Wiring In Series (pro vs con)

[ramblinrod]

Originally Posted by s/v Jedi

The best thing you can do is wiring in series. There are 900Ah Lifeline 2V batteries: GPL-6CT-2V. Six of those in series is your optimal configuration

Nun uhh! One battery failure and your whole bank is useless.

[s/v Jedi]

Originally Posted by ramblinrod

Nun uhh! One battery failure and your whole bank is useless.

Why not just skip posting when the subject is not something you are versed in? Your statement is wrong: jumpering 2V cells has been done since forever and works just fine.

When you have parallel batteries and an internal short, that is when you can loose not just the battery bank but the whole boat if the batteries are powerful enough.

[camel2012]

Originally Posted by s/v Jedi

Why not just skip posting when the subject is not something you are versed in? Your statement is wrong: jumpering 2V cells has been done since forever and works just fine.

When you have parallel batteries and an internal short, that is when you can loose not just the battery bank but the whole boat if the batteries are powerful enough.

Just curios. has anyone lost a battery cell individually, or a single 2, 4, or 6 volt battery? I've shorted a cell in a lab but only after repeated electrical dump abuse that I would never do on a boat. Wondering how likely this situation is for planning purposes.

[Adelie]

Originally Posted by mickelsen

I confess to being not well versed on series or parallel. I thought they were very different. The diagrams are good however am I in series or parallel?

In both sketches above the batteries connected by blue jumpers are in series.

The strings connected by red & black leads are in parallel.

[a64pilot]

Loosing a battery before the whole bank is essentially toast is not very common, but can happen. I believe if a battery is "bad" they die an infant mortality kind of death, like in the first 30 days, or if properly cared for go for years. It's not like it has electronics or moving parts, but once in a while you get one with a cold solder joint or something, but again that shows up pretty quick usually

[ramblinrod]

Originally Posted by s/v Jedi

Why not just skip posting when the subject is not something you are versed in? Your statement is wrong: jumpering 2V cells has been done since forever and works just fine.

When you have parallel batteries and an internal short, that is when you can loose not just the battery bank but the whole boat if the batteries are powerful enough.

Seriously????

I am an electronic engineering technician from a well respected Canadian college program, with 38 years practical full time experience, and president of Sheen Marine, a Total Yacht Care service provider.

Pretty well versed in marine electrical systems. ;-)

Configuring a 6 battery house bank such that there is no redundancy, and a single battery failure renders the entire house bank useless, is a serious design flaw in my opinion.

All batteries will fail some day. Many will decrease in capacity; some will shed plate material causing a short between plates and instant total failure.

You can do what you please on your boat, but what you suggest, in my opinion, is a very, very bad idea.

Where are you getting your information? Can you cite one instance where a vessel has been lost because a 12 Vdc battery developed a shorted cell?

[camel2012]

I would go with 6, G30HT Lifeline 150 Ah AGM in parallel, not sure if it fits the same space wise but meets your total Ah goal.

@rambinrod. "all batteries will fail someday"... really? won't everything fail someday?[emoji14]

[ramblinrod]

Originally Posted by camel2012

I would go with 6, G30HT Lifeline 150 Ah AGM in parallel, not sure if it fits the same space wise but meets your total Ah goal.

@rambinrod. "all batteries will fail someday"... really? won't everything fail someday?[emoji14]

Correct. Marine battery life expectancy is between about 2 and 10 years depending on quality, use, and abuse, with the vast majority between 2 and 4 years. I would never recommend a 12 Vdc house bank of 1x 12Vdc, 2x 6Vdc, 3x4 Vdc or 6 x 2Vdc. No redundancy.

[Cheechako]

-The wiring is a bit expensive for good stuff
-proper size wiring is very stiff (if you do this pre bend your wiring while putting the ends on.)
-Any weak link in the chain is a deficit. Why add a bunch more links?
-every attachment is a corrosion point with possible conductive loss.
Why do you have to buy that brand?

[PaulinOz]

Originally Posted by ramblinrod

Correct. Marine battery life expectancy is between about 2 and 10 years depending on quality, use, and abuse, with the vast majority between 2 and 4 years. I would never recommend a 12 Vdc house bank of 1x 12Vdc, 2x 6Vdc, 3x4 Vdc or 6 x 2Vdc. No redundancy.

This is also what I believe as well, you may well be able to run some things on a reduced 10 volt bank but I am guessing it will not like seeing 14.5 volts from any of the chargers for to long.

I like redundancy options until able to get back to shore to repair/replace.

Happened last year to me day before departure 5 x fridges and freezers full of food. One of house bank of 6 x 12 volt 140 a/h AGM's, gets red hot and splits, venting H2S. The boss had been accusing me of flatulence for the prior few hours before I went bellow and discovered the issue.

Faulty battery removed and sat on 5 battery bank for next 6 days until full replacement set obtained and installed.

How long would a 10 volt bank last with 12 volt chargers connected?

[ramblinrod]

Originally Posted by s/v Jedi

As long as you have anything in parallel, all batteries should be the same. You can't just replace one a couple years later. Only in the all-series with 2V cells you can do this without any problems.
BTW when one cell fails you can jumper it and continue with just 5 cells in emergency mode. This is more than 10V and all critical equipment will work. Google for specifics.

When one jumpers one defective cell, with all others fully charged, they are left with 2.15 Vdc / cell x 5 = 10.75 Vdc, which will operate some devices, (others will drop out) until the bank becomes discharged somewhat (~80% SOC ) and then all is lost.

And low and behold, because it is no longer a 12Vdc nominal bank, the charging systems cannot be connected.

So now, in the middle of no where, with 10Vdc that won't operate anything (except some LEDs and maybe a dim incandescent, watcha gonna do?

Live off the start battery? $1000s in a house bank and no contingency? At that point, you'd be better off with house bank of 2 x Grp 24 dual purpose. ;-)

[roland stockham]

Can you post details of the 4v batteries, not seen these. 6v is generally built to be more durable than 12v, wondering if 4v is a step up again. Also may give other options for fitting if the footprint is different.

[jamesdavis]

Comment: when batteries are connected in series you add terminal voltages, but can only draw as much current as a single battery in the series can offer by itself.

Example:Three 4V batteries connected in series at 450A capacity each will yield 12V, but the series string can only produce 450A.

[Cheechako]

Originally Posted by jamesdavis

Comment: when batteries are connected in series you add terminal voltages, but can only draw as much current as a single battery in the series can offer by itself.

Example:Three 4V batteries connected in series at 450A capacity each will yield 12V, but the series string can only produce 450A.

Hmmmm... so a 12V battery is really 6 x 2 volts cells in series right? So does this mean your 12V battery is only the amperage of one cell?

[capt-couillon]

As A64 says.... nominal voltage of a wet cell lead acid battery is 2V. 12V battery is 6 cells (six caps) 6V battery is 3 cells (3 caps) External or internal connections are academic. Generally I prefer lower voltage cells in series. Lighter weight as single or 3 cell boxes. More flexibility as to where to stash them. If you run several series sets of 6V (12V each set) in parallel and loose a single battery, you have only lost a minor amount of your total available capacity (assuming you can easily remove it from the circuit).

Change several sets of 8D's a few times and you will feel the wisdom...


Just sayin'