Charging 4 Battery Banks

[moseriw]

If you really think that’s possible then have a low voltage alarm
Best you set the shutoff to 12,2V = 50% empty to use the batteries as diligent as you can.





batteries:
Full 12,6V
Half 12,2V
Empty 11,8V

Well yes I do have a low voltage alarm & shutoff
BUT: when you start the bowthruster your Voltage will drop from 12,6 to < 12V almost instantly and the battery is fully charged.

How do you manage that?

Looks like one can study DC boat electrics (nowadays) for half a lifetime making his university degree and in fact fails on the stupid devices.

[Michael Cobbe]

4. House bank (lithium)


Lithium batterries are well known for catching fire on planes and in cars. House battries should deep cycle such as Trojans. https://trojan-batteries-online.co.u...ure-batteries/ We had two 6 volt batteries in series, they last 5 years.

[moseriw]

Well I expect trojans - if well treated - to last 15 years like GEL
If not I'll skip that scrap

[hzcruiser]

Originally Posted by a64pilot

Understood, but unless you have a rather large boat it’s just not necessary to be putting batteries near the load,

It might not be necessary, but it is an option. I like having the biggest batts near the big inverter and some smaller ones in the wheel house for lights and radios, then another one at the windlass.

just as you say run larger cables, larger cables last forever and are very simple, ACR’s and multiple banks are not. Plus the obvious fact that your carrying around a lot of dead lead, weight that does nothing except when it’s time to raise the anchor, otherwise it’s wasted weight and money.

Interesting to consider a windlass batt as dead lead. Maybe there is a misconception here that it only serves to weigh anchor? If required it can and is being used to run everything else, too, albeit with a slight loss due to the cable length going back. Nevertheless, the smaller long-term consumers in the back use much less current.


I'm certainly not running massive cables all the way to the forepeak for those few seconds in a day when I need 100+A up there. That windlass batt can cover the windlass motor and gets recharged (or balanced, if you want) during some period afterwards. Oh, and no fancy electronics needed, the batts sort that out amongst themselves, based on Ohm's law.



IMHO, larger cables are much more of a dead weight and wasted money if you only need them for a minute or two a day.


There are so many other advantages of having a distributed storage system in place that I don't even know where to begin. E.g. weight distribution, better use of smaller spaces, individual smaller batts can be replaced easily on the fly or taken off the bus if the get weak. Not easy to do with a few sets of Trojan's, all in parallel.. then 2S.

[slug]

Originally Posted by hzcruiser

It might not be necessary, but it is an option. I like having the biggest batts near the big inverter and some smaller ones in the wheel house for lights and radios, then another one at the windlass.




Interesting to consider a windlass batt as dead lead. Maybe there is a misconception here that it only serves to weigh anchor? If required it can and is being used to run everything else, too, albeit with a slight loss due to the cable length going back. Nevertheless, the smaller long-term consumers in the back use much less current.


I'm certainly not running massive cables all the way to the forepeak for those few seconds in a day when I need 100+A up there. That windlass batt can cover the windlass motor and gets recharged (or balanced, if you want) during some period afterwards. Oh, and no fancy electronics needed, the batts sort that out amongst themselves, based on Ohm's law.



IMHO, larger cables are much more of a dead weight and wasted money if you only need them for a minute or two a day.


There are so many other advantages of having a distributed storage system in place that I don't even know where to begin. E.g. weight distribution, better use of smaller spaces, individual smaller batts can be replaced easily on the fly or taken off the bus if the get weak. Not easy to do with a few sets of Trojan's, all in parallel.. then 2S.

Separate battery located next to the consumer is a common solution

The only issue is charging the battery

I normally see dc/dc chargers

[hzcruiser]

Originally Posted by slug

Separate battery located next to the consumer is a common solution

The only issue is charging the battery

I normally see dc/dc chargers

Well, it's not a generally accepted practise on this forum, it seems. Nevertheless, charging would not be an issue either if you would feed the charge into a central location, then the voltage drop would be about the same to all batts.
Even if you don't use that option (don't look at me...), batts on a bus reach a "natural" balance as the currents between them go down exponentially.

And remember: those smaller balancing currents also cause smaller differential voltage drops between the batts.


Finally, to help it all along, a proper management system that checks Ah in and out of every bat can be a tremendous help.

[hzcruiser]

Originally Posted by moseriw

Well I expect trojans - if well treated - to last 15 years like GEL
If not I'll skip that scrap

From what I've seen and read here, that's a rather high expectation. Unless your boat is in storage 8 months a year, with a proper trickle charge.

