Charging lithium battery

[martinriches]

I am replacing the LA house battery on my yacht with a 155ah lithium battery. I will be using a 60amp b to b chargers between the start battery and the lithium. I would like some advice about what to do about the mains shore power charging. At the moment there I have a 25a charger with 2 outputs one to each battery. It doesn't have a lithium setting. Can I just leave it connected to the start battery only and therefore charge the house battery through the b to b charger?

Martin Riches

 

[gregcope]

Sounds sensible to me. Your b2b chargers sound more than upto the task of keeping up with the shore charger.

 

[Richard10002]

I am replacing the LA house battery on my yacht with a 155ah lithium battery. I will be using a 60amp b to b chargers between the start battery and the lithium. I would like some advice about what to do about the mains shore power charging. At the moment there I have a 25a charger with 2 outputs one to each battery. It doesn't have a lithium setting. Can I just leave it connected to the start battery only and therefore charge the house battery through the b to b charger?

Martin Riches

What's the make and model of the shore power charger. I use a custom setting on my Sterling. Yours might have a setting that works for lithium, even if it doesn't call it lithium. On mine I set it to charge up to 14.1v, with a float of 13.3v when using shorepower. Allowing for voltage drop, this means they seem to get a max of 13.9v.

 

[martinriches]

What's the make and model of the shore power charger. I use a custom setting on my Sterling. Yours might have a setting that works for lithium, even if it doesn't call it lithium. On mine I set it to charge up to 14.1v, with a float of 13.3v when using shorepower. Allowing for voltage drop, this means they seem to get a max of 13.9v.

Its
Quick SBC 250. 25 A. 14.1v absorbsion. 13.5 float.

Martin

 

[Richard10002]

Its
Quick SBC 250. 25 A. 14.1v absorbsion. 13.5 float.

Martin

I'm no expert, but I think that would be fine for your Li Bank. In which case you could use either your b2b 60A or the 25A charger.

Whatever the case, I would tend to turn off the shore power charging to the Li bank when I left the boat, (they are happy to be part charged). I would probably also turn it off when the Li bank is as charged as I want it to be, rather than leaving it to continue charging, float or otherwise. This is because Li batteries will draw whatever the charger can provide, to the point where they could be overcharged and damaged.

I'm sure someone else will be able to put it better than me

 

[martinriches]

The battery recommendation is 14.4 and 13.2 float. So perhaps it wont charge fully from the mains charger but would get toped up by the b2b . I will put a relay into the circuit so I can turn the mains charger off . I am a bit worried about damaging the battery as they cost so much.

Martin

 

[Poey50]

I'm aware that others will be reading over our shoulders so I just want to emphasise one point made in passing by Richard10002. Most people get that it is important not to have too high a target voltage when charging LFP and that you shouldn't float them (any 'float' voltage below 13.5 volts is fortunately no float at all). But there is one major difference from lead acid charging which sometimes gets overlooked which is that LFP has no self-limit when it comes to devouring current. it is easy to assume with lead acid that, for example with alternator charging, the internal regulator takes care of voltage and current but it generally only sets an upper limit for voltage and it is the lead acid that regulates how much current is taken. We inherited a dog a few years ago which would, if left to it's own devices, eat itself to death. This was a shock after years of looking after fussy-eating cats. It's the same with LFP except the dog wouldn't go into thermal runaway if left to its own devices and burn the house down. (Obviously the BMS is there to prevent this - one reason why I quake a little when people say they manage their LFP without a BMS.) People sometimes think that lowering the target voltage will take care of things but a LFP pack will eventually eat itself to death with any constant voltage over 13.65 volts.

So the extra thing to look out for beyond absorption voltage and float is length of absorption time. For some chargers this can, apparently, be up to four hours and if combined with an aggressive absorption voltage (e.g. 14.6 volts - still found on some chargers as an LFP setting) then this will overcharge the LFP even with a BMS with high voltage disconnect since they are often set too high. Your boat is unlikely to be destroyed but your expensive battery can permanently lose capacity. So personally I would either go with your original plan and accept the inefficiency of sending the power through the mains charger and then through the B2B or buy a new mains charger that is fully configurable for target voltage, 'float' and absorption time and charge the LFP directly. There is a very neat Victron that will do that. Other specific charging requirements for LFP include disabling temperature compensation, any equalisation feature and ensuring charging can't happen below zero degrees C.

