Lithium LifePO4 charging regime, I’m confused!

[glascoed]

This site has a wealth of info on Lithium leisure batteries and their care. I’ve trawled through a lot of it over the last week or so. There are evidently many very well-informed people posting with an obvious in-depth expert knowledge on the subject that I respect.

There seems to be a consensus among them that the charging regime needs to be at or below 14.2volts with many warnings that charging at a higher voltage would lead to damage to the battery.

I’ve installing some at the moment. The Sterling (a well known supplier of electronics that has stands at all MH national shows) tells me that I should charge at 14.6v quoting a range of 14.4v to 14.8v (max). They have personally emailed me to confirm that and the manufacturer (AMPS) also gives those figures in their accompanying literature and warranty.

Fogstar on their site also recommends charging at 14.6v and a float of 13.6v. Both of these supplies give 5year warranties (provided correct charging voltages being adhered to)

See my confusion? Don’t want to void my warranty OR damage my batteries by over charging. I will use a Victron IP22 and set parameters by Bluetooth.

Your thoughts would be greatly appreciated.

 

[headlight]

This site has a wealth of info on Lithium leisure batteries and their care. I’ve trawled through a lot of it over the last week or so. There are evidently many very well-informed people posting with an obvious in-depth expert knowledge on the subject that I respect.

There seems to be a consensus among them that the charging regime needs to be at or below 14.2volts with many warnings that charging at a higher voltage would lead to damage to the battery.

I’ve installing some at the moment. The Sterling (a well known supplier of electronics that has stands at all MH national shows) tells me that I should charge at 14.6v quoting a range of 14.4v to 14.8v (max). They have personally emailed me to confirm that and the manufacturer (AMPS) also gives those figures in their accompanying literature and warranty.

Fogstar on their site also recommends charging at 14.6v and a float of 13.6v. Both of these supplies give 5year warranties (provided correct charging voltages being adhered to)

See my confusion? Don’t want to void my warranty OR damage my batteries by over charging. I will use a Victron IP22 and set parameters by Bluetooth.

Your thoughts would be greatly appreciated.

Actually Fogstar recommend 14.4v charge and 13.6v float unless your charge sources are Victron in which case they recommend 14.2v charge and 13.5v float.
I am running a 230AH Fogstar Drift, Victron MPPT solar controller and Sterling 60amp B2B and that is what Fogstar told me and is shown in their literature.

 

[LithiumConvert]

The one thing which is most important is to disconnect any split charge relay and fit a B2B. To protect the alternator, not the batteries.

Other wise, I stick to the recommendations that came with my Sterling Power (AMPS) batteries.

 

[bigtwin]

To protect the alternator, not the batteries.

Is that to protect it from overheating?

Ian

 

[poppycamper]

KS Energy charge voltage 14.4v float 13.2v to 13.3v

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[Raul]

This site has a wealth of info on Lithium leisure batteries and their care. I’ve trawled through a lot of it over the last week or so. There are evidently many very well-informed people posting with an obvious in-depth expert knowledge on the subject that I respect.

There seems to be a consensus among them that the charging regime needs to be at or below 14.2volts with many warnings that charging at a higher voltage would lead to damage to the battery.

I’ve installing some at the moment. The Sterling (a well known supplier of electronics that has stands at all MH national shows) tells me that I should charge at 14.6v quoting a range of 14.4v to 14.8v (max). They have personally emailed me to confirm that and the manufacturer (AMPS) also gives those figures in their accompanying literature and warranty.

Fogstar on their site also recommends charging at 14.6v and a float of 13.6v. Both of these supplies give 5year warranties (provided correct charging voltages being adhered to)

See my confusion? Don’t want to void my warranty OR damage my batteries by over charging. I will use a Victron IP22 and set parameters by Bluetooth.

Your thoughts would be greatly appreciated.

