Batteries?

[contrail]

Originally Posted by john61ct

What makes you think that?

20-hour load is the standard rate for comparing House batts

Those Trojans AGMs are rated at 100AH

Crown 31T-1000 and Deka / Duracell SLI31MDC are 105AH

US Battery 31DCXC are 130Ah !


As stated earlier, not as good value as GC but *much* better than going AGM unless you really need to.

For that matter, the top version of Lifeline G31 is rated for 125 AH. The Firefly is rated for 116 AH, but allows for an 80% depth of discharge rather than 50% for the FLA or Lifeline, so their usable capacity is far greater. Because of the potential to more deeply discharge, they can also be charged for much longer in the bulk and absorption phases, so can be much more than "only 10% more efficient".

But, I am getting redundant and I think the OP already understands my reasons for the choice, so I will bow out. Best of luck to the OP!

[john61ct]

Originally Posted by hellosailor

That's just...not flattering.

Again I never thought you were doing that. I meant them selling to Fisheries.

And they were approaching me as a reseller not a consumer.

And yes Asian companies often do not follow the same business practices we in the West consider best.

If Bruce weren't in the supply chain I'd be a lot more wary about things like QA and warranty issues.

Still a fine product for a niche use case though.

[john61ct]

Originally Posted by Chris777

Looks like we will go with 2, 8D if we can afford them. At 20 hr they rate at 230 amps, and the 31's at 100/105. So the 31 will give me 400/420 at 20 hr's the 8D's 460 at 20 hrs. This is the only 2 that measurs up to my 9 3/4 height limitation.

Wow sure getting your money's worth tonight 8-)

Again, you need to be sure you are getting true deep cycling.

Which in 8D is very rare, afaik only Rolls & Dyno.

All the rest are "dual use" starter, only pseudo deep cycle, and won't last long if you're actually drawing them down below any more than 10-20% DoD on a regular basis.

The 130A I gave you x 4 gives over 500A in G31, excellent maker.

[zboss]

Originally Posted by contrail

I don't think you can overstate the tested advantages of the Firefly AGM's with regard to real use scenarios and ability to withstand Partial State of Charge Use. Huge advantage over Lifelines and other batteries. Greater depth of discharge, too, all adding up to the ability to use a smaller bank. "poor man's Lithium battery" they have been called. Zboss, how long have you had yours, and how do you like them.

They have been hard to source, but I found a good supply at Fisheries Supply in the PNW, and mine are on their way. Looking forward to putting them in shortly.

Brand new... just put them in so I don’t have any experience yet.

[ranger58sb]

Originally Posted by Chris777

The AGM's apear to produce much more amps than regular led acid (wet) batteries. What would you do? My box is limited to 23 1/2" x 21 1/5 x 9 3/4".

No. 100-Ah AGMs and 100-Ah FLAs are pretty much equal in capacity. Considering other virtues, there are pros and cons for each, but 100-Ah is 100-Ah.

Originally Posted by Chris777

Looks like we will go with 2, 8D if we can afford them. At 20 hr they rate at 230 amps, and the 31's at 100/105. So the 31 will give me 400/420 at 20 hr's the 8D's 460 at 20 hrs. This is the only 2 that measurs up to my 9 3/4 height limitation.

Sounds like a possibility, considering only height. I don't remember being able to fit two 8Ds in the same space as four AGMs, but... if you triple-check your measaurements... at least you'd be maximizing capacity. Hire a guy to do the install.

-Chris

[kenbo]

Originally Posted by john61ct

Wow sure getting your money's worth tonight 8-)

Again, you need to be sure you are getting true deep cycling.

Which in 8D is very rare, afaik only Rolls & Dyno.

All the rest are "dual use" starter, only pseudo deep cycle, and won't last long if you're actually drawing them down below any more than 10-20% DoD on a regular basis.

The 130A I gave you x 4 gives over 500A in G31, excellent maker.

