LiFePO4 upgrade but keep 2000w Xantrex?

[TR4]

Originally Posted by corvetteSS

Internet wives tales? Really? I like Progressive Dynamics Charging systems. hmm... go read their info. They recommend changing to a lithium charger and do not recommend that you use their AGM rated chargers for lithium. That's why they make the lithium chargers. Now I am sure that an AGM charger will charge a Lithium battery to some extent. However, talk to me in 10 years if your very expensive lithium battery is still happy after you went on the cheap and didn't change your charger to match it. I am sure that if you tried hard enough that you could charge your battery by rubbing two sticks together, and clicked your heals together 3 times, but after spending big bucks on a battery that is to last 10 years, I would not want to risk charging it for its lifetime with a charger not designed specifically for that battery model. Bottom line is if your AGM charger states that it supports lithium in it's specs, great, then use it. If it does not, then get something that does. No wives tale here.

Sorry, I have to agree with Paul. I’m using a a twenty year old Trace inverter/charger to charge my my 560 amp hr batteries. They only get charged to a little more than 90%, but that’s where I’d want them anyway.

I’m also using an old Morningstar SCC for charging which doesn’t have a lithium profile. I basically set it up as a “switch” in the special settings.

I don’t use the alternator for charging, the solar has taken care of this.

I wouldn’t have moved from golf cart batteries to lithium if all new equipment was needed.

Bill

[paul65k]

Originally Posted by corvetteSS

Internet wives tales? Really? I like Progressive Dynamics Charging systems. hmm... go read their info. They recommend changing to a lithium charger and do not recommend that you use their AGM rated chargers for lithium. That's why they make the lithium chargers. Now I am sure that an AGM charger will charge a Lithium battery to some extent. However, talk to me in 10 years if your very expensive lithium battery is still happy after you went on the cheap and didn't change your charger to match it. I am sure that if you tried hard enough that you could charge your battery by rubbing two sticks together, and clicked your heals together 3 times, but after spending big bucks on a battery that is to last 10 years, I would not want to risk charging it for its lifetime with a charger not designed specifically for that battery model. Bottom line is if your AGM charger states that it supports lithium in it's specs, great, then use it. If it does not, then get something that does. No wives tale here.

If you say so

[757driver]

I would also have to agree with paul65k. I have yet to see a charger with a “lithium setting” that I would use on my lithium bank. Not one!

Magnum’s lithium setting is Absorb 14.4v and Float 13.6v. This tells me once the battery is fully charged it will be held at full charge by the high float voltage. I have the newer Magnum RC remotes that have a lithium setting and I do not use it. I prefer a final charge setting of “Silent”. If and when my battery bank hits a user settable low voltage the charger wakes up and charges back to a user settable Absorb voltage, and then it stops charging and does not hold the bank at 100% SOC. I am not stuck with a charger manufactures arbitrary value of 14.4v or 14.6v.

In reading up on the PD lithium chargers I also would not use this charger. It charges to Absorb of 14.6v and then at a preset tailing charge current it switches to a Float voltage of 13.6v. What the tail current is seems to be a secret. But once again once the battery is fully charged it is held there at 100% SOC with a float of 13.6v. I have yet to come across any credible information on why it is necessary or good for a lithium battery to be floated at such a high voltage. An argument could be made for a float voltage in the low 13.x range but that is a separate discussion.

Any charger that can charge to 14.xx volts (user settable) and then either stop charging or have a user settable Absorb time limit and user settable float voltage is far superior to any so called “lithium chargers” that I have seem.

[hclarkx]

Originally Posted by paul65k

For instance, a Magnum MS2812 with an RC50 controller can and does charge lithium batteries but it uses the AGM profile and relies on the BMS to do some work.....simply upgrade the controller to the ARC50 and you can tailor the charge profile to charge your batteries perfectly for around $225!

The problem here is that the vast majority of BMS and probably all that we as RV'ers would ever have are no help in this situation. The BMS is an on/off device that cuts charging only when significant damage is in the offing. For instance, a BMS will open the charging circuit at around 15 volts, but will let the absorb stage continue at 14.X volts as long as it will.

[hclarkx]

Originally Posted by woodflycamp

I have a Xantrex Freedom SW3000 set to AGM where the Bulk/Absorption ramps up to 14.3V. I set the charger in Xantrex unit to 2 stage, where the charger finishes the absorption charge but does not go into float. Also the AGM setting will not go into Equalize.