If the road speed is 70mh, do you have to do 70? Can you not do 60-65 and save some fuel and consumables? The lifepo4 can fully charge at 13.8v any higher it’s the comfort of fast charging. Anything above 14.4v will leave no room for errors or imbalance.
Sterling don’t build batteries, and their equipment is not immune to failures, I have sour experience with sterling, never touch it again.
Victron it’s been in business for decades, and they had lifepo4 in the market for over 20 years, way before we seen any in UK. They learned along the way from their failures and adjusted to reality. What Victron recommends is to protect their reputation and warranty claims, the values given by Victron for charging Lifepo4 are better than any lifepo4 resellers, no doubt.

 

[RogerIvy]

Victron have settled on a LiFePO4 voltage of 14.2, based on a max cell voltage of 3.55
We go with that recommendation as a good balance between getting as much out of your battery as possible and having it last a reasonable length of time.
If we test capacity we go to 3.65v per cell (14.6v for the pack) but only do that once or twice.
Some BMSs default to 3.75v for the highest cell which (IMO) is silly. For the tiny bit of extra capacity you greatly reduce lifespan of the cells.

As Raul says, you don’t need 100% of the capacity. 95 or 90 should do fine.

It’s also good practise, if you can, to set all your chargers to the same voltage as your battery. The BMS then becomes the last line of defence instead of the only line of defence (to protect the cells).

 

[bigtwin]

The BMS then becomes the last line of defence instead of the only line of defence (to protect the cells).

Are you aware of any BMS’ that provide two levels of cutoff protection? For example, an initial level of cutoff at your suggested 3.55V/cell and a second line of protection at, say, 3.75V in the event that the initial 3.55V cutoff were to fail.

Ian

 

[RogerIvy]

Are you aware of any BMS’ that provide two levels of cutoff protection? For example, an initial level of cutoff at your suggested 3.55V/cell and a second line of protection at, say, 3.75V in the event that the initial 3.55V cutoff were to fail.

Ian

No, don’t know of any that do that.
I’ve never heard of a JK or JBD BMS failing to cut off, but we suspect Daly do have some failures.

 

[Ian_H]

Victron have settled on a LiFePO4 voltage of 14.2, based on a max cell voltage of 3.55
We go with that recommendation as a good balance between getting as much out of your battery as possible and having it last a reasonable length of time.
If we test capacity we go to 3.65v per cell (14.6v for the pack) but only do that once or twice.
Some BMSs default to 3.75v for the highest cell which (IMO) is silly. For the tiny bit of extra capacity you greatly reduce lifespan of the cells.

As Raul says, you don’t need 100% of the capacity. 95 or 90 should do fine.

It’s also good practise, if you can, to set all your chargers to the same voltage as your battery. The BMS then becomes the last line of defence instead of the only line of defence (to protect the cells).

I have recently had installed a 230Ah fogstar with victron solar and mains chargers. On Fogstars advice I upped the mains charger bulk voltage to 14.3V because at 14.2V the bms would not go to 100% charge, which I believe it needs to when calculating/adjusting capacity. I saw exactly the same thing with the solar controller. Ben at Fogstar had replicated this himself with a victron on the bench. With our original Schaudt B2B the lithium setting delivers 14.4V with no reduction for absorption. I challenged Schaudt (Lippert) tech dept and their answer was the "bms regulates the power"! They did add that I could use the lead setting, which at least drops from 14.4V to 13.8V. This I have done. I have also fitted a switch in the D+ to the B2B, and may use this on longer drives if the battery is already fullish. I am also considering dropping the victron settings, and using the B2B to reset the SOC at the start of each holiday. What is the required voltage/time for cell balancing to occur, as I guess this is another consideration?

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[headlight]

I have recently had installed a 230Ah fogstar with victron solar and mains chargers. On Fogstars advice I upped the mains charger bulk voltage to 14.3V because at 14.2V the bms would not go to 100% charge, which I believe it needs to when calculating/adjusting capacity. I saw exactly the same thing with the solar controller. Ben at Fogstar had replicated this himself with a victron on the bench. With our original Schaudt B2B the lithium setting delivers 14.4V with no reduction for absorption. I challenged Schaudt (Lippert) tech dept and their answer was the "bms regulates the power"! They did add that I could use the lead setting, which at least drops from 14.4V to 13.8V. This I have done. I have also fitted a switch in the D+ to the B2B, and may use this on longer drives if the battery is already fullish. I am also considering dropping the victron settings, and using the B2B to reset the SOC at the start of each holiday. What is the required voltage/time for cell balancing to occur, as I guess this is another consideration?

