I'm looking at buying a couple of 6v deep cycle batteries that have 225 Amp Hours (AH)@20 Hr.
Does this translate into 450 Amp hours when you connect them in series for 12 volts.
thanks
Fred
Nope, still 225 ah, when you build 2 to 12 volts, but you did double the available WATTAGE.
You can't double the proportions twice!
Using watts is a popular "apples and oranges" solver
Happy coaching!
Buswarrior
In parallel batteries will increase amperage with the same voltage. Two 6v batteries with 225 Ah connected in parallel will provide 6v with 450 Ah. This is how 12v batteries are usually connected to make a 12v battery bank.
In series batteries will increase voltage with the same amperage. Two 6v batteries with 225 Ah connected in series will provide 12v with 225 Ah. This is how 6v batteries are usually connected to make a 12v battery bank.
We've got two pairs of 6v batteries connected in a combination of parallel & series, which double both the voltage and the amperage. Each pair is connected in series to make 12v, and the two pairs are connected in parallel to double the amperage.
Lots of ways to skin this particular cat.
Why is it generally accepted that 2x6 v batteries is better than 1 12v?
Better in what way? Never heard of that. Maybe two batteries cost more than a single of same spec.
Apples and oranges.
It is mostly about the lead.
Equal weight and style of internal construction will yield equal results.
Too many variables to make a blanket statement like that regarding 6 volt or 12 volt.
Uninformed vs educated?
Happy coaching!
Buswarrior
"Better in what way? Never heard of that."
The implication seems to be that you get more power from 2 6v batteries than one 12 v. When it comes to fork lifts, golf carts ans similar machines they almost always advertise 6 volt batteries.
Quote from: Fred Mc on October 02, 2018, 12:30:11 PM
Why is it generally accepted that 2x6 v batteries is better than 1 12v?
Can't speak for anyone but myself on this one. I went with two pairs of 6v (Trojan L16) because that combination allowed me to get the maximum Ah capacity in the physical space I had available and still be able to lift the individual components by myself.
Was that the best way? Don't know. But it worked for me.
a buddy of mine has a tag trailer and had 2 x 12 volt batteries at 12 volts . I told him he would do better with 2 x 6 v batteries at 12 volts
his words not mine way way better !
dave
To answer the 6v or 12v battery question-is weight of each battery! A Trojan T-105 220amp/hr battery weighs 62lbs. My 8D 12v Lifeline AGM battery with a bit more power at 255amp/hr weighs 165lbs and is a bear to lift.
I'm going to use the 6PL-6CT Lifeline batteries that are 6v and 300amp/hr ea. They are about 3.1" taller with the same foot print as the T105 and weighs 90lbs. A lot easier than the 165lb 8D beasts. Good Luck, TomC
I use 4 of these.
https://www.interstatebatteries.com/products/srm-4d
Quote from: TomC on October 03, 2018, 07:05:44 AM
To answer the 6v or 12v battery question-is weight of each battery! A Trojan T-105 220amp/hr battery weighs 62lbs. My 8D 12v Lifeline AGM battery with a bit more power at 255amp/hr weighs 165lbs and is a bear to lift.
I'm going to use the 6PL-6CT Lifeline batteries that are 6v and 300amp/hr ea. They are about 3.1" taller with the same foot print as the T105 and weighs 90lbs. A lot easier than the 165lb 8D beasts. Good Luck, TomC
This is part of why we went with the L16. Provides 390 Ah and weighs 115lbs. That was the limit of my desire to lift a battery.
"I use 4 of these."
So what are they rated in amp hours?
Their description says 390@ 25 amps
My bus came with (6) 4D 12V batteries. That are quite a few amp hours. I switched over to (8) 6V Trojans and am much happier with the results. The 4Ds were not truly deep cycle so they just did not work as well. The 6V batteries seem to be holding longer charges. Besides, the 8Ds seemed to get heavier every time I had to replace them. ;D
The Interstate batteries linked to show a reserve capacity of 390 @ 25 amps. Reserve capacity seems to be usually listed in minutes @ a stated draw rate. That's not the same thing as the Ah capacity, which is usually measured at the 20-hour mark. I'm guessing that these would have somewhere around 240 Ah @ 20 hours.
With the dual purpose batteries (marine batteries or any battery meant for both starting and deep cycle use) you usually get a compromise on both purposes. The true deep cycle batteries usually provide much more in the way of capacity and the ability to draw down without damage.
As stated earlier, it's all about the lead.
I believe true deep cycle batteries aren't rated in ampere hours. More like minutes at a specific amp draw.
This was taken from: https://www.batterystuff.com/kb/articles/battery-articles/battery-basics.html
Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80°F will discharge 25 amps until the battery drops below 10.5 volts.
An amp hour (AH) is a rating usually found on deep cycle batteries. The standard rating is an amp rating taken for 20 hours. What this means for a 100 AH rated battery is this: Draw from the battery for 20 hours, and it will provide a total of 100 amp hours. That translates to about 5 amps an hour. (5 x 20 = 100). However, it's very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 amp hours.
I've used the amp hour rating when comparing deep cycle batteries. Seems to be the standard rating for them. Since none of us are going to purposefully discharge a battery to 10.5v the reserve capacity didn't seem as valuable.
The interstate 4D's linked are start batteries, not deep cycle, so as mentioned they usually don't have an amp hour rating. A mixed use marine battery might or might not have both start and ah ratings. The reason the 6V golf cart batteries are regarded as better for RV house use is they are optimized for deep cycle use, not start use. As mentioned, it's all about the lead, and the way the lead is built into plates. Weight is not the only factor, although it's a good indication of how much battery you are getting. 4D's are certainly available in both start and deep cycle, and are a favored size for a lot of marine use, my buddy has them in his sailboat. I just bought 4 6V golf cart batteries for a great price from Costco, 25% less than anywhere else, 225 AH, for a 225 AH 24 volt house bank. A lot of manufacturers will list the AH rating for deep cycle batteries in a variety of discharge rates, from 1 hour to 100 hours, and will list predicted charge cycle life expectancies for each. The rule of thumb for lead acid batteries is don't discharge them past 50%, but if you only discharge to 80% you can really extend the life of the battery. It's like "buy it, but don't use it, and it will live forever..."
As a fellow Canadian :) AND costco member Id be interested in what battery you got and the price.
Regards
Fred
Why use 6v instead of 12v? Well I'd use 2v if I could find them reasonably priced. 2 Reasons:
- Easier to move per battery. I'd Rather have many small parts vs one large (heavy) part
- Less cells to possibly go bad. a 12v battery has 6 cells, each 2v. A 6v battery has 3 at 2v. So if a 6v battery goes or a cell in it goes, I replace the single battery vs the whole 12v battery.
I'm buying the GC115 , a relabeled Deka Battery https://www.batteriesplus.com/productdetails/sligc115 I've told the story a few times, but here it is again. In my store, if I ask for the on-line discount in-store, they'll sell me the battery for about $100 each. I buy 4 at a time. It's really hard to beat it. I'm aiming to leverage Peukets Law and make my bank larger to try and get my amp draw below the 20 hr rate, this will increase my realized capacity as well.
😱
Quote from: Fred Mc on October 04, 2018, 10:12:52 AM
As a fellow Canadian :) AND costco member Id be interested in what battery you got and the price.
Regards
Fred
They only have one 6V battery, this one, and I paid $140-ish, forget the exact price. https://www.costco.ca/Automotive%2C-Marine%2C-Lawn-%2526-Garden%2C-and-Golf-Cart-Batteries.product.100017095.html
You have to call the store near you to see if they have any. I went to two stores to get my four.