lithium batteries or AGM

[john61ct]

Originally Posted by Pelagic

What would a 1040AH @ 24v new technology battery package weigh in at?

720AH about the same usable capacity, under 400 lbs and also less space

[john61ct]

Sorry 180kg

[Pelagic]

Originally Posted by john61ct

720AH about the same usable capacity, under 400 lbs and also less space

Ok...I understand that is because the LFP can be discharged down to a much lower (??) SOC without damaging lifespan. BUT....I calculated my AGM capacity to consume just under 10% in 24hrs at anchor....(not really conserving)

This allows me to bulk charge in the 70-80% SOC range with my 2 Victron chargers and generator in about 70 minute's

Motor sailing or running aircons in a rainy/buggy anchorage would top them up once a week.

It would also give me about 5 days grace period to get down to around 40-50% if I had a charging problem.

So would I have that same grace period with 750ah?

[hzcruiser]

Originally Posted by Pelagic

That is a huge consideration!
In my installation, I have 8 x Fullriver AGMs dc-260ah-12v
for a 24v House bank of 1040ah
Each weighs 77.3kgs so totals
618.4kgs.

Holey maloney, 1040Ah @ 24V is pretty big! Then again, you might only want to use 50% of the capacity?

What would a 1040AH @ 24v new technology battery package weigh in at?

I've got different sized CALBs (for testing purposes of my BM system), the biggest ones are 180Ah cells (that's 3.2V each) weighing in at 5.6kg, like so:

CALB 180 Ah CA Series Lithium Iron Phosphate Battery, EV West - Electric Vehicle Parts, Components, EVSE Charging Stations, Electric Car Conversion Kits

You'd need 8 of those handy little buggers to get 24V nominal, that's 44.8 kg, but in more manageable chunks. That's 0.275kg per Ah @ 24V.

Yours would come to 0.59 kg/Ah or more than double the weight.

On top of that, an LFP bank can be sized smaller as you can make use of 80% (or more) of the capacity as opposed to 50% (or more) for most people using LAs.

Hence your 1040Ah bank would usually deliver around 520Ah. That would be equivalent to 650 Ah of LFP capacity with a gravity of 178kg and a nice hole in your pocket of about 7-8 boat units if we round it up to 720 Ah or 4 sets of 8 LFP cells.

And by the way, due to the global shortage (or high demand), the batt prices for LFP won't come down within the next 2-3 years. In fact they went up more than 10% in the last year.

Full disclosure: I'm holding lots of shares in Australian Lithium mining companies.

[hzcruiser]

Originally Posted by Pelagic

So would I have that same grace period with 750ah?

Yes, you would. What matters is the usable capacity of the bank(s).

I think you're more tech-savvy than you let on, if you know the SOCs and cycling behaviour of your batts!?

[Pelagic]

Originally Posted by hzcruiser

And by the way, due to the global shortage (or high demand), the batt prices for LFP won't come down within the next 2-3 years. In fact they went up more than 10% in the last year.

Full disclosure: I'm holding lots of shares in Australian Lithium mining companies.

So unless they can source new large deposits of Lithium... or find a cheaper substitute, someone mentioned 7 times the cost factor of AGM's for LFP.???

This sort of reminds me of the Superyacht builder meetings, where the builders specified Gold fixtures for the "practical" reasons that they never rusted!

Obviously weight is not a big issue for my boat and the AGMs are low down midships in a sub floor.

I am at 6 years for my AGM's so hard to justify the switchover for my application.

[hzcruiser]

Originally Posted by Pelagic

So unless they can source new large deposits of Lithium... or find a cheaper substitute, someone mentioned 7 times the cost factor of AGM's for LFP.???


I am at 6 years for my AGM's so hard to justify the switchover for my application.

Yep, price is the biggest hurdle and depending how you tweak the numbers (useable capacity, life span etc) some people brought the cost of LFP to almost par.

But in your case there is no need to even consider a switch over anytime soon.