These setting have been working great.

I have 6 Lion Energy Lithium batteries (630AH) in this 12v system when using the Xantrex charger will bring these up to 95-98% and then let my solar top everything off.

Yes, this will work great. But, it will take life out of the LiFePO4 battery. LiFePO4 is fine without floating but it's that Absorb stage that is the issue. If it holds the LiFePO4 at 14.3V for some hours, that's better than 14.4V but it is not good for the battery. The problem is that you won't know for maybe 10 years that you've taken life out. Though maybe losing a year or two of life at 10 years isn't worth spending $$ on a LiFePO4 charger.

[hclarkx]

Originally Posted by TR4

Sorry, I have to agree with Paul. I’m using a a twenty year old Trace inverter/charger to charge my my 560 amp hr batteries. They only get charged to a little more than 90%, but that’s where I’d want them anyway.

I’m also using an old Morningstar SCC for charging which doesn’t have a lithium profile. I basically set it up as a “switch” in the special settings.

I don’t use the alternator for charging, the solar has taken care of this.

I wouldn’t have moved from golf cart batteries to lithium if all new equipment was needed.

Bill

I trust that you know what you are doing, but to be sure ...........

Charging to 90% is a two-edged sword. It can be done by stopping the charge at an indicated 90% SOC reading, but the SOC monitor needs to be recalibrated often with a full charge to around 14.4V to read correctly. Also, cutting the charge at 90% (even if the SOC has been calibrated and is reading correctly) will typically halt charging before balancing has occurred. Losing balance in a LiFePO4 battery is a whole bucket of worms that would not be good.

[hclarkx]

Originally Posted by 757driver

Any charger that can charge to 14.xx volts (user settable) and then either stop charging or have a user settable Absorb time limit and user settable float voltage is far superior to any so called “lithium chargers” that I have seem.

Agree! There may be appropriate LiFePO4 chargers out there, but the only really good one that I've found is a solar controller with a "user" option. In the one I use every parameter is user set in "user" mode.

[paul65k]

Originally Posted by hclarkx

The problem here is that the vast majority of BMS and probably all that we as RV'ers would ever have are no help in this situation. The BMS is an on/off device that cuts charging only when significant damage is in the offing. For instance, a BMS will open the charging circuit at around 15 volts, but will let the absorb stage continue at 14.X volts as long as it will.

Well that certainly is not the case with my Lion Energy batteries. Once they get to full charge they simply will no longer accept any more charge.... not sure which batteries you have experience with but mine simply accept nothing past ~14.0 which is fully charged and then settles to 13.6 and my batteries are all within .1 V of each other

[xc-mark]

Originally Posted by hclarkx

Agree! There may be appropriate LiFePO4 chargers out there, but the only really good one that I've found is a solar controller with a "user" option. In the one I use every parameter is user set in "user" mode.

Victron IP22 charger has user defined setting. You can set the voltage down to 14.XX and float to 13.XX if you so choose. The absorsion time is can be set where ever you want with user defined % of amps, So if you have a 30 amp charger and you select 10% it will finish at 3 amps for its the time programed. I plan on useing this charger for storage to keep the battery under 80%SOC but over the 50%

[TR4]

Originally Posted by hclarkx

I trust that you know what you are doing, but to be sure ...........

Charging to 90% is a two-edged sword. It can be done by stopping the charge at an indicated 90% SOC reading, but the SOC monitor needs to be recalibrated often with a full charge to around 14.4V to read correctly. Also, cutting the charge at 90% (even if the SOC has been calibrated and is reading correctly) will typically halt charging before balancing has occurred. Losing balance in a LiFePO4 battery is a whole bucket of worms that would not be good.

I’m new to this as many of us are. So far so good with the settings. I don’t charge using SOC, I charge using cell voltage. My 90-95% SOC leaves me with a .056 delta on the cells. I balance on charge only and start at 3.4v. My cells never see a full charge, which is what I want.

Do you think I should start balancing at a lower voltage? Delta to balance is set to 15mv.

Bill

[hclarkx]

Originally Posted by paul65k

Well that certainly is not the case with my Lion Energy batteries. Once they get to full charge they simply will no longer accept any more charge.... not sure which batteries you have experience with but mine simply accept nothing past ~14.0 which is fully charged and then settles to 13.6 and my batteries are all within .1 V of each other

Interesting. Is this the Lion battery that you have?

https://lionenergy.sirv.com/manuals/...l_20201216.pdf

If this is your Lion battery ..............

