battery charging

[nautic75]

Good morning, I am looking for some feed back on reconfiguring a 12 volt battery system (2 engine system) we are looking to have 1 each starting batteries, 1 generator battery 1 house battery and 1 inverter battery

port engine to charge 1 starting battery and house battery with the use of a 2 battery isolator stbd engine to charge 1 starting battery, 1 inverter battery and the generator battery by using a 3 battery isolator.
Shore power or Gen power will energize the 120 volt 3 leg battery charger which will charge as follows one leg to house battery with a Cole Heree smart battery isolator connecting 1 starting battery another leg to house battery with a Cole Hersee smart battery isolator connecting another starting battery and 3rd leg to generator. Does that sound about right thank you for any help

 

[tiltrider1]

You can do it that way but it is not how I would do it. I do not understand why you would have separate house and inverter batteries. I also do not like using isolators. I do not like using combiners on dissimilar battery banks. I prefer sending all the charging capacity to the house bank and then using smart-combiners or DC to Dc chargers to keep other banks charged up.

 

[rgano]

You can do it that way but it is not how I would do it. I do not understand why you would have separate house and inverter batteries. I also do not like using isolators. I do not like using combiners on dissimilar battery banks. I prefer sending all the charging capacity to the house bank and then using smart-combiners or DC to Dc chargers to keep other banks charged up.

 

[C lectric]

Combine the house batteries and the inverter battery into one bank. You will actually lose overall capacity by separating them and the inverter batt. will likely have the highest impulse loads so it will lose even faster. One bigger bank will do better than two smaller ones.

Get rid of any diode isolators as they result in ~ 0.7 v drop across the diodes.

There are FET type isolators that do the same thing as the older diode types but at about 0.1 V drop. Does not sound like much to us but to a battery the difference is a LOT.

Or do as Tiltrider suggested.

Rearrange the engine starter batteries so one alternator charges them
and the other alternator charges the other, house, batteries.

THe two starter batts. can be isolated when not charging by the use of an ACR which will combine them when the alternator is running. You should also have a H.D. ON/OFF jumper or parallel sw. so if one of the start batts decides to lay low one day you can still get the engine started. Start the one with the good batt first, then flip the parallel sw. so it and the good battery will help start the reluctant engine.


Let the generator look after its own battery.


There is FAR. FAR more to setting up a good system than this so I am going to leave it here.
Ask more questions and others I am sure will chime in.


My last suggestion for now is find and buy a copy of

The Boat Owners Mechanical and Electrical manual by Nigel Calder.

About $50 but will save you from some potentially serious errors and reworks.
But you will have to READ it. Excellent book.

Mine is the first edition. I think it is now up to the 4th edition which encompasses more about electronics and newer battery and charger info. Used previous issues would cover a lot of your questions but maybe not my now much older edition.
THe newer editions get into the smart chargers, and fancier batteries and their needs. And they do have specific needs if you wish to get their best service.

 

[FF]

DC switches lead a tough life compared to AC switches.

The best long term solution is silver on the contacts , only some companies offer real marine service switches.

12 Volt DC switches,12 and 24 volt heavy duty toggle switches,push pull switches

one company that sells them, mostly made by Cole - Hersey

colehersee.com.au › resources

 

[OldDan1943]

A thought. Generator batteries are usually and wisely independent of the rest of the batteries. I have considered but, not yet accomplished, a separate battery isolation manual switch for the day when the generator battery is "flat". If that happens, drop down into the ER, turn the switch, start the generator off either an engine battery or a house bank. Start the generator and isolate the generator from the rest of the battery system.

 

[tiltrider1]

My fail safe should my generator battery fail. 1) there is a batter of equal size in my dingy. 2) I have a pair of jumper cables that can reach either my house bank or my start bank.

I doubt that I will ever be desperate enough to need these options

 

[Bmarler]

A thought. Generator batteries are usually and wisely independent of the rest of the batteries. I have considered but, not yet accomplished, a separate battery isolation manual switch for the day when the generator battery is "flat". If that happens, drop down into the ER, turn the switch, start the generator off either an engine battery or a house bank. Start the generator and isolate the generator from the rest of the battery system.

i have that. i have manual switches that allow me to use any bank for starting, or any bank for house loads. generally those switches are all in the off position and an automatic combiner handles the charging connections.

 

[rgano]

Always had a switch to "help" the gen batt.

 

[tiltrider1]

I have switches that allow me to cross connect between the house bank and the start bank. I purposefully do not have the generator battery circuit switchable. This way no one can purposefully or inadvertently tie the generator battery into the house bank.

 

[rgano]

Had to switch the gen batt into the start to get the single main on line in a place where there was NO other option. Then right back to off. Thank goodness it was available as an option.

 

[AlanT]

My fail safe should my generator battery fail. 1) there is a batter of equal size in my dingy. 2) I have a pair of jumper cables that can reach either my house bank or my start bank.

I doubt that I will ever be desperate enough to need these options

I have jumper cables but I also have greater distances than they will cope with for some eventualities. An alternative for those with lengthy distances between good and bad batteries is this item from Costco. Only $110. I have one on my boat and one in each vehicle I own. It will start a vehicle/genset/dinghy, it has an LED spotlight, an air compressor up to 110PSI and USB charging ports.

