Correct use of batteries

I have just replaced our two x 200amp, combination house/starting batteries after five years.

I always use the batteries on the 'both' setting rather than battery 1 or 2 setting.Apart from the obvious downside that if I flatten the batteries, the boat won't start, is there any other reason why this is not a good idea?

Andy G said:

I have just replaced our two x 200amp, combination house/starting batteries after five years.

I always use the batteries on the 'both' setting rather than battery 1 or 2 setting.Apart from the obvious downside that if I flatten the batteries, the boat won't start, is there any other reason why this is not a good idea?

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If they are flooded batteries, 5 years is a pretty good service life. It shows that you have been taking good care of them. You could by monitoring them closely use them one at a time. That would keep one in reserve. Probably a good thing to do in remote places.

You didn't ask, but it would be a good idea to separate your starting and house banks by adding another battery. Just a suggestion as it seems you have been doing OK.

No.

David

Andy, if you have a bad cell on one battery and its voltage drops and they are tied together in "ALL" or "BOTH", the good battery voltage will be dragged down by the bad battery.

Better to use a combiner to allow both to charge together then automatically separate when the charge stops.

Andy G said:

I always use the batteries on the 'both' setting rather than battery 1 or 2 setting.Apart from the obvious downside that if I flatten the batteries, the boat won't start, is there any other reason why this is not a good idea?

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From my experience, when the engines are running, It's fine to leave the switch on both. But when you stop, anchor or dock. Switch to one battery or bank. You will get better battery life, avoid an accidental flattening and allows your smart charger to analyze, charge and float each of your batteries at the proper level. If you leave them on both when they're on the charger, all will charge and float at the same voltage.

I have always used flooded batteries ( I have a generator and I'm not afraid to use it, ) and I have one battery bank that is eleven years old and holding fine.
Larry B

Despite this photo, I normally keep the "parallel" switch turned to the off position for previously-stated reasons given by others. Having separate battery banks for engine starting versus house is also wise.



A battery monitor for the house bank is also a good idea ...



... here showing an 84.8% charge level.

is there any other reason why this is not a good idea?No, this is the modern way to use batts.

The old 1-2 them actually cuts the bank capacity in half , requiring 2x the discharge from the 1 working batt.

The less any batt is discharged , and the longer SOC is less than 100% the shorter the batt set life.

My question is why "combination " batts , which are usually poorer at either starting or cycling?

In warm climates most "Deep Cycle" batts will easily have the amperage for engine or noisemaker starting.

Since its the down cycling that wears the batt , not the starting any boat that can operate with deep cycles as starts will get longer batt set life.

Boats that operate in the cold ( under freezing) with no block heaters will need start batts to spin the crank faster to build enough heat for self ignition of the fuel.

I would say bad idea.
For the main reason you stated. The boat won't start.

I would always keep the start batterie for just starting the engine.

Nothing worse than dead in the water because you ran the batteries down.

Sd

Andy, For what it's worth, our philosophy has always been, if it ain't broke don't fix it. It it has worked for you for 5 years, why would you even wonder if there is a reason to change it? We ran one boat for 17 tears with only a house bank always connected. Don't complicate things if it's not necessary. Chuck

So basically, you have a single 400a/h battery?
I like knowing I have a fully charged battery in reserve for emergency starts.

Andy G said:

I have just replaced our two x 200amp, combination house/starting batteries after five years.

I always use the batteries on the 'both' setting rather than battery 1 or 2 setting.Apart from the obvious downside that if I flatten the batteries, the boat won't start, is there any other reason why this is not a good idea?

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If you always leave the switch set on "Both", you don't need the switch, just wire them in parallel and be done with it. That's what the switch is doing in the "Both" position.

You should be reserving one position for engine starting and the other for use while anchored or otherwise without charging current. So - Switch to #1 to start the engine, switch to Both while underway so they both charge, then switch to #2 while anchored and using electrical power such as lights, radio, etc., then switch back to #1 to start the engine and back to Both so they both get recharged.