It is worth digging further into the LFP charging issue and this from Rod Collins of Marine How To is memorable and hair-raising.

Autopsy of a Mastervolt MLi 24/160 LiFePO4 Battery by Compass Marine How To

 

[Poey50]

The battery recommendation is 14.4 and 13.2 float. So perhaps it wont charge fully from the mains charger but would get toped up by the b2b . I will put a relay into the circuit so I can turn the mains charger off . I am a bit worried about damaging the battery as they cost so much.

Martin

Yes, do worry! See my post above.

 

[martinriches]

I'm aware that others will be reading over our shoulders so I just want to emphasise one point made in passing by Richard10002. Most people get that it is important not to have too high a target voltage when charging LFP and that you shouldn't float them (any 'float' voltage below 13.5 volts is fortunately no float at all). But there is one major difference from lead acid charging which sometimes gets overlooked which is that LFP has no self-limit when it comes to devouring current. it is easy to assume with lead acid that, for example with alternator charging, the internal regulator takes care of voltage and current but it generally only sets an upper limit for voltage and it is the lead acid that regulates how much current is taken. We inherited a dog a few years ago which would, if left to it's own devices, eat itself to death. This was a shock after years of looking after fussy-eating cats. It's the same with LFP except the dog wouldn't go into thermal runaway if left to its own devices and burn the house down. (Obviously the BMS is there to prevent this - one reason why I quake a little when people say they manage their LFP without a BMS.) People sometimes think that lowering the target voltage will take care of things but a LFP pack will eventually eat itself to death with any constant voltage over 13.65 volts.

So the extra thing to look out for beyond absorption voltage and float is length of absorption time. For some chargers this can, apparently, be up to four hours and if combined with an aggressive absorption voltage (e.g. 14.6 volts - still found on some chargers as an LFP setting) then this will overcharge the LFP even with a BMS with high voltage disconnect since they are often set too high. Your boat is unlikely to be destroyed but your expensive battery can permanently lose capacity. So personally I would either go with your original plan and accept the inefficiency of sending the power through the mains charger and then through the B2B or buy a new mains charger that is fully configurable for target voltage, 'float' and absorption time and charge the LFP directly. There is a very neat Victron that will do that. Other specific charging requirements for LFP include disabling temperature compensation, any equalisation feature and ensuring charging can't happen below zero degrees C.

It is worth digging further into the LFP charging issue and this from Rod Collins of Marine How To is memorable and hair-raising.

Autopsy of a Mastervolt MLi 24/160 LiFePO4 Battery by Compass Marine How To

In that case I could fit a Sterling battery charging module to the mains charger output. That would enable the original charger to charge both battery types correctly. It seems a complicated issue.

Martin

 

[Poey50]

In that case I could fit a Sterling battery charging module to the mains charger output. That would enable the original charger to charge both battery types correctly. It seems a complicated issue.

Martin

That looks like a very expensive solution. I would have thought it gave much improvement over your original suggestion of charging indirectly via the engine battery and B2B. It has a high target voltage of 14.6 volts, a reasonably short absorption time (except at 14.6 volts I would want the charging to cease immediately) and an alarming float setting of 14.4 volts!

It all looks complicated because of the problem of chargers designed to smart charge lead acid having to adapt to LFP which actually has very different but in many way more straightforward charging needs.

 

[Travelling Westerly]

A LFP pack will eventually eat itself to death with any constant voltage over 13.65 volts.

So the extra thing to look out for is length of absorption time. For some chargers this can, apparently, be up to four hours and if combined with an aggressive absorption voltage e.g. 14.6 volts

Poey, I hope you don't mind but I've cut down some of your post as above so I can ask a couple of questions about what you have said

Sterling Lifepo4 AMPS range of batteries are quoting a different set of voltage specifications and I'd be interested in your take as they seem at odds to your recommendations.

They are saying that Absorption voltage is a max of 14.6v with a recommended 14.4v and a 'float' of 13.8v. They are supplied with a 5 year warranty so if floating at 13.8v (above your 13.65v advisory) then surely they will be getting some warranty claims coming through soon?

