High end custom trailer build

[FlyLow]

The voltage settings on the CC are not excactly what sun extender wants, it it critical to make custom charge settings?

The preprogrammed Morningstar AGM settings are
Absorb 28.8
Float 27.4

Sun xtender says
Absorb 28.4-28.8
Float 26.4-26.8

[reed cundiff]

I guess you have a 24V system and our is 48V nominal, ergo, our absorb/float voltages are about exactly double yours
Reed and Elaine

[Sunking]

The voltage settings on the CC are not excactly what sun extender wants, it it critical to make custom charge settings?

The preprogrammed Morningstar AGM settings are
Absorb 28.8
Float 27.4

Sun xtender says
Absorb 28.4-28.8
Float 26.4-26.8

For solar settings are pretty much useless. For solar you want the setting for maximum where Bulk = Absorb = Float. For AGM = 29 volts. With solar there are not enough Sun Hours in a day to go through all the slow 3-stage charging algorithms. It can take 12 to 16 hours and that is kind of hard to do when you only have 3 to 6 sun hours in a day.

[reed cundiff]

Our system will deliver over 1300 W to controller and 1150 W to battery charge. Have not done a full daytime determination of how much energy the battery bank will absorb in a day; however, we have started the day at -4500 W-hrs and been fully charged by one in the afternoon. This was with no clouds and no shade.

Particulars of system are:

Per cell [U Bank[/U] Units
Absorb 3.6 57.6 V
Max cell volt 3.9 62.4 V
Float 3.4 54.4 V
Disconnect 3.1 49.6 V

[Sunking]

Our system will deliver over 1300 W to controller and 1150 W to battery charge. Have not done a full daytime determination of how much energy the battery bank will absorb in a day; however, we have started the day at -4500 W-hrs and been fully charged by one in the afternoon. This was with no clouds and no shade.

Particulars of system are:

Per cell [U Bank[/U] Units
Absorb 3.6 57.6 V
Max cell volt 3.9 62.4 V
Float 3.4 54.4 V
Disconnect 3.1 49.6 V

That does not mean the batteries are fully charged.

[FlyLow]

I don't understand your response Sunking, could you dumb it down for me please?

[Sunking]

I don't understand your response Sunking, could you dumb it down for me please?

Don't understand what?

[FlyLow]

I don't understand bulk=absorb=float.
"Solar for maximum"?
This is the first I have read that the stages are useless, it makes sense I just know how to adjust accordingly. From what I gather from your post set the CC to 29V and walk away?

Thanks for your help
Jordan

[Mike90250]

Simply getting batteries to a "voltage" does not mean they are charged, they need to have hours of amps pumped into them at that voltage before they are full. Bulk, Absorb and Float are 3 stages of charge. Bulk is the only one with a target voltage.

[reed cundiff]

I believe this one of the primary purposes to having a battery management system with LFP batteries. The battery bank goes to 57.6V during absorb and then adjust to 54.6V to float as the bank. LFP can charge quite fast to absorb level and then it remains there for an hour or more before it drops to float. We ran the a/c a bit during the afternoon yesterday and we are at -2700 W-hours. We shall be driving to Glacier NP today and shall be in full sun (as opposed to quite a bit of shade in Missoula) and should be to float by late morning.
Reed

[Sunking]

I don't understand bulk=absorb=float.
"Solar for maximum"?

Very simple set Bulk, Absorb and float to the exact same voltage.

With any lead acid or lithium battery, the battery is fully charged when the charger voltage is set to a Float Value and the charge current has tapered down to 1 to 3% of C where C = the rated Amp Hour Capacity of the 20 hour rating. So if you have a 12 volt 100 AH battery, it becomes fully charged when a constant voltage of 12.6 volts with a current that taper down to 1 to 3 amps. That takes 10 to 12 hours on float. There is no place on earth that has that kind of sun hours to get through all 3 chagrining phases. For get equalize as that takes 12 to 24 hours.

Battery manufactures has since been getting high warranty replacement claims for their batteries used in Solar Applications. Major failure is under charged sulfated batteries. Manufactures have responded by changing charging set points to just using 2-stages. 1. Is now called Daily Charge which is a Constant Voltage with Taper Current, and 2 is Equalize. Example Trojan and Rolls have done away with 3-stage, and now recommend only two stages. 1. Daily Charge = 14.8 volts, and EQ = 15.5 volts.

So to get that you set your 3-stage Charger to Bulk = Absorb = Float = 14.8 volts, and EQ to 15.5 volts per 12 volt of battery. Then once a week or two, or when required, run on your generator to EQ and saturate the battery.

[reed cundiff]

LFP have to go through absorb to fully charge as with any other battery but it does not take the amount of time as PbS. The charging rate is quite linear. We noted last year that we were at -3000 W-hrs and were charging at 1500 W and it took two hours to hit absorb and another hour to achieve float. PbS seems to go asymptotically. There are numerous articles on line that discuss these characteristics

[FlyLow]

Sunking, I know you are a expert and are very knowledgable, with that being said I'm being cautious before I change the CC settings to your recommended V.

I am scared to set my CC to 29.6 volts when the sticker on the battery says 28.8V. Could you tell me why going to that voltage would be good for the batteries? How high can the voltage go before it blows up or melts or catches fire etc? I'm sure you have seen some wild stuff?

[Sunking]

I am scared to set my CC to 29.6 volts when the sticker on the battery says 28.8V.

What make and model number? Let's look them up.

28.8 is great if you are using commercial power to charge your batteries as there are no time and power limits other than the amp rating of the charger. In that application a battery can easily go through all 3-stages in sequence. That can take up to 12 hours. There is no such thing as a 12 Sun Hour Day.

I am not saying take my advice, Lets look up your batteries and see what they say. What I am telling you manufactures are changing voltage set points for RE systems like solar because they have had too many warranty claims with customers using the old standard s-stage algorithm use din conventional battery chargers. So now many that I know of like Trojan and Rolls have changed and call it something like a DAILY CHARGE and EQ which is just a little higher voltage. Point is to get it charged up ASAP because you do not have the luxury of time using solar. Thus a lot of folks with undercharged batteries and failures.

[paulcheung]

Sunking, I know you are a expert and are very knowledgable, with that being said I'm being cautious before I change the CC settings to your recommended V.

I am scared to set my CC to 29.6 volts when the sticker on the battery says 28.8V. Could you tell me why going to that voltage would be good for the batteries? How high can the voltage go before it blows up or melts or catches fire etc? I'm sure you have seen some wild stuff?

I set my Rolls at 60 volts on 48 volt system which is 15 volts per 12 volts. since then I have less under charge problems.