Lithium leisure battery

[GRW]

Forklift batteries get loads of abuse. They are charged relatively quickly and deep discharged day in day out. They still last many years.
Your 50% figure is deliberately pessimistic. 70 to 75% is more accurate. So how much for a 38kwh battery bank?
If they are still good enough for hunter killer submarines they should be good enough for most people!

As per my reply to Misterg above. Forklift batteries really ARE stronger as their output rating is tested & certified on much bigger loadings (& batts are far better at small loads over long duration than big loads over short duration). Ergo a (say) 200ah Forklift cell is actually significantly more powerful than its 200ah Leisure (C20) alternative.

The flattest part of the discharge curve of a lead-acid is between 20 & 80-odd percent, so you get the most current for the least voltage drop. On off-grid inverter-charger-battery setups, the charge voltages would be set to utilise this 60% zone for longevity & performance, (80 - 100% only being engaged during periodic "Equalise" cycles to minimise stratification, sulphates & to boost SG levels in the Electrolyte). It's going below 20% (where voltage plummets under load on the curve) that needs avoiding.

Like all selling fluff - I think there us some exaggeration of the DoD on the trendy Lithium capability - and under-playing of the DoD that Lead-Acid can handle (& it's put about enough that the exaggerated performance difference is greater that this becomes established "fact").
IMO Lithium Leisure Batteries extra cost isn't justified of warranted given the real performance difference (unless like the OP, the weight is the most important factor)

 

[sg66]

A 100ah is only 10kg, but a 200ah is 50-60kg? Guessing the 200ah is much stronger kit & a proper deep-cycle build.
Technically I have 200ah at 48kg (but not the same DoD though).

Pre-made Camper furniture is silly money indeed. Like you I made my own. (Unlike you mine isn't very light though... or that well-made - a cabinet maker I ain't!).

I'd be interested to see pics of your pod once done though for sure

The 100ah lithium 10kg the 230ah lithium 25 the 230ah AGM lead 60kg

 

[Misterg]

If I were doing it again, I'd have another look at lithium

Out of curiosity, I looked up current prices:

T-105s have gone up from £275 to £340 the pair. (225Ah lead acid)
Cost/cycle* : £0.10

Victron 100Ah lithium has come down from ~£1100 to £866
Cost/cycle : £0.12

Sterling 100Ah lithium is now ~500
Cost/cycle : £0.06

For the extra outlay, I'd probably go with the Sterling lithium (or equivalent) now, provided that user feedback was good.

*based on a 40Ah cycle.

 

[sg66]

Out of curiosity, I looked up current prices:

T-105s have gone up from £275 to £340 the pair. (225Ah lead acid)
Cost/cycle* : £0.10

Victron 100Ah lithium has come down from ~£1100 to £866
Cost/cycle : £0.12

Sterling 100Ah lithium is now ~500
Cost/cycle : £0.06

For the extra outlay, I'd probably go with the Sterling lithium (or equivalent) now, provided that user feedback was good.

*based on a 40Ah cycle.

Fogstar are way better on price than those

 

[GRW]

I think the proof of the pudding etc... & like all things I'm sure the quality & lifespan of all Lithium batts are not remotely equal.

Personal choice, but the general history, safety and performance of lead-acid for the buy cost (& I'm not atm overly worried about weight) makes LA a low cost, low risk choice.
Again, cheaper-end Lithium unknown-brand stuff has to represent taking more of a punt, than established more pricey stuff.

Personally I'd rather risk £100 and get a dud LA, rather than hundreds more on complex, electronic LIPO batteries & chargers & get a dud (& my time on that self-build group suggested that failing Lithium batts (failing to charge not going up in smoke/flames that is) - is not at all uncommon. There were regular posts from people with issues).

 

[fizzy]

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A 38kw/h battery for £2400. Ok so you only get say 28kw/h capacity usable but it is still about 1/3 to 1/4 the cost. And you get back about £800 when you scrap it

 

[sg66]

I think the proof of the pudding etc... & like all things I'm sure the quality & lifespan of all Lithium batts are not remotely equal.

Personal choice, but the general history, safety and performance of lead-acid for the buy cost (& I'm not atm overly worried about weight) makes LA a low cost, low risk choice.
Again, cheaper-end Lithium unknown-brand stuff has to represent taking more of a punt, than established more pricey stuff.

Personally I'd rather risk £100 and get a dud LA, rather than hundreds more on complex, electronic LIPO batteries & chargers & get a dud (& my time on that self-build group suggested that failing Lithium batts (failing to charge not going up in smoke/flames that is) - is not at all uncommon. There were regular posts from people with issues).

Well fogstar have been going 8 years now so as long as they manage another 10 my warranty should be fine

I think big part of the problem is the price point, lots and lots of cheap lithium batteries made with untraceable cells of any quality cause there is a market for cheap.

A house blew up in Germany triggered by lifepo batteries going bang in a big way, so certainly potential for things going badly wrong.

The battery monitoring system plays a big part in keeping things safe, I watched a few strip down vids on some of the cheap batteries available and on more than one board there was no heat sensor, so although it had the ability to shut down on over temp it didn't have the ability to sense it.

Also some of the packing and connections and adhesives used were dubious to say the least.