Also, if I've read it correctly, you are suggesting that an absorbsion time of more than 4 hours is an issue? Have I got that right? I ask as surely the absorbsion time is variable and maybe a lot longer depending on set up? IE I am currently charging my 240Ah pack via my Victron Phoenix at the 25Ah rate and not the 50 Ah rate. This is because it seems to tax the BMS balancing operation less at the moment (different story).
However the charger does not actually reach the full absorbsion voltage until nearing the tail current set up (6% from memory) at which time the charger switches into float stage. Is this what you're saying? That some chargers actually charge at say 14.4v or whatever for a long period? Unlike the Victron which starts at a lower voltage to begin with, ramping upto full absorbsion voltage set point just prior to entering float set point voltage?

Hope that makes some sense and thanks for your help.

 

[Poey50]

Poey, I hope you don't mind but I've cut down some of your post as above so I can ask a couple of questions about what you have said
Sterling Lifepo4 AMPS range of batteries are quoting a different set of voltage specifications and I'd be interested in your take as they seem at odds to your recommendations.
They are saying that Absorption voltage is a max of 14.6v with a recommended 14.4v and a 'float' of 13.8v. They are supplied with a 5 year warranty so if floating at 13.8v (above your 13.65v advisory) then surely they will be getting some warranty claims coming through soon?

Sterling is behind the curve on current thinking on suitable charging for LFP. All the major firms had high recommended voltages when LFP first came on the scene - most have lowered their recommended voltages. Sterling is now an outlier. If you read the Rod Collins article you will see that he has proved that LFP can be overcharged at constant charging voltage of 13.65 volts. I'm not sure there is anyone who knows more about LFP in marine installations than him because of his extensive testing.. Whether this will result in warranty claims depends on whether people become aware of their gradual loss of capacity if actually floated at 13.8 volts. The first thing I did when I bought my cells was to do an accurate capacity test - I'll repeat every two years to check. I doubt many people buying drop-ins do this. 14.6 volts might passably be OK but charging should stop immediately when this voltage is reached. If the cells are unbalanced then one cell could be well about 3.65 volts (the maximum individual recommended voltage) before 14.6 volts are reached - for example 3.2v + 3.2v + 3.1v + 5v = 14.5 volts. Cell four will be in trouble unless the BMS has isolated the pack because of high voltage disconnect but this is often set too high to avoid nuisance BMS triggering - but at the cost of accumulating damage.

Also, if I've read it correctly, you are suggesting that an absorbson time of more than 4 hours is an issue? Have I got that right? I ask as surely the absorbsion time is variable and maybe a lot longer depending on set up? IE I am currently charging my 240Ah pack via my Victron Phoenix at the 25Ah rate and not the 50 Ah rate. This is because it seems to tax the BMS balancing operation less at the moment (different story).

No, I'm saying that for LFP absorption time is a very important variable that people can sometimes overlook. A fixed absorption time of four hours is one of the worst examples especially if combined with a high target voltage of say, 14.6 volts. For my set-up I use 13.8 volts which allows me to have an absorption time of say 30 minutes which is then useful for balancing the cells - mine balance above 3.4 volts per cell.

I ask as surely the absorbsion time is variable and maybe a lot longer depending on set up? IE I am currently charging my 240Ah pack via my Victron Phoenix at the 25Ah rate and not the 50 Ah rate. This is because it seems to tax the BMS balancing operation less at the moment (different story).
However the charger does not actually reach the full absorbsion voltage until nearing the tail current set up (6% from memory) at which time the charger switches into float stage. Is this what you're saying? That some chargers actually charge at say 14.4v or whatever for a long period? Unlike the Victron which starts at a lower voltage to begin with, ramping upto full absorbsion voltage set point just prior to entering float set point voltage?

I'll have a go at the specifics of this later ... I have to catch up on Succession, first ...

 

[Pete7]

CW, I have chosen to lower the absorption voltage for my Sterling LFP down to 13.8 and float at (I think) 13.45 on the Victron MPPT with the offset at 0.1v. This is aimed at providing solar power for domestics during the day rather than taking power from the LFP. Only when the LFP drops below 13.45 v does the MPPT switch back to bulk and absorption. There is a fine balance to be taken here. You don't want to carry on charging whilst in float which can happen with 13.8v and you don't want to waste solar because the MPPT drops to a low float so power comes from the batteries.

