Wiring In Series (pro vs con)

[ranger58sb]

Originally Posted by Rick

... with today's technology there is no reason to have series connected batteries for 12-volt systems

Originally Posted by rwells36

Rick, there are reasons for others that may not be reasons for you.

Yep. Example: I can fit one 12V 8D, three 12V G31s in parallel, or four 6V GC2s in series/parallel in one of our dual-purpose battery spaces. Which means approx 245, 300, or 440 Ah for house loads.

440 is more useful for us than 245 or 300.

-Chris

[ramblinrod]

Originally Posted by ranger42c

Yep. Example: I can fit one 12V 8D, three 12V G31s in parallel, or four 6V GC2s in series/parallel in one of our dual-purpose battery spaces. Which means approx 245, 300, or 440 Ah for house loads.

440 is more useful for us than 245 or 300.

-Chris

Hmmm, there seems to be an obvious omission.

What about 4 x Grp 27s for 400 A-hr?

[ranger58sb]

Originally Posted by ramblinrod

Hmmm, there seems to be an obvious omission.

What about 4 x Grp 27s for 400 A-hr?

Footprint won't quite fit... but 440 is better than 400 anyway.

Not seeing G27 products with same predicted cycle life as GC2s, although I haven't checked Rolls? (Yes, lab cycles are different than real world cycles, but given lack of better data for comparison... it's better than nothing.)

-Chris

[ranger58sb]

Originally Posted by ranger42c

Footprint won't quite fit... but 440 is better than 400 anyway.

Not seeing G27 products with same predicted cycle life as GC2s, although I haven't checked Rolls? (Yes, lab cycles are different than real world cycles, but given lack of better data for comparison... it's better than nothing.)

-Chris

Just double-checked my memory about installation in the available space. The Trojan G27 AGMs (for example) are actually almost close to fitting. Tray or box would have to have near-zero clearance, and even then... not sure.

But I also see they're rated as 89Ah each (20-hr rate) so 4x would only give a total of 356 Ah. Not really competitive with 440... I think that's why I eliminated those early on... but yes, would have been appropriate for me to cite G27s as a possibility in my earlier post.

-Chris

[a64pilot]

Originally Posted by socaldmax

In a case like this, you just stop arguing, it doesn't do any good.

I quit pages ago

[GrowleyMonster]

Originally Posted by a64pilot

I quit pages ago

Hey, I know... Let's have another anchor or gun thread! The CF version of religion and politics!

[rwells36]

Originally Posted by GrowleyMonster

Hey, I know... Let's have another anchor or gun thread! The CF version of religion and politics!

Touché

[Rick]

Not all Chargers will detect assorted cell they will attempt to keep voltage constant which overheats all of the other cells gassing them ultimately resulting in failure some RVs and boats have been practically destroyed by the sulfuric acid getting out from flooded batteries that's one advantage of an AGM or gel I have seen this happen

[Rick]

I guess if you are stuck with an existing box and cannot design a new one and you have to replace what is there

[ramblinrod]

Originally Posted by ranger42c

Footprint won't quite fit... but 440 is better than 400 anyway.

Not seeing G27 products with same predicted cycle life as GC2s, although I haven't checked Rolls? (Yes, lab cycles are different than real world cycles, but given lack of better data for comparison... it's better than nothing.)

-Chris

Some Grp 27s have 100 A-hr and higher 20 hour rate.

To me a 10% reduction in capacity is an acceptable compromise to have 12 volt batteries in parallel vs 6Vdc batteries in series.

[john61ct]

Yes you do keep saying that, but I've only seen others disagreeing, at least on that particular point.

[TeddyDiver]

Originally Posted by ramblinrod

Some Grp 27s have 100 A-hr and higher 20 hour rate.

To me a 10% reduction in capacity is an acceptable compromise to have 12 volt batteries in parallel vs 6Vdc batteries in series.

Just to point that trying to fit a bigger (Ah) battery in the same footprint compromises something as longevity and deepcycle performance. It's not much anyone can do for lead-acid chemistry..