Or, just install a battery combiner or voltage sensing relay and have it done automatically for you. The part should be under $100 and they are very easy to install.

R Widman says "switch to both while underway --" On some vessels this may be problematic for the diodes in the on engine alternator dependent upon the type of 1-2- both - off switch you have.

rwidman said:

If you always leave the switch set on "Both", you don't need the switch, just wire them in parallel and be done with it. That's what the switch is doing in the "Both" position.

You should be reserving one position for engine starting and the other for use while anchored or otherwise without charging current. So - Switch to #1 to start the engine, switch to Both while underway so they both charge, then switch to #2 while anchored and using electrical power such as lights, radio, etc., then switch back to #1 to start the engine and back to Both so they both get recharged.

Or, just install a battery combiner or voltage sensing relay and have it done automatically for you. The part should be under $100 and they are very easy to install.

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To much to remember when trying to relax and enjoy a boating experience.
The best way IMHO is 3 on off switches as on Marks Coot.
one for house. One for start and one to combine all batteries for a sure start.

Sd

skipperdude said:

To much to remember when trying to relax and enjoy a boating experience.
The best way IMHO is 3 on off switches as on Marks Coot.
one for house. One for start and one to combine all batteries for a sure start.

Sd

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With the combiner there's no need to remember anything. That was my point. I probably should have been more clear.

If you have a fully charged starting battery but have discharged your house battery (bank) and combine them for starting, the fully charged starting bank will be trying to charge the house bank as it is also trying to start the engine.

Are you saying that a full or partial charged start battery will not get juice from a partially charged house bank if the two banks are paralleled.

Sort of like dumping a 1/2 bucket of water into another 1/2 bucket of water to get a full bucket.

Or doesn't it work like that?

In my experience it always seems to work that way. I have had a start bat run down and when I switch the parallel I get more cranks.

SD

skipperdude said:

Are you saying that a full or partial charged start battery will not get juice from a partially charged house bank if the two banks are paralleled.

Sort of like dumping a 1/2 bucket of water into another 1/2 bucket of water to get a full bucket.

Or doesn't it work like that?

In my experience it always seems to work that way. I have had a start bat run down and when I switch the parallel I get more cranks.

SD

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Are you responding to my post?

I am saying that if you have a discharged house battery or bank and you parallel it with a fully charged starting battery or bank and then try to start your engine, the fully charged battery or bank will be trying to charge the discharged bank at the same time it is trying to start the engine. It would be a better plan to start the engine using the starting batery alone and then switch the two together so they can both be charged by the alternator.

If the starting bank is discharged to the point where it cannot start the engine by itself, switching in the house bank may provide enough power to start the engine. It depends on the state of charge of both banks.

If the boat is wired properly with a combiner or VSR, the starting battery will be charged and ready to start the engine unless it is defective or incapable of starting the engine because it doesn't have the capacity to do so in the first place. Or you've run it down trying to start an engine with another problem.

skipperdude said:

...... Sort of like dumping a 1/2 bucket of water into another 1/2 bucket of water to get a full bucket..........

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More like connecting the buckets together with a hose. One is full, the other 1/2 full and you end up with two buckets, each 3/4 full.

Ok so how does this happen? Do the electrons flow first to the undercharged bank before performing the work of starting the engine?

I can understand a charger doing that but one battery charging another.
I was not aware that was how it works.

I understand that electrons move at the speed of light. Of coarse taking Ohlms law into account for resistance.

Interesting.

Sd

skipperdude said:

Ok so how does this happen? Do the electrons flow first to the undercharged bank before performing the work of starting the engine?

I can understand a charger doing that but one battery charging another.
I was not aware that was how it works.

I understand that electrons move at the speed of light. Of coarse taking Ohlms law into account for resistance.

Interesting.

