Comments on Changing by Battery arrangement

[timjet]

Based on your comments on previous threads I've decided to upgrade by battery system. I currently have 5 AGM batteries, one for generator start, two connected in parallel and connected to the #1 position of the Battery selector switch and two more connected in paralled and connected to the #2 battery selector switch.

I'm changing this so that the 4 batteries connected to the 1 and 2 positon of the battery switch are now all connected in parallel and connected to the #1 positon of the battery switch. I'm adding a wet cell engine start battery and connecting this to the #2 position of the battery selector switch.

This gives me 420 amps for the house which I need due to my energy hungry fridge.

Attached are the schematic diagrams, the first is the current state and the second is my revised state.

One question; Notice that in the revised state schematic the Engine start battery negative terminal is connected to the negative terminal of a battery in the house bank. I did this because it is much easier than running a separate negative cable to ground. Anything wrong with this??

Any suggestions please post.

Thanks

Note: Pressing ctrl + will enlarge the images


-- Edited by timjet on Sunday 25th of March 2012 03:54:17 PM

 

[Tom.B]

Nothing wrong with all the grounds connecting together as long as the eventually make it to the engine blocks (assuming your starters use the block as ground). However, my opinion leans to getting rid of the 1,2,All switch. That is a single point of failure there and stacking all those connections is also not ideal. Separate the entire starter circuit and the house system so that any failure in one will not drag down all the rest of them. As it is right now, a failure in the 1,2,All switch with leave you with no house power, no starter power... nothing. Nor can you isolate any catastrophic failure to a specific bank.

I'm sure RickB will prove me wrong because I seem to always get his advice wrong ;-) Still, he has helped me a ton. Make sure you get your plan completely worked out before you start.

 

[timjet]

Thanks Tom, I had not considered a battery switch failure as a possibility. The switch is original and looks pretty robust. I don't think anything has changed since the boat was built concerning the battery switch. However you make a good point. A failure of the switch would render the boat useless.

Since we are headed to the Bahamas in May I'm going to carry a pair of jumper cables that should allow me to get the engines running in the event of a switch failure or other battery issue. Without house power my chart plotter would be useless and that's a major problem. Since you brought this up, I'm going to carry a portable battery operated hand held GPS and get extra batteries for it and my hand held VHF.

The battery switch is in such a location that it is very difficult to get to the wires and cables connected to it, and I mean very difficult. I could possibly isolate the starting circuit but the alternator charging wires would be a major issue to remove and relocate.

 

[JD]

timjet wrote:
Thanks Tom, I had not considered a battery switch failure as a possibility. The switch is original and looks pretty robust. I don't think anything has changed since the boat was built concerning the battery switch. However you make a good point. A failure of the switch would render the boat useless.

Since we are headed to the Bahamas in May I'm going to carry a pair of jumper cables that should allow me to get the engines running in the event of a switch failure or other battery issue. Without house power my chart plotter would be useless and that's a major problem. Since you brought this up, I'm going to carry a portable battery operated hand held GPS and get extra batteries for it and my hand held VHF.

The battery switch is in such a location that it is very difficult to get to the wires and cables connected to it, and I mean very difficult. I could possibly isolate the starting circuit but the alternator charging wires would be a major issue to remove and relocate.

On the set of AGMs that you have as your house bank it is important that the B+ on battery 1 in the line of four batteries is where your Red wire for the house*bank goes and then on the fourth battery the B- is*where your ground cable goes.* That way all of the current goes through each and every cell in each and every battery.* The start battery ground needs to be connected either directly to the engine, a*ground bus bar or it can be connected to the ground B- post on the number four battery.* Not on the B- of*any of the other batteries in the series.*


-- Edited by JD on Sunday 25th of March 2012 09:14:54 PM

 

[FF]

"I need due to my energy hungry fridge'

When you finish , your fridge will still be in charge , and a huge pain.

DEEP SIX the fridge?

 

[timjet]

JD wrote:

On the set of AGMs that you have as your house bank it is important that the B+ on battery 1 in the line of four batteries is where your Red wire for the house*bank goes and then on the fourth battery the B- is*where your ground cable goes.* That way all of the current goes through each and every cell in each and every battery.* The start battery ground needs to be connected either directly to the engine, a*ground bus bar or it can be connected to the ground B- post on the number four battery.* Not on the B- of*any of the other batteries in the series.*



-- Edited by JD on Sunday 25th of March 2012 09:14:54 PM

*JD, thanks.