The manual makes no mention of the BMS having the capability you mention. In fact it allows charging up to 14.6V (see page 4) or a bit more. Where are you seeing ~14.0 volts? If the BMS is involved, this would be an internal voltage that you would not see unless the BMS has bluetooth capability.

A LiFePO4 taking no more charge at some point is not a BMS function. It's the natural behavior of LiFePO4. The charge current will go to zero at any credible charge voltage, say between 13.5V and 14.6V.

You mention 0.1 volts. When and where are you measuring this?

[hclarkx]

Originally Posted by TR4

I’m new to this as many of us are. So far so good with the settings. I don’t charge using SOC, I charge using cell voltage. My 90-95% SOC leaves me with a .056 delta on the cells. I balance on charge only and start at 3.4v. My cells never see a full charge, which is what I want.

Do you think I should start balancing at a lower voltage? Delta to balance is set to 15mv.

Bill

Bill,

Starting balancing at 3.4 volts is excellent IMHO. At least it is if the BMS has only a modest balancing capability. Some BMS balance with hundreds of ma and some over an amp; those just don't need to start balancing so close to normal voltage (though there's no harm in doing so). I have some LiFePO4 (200 Ah) with Overkill BMSs that have only 60 ma balancing, so I start balancing at 3.35 volts. Balancing only occurs during charging with this BMS (and most others I think) so I could set balancing to start lower but there's no point since voltage goes above 3.35V per cell (13.4 total) shortly after charging starts. In my case the batteries are only charged from solar so they see a lot of low-current charging (e.g., early morning) so get lots of balancing time.

If a battery is charged at a high rate, say, 0.5C, for just an hour or two and the balancing current is modest (60 ma in my case) there might not be enough balancing.

I'm curious, how are you limiting the charge to 90-95%. Doing so is tricky. Are stopping the charge manually when the cells get to about 3.320 or 3.325V?

You mention 56 mv unbalance (highest cell to lowest). That's a very large unbalance if you are measuring this with the battery down around it's normal voltage range (13.34 or a bit below, about 3.325V per cell). Normally one expects 20-30 mv or more only well up the charge curve, say 13.8V or above. And less than 10 mv when idle or with some load (battery at 13.34V or below).

[Tskadberg]

Originally Posted by paul65k

Well that certainly is not the case with my Lion Energy batteries. Once they get to full charge they simply will no longer accept any more charge.... not sure which batteries you have experience with but mine simply accept nothing past ~14.0 which is fully charged and then settles to 13.6 and my batteries are all within .1 V of each other

I am still learning so I’ll stick with what I have seen, balancing also takes place inside drop in batteries. I have Renogy Bluetooth 100Amh so I can see the volts on the 4 cells in the battery keeping them balanced does require specific type of charging, and happens at the end of the charge.

I also just learned a lot about my victron smart shunt and it does like to recalibrate with a full charge.
SOC is a complicated accounting act and a full charge is a chance to reconcile

[TR4]

Originally Posted by hclarkx

Bill,

I'm curious, how are you limiting the charge to 90-95%. Doing so is tricky. Are stopping the charge manually when the cells get to about 3.320 or 3.325V?

You mention 56 mv unbalance (highest cell to lowest). That's a very large unbalance if you are measuring this with the battery down around it's normal voltage range (13.34 or a bit below, about 3.325V per cell). Normally one expects 20-30 mv or more only well up the charge curve, say 13.8V or above. And less than 10 mv when idle or with some load (battery at 13.34V or below).

My old Trace inverter/charger, on the gel setting, will only charge to about 13.6 v (3.4 v/ cell), or a little over 90% SOC.

My Morningstar SCC is set to charge to 13.88 v (3.47 v/cell) or a little over 95% SOC. Since the Morningstar is an older unit, it doesn’t have a Lithium profile. I have it set up this way. High voltage disconnect set at 13.88 v. High voltage reconnect set at 13.31 v.

My unbalance is highest right after charging as you say. The cells settle in at under 8 mV.

I could squeeze out a few more AH by upping the HVD on the Morningstar, but feel I don’t need it and will stay more conservative.

Bill