House bank 6 volt vs 2 volt cells

[foggysail]

Originally Posted by Jim Cate

A fully charged 10.5 volt 5 cell battery contains a lot of energy. A 12 volt, 6 cell battery discharged down to 10.5 volts contains damn little energy.

There is a difference, and Jedi's point is that you may be able to utilize the energy in the 5 cell battery.

It is not irrelevant.

Jim

OH REALLY! Please inform my Kohler 7.5KW generator....and yes, people still use those reliable machines. It has a low voltage protection circuit that prevents the starter from cranking with less than about 11.5 volts.

I am certain there are many other products that will refuse to work at 10.5 volts regardless of the source's energy capacity. I think the idea of using a 10.5vdc battery in a 12vdc system is wacky

And another consideration.... there are 6 each 2vdc cells in series. So presuming that one has gone south, the other cells most likely will be energy limited because the bank will have trouble accepting charging current. Sure, by all means in an emergency situation anything that will get you beyond stop is worth trying.

[deckofficer]

We can agree to disagree. Why would any gen set have a low voltage cut out for starting? And 11.5 volts? Most weak kneed 12 volt batteries even with 50% state of charge is going to sag to 11.5 volts or less under the 3000 watt load of the starter motor.

Single series string is the way to go, if you need more capacity then each battery in the string is larger to handle that. If you need 250 a-hr at 12 volts, then (2) 6 volt golf cart batteries is fine, but if you need 700~1250 a-hr, 2 volt cells are the way to go if you are staying with lead. I've moved on to LiFePO4 and will never go back to lead. Why do you think the common 3.2 volt LiFePO4 cells come in 40, 60, 90, 100, 160, 200, 400, 700, 1000 a-hr? So that you can assemble a single series string for whatever voltage and capacity you need.

Watts is work done, the above exhausted 12 volt battery that has dropped to 10.5 volts, when the load of a starter is applied, the voltage will sag further and the amps won't be much either, so lets say the sag pulls you to 6 volts and the exhausted battery manages 30 amps, that is 180 watts and that isn't going to spin your starter. Now take the 2 volt string with one cell removed, you have 10.5 volts at whatever cranking amps the battery is rated at, so no problem spinning the starter, in fact the starter might still get close to the same watts because it would pull more amps at 10.5 volts than what it would at 12 volts. Jedi as always, is 100% correct.

[Maine Sail]

Originally Posted by foggysail

I once purchased 12 vdc Surettes for my sailboat. WHAT A MISTAKE!!! TALK ABOUT MARKETING HYPE---- there is sooooo much of it they actually get people to swear the batteries are worth the ransom demanded at time of purchase.

Hands down the Rolls Surrette brand of batteries consistently has the longest life I see, other than some GELS, and takes the most abuse. My data is not an n=1....

I replaced a dead bank of 16 month old Trojan's last week does that make them "marketing hype".. Most batteries are murdered by their owners and even the best of the best can get murdered.....

Was working on a race boat recently with 5 month old Trojan batteries resting at 11.7V. I am certain when they die at a year or two old the owner may assume that Trojan batteries suck He does not want to add solar or to run the motor for more than getting out of the anchorage... I told him to expect about two years out of his Trojan's and he seemed to be fine with that..

His last bank of GEL batteries lasted 7 years with this sort of abuse which is simply amazing..

[Capt Hugh Wilde]

each main engine has an 80 amp alt. They have been modified for Balmar regulators with temp sensors. They are controlled with a Balmar Crossfielder II, and both are connected to the house bank.

The engine start batteries are charged with a Balmar digital duo charger for each engine off of the house bank.
The charging system is also wired that if the house bank failed with the flip of 2 switches on each engine, and switching the crossfielder II off, that it would charge the engine batteries, and there is a provision to switch to the port engine start battery for limited 12 VDC power.

The engine starts are 110 amp hr Lifeline group 31 batteries.

The planned house bank is 900 amp hr at 12 VDC. I wanted more but that is what the owner would spring for.