The batteries as shown in the second picture are sequenced from the Battery switch to the #4 #1 #2 #3 batteries with a ground at #4 and #3. I believe what you're saying is to remove the ground at #4 and leave the ground at #3. This would ground the last battery in the sequence only.

I will do that and use the ground that I removed from #4 battery and attach it to the engine start battery ground.

Does this sound right??


-- Edited by timjet on Monday 26th of March 2012 04:45:06 AM

 

[RickB]

GonzoF1 wrote:
Separate the entire starter circuit and the house system so that any failure in one will not drag down all the rest of them.

Spot on with that advice, Gonzo.

Engine starting should not have any connection to other consumers. The voltage sags and spikes created during a start can destroy electronic equipment powered off the same circuit.

Install a starting battery for each engine, include an isolator switch if you like and buy a good set of jumper cables for emergency starting.

*

 

[timjet]

FF wrote:
When you finish , your fridge will still be in charge , and a huge pain.

DEEP SIX the fridge?

*Patiently waiting for the Norcold to fail.

 

[timjet]

RickB wrote:Engine starting should not have any connection to other consumers. The voltage sags and spikes created during a start can destroy electronic equipment powered off the same circuit.
*

*Thanks Rick. This is probably fairly easy to do without having to monkey with the Battery switch. I'll study this.

However under my proposed configuration the start battery is on the #2 bank and as long as I am careful to position the battery switch to the #2 position during engine start I should have no problem with voltage sags during start on the #1 bank or house bank. Additionally I have the advantage of using the house bank to start the engines if necessary, in which case turning off electronic equipment would be advisable.

Another issue to consider is if I remove the start battery from the battery switch and isolate it as you say I would loose the ability to use both engine alternators to charge the house bank. Under my current setup the current from both alternators goes thru the battery switch and is directed to the selected battery. The house bank (#1 bank) is* generally the bank in need of most charge. After an overnight stop with the house bank low, I would start the engines and position the battery switch to the house bank allowing both alternators to change that bank. If I isolated the engine start bank, presumable one alternator would change the start bank and one the house bank. This would be a real problem and require twice the engine run time to charge the house bank.

 

[RickB]

There are several combiners and isolators available that will deal with your concerns.

 

[JD]

timjet wrote:JD wrote:

On the set of AGMs that you have as your house bank it is important that the B+ on battery 1 in the line of four batteries is where your Red wire for the house*bank goes and then on the fourth battery the B- is*where your ground cable goes.* That way all of the current goes through each and every cell in each and every battery.* The start battery ground needs to be connected either directly to the engine, a*ground bus bar or it can be connected to the ground B- post on the number four battery.* Not on the B- of*any of the other batteries in the series.*



-- Edited by JD on Sunday 25th of March 2012 09:14:54 PM

*JD, thanks.

The batteries as shown in the second picture are sequenced from the Battery switch to the #4 #1 #2 #3 batteries with a ground at #4 and #3. I believe what you're saying is to remove the ground at #4 and leave the ground at #3. This would ground the last battery in the sequence only.

I will do that and use the ground that I removed from #4 battery and attach it to the engine start battery ground.

Does this sound right??



-- Edited by timjet on Monday 26th of March 2012 04:45:06 AM

That is correct.*

Your almost there you will need a ground wire from #1 B-*to #2 B-.* Once you do that old*#4 becomes #1,*old # 1 becomes #2, old #2 becomes #3, old #3 becomes #4.

 

[skipperdude]

I would get rid of the 1,2 both switch and go with 3 on*off switches.

So you don't have to worry about where the switch is set.

One on/ off switch for the start batteries.

One on /off switch for the house bank.

one on/ off switch to combine all banks (this one us usually off. Only needed when you have to combine the two)

use a battery combiner to rout power through both banks. It charges the start bank first then switches over to charge the house bank.

In this set up you never have to worry about running you start battery down because someone forgot to switch the switch.

It is what I use and has performed flawlessly until the cheap switch went bad. I replaced it with a good one now it's perfect.

SD

*

 

[JD]

skipperdude wrote:
I would get rid of the 1,2 both switch and go with 3 on*off switches.

So you don't have to worry about where the switch is set.

One on/ off switch for the start batteries.

One on /off switch for the house bank.

one on/ off switch to combine all banks (this one us usually off. Only needed when you have to combine the two)

use a battery combiner to rout power through both banks. It charges the start bank first then switches over to charge the house bank.

