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Drop In LiFePo4 Batteries Round 2

4759 Views 30 Replies 6 Participants Last post by  colemj, 
Don L
I saw some to me unbelievable low priced 100Ah drop in LFP batteries on Amazon today (Amazon.com). At least low priced to me who got my last set of batteries only 2 years ago and was comparing costs of LFP to the FireFly batteries I got. Now I read Rod's article slowly this morning:

marinehowto.com

Drop-In LiFePo4- Be an Educated Consumer

Lead is Dead (almost) Warning: This article is long and detailed. It may require two reads so the nuances and detail are not missed. You may be wondering why I am saying lead is dead ?The answer to that is simple; lead acid battery makers dug their own graves
marinehowto.com

and chased down the full spec sheet attached.

To my reading this seems a good LFP battery spec compared to the items Rod's article

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No Agenda
capta said:
I was thinking of using this on my LifePo batteries. Anbody see a problem? View attachment 145415
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It is recommended that a class T fuse should be used because of the potentially high discharge current.
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Don L
I want to bump this thread back into drop in replacement discussion. I was 99% close to installing LFP batteries 30 months ago (I had ordered but they hadn't shipped) and changed directions to FireFly batteries. These are looking to be a false promise and I could have saved $1500 with replacement T105s for batteries to last 2.5 years. So:

In post 1 I posted a drop in battery I found on Amazon (https://www.amazon.com/ECI-Power-Re...fos.765d4786-5719-48b9-b588-eab9385652d5&th=1).

You can get 400ah, 2-200AH batteries, for $1200. To me that seems just too good to believe after my research just 2.5 years ago. And it isn't uncommon. Yet there are other builders selling 100AH "drop in" LFP for $1000, These ECI batteries have good charge/discharge specs, meaning they are good match to my current charging system etc. It has built in BMS and even has bluetooth (cheap way to meet the new tech requirement). To me they tick off all the cautions in Marinesails warning article.

Am I missing something or am I headed down another sucked path?
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Skipper Jer
Don L said:
In post 1 I posted a drop in battery I found on Amazon (https://www.amazon.com/ECI-Power-Re...fos.765d4786-5719-48b9-b588-eab9385652d5&th=1).
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A lot of features for the price, bluetooth and cold temp shut down. Considering the reviews on Amazon I'm a bit skeptical of the cell quality BUT the company did respond with replacements. Maybe someone can jump in on why advance warning of BMS disconnect is needed.
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Don L
Well my battery voltage got low enough last night that my freezer turned off. The Firefly batteries should have been about 75% charged but the voltage was only 11.5V at a 5A load. So I can not take off to the boonies with these and this drop in LFP battery issue is now a must do decision. So choices:

  • some G31 batteries that will probably last 2-3 years $600
  • some LFP drop in batteries that whose knows how long they may last $1200
  • some more expensive LFP drop in LFP $2500+
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Don L
So I had to act. Watched some utube tear aparts and decided the $300-350 100aH drop ins overall all are pretty good. Funny boaters will get all hair splitting over LFP batteries considering the pretty much unknown construction of the batteries they have used for years.

In the end i ordered 4 100ah Power Queen batteries off Amazon for $1319 all in. That is what boaters have been paying for agm batteries in the past and is $700 less that i sucker paid for my FireFly batteries 2.5 years ago.
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colemj
What changed your mind about the ones in your previous link?

Mark
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Don L
colemj said:
What changed your mind about the ones in your previous link?

Mark
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The 2- 200aH ones didn't space fit as well as as 4-100aH ones. I watched some tear apart tests of both and they pretty much appear to be the same. I think I may even have gotten confused by the end and didn't really order the one I met too. I was going to order the ones that had a GA warehouse that I thought might be a fast delivery time for my in FL as they are shipping to daughter's house in Jacksonville and I am in West Palm Beach and have to drive up to get and hoped to do on the Christmas trip up.

They all just just became what smoke and mirrors to believe in really.
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Don L
Only been 1.5 days with the LFP, but the boat appears to like them a lot. The electric head really likes the extra 1v and sucks a bowl full right down. Feel I got the batteries fully charged yesterday as the 4 got to 14.4v and were only accepting 6.8A. Feels funny this morning getting up to batteries that are 75% SOC and 13.2+ V
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colemj
Your solar will also charge more efficiently into the lower nominal charging voltage of the LFP vs LA. Everything else will run more efficiently with the higher load voltage of LFP vs LA. If you still had a DC watermaker, it would make closer to its rated output now.

Mark
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D
colemj said:
No, those are common fuses used in LFP systems. The main fuse to the battery would be better to be a class-T fuse for interrupt current rating. Otherwise, those MRBF fuses are great branch circuit fuses.

Mark
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Not sure I follow your statement <branch circuit fuses> since those are specifically designed for battery mount. When I switch to Lithium I will have to rework my battery bank(s). Are you suggesting one of those on each battery, then a T-type somewhere on the main lead from the bank, or just drop the MRBF ? I have read that a fuse on/near each battery is recommended in case of BMS failure or meltdown.
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colemj
dcruz99801 said:
Not sure I follow your statement <branch circuit fuses> since those are specifically designed for battery mount. When I switch to Lithium I will have to rework my battery bank(s). Are you suggesting one of those on each battery, then a T-type somewhere on the main lead from the bank, or just drop the MRBF ? I have read that a fuse on/near each battery is recommended in case of BMS failure or meltdown.
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Those can work as a main fuse, but they only go to 300A and some installations need higher. It is better to use a classT fuse for the main fuse right off the battery, as that has a higher interrupt rating, but that rating for MRBF is fine. Something like a MEGA fuse would not be appropriate as a main fuse. I use those MRBF's on buss bars after a classT to branch circuits for some things. You don't want a bunch of them on the batteries themselves going to branch circuits, however.

Mark
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