You only have to remember to plug it in once a month!

https://www.costco.com/cat-1200-peak-amp-digital-jump-starter.product.100799044.html

~A

 

[OldDan1943]

In my case, the switch will connect the house batteries to the generator start battery. After starting the generator, open the switch between the house batteries and generator battery, sit back and watch the generator charge its own battery, recharging the house battery. Starting the main engine and everyone is 'home free' while the generator provides 120vt to the buss or is bus.
The key is to remember to open the switch once the generator has started.

 

[rgano]

Jumper cables on a boat bother me for lots of reasons like cramped space, possible boat motion, stressed out person doing the work, and on and on. In thirty years carrying them, I never used them because I had switches. This boat is so limited in storage that j cables never even entered my mind to carry.

 

[OldDan1943]

Jumper cables on a boat bother me for lots of reasons like cramped space, possible boat motion, stressed out person doing the work, and on and on. In thirty years carrying them, I never used them because I had switches. This boat is so limited in storage that j cables never even entered my mind to carry.

Rgano, I agree, no space on a 34ft boat to stow the cables. With switches and and proper understanding and proper operation, we can leave the space consuming cables on the dock.
Remember, document, document, document for you (and your brain farts) and also the next owner.

 

[FlyWright]

You can do it that way but it is not how I would do it. I do not understand why you would have separate house and inverter batteries. I also do not like using isolators. I do not like using combiners on dissimilar battery banks. I prefer sending all the charging capacity to the house bank and then using smart-combiners or DC to Dc chargers to keep other banks charged up.

Combine the house batteries and the inverter battery into one bank. You will actually lose overall capacity by separating them and the inverter batt. will likely have the highest impulse loads so it will lose even faster. One bigger bank will do better than two smaller ones.

Get rid of any diode isolators as they result in ~ 0.7 v drop across the diodes.

There are FET type isolators that do the same thing as the older diode types but at about 0.1 V drop. Does not sound like much to us but to a battery the difference is a LOT.

Or do as Tiltrider suggested.

Rearrange the engine starter batteries so one alternator charges them
and the other alternator charges the other, house, batteries.


Let the generator look after its own battery.


My last suggestion for now is find and buy a copy of

The Boat Owners Mechanical and Electrical manual by Nigel Calder.

About $50 but will save you from some potentially serious errors and reworks.
But you will have to READ it. Excellent book.

A thought. Generator batteries are usually and wisely independent of the rest of the batteries.

Great advice!! I hope the OP is taking notes.

I'd go one step further and suggest that maybe 2 start batteries are not required. I start both Perkins off one Group 31 start battery or use the generator or can parallel with the house bank if ever needed. Have never had a problem in over 10 years.

Genset batts can stand alone with a jumper cable backup system if you don't have a switch.

When I recabled my boat, I split the charge and load sides by cabling the alternator charge directly to their respective battery bank and separate from any load cables. This allows the loads can be controlled separately from the charge sources like an airplane.

I also repositioned my battery selector switches to a location outside of my ER but near the batts. This allows me to kill all DC power immediately without having to enter a smoke-filled ER to access the switches. I'm definitely a fan of switchable combiners over isolators (voltage drop) or non-switchable combiners.

 

[FF]

Battery switches are nice , BUT remember if you take the battery an alternator is charging out of the circuit (with out first shutting off the alt,) it will probably fry the alt diodes.

 

[Bacchus]

Here's a link to what I changed when faced with a similar set up I didn't like. Seec120V & Alt Charging Mods
https://dkloeber.wixsite.com/bacchus/project-pg-4
I eliminated diode isolators on both Alt & shore charger. Made the gen batty stand- alone charged from its own alt. I did replace the on/off Sw with a 1-2-all (same foot print & bolt holes) to be able to start or charge from house with a short jumper. I have since moved start to my thruster bank tonleave a pure house bank.
This suits our style of cruising and batty use but obviously lots of ways to satisfy needs and not completely right or wrong

 

[OldDan1943]

Here's a link to what I changed when faced with a similar set up I didn't like. Seec120V & Alt Charging Mods
https://dkloeber.wixsite.com/bacchus/project-pg-4
I eliminated diode isolators on both Alt & shore charger. Made the gen batty stand- alone charged from its own alt. I did replace the on/off Sw with a 1-2-all (same foot print & bolt holes) to be able to start or charge from house with a short jumper. I have since moved start to my thruster bank tonleave a pure house bank.
This suits our style of cruising and batty use but obviously lots of ways to satisfy needs and not completely right or wrong

Maybe I am reading the above wrong.
I always unload the generator before shutting it down. Not good to drag the generator down and it doesn't do any good for the loads you forgot to disconnect.

On my boat, the alternator, solar panels and generator along with the battery charger always 'play nice' with each other. No smoke, no sparks.

 

[Bacchus]

Maybe I am reading the above wrong.

I always unload the generator before shutting it down. Not good to drag the generator down and it doesn't do any good for the loads you forgot to disconnect.