[a64pilot]

In your facts, you have a 225 AH house bank?
He is going to Lithium and one of the reported advantages is they don’t sag in voltage, then add in the small fact that I don’t think many operate their bow thrusters and or windlasses with the engine off. Which of course adds voltage and alternator output to the available power
Majority of boats don’t have separate windlass banks, so I guess we all have inoperative burned up windlasses and just aren’t aware of it?

People argue all the time about having anchor chain weight in the bow and some even put it further back in the boat and take their anchors off the bow and store them for passages.
So they need a hundred lbs of batteries or more in the bow now?

I have one bank, pretty much center of the boat. Boat was designed that way, it’s actually two banks but as I leave the switch to both in reality it’s one, it easily starts the engine, the generator and runs the windlass with no problem, how do you explain that?

[moseriw]

Majority of boats don’t have separate windlass banks, so I guess we all have inoperative burned up windlasses and just aren’t aware of it?

Won't discuss this - check it.
I wrote about my checked figures and I think it might be a hell of a good idea for everyone to check his installation for himself.

[donradcliffe]

The Lithium batteries complicate things, and there are too many bits of advice from posters without lithium experience.

First, Lithium operating voltage range is higher than AGM's, and they should not be interconnected unless you have a strong charging source like an alternator or generator/charger which takes the system voltage above 13.5 volts. Secondly, the lithium BMS's get expensive for currents over 100 amps, so using the lithium bank for starting should be only with jumper cables to charge an AGM. If you are only charging lithium batteries with an alternator, a High Voltage cutout on the BMS will fry your alternator--better to have the alternator hooked to an AGM and then a Battery to Batttery unit to charge the lithiums at the voltages they require.

Redundancy is a major factor in the system design, but having both a genset start and an engine start is overkill on your size boat. Assume that each part of the system will fail (its a boat), and have a plan for supplying essential electrical power. Blackout recovery would be easiest with the genset (less than 1 amphour to start with a decent battery voltage, which could be as little as 10 minutes of solar). If the genset is down, then the main engine takes a bit more battery charge, but its not the end of the world if you have solar or some separated batteries you can tap with interconnects or even jumper cables. All of your batteries are not going to short a cell at the same time (although a shorted cell in one battery will discharge every battery its is paralleled to).

[CassidyNZ]

Originally Posted by Starblossom

I suggest you look into the Sterling alternator to battery charger. It will simplify your life

AFAIK the Sterling device you refer to is a pseudo smart regulator that takes the place of a real smart regulator. How would that simplify my life?

My life (electrically) is already simple. I check my batteries via a battery monitor and then direct charging sources to two banks as required by simple switches.

There is a plethora of electronic devices “recommended” on this board that are intelligent enough to know that the best time to fail is when they’re 1000nm from support.

My switches never fail.

[dougweibel]

Originally Posted by CassidyNZ

My switches never fail.

Your switches have not failed yet. Switches fail too. My engine battery switch died recently at the young age of 6 years. It happens. Why else to you think West Marine has so many on the shelf.

[a64pilot]

The switches do fail, and it seem the ones that fail most often are the ones that are never switched, perhaps the contacts oxidize.
But they are simple to wire around or carry a spare

[CassidyNZ]

Originally Posted by hzcruiser

I'm certainly not running massive cables all the way to the forepeak for those few seconds in a day when I need 100+A up there. That windlass batt can cover the windlass motor and gets recharged (or balanced, if you want) during some period afterwards. Oh, and no fancy electronics needed, the batts sort that out amongst themselves, based on Ohm's law.

IMHO, larger cables are much more of a dead weight and wasted money if you only need them for a minute or two a day.

Yes, I wasted money on a reel of HD battery cable to run it from my engine room to the forepeak to support the anchor winch battery but the cable languishes in a cupboard in the workshop.

I have two charge wires that keep the front battery charged from the back with a temperature sensing switch that opens the circuit in the event that the anchor winch battery gets “soft” and starts drawing current from the back.

The front battery also powers a water pump for chain washing that runs when the winch is reeling in chain.

[a64pilot]

Originally Posted by moseriw

If you really think that’s possible then have a low voltage alarm
Best you set the shutoff to 12,2V = 50% empty to use the batteries as diligent as you can.





batteries:
Full 12,6V
Half 12,2V
Empty 11,8V

Well yes I do have a low voltage alarm & shutoff
BUT: when you start the bowthruster your Voltage will drop from 12,6 to < 12V almost instantly and the battery is fully charged.

How do you manage that?

Looks like one can study DC boat electrics (nowadays) for half a lifetime making his university degree and in fact fails on the stupid devices.

The alarm will sound only when the voltage is below the set point, think of it like the low oil PSI alarm for the engine, yes it’s a little annoying, but only for a second or so.

I believe most 12V lead batteries are dead or 100% discharged at 10.5V, but 50% is real close to the 12.2 you quote.