Trojan FLA batteries??

DJuan222 · February 2017

I was reading 12v vs 6v and 2v and ran into this,

why are the Trojan 6v about 325ah and the 12v 175ah and 100lbs??

I would be better off with 2x6v being lighter and more amp hours correct??

or am I missing something

edit: in fact I went back to a site I found and they have http://www.southeasternequipment.net/product-p/tc370-2118.htm

and its a 420ah 6v

John

Vic · February 2017

Hi John,

So, is the 12 V Trojan battery the GC12, T-1275? It is about 85 Lbs.

The one in the Link is an 8L16, 6V and weighs about 114 Lbs.

In general, using the lowest voltage batteries that you can to achieve your needed Ah Capacity is usually the best. This goes hand-in-hand with trying to use a single string of batteries.

Often we do not need to move or handle batteries very often, so battery weight is not a overriding concern until one gets to forklift batteries ... depends upon just where the batteries need to reside, of course.

FWIW, Vic

DJuan222 · February 2017

Hey thanks Vic,

I started out looking at the 12v 175ah Trojan J185E-AC and yes the weight is the same on both at a little over 100 lbs

I guess it throws me that the lower volt battery has so much more in Ah capacity.

So what is the reason behind "using the lowest voltage batteries that you can to achieve your needed Ah Capacity is usually the best"

I still need a 12v sum for my inverter in this case 2 of those 8L16 420Ah. This is just a beginning project for my kids and I so it will be just those 2 with my cheapish inverter. even the renology I was looking at for future upgrades is still 12v input

https://smile.amazon.com/gp/product/B01MUCN1WJ/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A05654602L3XUQ70M87BV

John

westbranch · February 2017

If you calculate the watt hrs in them you will see they are very similar... 1950Wh vs 2100Wh

Estragon · February 2017

As a very general proposition, for deep cycle lead acid batteries, more weight = more power (watt-hour) capacity. The voltage is determined by how cells are connected, as all lead acid cells are 2v nominal.

It would help to know more about the project in terms of the loads you will want to power.

DJuan222 · February 2017

Right now its just a simple setup to do with my 3 and 5 yo as they like doing this kind of activity; however, I plan on growing it a bit to power the fridge and chest freezer if needed during extended power outages or just to use less elect co. power.

I don't own the house Im in or Id look at more into a larger system!!

So should I be looking at the watt hours or Ah in batteries? as well as inverters they seem to be 12v to 120v but some of you are running 24 and 48v systems..this is where I get confused

Estragon · February 2017

Some of us run higher voltage systems in order to run larger loads, particularly loads like water pumps which have large startup currents. Using higher voltage allows us to use smaller wire for a given wattage. The downside is higher cost for equipment, and higher inverter losses.

As a project for kids/learning, a low voltage system is the safer choice. A large battery bank at 48v is not something I would let kids that age anywhere near. It might be more fun and instructive for them to get a solar garden light and take it apart to find out how it works and/or build such a thing from parts.

A backup power system for a fridge and freezer is getting into a bigger system than you might be ready for. You would need a big enough inverter to allow for the possibilty they both start together, which likely means a 24v or even 48v system. Each appliance likely runs 1.5kwh/day so around 4kwh/day total. Depending how long you want that to last you could be into a pretty big battery bank. Say 2 days and 50% discharge would be 16000 watt hours or about 700ah@24v or 350@48v - maybe $2000 worth of battery and about the same again for inverter/charger, cabling, etc. You could probably get away with running one or the other on a 12v system, which might work for an attended backup system with someone to switch power between the appliances.

Vic · February 2017

Hi John,

Regarding choosing the lowest voltage batteries possible ...

For smaller systems, this is not as important. But, fewer cells per battery means that if one cell becomes defective, and that battery needs to be replaced, a lower voltage battery will mean that fewer good cells in the battery will be thrown away, along with the bad one.

With proper equipment, one can charge single batteries in a string (if one is careful). So having single cells per battery could allow one to individually charge a single lagging cell ... a bit obscure for some of us.

Measuring individual battery voltages can be a quick indication of balance of each battery to the others in a string. More cells per battery means that this is a less precise indicator.

When larger battery Capacity is needed, it is common to select a lower battery voltage, which allows a fairly wide range of available Capacity per battery. This allows choice of batteries with needed Capacity in a single string of batteries. Parallel batteries are often very difficult to manage, and keep charge/discharge currents balanced in each string. And parallel strings of Flooded batts multiply the number of cells that need SG measurement, cells to fill, etc. For any type of battery, interconnects are multiplied by the number of strings, and each interconnect will have possible poor connection issues, and so on.

FWIW, Vic

DJuan222 · February 2017

Heres whats throwing me with setups. this is from here https://www.solar-electric.com/outback-flexpower-preassembled-inverter-system-fp1-vfxr3524a.html

6v battery with a 24v inverter /w Nominal DC input voltage: 24 Vdc??? I guess because Im learning Im always thinking you need to sting batteries together to in this case make 24v for that inverter but it comes with 1 6v Trojan.

Im missing some key point somewhere on how stuff works. I currently have a Potek 1500 watt inverter 12v. it doesn't say I can run 6 24 0r 48v into it

John

Estragon · February 2017

Where does it say it comes with one 6v trojan?

Your 12v inverter needs 12v input (nominal - actual voltage will be around 10.5 to 15v). It won't run on 6/24/48v. At best the wrong voltage will fault it. At worst you let the magic smoke out.

DJuan222 · February 2017

Sorry the link was just the inverter. The package I got to it thru had a 6v battery, I'll find it when on pc.

Estragon · February 2017

A single 6v battery won't do anything with that package. You need 4@6v or 2@12v (or 12@2v, etc.) for it.

I use the 48v version of that inverter and it won't turn on with low battery voltage, even if it has AC IN available.

DJuan222 · February 2017

here you go, this is where I was looking at different products, I didn't pay attention its 8 of the batteries

just 1 pictured, I need to pay attention

https://www.solar-electric.com/outback-power-off-grid-kit-2160-watts.html

Estragon · February 2017

Yeah, that picture is a bit confusing if you don't quite grok the off-grid solar thing. I guess it's meant to show it includes batteries (9 grand with no batteries wouldn't make me look at the specs).

We all started off knowing nothing. You have found a forum to learn from though. I spent a lot if time lurking here to learn before buying my gear. It starts making a lot of sense once you get past some of the initial confusion.

westbranch · February 2017

Don't be afraid to call the vendor, our sponsor they have some very knowledgeable people there... I called for dome small add-ons I needed and the voice at the other end asked if I NEEDED X,Y &Z.... Big OOPS! totally forgot about those parts...

Trojan FLA batteries??

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