 

[not done it yet]

I think big part of the problem is the price point, lots and lots of cheap lithium batteries made with untraceable cells of any quality cause there is a market for cheap.

A lot of chinese batteries are made from cells recovered from already used batteries - hence cheap.

I believe CATL can now supply cells that are warranted for the life of the EV into which they are fitted. That may be to 75% or perhaps 70% of original nominal capacity.

 

[Martin Hocking]

I’ve found this thread quite interesting but I’m definitely too stupid to understand properly.

Can someone explain what the amp-hour rating of a battery actually means?

I thought I meant the current that could be sustained for one hour before full discharge or is it the number hours at 1 amp before full discharge? Or neither?

Seemingly an amp hour is different in practice depending on the type of battery too.

I’ve got four of these (below) that I think are in good shape, I fancied mucking about with a bit of solar for my shed but even after looking at the data sheet I’m not even sure how much capacity they have.

Probably not a good place to start for playing with sparks but hey ho..,

 

[sg66]

I’ve found this thread quite interesting but I’m definitely too stupid to understand properly.

Can someone explain what the amp-hour rating of a battery actually means?

I thought I meant the current that could be sustained for one hour before full discharge or is it the number hours at 1 amp before full discharge? Or neither?

Seemingly an amp hour is different in practice depending on the type of battery too.

I’ve got four of these (below) that I think are in good shape, I fancied mucking about with a bit of solar for my shed but even after looking at the data sheet I’m not even sure how much capacity they have.

Probably not a good place to start for playing with sparks but hey ho..,

View attachment 461345

It's just the amount of current v time a 10ah battery would run a 1amp device for 10 hours or a 10 amp device for 1 hour a 20 amp for 30mins etc

 

[sg66]

One of the other advantages of lithium is you can fit it any way you want, on its side, upside down doesn't matter it will burn in any orientation I mean run.....

 

[voipio]

The Amp hour rating of a battery is normally estimated as the cumulative current drawn (i.e. current x time; usually Amps x hours, or milliAmps x hours for smaller batteries), starting from full charge, to a defined end point voltage per cell (e.g. 1.8V for a lead acid cell). The Amp hour rating is affected by the discharge rate. The higher the discharge rate the lower the actual Ah capacity estimate tends to be, for a given battery design. The "standard" discharge rates in Amps tend to be C10, or one tenth the Ah capacity (e.g. a 110Ah battery being discharged at 11A), but some manufacturers will state the C20 capacity, or even C5 capacity, the latter being typically quoted for traction batteries for forklifts. Discharging a 110Ah C10 lead acid battery at 110Amps (i.e. C1 rate) will result in somewhat less than one hour's run time to the end point voltage.

 

[sg66]

So fridge been on a week now 193ah left and I'm up to 3 on the normal settings

It runs for just over 3mins about every 20mins so starting to run a little longer and a small amount of heat build up in the compressor, still barely warm to the touch.

Definitely safe to say I'm ok for a long weekend

 

[not done it yet]

It's just the amount of current v time a 10ah battery would run a 1amp device for 10 hours or a 10 amp device for 1 hour a 20 amp for 30mins etc

Time for discharge also needs specifying. A lead/acid battery is usually rated for 20 hours for the discharge. Shorten the time (increase the Amps) and the battery capacity will decrease.

One of the other advantages of lithium is you can fit it any way you want, on its side, upside down doesn't matter it will burn in any orientation I mean run.....

Gel and AGM lead/acid can also be fitted most ways (but not upside down I expect).

 

[sg66]

Time for discharge also needs specifying. A lead/acid battery is usually rated for 20 hours for the discharge. Shorten the time (increase the Amps) and the battery capacity will decrease.



Gel and AGM lead/acid can also be fitted most ways (but not upside down I expect).

It was just a rough idea for someone who didn't understand the concept of the rating, mine one will do a max continuous discharge at 250a but seeing as I have a 30a fuse from the battery it's safe to say I'm not planning on it, handy if you want to flatten it quickly with a 2500w inverter but I'm not..

 

[Martin Hocking]

Thanks @sg66 and @voipio that helps tonnes.

I still can’t say I understand the way the people who make the batteries I have rate theirs, because the rating over time seems to be the opposite of what @not done it yet has said (which made perfect sense).

Still, now I understand a bit clearer I’d take a stab at saying that the batteries I have are around 60ah measured as C1.

 

[Martin Hocking]

Having just posted the above and re-read the helpful replies I still haven’t got it right have I!

I’m sure I used to understand this, the more I look at it, it almost seems like all the different ways the ah capacity is measured seem to make it almost arbitrary.

I do think I’m not incorrect in my saying that the batteries I have can discharge approximately 60amps for 1 hour. But they aren’t what would be called a 60ah battery.

 

[Misterg]

I do think I’m not incorrect in my saying that the batteries I have can discharge approximately 60amps for 1 hour. But they aren’t what would be called a 60ah battery.

You are correct. Most commonly, capacity at the 20 hour rate is quoted making yours 100Ah.

 

[sg66]

Fridge still going as is battery now on highest or lowest setting before coming a freezer, on no 3 the temp is 4.6, all of the temps are very consistent.

 

[sg66]

Still going, been through all the normal settings and now it's onto freezer mode