That leads to the Daly BMS settings, which I have also adjusted as the original settings when supplied by Sterling needed adjustment, particularly the Balanced Open Start voltage to 3.3 and Balanced Open Difference voltage to 0.01v.

Andy on the Off Grid Garage on YT has done some sterling work investigating the Daly BMS and charging LFP which are worth following.

Pete

 

[Travelling Westerly]

CW, I have chosen to lower the absorption voltage for my Sterling LFP down to 13.8 and float at (I think) 13.45 on the Victron MPPT. This is aimed at providing solar power for domestics during the day rather than taking power from the LFP. Only when the LFP drops below 13.45 v does the MPPT switch back to bulk and absorption. There is a fine balance to be taken here. You don't want to carry on charging whilst in float which can happen with 13.8v and you don't want to waste solar because the MPPT drops to a low float so power comes from the batteries.

That leads to the Daly BMS settings, which I have also adjusted as the original settings when supplied by Sterling needed adjustment, particularly the Balanced Open Start voltage to 3.3 and Balanced Open Difference voltage to 0.01v.

Andy on the Off Grid Garage on YT has done some sterling work investigating the Daly BMS and charging LFP which are worth following.

Pete

It's good to see somebody else has the Sterling AMPS batteries

I originally had the bulk voltage setting at 14.4v but the Daly BMS kept tripping on cell over voltage set at 3.71v. I spoke at length with Sterling who suggested lowering the voltage to 14.2v but again runner cells kept tripping the BMS towards the end of the bulk charge phase. In the end I lowered the bulk charge to 14v which has at least stopped 1 pack from tripping early but the other pack is still tripping on a runner. I have also set the 'float' at 13.5v.

I did notice that if I reduced the cell over volt setting to 3.65v (general recommended level) then the BMS app stopped registering any charge current at all! Very strange but I guess it's only an app and does not affect the battery performance. I put a clamp meter on both packs positives and got 12.5A so I know the charger is suppling 25A despite the Daly app suggesting not!

When I discussed these settings with Sterling, he said the runners should get better the more time goes on but the 14v bulk setting was not enough to fully charge the batteries.
We adjusted the balance settings like you on the BMS which means the balancing is happening whenever the batteries are being charged. That may help but I'm not really sure yet as 1 pack still hits a cell voltage of 3.71v towards 14v peak bulk phase.

Ive found DIY Solar forum has some very helpful and very knowledgeable guys on there with up to date experience. I've read the marine site that Poey has told me about but DIY solar forums just feel a bit more current. I may be wrong there but at least you can talk to somebody on there.

 

[Pete7]

I think one of the problems with the Daly BMS is that it only balances at 30MA or 0.030A which isn't very much when 20+ A are pouring into a battery, hence lowering the start point for balancing. I have also noticed that charging the LFP in December with low Ah as the solar isn't great at this time of year helps keep them closer in balance. I really need to spend a day slowly tickling them up to full charge, stopping as soon as one cell runs away then with a quick discharge take them down a bit and then carry on. However, during the summer I tended to stop charging once the cells got to 3.5v. Whilst they can go to 3.65v the amount of difference is a tiny part of the charge curve. In addition if you want a long life from the battery, everyone seems to say avoid that final charge frequently.

What is really nice about LFP though is the ability to charge with everything you have and discharge at rates lead acid just couldn't support. For our summer cruise we never used the kettle on the stove, but a mains voltage kettle off the inverter. This saved quite a bit of gas, useful given the Calor gas fiasco. We intend to make more use of the induction stove next year.

 

[Poey50]

It's good to see somebody else has the Sterling AMPS batteries

I originally had the bulk voltage setting at 14.4v but the Daly BMS kept tripping on cell over voltage set at 3.71v. I spoke at length with Sterling who suggested lowering the voltage to 14.2v but again runner cells kept tripping the BMS towards the end of the bulk charge phase. In the end I lowered the bulk charge to 14v which has at least stopped 1 pack from tripping early but the other pack is still tripping on a runner. I have also set the 'float' at 13.5v.

I did notice that if I reduced the cell over volt setting to 3.65v (general recommended level) then the BMS app stopped registering any charge current at all! Very strange but I guess it's only an app and does not affect the battery performance. I put a clamp meter on both packs positives and got 12.5A so I know the charger is suppling 25A despite the Daly app suggesting not!