BR Teddy

[ranger58sb]

Originally Posted by ramblinrod

Some Grp 27s have 100 A-hr and higher 20 hour rate.

To me a 10% reduction in capacity is an acceptable compromise to have 12 volt batteries in parallel vs 6Vdc batteries in series.

Yeah, but they start getting longer, too. The Trojan 27MTH and the SCS200 say 115 Ah (20 hr rate), but they're also each 3/4" longer and minor as that seems, that makes them essentially the same size as our current G31s and it means I could only stuff three of them in there. And as I said, four of the slightly smaller 27 AGMs -- still more like a 20% difference in capacity -- may only barely fit, given each is only an inch less long than the current 3x G31s I've got in there now.

Seems odd to me that Trojan's various "deep cycle" (their label) G27s can vary so widely in capacity. 115 Ah vs 89 Ah? (When many manufacturers rate their normal G31s at either 100 or 105 Ah, or 111 in Trojan's 31 AGM instance).

Seems odd to me the flooded 27MTH @ 115 Ah weighs 1-lb less, and the SCS200 weighs 2-lbs less, than the 27 AGM @ 89 Ah. Same as it seems odd to me a G27 can offer more capacity than slightly larger G31s.

Flooded batteries would be a pain in the neck to service, in our installation. I can't really get to the outboard batteries easily enough, and one of the batteries is obstructed overhead. While a watering system might be feasible (or not; not sure I'd have overhead clearance over that one battery), pretty much eliminating battery service altogether with AGMs means I can divert my labor hours to other stuff.

I suspect you're willing to start with "I'll wire 12V batteries in parallel, now how much capacity can I get." I've started with "How much capacity can I stuff in there, and how must I wire it to get there from here."

-Chris

[TeddyDiver]

I don't know these particular batteries but some remarks about why it is the way it is..

Originally Posted by ranger42c

Seems odd to me that Trojan's various "deep cycle" (their label) G27s can vary so widely in capacity. 115 Ah vs 89 Ah? (When many manufacturers rate their normal G31s at either 100 or 105 Ah, or 111 in Trojan's 31 AGM instance).

Manufacturers use standard size housings for various batteries

Seems odd to me the flooded 27MTH @ 115 Ah weighs 1-lb less, and the SCS200 weighs 2-lbs less, than the 27 AGM @ 89 Ah. Same as it seems odd to me a G27 can offer more capacity than slightly larger G31s.

Plate thickness varies. Everything else being the same thicker plates weight more, provide as much capasity but much more cycles

I suspect you're willing to start with "I'll wire 12V batteries in parallel, now how much capacity can I get." I've started with "How much capacity can I stuff in there, and how must I wire it to get there from here."

I start with " how much capasity I need, and make the room for it" if there were limited space going with thinner plates and less longevity helps. My present dilemma is whether I choose OPzS6/600 twelve in series 1800*210*710mm or OPzS10 six in series 1300*240*710mm

-Chris

BR Teddy

[ranger58sb]

Originally Posted by TeddyDiver

I don't know these particular batteries but some remarks about why it is the way it is..

Seems odd to me the flooded 27MTH @ 115 Ah weighs 1-lb less, and the SCS200 weighs 2-lbs less, than the 27 AGM @ 89 Ah. Same as it seems odd to me a G27 can offer more capacity than slightly larger G31s.

Plate thickness varies. Everything else being the same thicker plates weight more, provide as much capasity but much more cycles

Haven't been able to find info about predicted cycles on all of them, and truthfully haven't spent much time shopping on these since horizontal dimensions are problematic for my installation...

But without cycle info, the relationship seems backwards to me: a fair amount more capacity (29%) weighs (slightly) less in these examples. All three marketed as "deep cycle" but I didn't see specific info about plate thickness for each.

The 29% claim seems a bit adventurous, anyway. (ur current G31s are rated at 100 Ah and weigh 78-lbs each, compared to these G27s at 60, 61, and 62-lbs respectively.

I realize overall weight isn't a very perfect predictor, though...

-Chris