Two more pretty Lithium batteries arrived today.
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I am going to reply to this and compare the LFD90 battery with an RB100.
Datasheets are attached.
If you only discharge your batteries to 50% you should get 200 cycles (with 80% capacity remaining). The RB100 should give 10,000 cycles at 50% discharge (with 80% capacity remaining). So you will need to buy 50 LFD90s over time (50 x £95 = £4750). But let us say that we are going to discharge the lithium battery to 100% and get the full 100Ah on every cycle we should still achieve 6000 cycles meaning that the Lithium has more than the capacity of 2 LFD90 batteries (actually more than three if you use an inverter a lot like me). So if you use the full 100% DoD you will need to buy 60 (30 x 2) LFD90s over time (60 x £95 = £5700).
But that is not the main reason for buying lithium batteries.
We charge our batteries with limited energy resources like solar or from the dual charge circuit and lithium batteries store more of the input energy as usable energy. Lead acid batteries are like leaky buckets that can lose 20% of the input energy to poor charge efficiency.
Lithium batteries can take a higher charge current and charge faster, so the energy is being stored not slowed down with multi-stage charging.
If people use an inverter then lithium is king. When you discharge lead-acid batteries at a higher rate (say 50 amps) then you reduce the capacity. you will no longer get 45Ah form your 90Ah battery, you will get about 30Ah (50% DoD).
So to sum up:
I know these batteries are expensive, but for the off-grid motorhomer they really make sense.
Datasheets are attached.
If you only discharge your batteries to 50% you should get 200 cycles (with 80% capacity remaining). The RB100 should give 10,000 cycles at 50% discharge (with 80% capacity remaining). So you will need to buy 50 LFD90s over time (50 x £95 = £4750). But let us say that we are going to discharge the lithium battery to 100% and get the full 100Ah on every cycle we should still achieve 6000 cycles meaning that the Lithium has more than the capacity of 2 LFD90 batteries (actually more than three if you use an inverter a lot like me). So if you use the full 100% DoD you will need to buy 60 (30 x 2) LFD90s over time (60 x £95 = £5700).
But that is not the main reason for buying lithium batteries.
We charge our batteries with limited energy resources like solar or from the dual charge circuit and lithium batteries store more of the input energy as usable energy. Lead acid batteries are like leaky buckets that can lose 20% of the input energy to poor charge efficiency.
Lithium batteries can take a higher charge current and charge faster, so the energy is being stored not slowed down with multi-stage charging.
If people use an inverter then lithium is king. When you discharge lead-acid batteries at a higher rate (say 50 amps) then you reduce the capacity. you will no longer get 45Ah form your 90Ah battery, you will get about 30Ah (50% DoD).
So to sum up:
- They weigh less (about 33% of the equivalent lead-acid usable Ah)
- They are safer than lead acid (no acid or explosive gases) Lifepo4 batteries are very safe.
- They are cheaper over time (much higher cycle rate)
- They charge faster (they take a full charge current until almost completely charged)
- They charge more efficiently storing more of the available energy (lithium 99% lead-acid 80%-85%)
- You can use all their capacity so 1 RB100 is the equivalent of 2 100Ah lead acid batteries
- They do not lose stamina under high discharge currents (most 100Ah lead-acid batteries will lose 40% of there capacity under a 50 amp load)
I know these batteries are expensive, but for the off-grid motorhomer they really make sense.
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Trek
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Yep i read all the blurb before i replied previously but the cost difference still outways the advantages in my eyes
Crikey my pair of Varta LFD90’s are 10 years old and only 1/10th of the cost at todays prices
Would have to live and continue motorhoming for a heck of a long time ( 50 times 10 years mmh!)
Yes if I had loads of spare dosh I would probably consider buying them ( I managed to justify to myself the cost of an E&P levelling system )
And i always take new product claims with a pinch of salt , will these new technologies really last as long as they claim?
Eg off topic but shows how a new product can make false claims
Many years ago I bought new bathroom taps which came with the latest new Ceramic inserts claiming that i will never suffer from a dripping tap again - soon proved wrong as these ceramic cartridges found in most taps these days can start to drip after a couple of years
Crikey my pair of Varta LFD90’s are 10 years old and only 1/10th of the cost at todays prices
Would have to live and continue motorhoming for a heck of a long time ( 50 times 10 years mmh!)
Yes if I had loads of spare dosh I would probably consider buying them ( I managed to justify to myself the cost of an E&P levelling system )
And i always take new product claims with a pinch of salt , will these new technologies really last as long as they claim?
Eg off topic but shows how a new product can make false claims
Many years ago I bought new bathroom taps which came with the latest new Ceramic inserts claiming that i will never suffer from a dripping tap again - soon proved wrong as these ceramic cartridges found in most taps these days can start to drip after a couple of years
Trek
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Should have added that its the solar panels that i have bought that are the weak link
they claim to have 15 / 20 year lifespans
I have had three fail in 6 years first one failed after about 14 months replaced under warranty ! Second one after 2 years replaced under warranty , they wouldnt change it when the third one failed
All by same manufacturer all flat walk on type that was bonded directly onto roof
they claim to have 15 / 20 year lifespans
I have had three fail in 6 years first one failed after about 14 months replaced under warranty ! Second one after 2 years replaced under warranty , they wouldnt change it when the third one failed
All by same manufacturer all flat walk on type that was bonded directly onto roof
Steveandjulie
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Very informative Phil thanks for posting.