In this set up you never have to worry about running you start battery down because someone forgot to switch the switch.

It is what I use and has performed flawlessly until the cheap switch went bad. I replaced it with a good one now it's perfect.

SD

*

*I would not charge the start first.* I would send everything to the house from the Alt or the 110V charger.* Then use an Echo charge to charge the start.* After being on the hook for any length of time the house battery bank is down amperage not the start battery.* The start battery is still full up from*when you anchored.* The start of the engine doesn't take but a couple of Amps out of the start battery.* Think about it.* Lets say that the starter draws 100 amps for ten seconds. Which is doesn't but lets say it does.* That comes out to just a few amps actually out of the start battery per engine start.* So it won't take the Echo charger anytime at all to top up the start battery as the Alt feeds the house bank the full out put of the Alt.

 

[skipperdude]

I don't know man.

I want my start to be a priority.

*I can do without everything on the boat but the motor.

I need that to start every time I hit the switch.

Therefor the start bank is priority one. If you drain your house bank down listening to Buffet. then you would have to fully charge the house bank before anything gets to the start battery. It does no good to sit and drink a cold one waiting for a tow.

SD*

 

[RickB]

skipperdude wrote:

Therefor the start bank is priority one.

If you drain your house bank down listening to Buffet. then you would have to fully charge the house bank before anything gets to the start battery.

*That is why the start batteries*should be*isolated.

If you drain your house bank down it doesn't matter. The start battery will still start the engine. Once the engine is running the alternator(s) will supply all the house power you need and recharge the house bank.

Those jumper cables will handle the unexpected. Reducing complication will take care of the rest.

 

[JD]

skipperdude wrote:
I don't know man.

I want my start to be a priority.

*I can do without everything on the boat but the motor.

I need that to start every time I hit the switch.

Therefor the start bank is priority one. If you drain your house bank down listening to Buffet. then you would have to fully charge the house bank before anything gets to the start battery. It does no good to sit and drink a cold one waiting for a tow.

SD*

*Not so SD.* In the first place if you drain your house the start is still fully charged.* But suppose it isn't for some reason (I can't think of one).* The Echo charge senses the amount of charge that the start needs and feeds some of the charge from the Alt to it.* Now true if you can't start the engine you can't charge either but then what difference dose it make.* If the engine won't start due to a dead battery and the house is drained and you can't start the engine how is the Alt going to charge anything anyway? No matter which battery it is going to.

Steve D'Antonio is the one who suggests this method.* He said in one of his classes several years ago that he had a boat in his yard that went all summer one year and then in*about the middle of August it would not start one day.* Nothing, would not turn over.* When he looked into it he found that the wire from the Alt to the start battery had been left off when the boat was recommissioned in the spring.* This boat had been used almost every weekend all summer long and started every time but the battery was never getting a charge from anything.* His point was that a start battery can go a long time*without being recharged if all it is used for is starting the engines.

 

[skipperdude]

I understand the scenario.

Sorry I will not take a chance.* There are a million reasons why the start battery was not fully charged. I choose to eliminate all those reasons I can

Start battery isolated with one on off switch.

I want the start battery charged first and foremost.

I reread your post do you say you have two chargers. The regular and the echo.

If that is the case I could agree but I would think most people only have one charger.

With one charger I think my way is best.

I will not be out on the water and have my boat not start because of a battery issue.

*

*

SD


-- Edited by skipperdude on Monday 26th of March 2012 03:47:39 PM

 

[Tom.B]

An echo charger it the route I am headed too. But I also have a starting booster box for that added boost should I need it. For now, I am leaving the alternator on the start with the echo to the house, but that will change by the end of the summer. Going to try both and see which I like better. With my new rig, it will take seconds to swap it around and see which works best. In the long run, I am going to add a second alternator before we go cruising.

 

[timjet]

JD, thanks again for pointing out the lack of a ground cable. Attached is the revised schematic.

I understand skipperdudes concern about not being able to start the engines. An inattenative person could forget and leave the battery switch in the both positon thus drawing down both battery banks. However the designers of my boats electrical system presumably took that into consideration when they installed the genset start battery with no connection to the main boat Battery Switch (see attached schematic). If the house and start bank are completely drawn down I would have the option of starting the genset and charging the batteries with the 120v battery charger or using jumper cables off the genset battery to start the engines. It would seem unlikely that I would be unable to start the engines even if I forget to repositon the Battery Switch to the house bank when at anchor. However as previously discussed a failed Battery Switch could cause a loss of electrical power to the house bank, but I should still be able to start the engines with the genset battery.