3 - 285 watt solar panels with a victron energy controller.

A 3000 watt victron inverter charger. It is fed by the house bank, shore power, and a 5.5 kw gen set.

The boat has A/C but it only runs on shorepower or gen set.
The refer is 12 VDC, 115 VAC and propane.
Stove is propane
Freezer is 12 VDC 115 VAC

All lighting LED

Hot water. like the AC, works only on shorepower or gen set, but has a heat exchanger off of the starboard engine and 2 solar panels with an electric solar panel that runs the pump to move the water from the water heater to the panels and back to the water heater.

Watermaker is Spectra. 12 VDC

We should be in good shape as far as power with the mains online, and the solar should stay ahead of the power usage. It is nice having the area for this much solar.

[deckofficer]

Maine, you work in the industry, have you ever heard of a low voltage cut out for any engine starting circuit?

[foggysail]

Originally Posted by deckofficer

Maine, you work in the industry, have you ever heard of a low voltage cut out for any engine starting circuit?

I learned my generator's limitation when it would not start but would crank and crank. Fortunately I had the wiring schematic to help trouble shoot my problem. There is a relay in the control unit that will not pick up unless there is more than a minimum voltage.... I didn't experiment trying to find what that voltage was but I did measure the +12 to find that while the genny was cranking, the +12 dropped to around +11. Was this a design feature??? Maybe not, more than likely it was a specification problem for the purchase of that particular relay.

The starting problem has occurred several times forcing me to disconnect the fault circuit by actually removing the wire that grounds out the magneto. And I also found that wire MUST be replaced or you cannot shut the genny off.

Originally Posted by Maine Sail

Hands down the Rolls Surrette brand of batteries consistently has the longest life I see, other than some GELS, and takes the most abuse. My data is not an n=1....


.

Mainsail-- I cannot challenge your experience after following many of your professional posts here in the forums. However I do challenge Surrette's battery supposed superiority. Lead acid technology is no secret, the stuff has been around since 1859 when first introduced by Gaston Plante in France.

Batteries over the years have had heroic names such as Mule Battery, the one with the kick and who has not heard of Die-Hard???? How can one ignore such reputed products??? Marketing will tell the purchaser's whatever it is they want to hear. Remember Tony Tiger...."put a tiger in your tank?"

I say that the technology now over 150 years old is well understood. The only variable left resides in the product packaging with modern glass mats and plastics. The old wood and hard rubber cases of yesterday were long ago replaced with plastics.

I believe that those who pay big and I do mean big bucks for something such as Surrette's will cherish their batteries. Constantly check the water levels, maybe even take one out for an evening walk. My point.... they get the best of all care which helps foster a better life than those purchased by guys like me. Although I will say that over the years my batteries have received better treatment especially with the advent of the 3 stage chargers with equalization and solar with regulators that float at much higher than 13.8v

I cannot change your opinion of Surrettes nor can I change my history with them. They remain over rated by great marketing IMHO. I do not imply they are junk, I do however remain unconvinced of their superiority over numerous, less expensive competitor products.

Foggy

[foggysail]

Originally Posted by Capt Hugh Wilde

The planned house bank is 900 amp hr at 12 VDC. I wanted more but that is what the owner would spring for.

3 - 285 watt solar panels with a victron energy controller.


We should be in good shape as far as power with the mains online, and the solar should stay ahead of the power usage. It is nice having the area for this much solar.

AAAHHhhhh I envy you having the space for high power solar. Maybe if I had put more time into my panel selection I could have more than my measly 580 watts from 4 each 145 watt panels.

Your power system is one not often found on small boats......is your boat larger than 80'

Foggy

[deckofficer]

580~855 watts of solar is a great range to be in if you have the deck real estate. My first cruiser had (2) 68 watt panels, but that was before computers and other big draws. Just enough to run the fridge in Baja.