When I discussed these settings with Sterling, he said the runners should get better the more time goes on but the 14v bulk setting was not enough to fully charge the batteries.
We adjusted the balance settings like you on the BMS which means the balancing is happening whenever the batteries are being charged. That may help but I'm not really sure yet as 1 pack still hits a cell voltage of 3.71v towards 14v peak bulk phase.

Ive found DIY Solar forum has some very helpful and very knowledgeable guys on there with up to date experience. I've read the marine site that Poey has told me about but DIY solar forums just feel a bit more current. I may be wrong there but at least you can talk to somebody on there.

I was about to write that I can't see any figure for the balance capacity of the BMS which I take to be a sign that this is very limited and I then saw that Pete7 had made the same point. But just to be sure - I'm assuming that the Daly BMS is the internal BMS for these Sterling LFP packs? Sterling themselves make no mention of this.

I think that there are three parts to your charging problem. 1. The cells have got out of balance. 2. The balance capacity is limited. 3. The target voltage is too high so the charging is going too fast and overwhelming the small balancing capacity and triggering either high voltage disconnect or disconnect on too large voltage differences between cells (delta voltage). Rinse and repeat getting worse with each cycle.

The advice that 14 volts is too low to charge LFP would only make sense if the balance threshold voltage can't be reached soon enough since, as you have read, any constant voltage over 13.65 volts can with time charge to full and beyond. Balancing whenever there is charge may not be the greatest solution as balance at mid-range of charging can actually be a cause of greater imbalance at the top of the curve a point made in one of the Off-Grid Garage Youtube series.

I would endorse Pete7s solution - slow charging (I suggest 13.8 volts target voltage and 3.3 volts threshold balance voltage) to start with so that the limited balancing has a chance to do its work before things move too fast. At the moment, balancing is like trying to board a train that is moving too fast. Lower voltage is slower charging so gives longer in the balance zone before the highest cell trips out. Once properly in balance you could increase to 14 volts and see how that goes. But you may have to slow charge then discharge and repeat on several occasions. I have to do this with my 123Smart BMS after 5 months of haul out. Mine has 1amp of passive balancing capacity and I had to do it three times until proper balance was achieved. My balancing capacity is quite modest - yours is by the look of it, if Pete7's figure is accurate is x33 smaller!

I have to say though that the Sterling voltages for float looks nuts. No one else in the world thinks that float for LFP should be a thing. It should never sit around at full charge anyway. But 13.8 volts is not float it is an extended absorption period and if anyone actually floated at that figure they would be ruining their battery progressively with frequent battery black-outs as the high voltage disconnect was triggered. My cells are about 18 months old and have been at full charge for maybe 15 minutes during that time. If they are every charged to full I begin drawing loads straight away.

Finally, I agree that the DIY Solar Forum i,s excellent and particularly good for these kind of issues. It isn't, as you know, a marine-specific forum but for general issues and knowledge of current prices it is top.

 

[Skylark]

I'm aware that others will be reading over our shoulders……..

Very true and a fascinating and insightful thread it is, too.

Hence may I jump in with a quick yes/no question. My house bank is 4x 110 Ahr and I plan to replace it prior to next season launch. I’ve often read within the forum that lithium batteries are not ideal/ready for the”average” sailor with a 6 month season, never usually far away from shore power.

Is this still the case?

 

[Travelling Westerly]

Pete, Poey

Thanks for the responses.

I think you have nailed it on the head re the 3 issues and I was thinking around those lines too, 30ma balance, bulk voltage too high and 2nd battery has only had 2 cycles so far.
I didn't realise having the balance set up to work whenever they were accepting a charge was a bad thing? I and Sterling, as they advised setting it up this way, thought allowing the very small balancer to work early on in the charge process would allow the 4 cells to equalise over a longer period. I still see that setup working in my mind as we only have 30ma to play with. Can you explain that bit again to me Poey, how does having it balance at the end stages of the charge profile mean its better than having them balance from the beginning - appreciate that if you can thanks.