That's interesting as I've recently fitted Fogstar lithium and Fogstar told me (and it's in their literature) to set my Victron MPPT to 14.2v charge and 13.5v float and my Sterling B2B to 14.4v charge and 13.6v float.

 

[Ian_H]

That's interesting as I've recently fitted Fogstar lithium and Fogstar told me (and it's in their literature) to set my Victron MPPT to 14.2v charge and 13.5v float and my Sterling B2B to 14.4v charge and 13.6v float.

Did they say why the Victron and Sterling settings should be different?

 

[headlight]

Did they say why the Victron and Sterling settings should be different?

Yes they said it's because Victron kit charges slightly differently due to its charging profile.
Any Victron kit, MPPT/B2B/chargers, should be set at 14.2v charge and 13.5v float and non Victron kit they recommend 14.4v charge and 13.6v float.
I've been told this by both Ben and Becs at Fogstar and if you read through their website and literature you'll find it in there.
I've also been told the same by Vanbitz.

 

[Ian_H]

Yes they said it's because Victron kit charges slightly differently due to its charging profile.
Any Victron kit, MPPT/B2B/chargers, should be set at 14.2v charge and 13.5v float and non Victron kit they recommend 14.4v charge and 13.6v float.
I've been told this by both Ben and Becs at Fogstar and if you read through their website and literature you'll find it in there.
I've also been told the same by Vanbitz.

That's where I started, but the SOC got to 98% and stuck there. Successive discharge/recharges saw the max %SOC achieved reduce a couple of percent each time. Then Ben talked me through changing the bulk victron setting to 14.3V, the SOC immediately jumped to 100% and the max Ah also reset. My 230Ah underseat battery is now a 238.7Ah....

 

[Lenny HB]

. I challenged Schaudt (Lippert) tech dept and their answer was the "bms regulates the power"!

I read up up on the Schaudt B2B some time ago and was not impressed, I think when my new van comes it will have one, it will be getting swapped out.

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[headlight]

I have a normal 230AH Drift battery.
My SOC gets to 100% and 230AH whether the battery is being charged at 14.2v by my Victron MPPT or 14.4v by my Sterling B2B or 14.4v from the mains charger.

 

[Ian_H]

I read up up on the Schaudt B2B some time ago and was not impressed, I think when my new van comes it will have one, it will be getting swapped out.

Yep, I'll see how it goes. I think I'll end up having the Schaudt turned off while at/around home. We also shouldn't need it for weekends away, so it will probably just get used on longer holidays if required.
Back to OPs point, I've often seen quoted that lithium should only be charged to 80-90% for max life, (and only run down to 20%). What set voltage would this be, and does anyone actually do this? I think my view is to just follow battery suppliers advice, the battery should last long enough anyway.

 

[Lenny HB]

Yep, I'll see how it goes. I think I'll end up having the Schaudt turned off while at/around home. We also shouldn't need it for weekends away, so it will probably just get used on longer holidays if required.
Back to OPs point, I've often seen quoted that lithium should only be charged to 80-90% for max life, (and only run down to 20%). What set voltage would this be, and does anyone actually do this? I think my view is to just follow battery suppliers advice, the battery should last long enough anyway.

Not very accurate to do it by voltage as the discharge curve is so flat best to use a shunt or the battery's BMS.
For maximum life charge to 90% and discharge 20% but 10% is OK if you don't do it every day.
In use charging to 100% is not really a problem as they will be cycling in use but when not in use turn off the charging and discharge to between 50 to 80%.
When not in use if you have a battery maintainer topping up the starter battery from the lithium check it at least once a month to see if it needs a top up charge.

 

[headlight]

Ian_H what I'm doing is on my last night of a trip I turn charge off in the app ( I leave discharge on).
That means that whatever I use on my last night is not replaced so when I park the van up in between use the battery is not at 100% (80% last time).
It also means that my solar isn't continually topping the battery up whilst it's not being used.
Then when I next use the van I turn charge back on so my B2B charges the battery and I arrive on a site, pub stop or whatever, fully charged.