Sd

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The charger acts just like another big battery except it is connected to a never ending source, 110VAC. That's what happens when you jump a battery. One is discharged to say 9V, so it can't turn the engine and the other is at 12V. Connect them together and you get 10.5V or so and the engine can start. That is also why you can't start a car if the battery is really low say the lights were left on and they drained every last volt out of the car battery. You can disconnect the car battery and connect the jumpers to the cars cables or you need to charge the car battery awhile so that the car can be jumped off.

skipperdude said:

Ok so how does this happen? Do the electrons flow first to the undercharged bank before performing the work of starting the engine?

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As soon as you connect the charged battery to the discharged battery, current flows from the charged battery to the discharged battery. Eventually, they will have the same state of charge, somewhere between charged and discharged.

If you're trying to start you engine, the fully charged battery is splitting its power between the starter and the discharged battery.

Andy,5 years from batteries is good and suggests good management.
There are 2 features of the early 1980s IG twin engine battery set up:
1. It has 2 200 amp hour batteries,one for each engine. they do both starting, and house supply.There is no dedicated house battery.
2. The batteries automatically parallel when you hit start.
The Owners Manual p9 says " The battery selector switch ....connects either or both batteries to the service system. Except in the case of charging both batteries by the same engine alternator the selector switch should not be used in the all position"
That seems to suggest using one or both for house,but it seems odd you should set to 1 or 2 when operating both engines.I also admit using the "both" position when running,with no obvious ill effect.Any ideas out there about this?
Because of the dual demands on batteries,I use Century Pro Cruiser N200M flooded batteries which are marketed as dual purpose.
If when anchored, you use 1 or 2 but not both, you risk overdrawing the one you use, whereas if you use both the draw is spread and neither may be overdrawn, but you risk overdrawing both if not careful. You could try alternating between 1 and 2 overnight, keeping the other as a fully charged start battery, effectively creating a de facto dedicated house and start set up, and see how it works by checking the voltmeter.
For a time I had one new and one "ok" but not new battery. Performance improved markedly when I renewed the "ok" one. Otherwise the better one drains to the worse one,and because the worse one can`t hold charge well, the draining never ends.
To maintain the batteries,mine are each fed by 90w of panels via regulators which include a monthly "equalization" phase to shake any sulphation off the plates back into solution.
Back up remains the genset. Mine has a regulated 25w panel for its 150 a/h battery. While running the eutectic refrigeration an hour morning and evening using the genset,I also charge batteries,and of course run the espresso coffee machine. BruceK

Greetings,
OK, you've got 2 batteries (or banks). The house battery is depleted to 9V- (and isolated via switches or what-ever) due to over-use of your disco ball and repeated showings of Saturday Night Fever. Not a hope of EVER starting your main(s) with that lot. You introduce your starting battery into the circuit (floating @ 14V+/- fully charged) to start main(s). What you are saying is: since being parallel with your depleted battery you will not have enough juice to start due to "fresh" battery draining to dead battery? Hogwash, in the short term. Yes, over time the two batteries will equalize to a state where there is not enough power to start your main(s) but you SHOULD be able to get going with the immediate added voltage.
As to keeping at least a minimum of battery(s) isolated and dedicated for main(s) start-up, I agree.

RTF, I think you are misreading my post. I am equally confident the fresh unused battery would start the engine,that`s why I talked about creating a de facto start and house system by selecting only one battery and preserving the other while on the hook. I agree draining from the "good" to the "bad' battery would take time. The IG system would parallel the batteries the instant you hit the starter, before any draining could occur. BruceK

Greetings,
Apologies for misinterpretation.

Phew, I thought I had wandered into ODT for a minute.

Thanks all for your views and advice. For the record I have a similar system to Bruce's IG. I would love a separate starting battery, simply no room in the engine bay, or up forward. I also use my 7KVA gen each morning and evening to recharge etc. when on the hook, so the present system does work, although it is not optimum.