I think I'm going to lower the all of my Victron chargers to bulk 13.8v and floats to 13.5v, as you both suggest. I assume these set points should be used on all 3 chargers, do you agree? I can't see any reason why not but worth getting some other thoughts. The 3 chargers are all fully customised, Victron units, Phoenix smart 50A 3 way, 100/20 MPPT & 30A B2B. The BMV 712 smart is networking to them providing a voltage reading from the lifepo4 terminals which takes into account any voltage drops in the wiring from the charge sources.
Looking at some voltage V SOC charts from Will Prouse, 13.8v is around 99.5%, 3.45v per cell (for a 12v set up).
I'm using a 6% tail current set point, do you agree with that for 240Ah pack? That was not a finger in the air, it was suggested on the DIY solar forum. Seems a common question asked on there too.

Interesting subject these Lifepo4 batteries, it's changed my liveaboard experience for the better. I'm using an induction hob for cooking etc (another 120ah pack to be ordered as I feel 240a is to small)

 

[Poey50]

Very true and a fascinating and insightful thread it is, too.

Hence may I jump in with a quick yes/no question. My house bank is 4x 110 Ahr and I plan to replace it prior to next season launch. I’ve often read within the forum that lithium batteries are not ideal/ready for the”average” sailor with a 6 month season, never usually far away from shore power.

Is this still the case?

I think it is partly that LFP is not yet ready for the average sailor and partly that that the average sailor is not yet ready for LFP. There is a lot to unlearn about lead acid to return oneself to a state of ignorance to then have a blank sheet for learning about the needs of this new and alien chemistry. As I've said repeatedly on this and other forums, converting to LFP using drop-ins looks like the easiest way to do it but is the least satisfactory. DIY installations from bare cells is, I think, the best and most cost-effective step but it is not for everyone.

In your shoes I'd replace like for like.

 

[Poey50]

I didn't realise having the balance set up to work whenever they were accepting a charge was a bad thing? I and Sterling, as they advised setting it up this way, thought allowing the very small balancer to work early on in the charge process would allow the 4 cells to equalise over a longer period. I still see that setup working in my mind as we only have 30ma to play with. Can you explain that bit again to me Poey, how does having it balance at the end stages of the charge profile mean its better than having them balance from the beginning - appreciate that if you can thanks.

It sounds logical to have the balancer on all the time but if this was generally useful then there would be no reason for any BMS to only balance above a particular threshold. Assuming a pack of four 3.2 volt cells to make a nominal 12 volt battery, each cell is autonomous and, because of small differences in resistance will have an independent charging profile. This is less the case for high quality cells with closely matched resistance and capacity (like Winston Thundersky) and more the case for most other cells including mine. If you balance cells when nearly empty (bottom balance) then they will be way out of balance at the top of the charging curve (top balance). This was particularly brought home to me by an Off-Grid Garage video when Andy tried out one of the new Heltec active balancers. This balances continuously and he was thrilled to find all his cells closely in balance. However once he charged to full everything was out of sorts - balanced cells at partial charge does not equal top balancing. My recommendation of 3.3 volts was based on Pete's use of that value and because it seemed sensible but you can play around with it.

I think I'm going to lower the all of my Victron chargers to bulk 13.8v and floats to 13.5v, as you both suggest. I assume these set points should be used on all 3 chargers, do you agree? I can't see any reason why not but worth getting some other thoughts. The 3 chargers are all fully customised, Victron units, Phoenix smart 50A 3 way, 100/20 MPPT & 30A B2B. The BMV 712 smart is networking to them providing a voltage reading from the lifepo4 terminals which takes into account any voltage drops in the wiring from the charge sources.
Looking at some voltage V SOC charts from Will Prouse, 13.8v is around 99.5%, 3.45v per cell (for a 12v set up).

What you are needing to do with charging is to slow down the power going into the cells to give the balancer a chance. Power (watts) = volts x amps. In situations of high amps - like the mains charger or the B2B you should turn down the volts to 13.8 or even a touch lower, at least until the cells are better balanced. But where the amps are low - as in most solar set-ups you may be able to go higher - say 14.0 volts and still slow down the power. You can experiment with these figures and write down the results - let your system teach you the best way to manage it. Check with other users and be rather cautious about the Sterling advice.

I'm using a 6% tail current set point, do you agree with that for 240Ah pack? That was not a finger in the air, it was suggested on the DIY solar forum. Seems a common question asked on there too.

I do have a BMV712 in my system but I don't recall what I used as a tail current. I don't tend to use it. I have a state of charge read-out on my 123 Smart which resets to 100% SOC when all cells are above 3.4 volts. I then resynchronise my BMV712 to 100%