Rather than change to LiFePo batteries, how about an intigrated 'Power Station?'

[Refueler]

See Sea Change reference to Rod Collins, I think he proves that long life, of LFP batteries, is quite possible. Human life is a bit more frail. Rod used to be Mainsail on CF

Here we go - I've done the hard work for you (but I misled - its not 15th Anniversary its 15th Birthday - apologies.)

Jonathan

The large batterys used are of low C rate .... the reason you can long life and reasonably high discharge rates is because of the Capacity x C rate equation. As I posted before ... Pauls 140A rate from his is most likely based on having high capacity ....

That Lithium Leisure battery linked to by another earlier ... once my meds had 'backed off' ... I looked again .... 100 A/Hr .... max discharge rate 100A ... means its a 1C system .... so if anyone pulled anything but short burst 140A out of that too often ... it will suffer and have reduced life. Pull 280A out of it and it definitely will go see its maker in short time ! The c loser you get to max discharge rate and if done often repeatedly - life of the battery will suffer.

This and previous have said about C rates x Capacity .... that's a factor that must be taken into account ... not just capacity alone. Do not forget also that if you have higher C discharge rate than what's generally in this form - the C charge rate does not necessarily follow ... at low C rate ... the C(D) rate and C(C) can be same ...

Its interesting as the more you look at these LiFePO4 .... they purposely keep the C rates low ... and rely on capacity to deliver the goods ...

Just for the record ... I do use LiFePO4 along with LiPo ... LiIon .... LiFe .... depending on the use and setup. In many sizes from tiny up to 20 A/hr ...... not your sizes I agree .... but the chemistry is still there ..... plus various have their Smart BMS etc ....

 

[Neeves]

I agree. We are mooring based and have 450AH of lead acid Trojans, charged by 320W of solar in sunny location. Does what we need, with fridge running 24/7 and the usual other bits running or on charge. I see no need or benefit for us in changing to lithium.

But you might do if you need to replace the lead acid house bank.

Never say 'never'

Jonathan

 

[Sea Change]

if anyone pulled anything but short burst 140A out of that too often ... it will suffer and have reduced life. Pull 280A out of it and it definitely will go see its maker in short time !

Actually the BMS would simply disconnect the battery when it sensed the over current, and no harm would be done to the cells.

 

[Sea Change]

On cost the Lithium fanboys discount all the 'spensive wiring stuff and tools you need to do a DIY install. Include that and on a like-for-like basis there's nothing in it if you wait for one of the many factory discounts that come along.

I try to remember to include everything.
Because I built from bare cells, I had to buy a bench top PSU to balance the cells (£40). If buying complete batteries you don't need this.
I also bought a hydraulic crimper (£25) which allows me to make leads using heavy cables.
I found a multimeter (£10) useful too.
Plus a socket set and spanners.
That's it for the tools.

On the 'wiring stuff' I upgraded my isolator (£60) and fuse (£100) to handle the higher current I was going to run. I chose a class T fuse because that is seen as the gold standard, but I've since learned that other types of fuse are just as good and much cheaper.
If you want to charge from your engine, a DC-DC charger is an easy solution, mine was £140.
Shore power charger ought to be lithium compatible, same for solar. My equipment already was so I don't have a cost for that. Any MPPT will be lithium compatible.
By the way, if your shore power charger is not lithium compatible, it's not the end of the world, it will still bulk charge the battery just fine, but you'll want to manually turn it off when full, otherwise the BMS will do that for you and your lights will go out.

So when you add it up, I had around £375 of costs I could attribute to the batteries being lithium.
My DIY batteries cost me under £1000, vs the £1380 I was originally going to spend on a set of eight Trojan T105s of the same useable capacity. The lithium would be noticeably cheaper at today's prices as I built mine over three years ago.
So even accounting for the extra costs of choosing lithium, I saved money.
Anybody who knows me knows that I'm a notorious skinflint. I wouldn't have gone down this route if it didn't save me money!

 

[PaulRainbow]

<snip>
By the way, if your shore power charger is not lithium compatible, it's not the end of the world, it will still bulk charge the battery just fine, but you'll want to manually turn it off when full, otherwise the BMS will do that for you and your lights will go out.

<snip>

The JK BMS (and no doubt others) would only cut the charging, the lights would stay on.

 

[PaulRainbow]

The large batterys used are of low C rate .... the reason you can long life and reasonably high discharge rates is because of the Capacity x C rate equation. As I posted before ... Pauls 140A rate from his is most likely based on having high capacity ....

Mine is 280ah at 24v. Rated for a max of 280a (1C). If it's used at 140a it's rated for 8000 cycles. I can run the 3000w inverter flat out, as well as the other "normal" stuff and barely go over the 140a, with the BMS cutting out at 200a to safeguard the batteries.