At 14t displacement the extra weight was of no consideration to me either. It was only that my AGMs "got killed" as Maine Sail would say, by the solar charger (which, of course, was installed by the PO). Still my fault for not catching the problem sooner when I moved from FLAs to AGMs.

[john61ct]

If you're saying you only use under 200AH per day, then get 360AH, those 180's at 8s2p.

They will accept 400+A charge rate at any reasonable SoC, so from Empty (10-15%) to Full (13.8V) in well under an hour any time you feel like burning dino juice.

200lbs, 90kg

[john61ct]

Yes Bruce @ Ocean Planet, a top recommended vendor for system installs (dunno if Maine Sail's doing them these days) himself says

They're really only getting bought by racing yacht owners where low weight is everything.

[hzcruiser]

Originally Posted by john61ct

If you're saying you only use under 200AH per day, then get 360AH, those 180's at 8s2p.

They will accept 400+A charge rate at any reasonable SoC, so from Empty (10-15%) to Full (13.8V) in well under an hour any time you feel like burning dino juice.

200lbs, 90kg

Makes sense, John, once his existing batteries are end-of-life.

[CascadeThumper]

I learned the hard way. AGMs said 240 ah, the fine print said: if discharged more than 1/2 capacity longevity is compromised. So, really, I only had 120 ah useable. I pushed their limits twice and then, no more. Lifespan if not abused 5 years. Small footprint is nice. Lithium is nice in cordless tools. I have never done the math for a boat. I went Old School with a big bank of DYNO lead acid batteries. Bigger footprint but 70% of the ah are useable without damage and so much less expen$ive.

[john61ct]

Originally Posted by CascadeThumper

I learned the hard way. AGMs said 240 ah, the fine print said: if discharged more than 1/2 capacity longevity is compromised. So, really, I only had 120 ah useable. I pushed their limits twice and then, no more. Lifespan if not abused 5 years. Small footprint is nice. Lithium is nice in cordless tools. I have never done the math for a boat. I went Old School with a big bank of DYNO lead acid batteries. Bigger footprint but 70% of the ah are useable without damage and so much less expen$ive.

AGM are also lead acid.

Yes flooded are better value, but even the best makes also should only be drawn down to 50% in normal usage for longevity.

IMO AGM only when sealed specifically required, or high CAR is impotant.

LFP is better on all these points, nothing to doe with the other lithium chemistries used for gadgets.

Just so expensive, therefore economically risky.

[StuM]

Originally Posted by CascadeThumper

I learned the hard way. AGMs said 240 ah, the fine print said: if discharged more than 1/2 capacity longevity is compromised. So, really, I only had 120 ah useable. I pushed their limits twice and then, no more. Lifespan if not abused 5 years. Small footprint is nice. Lithium is nice in cordless tools. I have never done the math for a boat. I went Old School with a big bank of DYNO lead acid batteries. Bigger footprint but 70% of the ah are useable without damage and so much less expen$ive.

AGM are "lead acid" (LA), but not Flooded LA. I presume your DYNO are FLA.

You are going to get real unpleasant surprise soon if you act on your last, erroneous, supposition.

[Pelagic]

Originally Posted by CascadeThumper

I learned the hard way. AGMs said 240 ah, the fine print said: if discharged more than 1/2 capacity longevity is compromised. So, really, I only had 120 ah useable.

That is exactly why I more than doubled my LA batteries from 400Ah to 1040Ah AGMs @24v

Chose the AGM so I could fit all in a "maintenance free" location and to remove any boiling off vapors when bulk charging.

Keeping my SOC between 70%-80% daily when charging every 24hrs at anchor has meant I "should" get maximum longevity if I top up once a week.

[Adelie]

Originally Posted by Giannisailing

many thanks for your suggestions....I guess I do have some bedtime reading ahead..haha.

Just one question...1000AH of AGM = 1000AH lithium? or Am I correct in thinking that because Lithium is more efficient in its delivery of its charge it would require less capacity?

1000a-hr nameplate LA is about 500a-hr usable.

You can go down to 80% DoD with LiFePo.

So 500a-hr usable / 80% = 625 a-hr nameplate.