It's something we will seriously consider when we retire and use our van more.
As that's a few years away yet hopefully price Will have come down as they become more popular
Okta
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I am really pleased with my Relion RB100, installed it last January to replace 2 x 110ah lead acid batteries. Most of the time I have been discharging less than 50% and recharging the next day but if I occasionally dip down to the bottom it isn’t going to worry me. 13.5kg instead of 50kg is another bonus.
This link shows how well constructed they are:
https://www.solacity.com/docs/RELiON/RELiON_Cell_Features_and_Design.pdf
I particularly like this bit:
CELL CIRCUIT PROTECTION
If the battery is penetrated by bullets or lodged metal from an accident the circuit board will seperate the impacted cells from the rest of the cells allowing the battery to continue functioning with less capacity.
If my battery is taking bullets I will probably be worrying about a change of underwear more than the cell construction.
This link shows how well constructed they are:
https://www.solacity.com/docs/RELiON/RELiON_Cell_Features_and_Design.pdf
I particularly like this bit:
CELL CIRCUIT PROTECTION
If the battery is penetrated by bullets or lodged metal from an accident the circuit board will seperate the impacted cells from the rest of the cells allowing the battery to continue functioning with less capacity.
If my battery is taking bullets I will probably be worrying about a change of underwear more than the cell construction.
wildebus
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Something that is a good idea in the colder areas is to fit something like a heating pad to keep the batteries warm enough to charge. I fitted one in my battery box for AGMS but far more important for Lithiums.
Still not convinced about the lifecycle argument as very few people 'use up' their cycles on such a regular basis unless their bank is seriously undersized or they just don't look after their batteries (in which case would they look after Lithiums any better?).
For fulltimers, I think they do offer a lot of benefit, especially in the winter months when the main charging method will be the alternator and solar is very little use.
To me the key things are weight if you are fairly critical on payload, and the fact that the voltage doesn't drop under heavy load like with lead batteries, so as phil has said, ideal for heavy inverter users. I know if I pull over 150A for too long (>30 minutes of so) the inverter tends to complain about low voltage even though I have plenty of capacity left (although that does mean I don't have any real risk of dropping the SOC to a 'bad' level as the big loads cannot be present, so works as a bit of a 'safety valve').
Still not convinced about the lifecycle argument as very few people 'use up' their cycles on such a regular basis unless their bank is seriously undersized or they just don't look after their batteries (in which case would they look after Lithiums any better?).
For fulltimers, I think they do offer a lot of benefit, especially in the winter months when the main charging method will be the alternator and solar is very little use.
To me the key things are weight if you are fairly critical on payload, and the fact that the voltage doesn't drop under heavy load like with lead batteries, so as phil has said, ideal for heavy inverter users. I know if I pull over 150A for too long (>30 minutes of so) the inverter tends to complain about low voltage even though I have plenty of capacity left (although that does mean I don't have any real risk of dropping the SOC to a 'bad' level as the big loads cannot be present, so works as a bit of a 'safety valve').
Okta
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I bought these 12v motorcycle hand grip warmers for less than £4 to put under my battery in case I need to warm it up for charging.
https://www.ebay.co.uk/itm/142674440723
Haven’t needed them yet and probably never will because my battery compartment is insulated and on the warm air heated circuit. But just in case the mh has stood idle in freezing weather I could if needed switch them on to warm the battery up. If you were a regular user in arctic conditions then Relion have just launched a new battery that takes the initial charging current and heats itself up with it before turning it over for charging. I believe the RB100 bms protects the cells from charging when the battery is too cold anyway.
https://www.ebay.co.uk/itm/142674440723
Haven’t needed them yet and probably never will because my battery compartment is insulated and on the warm air heated circuit. But just in case the mh has stood idle in freezing weather I could if needed switch them on to warm the battery up. If you were a regular user in arctic conditions then Relion have just launched a new battery that takes the initial charging current and heats itself up with it before turning it over for charging. I believe the RB100 bms protects the cells from charging when the battery is too cold anyway.
wildebus
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I am sure they do have the charging protection, but you want to be able to charge them, so heating is a better option then preventing charging
(the inside of my van goes sub-zero in the winter on a very regular basis).Also, Lithium batteries work better at warmer temps as well. You won't get the chance to use 100% of the capacity (which is a major selling point of Lithium) at the typical temperatures we get in the UK even in summer let alone winter.
I added a 20W heating pad to my battery box, enabled by a temperature controller so they don't go too low (not so important with AGMs, but still a useful exercise and totally transferable to a Lithium setup).
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They are drop-in replacements, the only thing you need to do is to make sure your onboard charger and solar charger are set to charge at 14.2 -14.6 volts for optimal charging.
wildebus
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How do the batteries deal with the Float? do they self-disconnect when full?
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As far as I am aware the onboard controller deals with this, but as it is not mentioned in the data sheets I have phoned Relion in the USA and I am waiting for a callback.
Just on the point of warming the battery, the RB100 has a charge temperature range of -20c to 45c
wildebus
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Could you confirm the charge temperature range with them as well? I know it quotes -20 to 45 Charging, and -20 to 60 Discharging in the specs, however the charts for the Charging shows examples of 5C to 45c, whereas the Discharge one matches the spec sheet with examples from -20c through to 60c. -20c for charging is pretty unusual for Lithium and I am wondering if that -20c in the spec is a typo!