 

[G1969]

Well all that has confused me now? I thought that once installed and set up correctly, I just leave them to do their thing ( solar top them up/ they maintain vehicle battery (via battery master) and then when I drive off the b2b does its stuff) or have I totally misunderstood??

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[bigtwin]

Well all that has confused me now? I thought that once installed and set up correctly, I just leave them to do their thing ( solar top them up/ they maintain vehicle battery (via battery master) and then when I drive off the b2b does its stuff) or have I totally misunderstood??

Once it’s all set up correctly, the only thing that you really have to be mindful of is that at the end of a trip you don’t want to leave them at 100% SoC.

Either you can switch off the charge source (via the App for your BMS) on your last night and just check the SoC before you park up at home. Folks suggest that anything below an 80% SoC is fine.

Ian

 

[Raul]

Well all that has confused me now? I thought that once installed and set up correctly, I just leave them to do their thing ( solar top them up/ they maintain vehicle battery (via battery master) and then when I drive off the b2b does its stuff) or have I totally misunderstood??

What bit got you confused? What you describe above its a lead acid mind set.
headlight mentioned to discharge the battery a bit if you set it to stand for some time, its a good practice to store at less than fully charged.

 

[Ian_H]

Not very accurate to do it by voltage as the discharge curve is so flat best to use a shunt or the battery's BMS.
For maximum life charge to 90% and discharge 20% but 10% is OK if you don't do it every day.
In use charging to 100% is not really a problem as they will be cycling in use but when not in use turn off the charging and discharge to between 50 to 80%.
When not in use if you have a battery maintainer topping up the starter battery from the lithium check it at least once a month to see if it needs a top up charge.

Hi Lenny
Do you mean to watch the charging and turn it off when 90% reached, cos that doesn't sound very practical.
Another conundrum.....I don't have a shunt so relying on the bms is a problem as it won't detect the drain from the Ablemail maintainer I've just fitted etc, so I'd need to charge the battery to 100% to get a reliable SOC!
Another potential hiccup: as mentioned before I set the Schaudt B2B to lead so that it switched down to 13.8V. This switch happens when the B2B current drops below 2A, and switches back up if the current rises above 2.5A. So if the compressor fridge is on or comes on, the B2B will put 14.4V back on the Fogstar. Do all B2Bs use current in this way?

Ian_H what I'm doing is on my last night of a trip I turn charge off in the app ( I leave discharge on).
That means that whatever I use on my last night is not replaced so when I park the van up in between use the battery is not at 100% (80% last time).
It also means that my solar isn't continually topping the battery up whilst it's not being used.
Then when I next use the van I turn charge back on so my B2B charges the battery and I arrive on a site, pub stop or whatever, fully charged.

That's sounds a good plan. But can you check something for me? With charge switched off in the app, turn on something to pull 3-4A (for me, the fridge). When I do this, charge switches itself on! When I turn the fridge off, charge in the app also turns off.....

 

[G1969]

What bit got you confused? What you describe above its a lead acid mind set.
headlight mentioned to discharge the battery a bit if you set it to stand for some time, its a good practice to store at less than fully charged.

Ah , I see, so in my case once I arrive back home, switch off the solar for a while, as they will then start to discharge due to the tracker/alarm drain. Simple I understand now. I think I would prefer to do that rather than mess with battery apps etc

 

[headlight]

Well all that has confused me now? I thought that once installed and set up correctly, I just leave them to do their thing ( solar top them up/ they maintain vehicle battery (via battery master) and then when I drive off the b2b does its stuff) or have I totally misunderstood??

My van gets used at least once a month in winter, more in summer.
If I was storing it for several months, like some do over winter, I would discharge the battery to around 50% SOC, turn off charge in the app but leave discharge on as I have a battery master to maintain my starter battery.
I check the van at least once a week when I'm not using it and the battery master uses very little.

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[headlight]

That's sounds a good plan. But can you check something for me? With charge switched off in the app, turn on something to pull 3-4A (for me, the fridge). When I do this, charge switches itself on! When I turn the fridge off, charge in the app also turns off.....

