charging Lifepo4 batterys

[Adam88]

Hello all
first of all sorry if this is in the wrong section. this is my first post.

I have a self build camper with 390w of solar on the roof and a 50amp mppt regulater charger and 2x 100amp lifepo4 batterys. and my problem is what setting to have the regulater on, there is a lifepo4 setting on there witch is fine it fully charges my battry to 14.6v then cuts out ( no float) but then though out the day i use power but the regulater will not cut back in until the following day. so i will lose a lot of power though out the day/night witch again is fine as long as there is sun the next day. but there is a lead acid setting on the regulater witch i tryed yesterday and charges the batterys to 14.4v then goes in to float at 13.5v witch in my head more sense as it keeps the batterys toped up though out the day and where still fully charged when the sun whent down but I have read that float charging lithium is not good for them?

hope that makes sence. any help or advise would be great
Thanks Adam

 

[Two on Tour]

Which make and model of solar charge controller are you using Adam ?

 

[Adam88]

its the sterling 50amp as i have the sterling lifepo4 batterys

Solar Charge Controllers / Regulators 10A | 30A | 50A

Solar Charge Controllers / Regulators 10A | 30A | 50A Instruction Manual PDF Product Information PDF 10A PWM - Performance category PWM Max solar input voltage 50V Max in solar input power 150W - 300W System voltage 12V / 24V Display 3 LEDS to display operation and faults USB output 5 V / 2.4 A...

sterling-power.com

 

[David and Sally]

 

[Two on Tour]

Sorry for not getting back to you sooner Adam88 but I did not receive a notification that you had posted again.

I had a look through the instruction manual and ECO Solar App for your unit and could see nothing that jumped out at me in the settings that looked that it could cause your problem.

Sterling Power are very approachable and helpful, so if I were you I would give them a ring and see what they come up with.

Sterling Power 01905 771771

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[Pausim]

LiFePO4 do not need a float charge but probably do need 14.6v to achieve a full charge. They do not need to be stored fully charged. As far as I know a float charge of 13.5v is unlikely to harm them, my LiFePO4 gets this when on mains hook up and does not seem to have suffered. I have looked at the Sterling information for your controller and whilst it says it will charge to 14.6v I can’t see anything about a lower voltage at which it would cut back in but presumably there is one. I hope it doesn’t only reset overnight when the panels are idle, that could be a problem.

 

[Adam88]

Thanks for the replys
Two on Tour yer they are a great company and been very helpfull they just have gone in to hibernation at the moment due to covid 19. So cant get hold of them. So just want to confirm having them on Float Was not doing them any harm.
Pausim this is the problem i have had them on the lithium setting for 2 weeks and have been fine but once they get fully charged they don't cut back in again until they reset over night. Hence why I changed to the other setting witch had the lower float witch seams be working better keeping them top up all day but just want to make sure that this is not harming them.

 

[Pausim]

Thanks for the replys
Two on Tour yer they are a great company and been very helpfull they just have gone in to hibernation at the moment due to covid 19. So cant get hold of them. So just want to confirm having them on Float Was not doing them any harm.
Pausim this is the problem i have had them on the lithium setting for 2 weeks and have been fine but once they get fully charged they don't cut back in again until they reset over night. Hence why I changed to the other setting witch had the lower float witch seams be working better keeping them top up all day but just want to make sure that this is not harming them.

I have a Relion battery but the construction looks very similar to the Sterling ones. This is an extract from one of the Relion information sheets;

RELiON lithium ion batteries need to reach between 14.4V and 14.6V to be at full charge and deliver optimal results. If your charging voltage is higher than this rangeand cannot be programmed to a lower voltage, it is not recommended for use with our batteries. Likewise, if your charging voltage is lower than the required 14.4V–14.6V range, your Relion Batteries will not reach full charge and thus will not perform to their full potential. If a float charge setting is necessary to program your charger, it should be set to 13.8V.

I have no first hand experience of the Sterling battery or any expert knowledge but I don’t think a 13.5v float is likely to cause any harm.