to 11,8V aka empty.

I'm not sure what kind of material your cable is made of, but with copper, a cable (2 cores), 95mm2 /12 m long has a resistance of 0.0043 ohms, so for 100 A the voltage drop in the cable is only 0.43V. If you lose 5 volts you must have a hell of a lot of resistance in the connections, and moving the battery close to the windlass won't help, your connections are still there.

0.43V on a 12V system is about the acceptable limit, it's around 5%. Having the battery close to the load is still a good idea, but I don't believe your voltage drop.