[foggysail]

Originally Posted by deckofficer

580~855 watts of solar is a great range to be in if you have the deck real estate. My first cruiser had (2) 68 watt panels, but that was before computers and other big draws. Just enough to run the fridge in Baja.

Yes Bob, I am happy with what I have ....some times though I get power greedy

I have an Atlantic Tower's hard top over my rear deck. I have the four panels mounted on top of it. Purchase the panels at Amazon last year for about $330 a pair delivered. Great price then now with tariffs could be higher.

I get almost 25 amperes charging in the sun!!!

[boatpoker]

So this 9volt should work ?

[Capt Hugh Wilde]

Originally Posted by foggysail

AAAHHhhhh I envy you having the space for high power solar. Maybe if I had put more time into my panel selection I could have more than my measly 580 watts from 4 each 145 watt panels.

Your power system is one not often found on small boats......is your boat larger than 80'

Foggy

No she is 45 X 20

[colemj]

Originally Posted by boatpoker

So this 9volt should work ?

I have used one to operate the 12V solenoid clutch on a hydraulic ram, which kind of proves the point about voltage and power.

However, removing a 2V cell out of a 12V system leaves 10.5V, not 9V.

As for operating on 10.5V, all of our electronics, including our autopilot, have input requirements of 9-16V. Our inverter cutoff is 10V (and user-variable), and our electrical thingies, like water pumps etc, will work on 10.5V, although they may heat up a bit.

The generator cutoff does not make sense to me. As long as the current is sufficient to start it, no further DC power is necessary for it to run.

Mark

[foggysail]

Originally Posted by colemj

The generator cutoff does not make sense to me. As long as the current is sufficient to start it, no further DC power is necessary for it to run.

Mark

The Kohler 7.5KW generator uses older technology for sensing faults. There are three faults that are sensed, oil pressure, water temperature and cylinder head temperature. NOw because there is no oil pressure before the engine is actually running, they incorporated a timer that prevents the oil pressure from actuating a shut down fault. If I remember the circuitry the timer actuates a 12 vdc relay that prevents the zero low or zero oil pressure sensor during the delay period.

Because the 12 vdc relay ........at least in my generator.......... will not actuate with 11 vdc, the oil fault circuit is not bypassed for the 5 second delay period and the magneto is disabled.

That is the best I can do for an explanation without looking at the actual circuit diagram. Now of course the entire fault circuit can be disabled which I have done several times when my generator's battery was low.

I did mention in one of the above posts of mine that I doubt this condition was planned by Kohler. They most probably mis spec'ed the relay operating voltage and the got what they ordered.

Foggy

EDIT: Those of you who have a Kohler 7.5KW need to be aware of this problem!!!!

[taildragerdrive]

This has been a very informative thread.

I have a Lifeline 6 x 2v house system in my boat installed in 2006 by the previous owner. The boat has solar panels that maintain them in a fully charged condition when I'm away. I also have a wind generator and of course engine charging.

Both the previous owner and I have maintained the house bank in good condition. The system seems to perform well even though it is now 7 plus years old.

I am new to sailing and have little experience with these systems.

So I'm wondering how long is this system likely to last?

Is this system likely to fail quickly or simply deteriorate some over time?

I'm about to start longer cruising trips should I be considering replacing the house batteries?

Thanks

[s/v Jedi]

Originally Posted by taildragerdrive

This has been a very informative thread.

I have a Lifeline 6 x 2v house system in my boat installed in 2006 by the previous owner. The boat has solar panels that maintain them in a fully charged condition when I'm away. I also have a wind generator and of course engine charging.

Both the previous owner and I have maintained the house bank in good condition. The system seems to perform well even though it is now 7 plus years old.

Considering most kill their batteries the first year or two, this 7 year run with still good 2V cells just illustrates what I've been saying all along in this thread: it's the real deal and the engineer's go-to setup.

You should just go on with these 7-year old Lifeline cells because they are good quality and only when the capacity isn't enough anymore I would replace them.

My last 2V cells lasted more than 10 years.