Wiring In Series (pro vs con)

[john61ct]

So that load has a discharge rate of .2C, 80A vs 400AH capacity.

That's pretty high, maximum about two hours and the bank is at its 50% floor.

Yes your bank would last a bit longer if you used propane instead, but if for truly short runtimes NBD.

[sstuller]

One of the virtues of batteries in series is the ease of confirming that the batteries are balanced. With two batteries in series each should read exactly half of the total voltage. If there is a discrepancy (>0.1 volts) then something is amiss. There may be a bad connection or a bad cell. FLA's let you check each cell with a hydrometer. A bad cell will show up quickly. Thanks.

[john61ct]

Some battery monitors have a midpoint voltage feature that automates warning you when series cells are getting out of balance.

Also there are automated balancers when V goes high ensures the two series-connected sides are equalized.

I see the value of the former more clearly than the latter.

[ramblinrod]

Originally Posted by TeddyDiver

Only the small ones intended for occasional use. Dunno about tow motors, unknown to me. Been working with heavy industrial ones mostly.
You are writing too much to respond to all your mistakes..

BR Teddy

Look, anyone can "CLAIM" someone else is wrong.

We could do "Is So / Is Not" ad inifinitum to absolutely no value to anyone.

I always attempt to support my position with facts, logic, critical thinking, and reasoning.

Please do same.

For example, your statement above "only the small ones for occasional use", (referring to lift trucks using 12 Vdc batteries) is incorrect.

Please refer to the following Deka lift truck battery selector guide, as the evidence that I offer to support my position.

EpipCatalog

Note that almost every lift truck manufacturer, makes versions based on 12 Vdc batteries, that are intended for regular commercial and industrial service.

Thank You.

[ramblinrod]

Originally Posted by sstuller

One of the virtues of batteries in series is the ease of confirming that the batteries are balanced. With two batteries in series each should read exactly half of the total voltage. If there is a discrepancy (>0.1 volts) then something is amiss. There may be a bad connection or a bad cell. FLA's let you check each cell with a hydrometer. A bad cell will show up quickly. Thanks.

Agreed.

And one who is inclined to monitor batteries closely like this, will watch capacity and detect unusual decline (in parallel or series configured banks).

So assuming connections are clean and tight (that can and should be done on any bank regularly via visual inspection) what is one really going to do with this information? Almost 100% of the time, perform equalization on a regular basis (if so inclined and equipped), and replace the entire bank when capacity falls below a level they decide to trigger, or a single battery when it completely fails well before others are near end-of-life.

So to me, while this has some value, it is certainly not a game changer, the disadvantages of series strings far outweigh any advantages.

[Sailor_Hutch]

Guns, Anchors, and Electronics. Who knew? Anyway, I always keep redundant parts for everything. Why not batteries too? I guess, depending on configuration, there's a balancing problem ... How many do this?

[camel2012]

Originally Posted by ramblinrod

Golf cars absolutely pale in comparison to the number of boats built per year. Boats have standardized on 12 Vdc. Boats absolutely pale in comparison to RVs. Rvs standardized on 12 Vdc. Rvs absolutely pale in comparison to construction and farm machinery. Farm machinery standardized on 12 Vdc. Farm machinery absolutely pales in comparison to the automobile industry. The automobile industry standardized on 12 Vdc.

Wrong on the order, boats pale in comparison to golf carts. I sell into all of these industries.

Also, you need to consider use cases and please don't assume... Any golfers out there .. go ask at the course next time how the carts are charged... may change your opinion on how strenuous of an environment they really experience. 50 to 90 F temps... If a battery dies, they recycle it and grab another from the shed ..

Lift trucks are typically all 2 volt cells in series forming 24, 36, or 48 V banks under the seat. They get rapidly charged after 8 hrs in a busy warehouse or sit nightly on a charger.

Class 8 trucks are almost always AGM and 4x 12V in parallel. The majority of sleeper cabs have electrical systems that rival boats with xbox, large flat screen tvs, toasters, fridges , and of course an inverter... they do this daily/nightly... in Fargo during the winter or Arizona during the summer...they have to experience constant 8 g shock in a battery box mounted on the frame typically right behind the engine which is dissipating extensive heat in its wake especially due high temps required by EGR emissions.
If a battery or bank dies , the truck needs an expensive tow from the middle of nowhere and often the load of whatever goes bad... very expensive.

I design and sell electrical equipment into all of these markrts. East Penn is the clear leader in HD truck batteries and believe me if their product couldn't survive then the OEMs would be putting them out of business with pass through warranty claims from dealers and fleets. Group 31 batteries are the worldwide standard for HD trucks and available everywhere.

Do what you want, but for me and with my own experience, I will be using parallel G31 banks until LiPo or some other technology proves itself in the same way.

[john61ct]

Yes a lot of fork trucks use 12V as the foundation, but I do think a minority.