One issue though, with the new batteries, my electrician suggested I put in Federal 908DFT's, flooded batteries.These were the largest batteries that would fit into the existing battery box's & one of the reasons for this choice being they are sealed, ie don't need topping up, which seemed a good idea to me, so went ahead and had them installed. I rang the Federal distributor here in Oz to have a chat and was told these batteries are not sealed and they would require topping up time to time.The invoice clearly states they are 'maintenance free', so I guess I'll need find out for sure, who is right. Want to keep these batteries for another five years if possible.

Andy G said:

Phew, I thought I had wandered into ODT for a minute.

Thanks all for your views and advice. For the record I have a similar system to Bruce's IG. I would love a separate starting battery, simply no room in the engine bay, or up forward. I also use my 7KVA gen each morning and evening to recharge etc. when on the hook, so the present system does work, although it is not optimum.

One issue though, with the new batteries, my electrician suggested I put in Federal 908DFT's, flooded batteries.These were the largest batteries that would fit into the existing battery box's & one of the reasons for this choice being they are sealed, ie don't need topping up, which seemed a good idea to me, so went ahead and had them installed. I rang the Federal distributor here in Oz to have a chat and was told these batteries are not sealed and they would require topping up time to time.The invoice clearly states they are 'maintenance free', so I guess I'll need find out for sure, who is right. Want to keep these batteries for another five years if possible.

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My Century branded (?Yuasa made) 200 a/h batteries are described as "low maintenance". Maybe for Federal, no= low. You may be better off able to top up. Mine need top up after using the 12v fridge when the batteries are active as the solar panels get to work, but most of all after the monthly equalization. Yours may need less attention. Be sure to get help lifting them in. BruceK

BruceK said:

RTF, I think you are misreading my post. I am equally confident the fresh unused battery would start the engine,that`s why I talked about creating a de facto start and house system by selecting only one battery and preserving the other while on the hook. I agree draining from the "good" to the "bad' battery would take time. The IG system would parallel the batteries the instant you hit the starter, before any draining could occur. BruceK

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The depleted battery will not help start the engine and the non depleted battery will have the extra load of the depleted one. It doesn't matter that it takes a while for them to reach an equal state of charge.

Think of the difference between starting your car with the headlights off and with the headlights on.

Andy G said:

Phew, I thought I had wandered into ODT for a minute.

Thanks all for your views and advice. For the record I have a similar system to Bruce's IG. I would love a separate starting battery, simply no room in the engine bay, or up forward. I also use my 7KVA gen each morning and evening to recharge etc. when on the hook, so the present system does work, although it is not optimum.

One issue though, with the new batteries, my electrician suggested I put in Federal 908DFT's, flooded batteries.These were the largest batteries that would fit into the existing battery box's & one of the reasons for this choice being they are sealed, ie don't need topping up, which seemed a good idea to me, so went ahead and had them installed. I rang the Federal distributor here in Oz to have a chat and was told these batteries are not sealed and they would require topping up time to time.The invoice clearly states they are 'maintenance free', so I guess I'll need find out for sure, who is right. Want to keep these batteries for another five years if possible.

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No such thing as a seal flooded battery. GEL and AMG yes flooded no. They need to breath due to the manufacturing of H. So there needs to be a way to add water. These batteries may have a better recapture system than regular batteries but they still will lose H2O to the atmosphere.

JD said:

No such thing as a seal flooded battery. GEL and AMG yes flooded no. They need to breath due to the manufacturing of H. So there needs to be a way to add water. These batteries may have a better recapture system than regular batteries but they still will lose H2O to the atmosphere.

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There are many "maintenance free" flooded batteries. Many cars and trucks come with them. "Maintenance Prevented" might be a better term but they are out there.

http://www.theautochannel.com/news/2005/11/30/150966.html

BTW: That would be "AGM", not "AMG".

rwidman said:

If you're trying to start you engine, the fully charged battery is splitting its power between the starter and the discharged battery.

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Not really, the internal resistance of the discharged battery is higher so more power flows from the charged battery to the starter. Very very little is used to charge the discharged battery as starter current flows.