My concern now is the engine start battery. My house bank and genset start battery are all AGM's. As we previously discussed the engine start battery should be a wet cell. However my battery charger is set to the higher charge voltage of AGM batteries meaning that it will eventually fry the wet cell engine start battery. Perhaps the best option is to get an AGM engine start battery even though it is not the best type of start battery.

 

[JD]

timjet wrote:
JD, thanks again for pointing out the lack of a ground cable. Attached is the revised schematic.

I understand skipperdudes concern about not being able to start the engines. An inattenative person could forget and leave the battery switch in the both positon thus drawing down both battery banks. However the designers of my boats electrical system presumably took that into consideration when they installed the genset start battery with no connection to the main boat Battery Switch (see attached schematic). If the house and start bank are completely drawn down I would have the option of starting the genset and charging the batteries with the 120v battery charger or using jumper cables off the genset battery to start the engines. It would seem unlikely that I would be unable to start the engines even if I forget to repositon the Battery Switch to the house bank when at anchor. However as previously discussed a failed Battery Switch could cause a loss of electrical power to the house bank, but I should still be able to start the engines with the genset battery.

My concern now is the engine start battery. My house bank and genset start battery are all AGM's. As we previously discussed the engine start battery should be a wet cell. However my battery charger is set to the higher charge voltage of AGM batteries meaning that it will eventually fry the wet cell engine start battery. Perhaps the best option is to get an AGM engine start battery even though it is not the best type of start battery.

*I'm not sure how much of a problem that will be with the Echo charger.* The charge rate will be low for the most part and only as needed.* However matching them all would be best.

The drawings look good.

 

[FF]

"However my battery charger is set to the higher charge voltage of AGM batteries meaning that it will eventually fry the wet cell engine start battery."

I always understood AGM could be charged with more AMPS ,

but if the VOLTAGE of a wet batt was used on an AGM the tiny amount of elecrolite could be boiled out.

I understood the better dock chargers had selection to lower the charge Voltage for AGM and gell.

 

[timjet]

FF wrote:
I understood the better dock chargers had selection to lower the charge Voltage for AGM and gell.

*You mean increase the voltage for AGM and Gell. Yes this is true of mine as well. However my 3 bank charger allows one selection for all 3 banks. I don't know of any charger that will allow you to charge banks and different voltages.

 

[JD]

timjet wrote:FF wrote:
I understood the better dock chargers had selection to lower the charge Voltage for AGM and gell.

*You mean increase the voltage for AGM and Gell. Yes this is true of mine as well. However my 3 bank charger allows one selection for all 3 banks. I don't know of any charger that will allow you to charge banks and different voltages.

*One thing you could do is find an old isolater.* An isolator uses a diode to keep the current from going in two directions.* That will drop the voltage .5V down stream from what is going in. But I'm not sure that is needed.

If you go to four different sites you get four different answers and this is all*from battery manafactuers.* Bottom line is AGMs Charge from between 14.2 V*- 14.8 V depending on who wrote the article.* Wet cells are in the same range 14.4 V*- 14.9 V again depending on who you believe.* So I'm not sure the charge voltage is the issue.* Float rate varies about the same as well.**So it seems that 14.4 V*-*14.6 V makes everyone happy as a charge rate for both types and with an adjustable regulator you should be able to get there.* I did find an article that explains the real problem with mixing them and in fact makes sense.

"Mixing Batteries

The reasons we do not recommend wet cell and AGM Batteries together are:

When charging, the AGM will reach full charge before the wet cell. This means that the charge system will do one of two things. It will keep charging until the wet cell is fully charged and may over-charge the AGM or it will switch off when the AGM is fully charged which means the wet cell is only partially charged.

The advantage of having 2 AGM batteries is that both can be used for starting or house use in an emergency and quicker charging means less drag on the alternator."

In my mind we are only talking one AGM here so just bite the bullet and get one.* You already have the major cost done with the for house bank AGMs.

 

[timjet]

JD wrote:

The reasons we do not recommend wet cell and AGM Batteries together are:

When charging, the AGM will reach full charge before the wet cell. This means that the charge system will do one of two things. It will keep charging until the wet cell is fully charged and may over-charge the AGM or it will switch off when the AGM is fully charged which means the wet cell is only partially charged.