Bringing AGM into the argument may well change things too, definitely a higher price point, to me not worth the extra unless needing to mount sideways. Especially losing the cheap and easy hydrometer SoC benchmarking to optimize charging/use patterns.

But one nice thing about getting the install space standardized on paralleled G31s, is the ability to go to Firefly Oasis to handle PSOC without having to go up to LFP before you're ready.

[ramblinrod]

Originally Posted by Sailor_Hutch

Guns, Anchors, and Electronics. Who knew? Anyway, I always keep redundant parts for everything. Why not batteries too? I guess, depending on configuration, there's a balancing problem ... How many do this?

In my opinion, it would be foolish to carry a redundant house bank battery.

Why not put your "spare" 12 Vdc house bank battery IN the house bank and enjoy:

1. Increased capacity.
2. Lower DOD.
3. Increase bank life.
4. No dead weight
5. Always included in charge regime.

That said, I do carry a 12 Vdc booster pack, so that I can boost start the boat, the car, anyone else's 12 Vdc starter system I encounter, and for use as a portable 12 Vdc supply for electrical testing and trouble shooting on my, friends, and customer's boats. It is USB charged and has a USB output for charging, plus a flashlight, so very useful.

[ramblinrod]

Originally Posted by john61ct

Yes a lot of fork trucks use 12V as the foundation, but I do think a minority.

Bringing AGM into the argument may well change things too, definitely a higher price point, to me not worth the extra unless needing to mount sideways. Especially losing the cheap and easy hydrometer SoC benchmarking to optimize charging/use patterns.

But one nice thing about getting the install space standardized on paralleled G31s, is the ability to go to Firefly Oasis to handle PSOC without having to go up to LFP before you're ready.

I recommend AGMs or Gels when ever the battery bank is not isolated (ventilation wise) from the occupied space.

I do recommend LiFeP04 when significant battery storage capacity is required, compartment space is a premium, the vessel is particularly weight sensitive, and the boater's budget can handle it.

This is yet another reason why a significant discussion is required about the boat and intended use BEFORE selecting a battery model.

[john61ct]

Sealed batts vent gas too. Not a danger unless allowed to build up in a sealed space (boom)

[Tasso]

Originally Posted by s/v Jedi

...

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.

Series is ALWAYS safer than parallel for this reason. In a parallel configuration - one shorted cell can cause battery explosion or worse. In my boat my two series banks are only in parallel for an emergency start - then back to isolated. My dual-controller solar charge system also has both banks isolated.

If possible - I'd go for each bank built up from series low voltage batteries. Economical and safe.

[Tasso]

Originally Posted by camel2012

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.

I have only heard of one - single cell short in a 12v battery. It is not common but catastrophic. Why take the risk when two 200Ahr 6volts are cheaper than two 100Ahr 12volts?

Should be an easy decision...

Also - should not just jumper a failed 2 volt battery in a series bank. This will overload your charging system and/or over heat your remaining batteries.

[ramblinrod]

Originally Posted by a64pilot

I brought up golf carts, because there are tens of thousands of electric golf carts produced yearly, They are not a small manufacturing concern at all, and their use of a battery bank closely mimics our boating use, boats being a tiny fraction of battery consumption compared to golf carts.
Golf carts would use the most economically viable battery available consistent with long life period, and that is the abundant golf cart 6V battery.
For an idea of production volume
https://www.golfcartsforsale.com/blo...er-golf-carts/

Actually, the other battery use that most closely mimics marine use is a land yacht (RV).

There is a 12 Vdc starting system that utilizes a start battery, and an isolated house bank that runs house loads when AC power from land hook-up is not readily available.

Note that most 12 Vdc batteries for house banks, are referred to as Marine / RV "Deep Cycle" batteries by the manufacturer.

Motive power applications, such as golf cars and lift trucks, do not mimic boat use nearly so closely.

Most cruising boats and RVs have a fairly steady 0-15 A-hr energy requirement. When higher energy draw is needed, a fuel powered alternator or generator is usually started.

For these applications, 12 Vdc Deep Cycle batteries are well suited, for all of the reasons stated throughout this thread.

[thomm225]

Originally Posted by Tasso

Series is ALWAYS safer than parallel for this reason. In a parallel configuration - one shorted cell can cause battery explosion or worse. In my boat my two series banks are only in parallel for an emergency start - then back to isolated. My dual-controller solar charge system also has both banks isolated.

If possible - I'd go for each bank built up from series low voltage batteries. Economical and safe.

If you have your batteries in parallel and they are fused, I'm thinking they are as safe as batteries in series.

My batteries are now fused to the load and to each other.

I don't have a starter battery. Well, I do but it's now in the house bank. It's one of my two 12 volt batteries in parallel. My engine is pull start.

The batteries are charged with solar.