He could be buying deep cycle 8d AGM's no?

[john61ct]

I thought the rationale for sealed turned out to be an oversight?

But yes, assuming such exists from a trusted vendor.

[zboss]

Originally Posted by ranger42c

No. 100-Ah AGMs and 100-Ah FLAs are pretty much equal in capacity. Considering other virtues, there are pros and cons for each, but 100-Ah is 100-Ah.




Sounds like a possibility, considering only height. I don't remember being able to fit two 8Ds in the same space as four AGMs, but... if you triple-check your measaurements... at least you'd be maximizing capacity. Hire a guy to do the install.

-Chris

The quality of the delivery is different. The ability of agm to deliver high current very quickly, such as needed for starting an engine or running a windlass, is an important aspect.

[a64pilot]

Originally Posted by zboss

The quality of the delivery is different. The ability of agm to deliver high current very quickly, such as needed for starting an engine or running a windlass, is an important aspect.

Only thing I would add to that is I’m sure my 660 AH bank would start a Bulldozer, or other huge Diesel with no problem, much less my little Lawnmower sized Diesel in my boat.
A few hundred pounds of lead acid battery has an enormous capability to deliver big amps for starting, regardless of the type.

[skipmac]

Originally Posted by zboss

The quality of the delivery is different. The ability of agm to deliver high current very quickly, such as needed for starting an engine or running a windlass, is an important aspect.

Never heard of this as an issue with FLA or as an advantage with AGMs. I've used plain old FLA starting batteries for years to crank engines, including a pair of large, V8 diesels in my old power boat, without a problem.

Are you possibly thinking about the ability for AGMs to accept a higher charging current?

[Chris777]

Well Folks, Thank you very much for all your input, you were very instrumental in my decision.... which now has been made. We went with 2 Trojan 8D generating 920 amps at 20 hrs. More than enough for us, cheaper than 4-Grp 31. The place I bought them at had great knowledge about the differnt batteries and we went thru it all. Not cheap but, but I feel very good about our decision.

Thanks again for all the particpants that were trying to read my mind... :-)

[john61ct]

Originally Posted by zboss

The quality of the delivery is different. The ability of agm to deliver high current very quickly, such as needed for starting an engine or running a windlass, is an important aspect.

Sorry, absolute bunk.

If you were talking LFP, yes.

But within the lead family, size in AH, State of Charge and State of Health are critical for the ability to deliver high C-rate discharge current, AGM won't be of significant advantage.

[john61ct]

Originally Posted by Chris777

We went with 2 Trojan 8D generating 920 amps at 20 hrs.

Storage capacity is in AH.

Were those GEL? Please post a link to the model.

To help others googling in future, there may be further critique of your choice, please don't take that personally.

[Chris777]

Originally Posted by john61ct

Storage capacity is in AH.

Were those GEL? Please post a link to the model.

To help others googling in future, there may be further critique of your choice, please don't take that personally.

Trojanbattery.com

Not GEL, AGM. Critics are welcome, I made de desicion..... so I guess I am done...

[Adelie]

Originally Posted by Chris777

Ok.... More questions. As I have stated above I am limited in my battery compartment to any thing less than 9 3/4" height. I can fit 4, Group 31, AGM or FLA. However I can fit 3 Group 31 FLA @105 amps each and 3 Group 24 FLA @75 amps each. This combo will maximize my batt comp....... BUT is it compatible to have these 6 batts wired in series for a total amp of 540 amp and 12 volt?

If not I will have to go with the Trojan Grp 31 overdrive at 180 amps each..... unless someone has a better idea.

I charge with a 100 amp alternator, 315W solar panel to be instaled shortly and shore power.

Starting battery is totally separate so we are only talking about "house".

36' Sailboat.

Thanks,

Chris

You need to wire them in parallel to get 540a-hr/12v.

If you are going to mix battery groups they need to all be the same manufacturer and battery type