In 12v terms it would be rated at 560a max, how much LA would you need to run a constant 560a load ? Unless it was a massive bank the voltage drop would be prohibitive.

<snip>

Its interesting as the more you look at these LiFePO4 .... they purposely keep the C rates low ... and rely on capacity to deliver the goods ...

LA would not like being discharged at that rate for very long at all, the voltage drop would be significant and you can only discharge to 50% DOD.

Using your 100ah battery as a comparison, would you put a 100a load on it for any length of time ? It would be effectively flat in just 30 mins and its life expectancy would be very short.

 

[Refueler]

Mine is 280ah at 24v. Rated for a max of 280a (1C). If it's used at 140a it's rated for 8000 cycles. I can run the 3000w inverter flat out, as well as the other "normal" stuff and barely go over the 140a, with the BMS cutting out at 200a to safeguard the batteries.

In 12v terms it would be rated at 560a max, how much LA would you need to run a constant 560a load ? Unless it was a massive bank the voltage drop would be prohibitive.

LA would not like being discharged at that rate for very long at all, the voltage drop would be significant and you can only discharge to 50% DOD.

Using your 100ah battery as a comparison, would you put a 100a load on it for any length of time ? It would be effectively flat in just 30 mins and its life expectancy would be very short.

You on my page !!

This is my point ....

Interesting though because you quoted 140A at 24 and 280A at 12v before ....

But Yes - agreed such amp rates are high and very few people would be dragging such rates for extended period ... but you only need someone with a high wattage Inverter and you can be pushing those limits ...

But I do wish people would start to think about those discharges .... just willy nilly saying 80% for x000 cycles is subject to the amp rate and also how often you push down to lowest charge state ... remembering that voltage drop during the high rate discharge ... battery may be 20% residual once off load and rested ... what was it just before load removed ??

As regards LA .. Cranking battery best not below 60% ... general leisure (too often confused with Deep Discharge) about 50 - 55% ... Deep Discharge (not for cranking) 45 - 50% ..... and charge up as soon as possible. IF you want decent life ........


I'm still a bit 'groggy' from Hospital ... will be back in fighting form tmrw .... !

 

[PaulRainbow]

You on my page !!

This is my point ....

Interesting though because you quoted 140A at 24 and 280A at 12v before ....

Apologies for any confusion. Mine are 280ah @ 24v, manufacturers quote 1C max (280A) and 0.5C (140A) They quote 8000 cycles @ 0.5C

The recommended SOC range is 10% - 90%

Obviously @12V it would be 560ah and double the discharge amps.

But Yes - agreed such amp rates are high and very few people would be dragging such rates for extended period ... but you only need someone with a high wattage Inverter and you can be pushing those limits ...

I have a 3000w continuous inverter/charger, with a 550w peak rating. I've limited mine to 3000w, anything more than that and the shore power or generator kicks in and "power assist" give me an additional 16/32a. My default is that the inverter is on all of the time, running the whole boat, aided by solar power. If there is a shortfall of solar and the batteries get down to a certain level shore power will kick in and charge the batteries to a set level, then switch off again and leave it up to the solar, ensuring that i get the max amount of available solar yield.

But I do wish people would start to think about those discharges .... just willy nilly saying 80% for x000 cycles is subject to the amp rate and also how often you push down to lowest charge state ... remembering that voltage drop during the high rate discharge ... battery may be 20% residual once off load and rested ... what was it just before load removed ??

It should go without saying that the discharge rate should be managed so as to fall into the manufacturers limits. If that's done and the minimum DOD is observed then there should be no reason to not quote the cycles.

Voltage drop is minimal, unlike LA.

As regards LA .. Cranking battery best not below 60% ... general leisure (too often confused with Deep Discharge) about 50 - 55% ... Deep Discharge (not for cranking) 45 - 50% ..... and charge up as soon as possible. IF you want decent life ........


I'm still a bit 'groggy' from Hospital ... will be back in fighting form tmrw .... !

Hop you're feeling better. Had more hospital visits in the past 18 months than i'd want in two lifetimes, hopefully, properly, on the mend now.

 

[Refueler]

"Hop you're feeling better. Had more hospital visits in the past 18 months than i'd want in two lifetimes, hopefully, properly, on the mend now."

Actually coming home may have been a good decision .. they asked if I wanted to stay more days ... but we agreed I was ready.

Right side of face is now about 90% back to normal ... just have to be careful for a while outside in the cold not to relapse.

Have Mastervolt to fit to MoBo once its jacked up and levelled on trailer properly ... and run Anit-freeze through that VP ... its 0C out there so I'm a little worried ... going to Hospital of course meant I couldn't get it done before temps dropped. I'm going to see if I can drop a small heater into the engine bay ...