On my boat, the alternator, solar panels and generator along with the battery charger always 'play nice' with each other. No smoke, no sparks.

I dont understand the comment about running the gen?
I certainly try to let the gen run unloaded/ light load before shutting it down as a best practice.
My comments were about separating the gen start batty from main eng alt or shore power charging systems where diode isolators were installed by Mainship.

 

[FlyWright]

Battery switches are nice , BUT remember if you take the battery an alternator is charging out of the circuit (with out first shutting off the alt,) it will probably fry the alt diodes.

Only a problem if you're switching the charge and with the load. Most boats I've seen use the start cable to provide both charge and load selection at one switch.

If the alternator charges are directed to the batteries by their own cables, switching loads cannot disconnect the alternator.

 

[rgano]

Battery switches are nice , BUT remember if you take the battery an alternator is charging out of the circuit (with out first shutting off the alt,) it will probably fry the alt diodes.

What? You seem to be talking about a switch of some sort between the alternator and the battery. A poor idea at best. Alternators should wire DIRECTLY to a battery positive post. Then you can switch away with abandon.

 

[FF]

By using a better grade of rotary switch , one with built in field disconnect, there is no fear when guests start rotating knobs.

The better switches have a "break before break" setup that kills the field before disconnecting the battery.

 

[angus99]

Great advice!! I hope the OP is taking notes.

I'd go one step further and suggest that maybe 2 start batteries are not required. I start both Perkins off one Group 31 start battery or use the generator or can parallel with the house bank if ever needed. Have never had a problem in over 10 years.

Genset batts can stand alone with a jumper cable backup system if you don't have a switch.

When I recabled my boat, I split the charge and load sides by cabling the alternator charge directly to their respective battery bank and separate from any load cables. This allows the loads can be controlled separately from the charge sources like an airplane.

I also repositioned my battery selector switches to a location outside of my ER but near the batts. This allows me to kill all DC power immediately without having to enter a smoke-filled ER to access the switches. I'm definitely a fan of switchable combiners over isolators (voltage drop) or non-switchable combiners.

Hi, Al. My setup goes yet another step further and uses a single Group 31 to start all engines, including the generator. It’s paralleled with the house bank and switched to allow the HB to crank the diesels in an emergency.

 

[Bacchus]

By using a better grade of rotary switch , one with built in field disconnect, there is no fear when guests start rotating knobs.

The better switches have a "break before break" setup that kills the field before disconnecting the battery.

Agree but have to wonder how many of those "better" switches are in place but not wired or wired correctly to protect the alternator.
I know our last 2 boats had them but were not wired for protection.
When in doubt - check it out!
And if you have the better switch(s) doubt they are wired correctly until YOU confirm they are.

 

[backinblue]

The alternative to jumper cables and other solutions, today you can carry one of these type devices. They also serve other purposes. Some even have an AC outlet for a light load, like a mini portable inverter. I don't know anything about this one in particular, just an example. There are much better and stronger ones available. I never believed it would do what it claims until I used one to jump a Nissan SUV that would not turn over.

https://www.amazon.com/dp/B091GFJH1...=zrBLL&ref_=sbx_be_s_sparkle_mcd_asin_0_title

 

[FlyWright]

The alternative to jumper cables and other solutions, today you can carry one of these type devices. They also serve other purposes. Some even have an AC outlet for a light load, like a mini portable inverter. I don't know anything about this one in particular, just an example. There are much better and stronger ones available. I never believed it would do what it claims until I used one to jump a Nissan SUV that would not turn over.

https://www.amazon.com/dp/B091GFJH1...=zrBLL&ref_=sbx_be_s_sparkle_mcd_asin_0_title

I have used one of these for years to charge devices in the dink or when I'm away from charging ports. My daughter used hers to start a Honda car in a Boston winter, but I seriously doubt it could start a diesel with a weak or dead battery.

 

[backinblue]

I have used one of these for years to charge devices in the dink or when I'm away from charging ports. My daughter used hers to start a Honda car in a Boston winter, but I seriously doubt it could start a diesel with a weak or dead battery.

It's not meant as a replacement for a starting battery, but if your battery is weak and needs some help it may do the job. Like I said there are more powerful ones as well. There are some videos of some units jump starting a diesel tractor trailor. None of these are meant to be the main source of power, but in a lot of cases could be about as useful as jumper cables, maybe even more so. Plus they are easier to store and carry. I laughed at them when I first saw them until I actually used one and it worked as advertised.

 

[FF]

"Agree but have to wonder how many of those "better" switches are in place but not wired or wired correctly to protect the alternator.
I know our last 2 boats had them but were not wired for protection."


No question , many boat "builders" cant be bothered with the time or knowledge required , but folks looking to up grade , this is cheap insurance .

 

[OldDan1943]

"Agree but have to wonder how many of those "better" switches are in place but not wired or wired correctly to protect the alternator.
I know our last 2 boats had them but were not wired for protection."


No question , many boat "builders" cant be bothered with the time or knowledge required , but folks looking to up grade , this is cheap insurance .

Am I wrong thinking when I plan on taking a lead from the house battery, put an On/Off switch to the start battery on the generator, for an emergency start of the generator?