My 105AH Fogstars did that but my 230AH Fogstar doesn't appear to.
And I use a shunt to determine SOC, remaining amps etc as it is far more accurate.

 

[PhilandMena]

This site has a wealth of info on Lithium leisure batteries and their care. I’ve trawled through a lot of it over the last week or so. There are evidently many very well-informed people posting with an obvious in-depth expert knowledge on the subject that I respect.

There seems to be a consensus among them that the charging regime needs to be at or below 14.2volts with many warnings that charging at a higher voltage would lead to damage to the battery.

I’ve installing some at the moment. The Sterling (a well known supplier of electronics that has stands at all MH national shows) tells me that I should charge at 14.6v quoting a range of 14.4v to 14.8v (max). They have personally emailed me to confirm that and the manufacturer (AMPS) also gives those figures in their accompanying literature and warranty.

Fogstar on their site also recommends charging at 14.6v and a float of 13.6v. Both of these supplies give 5year warranties (provided correct charging voltages being adhered to)

See my confusion? Don’t want to void my warranty OR damage my batteries by over charging. I will use a Victron IP22 and set parameters by Bluetooth.

Your thoughts would be greatly appreciated.

I have little to no Knowledge on Lithium battery charging. However, I have been an active member of Fun for many, many years and I am of the opinion that there is not a wealth of expert in-depth knowledge on this subject amongst members on this forum. There will be, in my opinion, a handfull of members who are knowledgeable, know there stuff and can be relied upon to give sound advice. i.e. autorouter. Others will be guessing or basing their opinion on there own experiance and there own set up. I have seen this time and time again on varios threads where members post differeing opinions on the same question. I beleive its all with good intent and blame the amount of miss-information and contradiction out there.
I would recommend you follow the advice of the battery manufacturer, in this case Frogstar. They have designed and built the battery and will know how best to maintain it. To ignore there advice would be foolish. As an example and for what its worth I have seen generlisation statements from a major battery supplier on how to maintain AGM batteries which differs from the recommendation from one particular battery manufacturer on how there AGM battery should be maintained.

 

[Lenny HB]

Hi Lenny
Do you mean to watch the charging and turn it off when 90% reached, cos that doesn't sound very practical.
Another conundrum.....I don't have a shunt so relying on the bms is a problem as it won't detect the drain from the Ablemail maintainer I've just fitted etc, so I'd need to charge the battery to 100% to get a reliable SOC!

As I said OK in use to charge to 100% and when you get home if it's fully charged just discharge it a bit.
Well worth fitting a shunt as it is the only way to correctly measure state of charge.

Another potential hiccup: as mentioned before I set the Schaudt B2B to lead so that it switched down to 13.8V. This switch happens when the B2B current drops below 2A, and switches back up if the current rises above 2.5A. So if the compressor fridge is on or comes on, the B2B will put 14.4V back on the Fogstar. Do all B2Bs use current in this way?

Sounds like it's wired for voltage sensing you need to connect a D+ feed to the trigger input then it will only turn on when the engine is running.

 

[Ian_H]

As I said OK in use to charge to 100% and when you get home if it's fully charged just discharge it a bit.
Well worth fitting a shunt as it is the only way to correctly measure state of charge.

Sounds like it's wired for voltage sensing you need to connect a D+ feed to the trigger input then it will only turn on when the engine is running.

Hi Lenny

I don't think you can wire these b2bs without a D+. I've put a switch in mine so I can turn it off if I want to. The trickle charging switchover is described above. I have no idea what the efficiency >=4% refers to!

 

[Whitebirdyman]

That's where I started, but the SOC got to 98% and stuck there. Successive discharge/recharges saw the max %SOC achieved reduce a couple of percent each time. Then Ben talked me through changing the bulk victron setting to 14.3V, the SOC immediately jumped to 100% and the max Ah also reset. My 230Ah underseat battery is now a 238.7Ah....

I have had the same problem with the quoted capacity keep dropping. This is with Vanbitz installed battery, solar and B2B - I am still discussing it with them.

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