The advantage of having 2 AGM batteries is that both can be used for starting or house use in an emergency and quicker charging means less drag on the alternator."

In my mind we are only talking one AGM here so just bite the bullet and get one.* You already have the major cost done with the for house bank AGMs.

*Yes, but am I really mixing wet cell and AGM's if they are on different banks? Won't the battery charger reduce the voltage on the AGM's when they are topped up and continue to charge the wet cell because it's on a different bank. I thought the charging voltage of a wet cell was less than the charging voltage of a AGM. If not then why do battery chargers have different settings for wet cell, gell, and AGM's?

 

[JD]

timjet wrote:*Yes, but am I really mixing wet cell and AGM's if they are on different banks? Won't the battery charger reduce the voltage on the AGM's when they are topped up and continue to charge the wet cell because it's on a different bank. I thought the charging voltage of a wet cell was less than the charging voltage of a AGM. If not then why do battery chargers have different settings for wet cell, gell, and AGM's?

*Tim

I don't think your charger can see the difference.* It will charge according to what ever you have it set to.* Wet or AGM.**It is only a program.* One or the other and the same*on all three legs.* As to the voltage being different as I said there are different voltages on different sites but the middle ground is about 14.4V on both.* The major difference is the rate that the battery can take the charge of a 100 amp charger.* The wet can take 50% of it's rated capacity so a 100 amp battery can take 50 amps.* Were as the 100 amp AGM can take 100% or 100 amps.* So if drawn down both*to 50% the wet cell would take a little over an hour to be recharged but the AGM hooked to the same charger will be at full charge in about 30 minutes.* So if the charger reduces the rate to float it cuts back to 13.3 V.* Which is fine for the AGM but not enough to fully charge the wet.* If the charger continues to charge the wet at 14.4 V then the wet will get to full charge but you over charge the AGM.

I would hook my charger and alternator to the B+ of the AGM house bank.* Use an Echo charger to charge the start battery.* If it is a wet cell it will always be a bit under charged.*I would bet that more than 50% of the batteries in boats are under charged as we speak. *If you change it to an AGM the problem goes away and*it will be just fine.* I would rather have the start battery a bit under charged (which is more than enough to start the engines) than to over charge the AGMs.* In the long run the under charged state will cut the life of the wet cell by say a year or two.* So say a wet cell lasts for 5-6 years and your lasts 4-5 and it costs $75 - $100.* The AGM lasts 7-8 years and because it is being charged correctly does last 7-8 years but it cost $225 - $275.* Replace the wet every 4-5 years and money wise you are better than even.*Or use the same set up and*buy the AGM and*forget about it.*


-- Edited by JD on Tuesday 27th of March 2012 10:48:12 AM

 

[FF]

One caution for AGM is never equalize the set.

16V or so ., even at a tiny amperage will kill them forever.

Be sure a solar regulator has the Equalizing feature disabled.

 

[timjet]

Thanks JD, good explanation. I'll probably just get a AGM for engine start and be done with it. Thanks.

 

[JD]

timjet wrote:
Thanks JD, good explanation. I'll probably just get a AGM for engine start and be done with it. Thanks.

*I think that is your best option.* You do realize that the way you have it set up that the house charger is going to split it's total 50 amps or what ever yours is,*by three.* So as an example a*50A*charger gives you 16.6 amps per leg.* Also the Gen set battery*is being charged like the AGMs at 16.6 amps.* You might consider an Echo from the*start battery to the Gen set which is the least used battery and splitting the house charger to two legs like the two Alts.* That would give you 25 amps per bank using my example of a 50 amp house charger.* When the Echo sees the Gen set as fully charged, as it will most of the time, the*start will get as much of the 25 amps as it needs.

 

[bobofthenorth]

FF wrote:
One caution for AGM is never equalize the set.

16V or so ., even at a tiny amperage will kill them forever.

Be sure a solar regulator has the Equalizing feature disabled.

I equalize my Lifeline AGMs in the bus at least once a year, usually every 6 months.* There's more than one opinion on whether it is necessary but it clearly hasn't killed them yet and they're about 10 years old now.

 

[Ron T]

Blue Seas and Charles have both introduced very smart battery chargers. One unit will charge correctly all 3 types of batteries. Gel AGM and wet cell. Nice feature if you have wet for start and AGM for house side.