40 Amp Power Supply to Charge LiFePO4 ?

[nut17]

I am really aiming this question at Terry. I am looking at this http://www.jaycar.co.nz/Power-Products- ... y/p/MP3090 as a mains charger to supplement the solar charging for my 600 AH LiFePO4 battery bank. I have my 80 Amp solar controller Bulk and Absorption stages set to 13.8v but do not have a mains charger with adjustable voltage parameters. My other solution is to fit one of these http://www.intervolt.com/product/voltag ... ng-relays/ to cut off the charge supply when it reaches the desired (13.8V)

Your thoughts?

Cheers
Chris

[T1 Terry]

For that sort of $$ I'd buy one of these http://www.ebay.com.au/itm/PROJECTA-IC5 ... xywh1TFpim and set it to either powersupply mode or Gel, the power supply mode will pump in 50 amps right up to the 13.8v and kick in with up to 50 amps to support any loads, the gel setting will get it up to 14v if you want to fill the batteries quickly before heading off again.
If you need to cut the leads remember to extract the small wires from the centre of each cable and connect them to the ends of the cable as these are the voltage sensing wires, it won't go at all without those wires connected.

T1 Terry

[tarbaby]

and set it to either powersupply mode or Gel, the power supply mode will pump in 50 amps right up to the 13.8v and kick in with up to 50 amps to support any loads, the gel setting will get it up to 14v if you want to fill the batteries quickly before heading off again.

So could I leave the charger hooked up to my batteries indefinitely in power supply mode? or in gel mode? I can't imagine why I would, just curious to know if there is any likelihood of overcharging cells. I have a Projecta IC3500, so just wondering

[BruceS]

Better tell us a bit about your setup to get the best advice.
Are they LiFepo4 batteries or AGM?
Oh, Welcome to the forum too!! Jump into your profile & fill out a few details when you get time!
Only one more post to be 'approved'.!!

[T1 Terry]

and set it to either powersupply mode or Gel, the power supply mode will pump in 50 amps right up to the 13.8v and kick in with up to 50 amps to support any loads, the gel setting will get it up to 14v if you want to fill the batteries quickly before heading off again.

So could I leave the charger hooked up to my batteries indefinitely in power supply mode? or in gel mode? I can't imagine why I would, just curious to know if there is any likelihood of overcharging cells. I have a Projecta IC3500, so just wondering

Welcome to the forum, if you do go lithium there is a mod we do to the charger to adapt the lithium control system to control the Projecta IC series chargers as well. With lead acid batteries you could leave it connected on what ever chemistry setting you are using and it has an automatic charge, maintain and top up function that it goes through to keep the battery in top condition for as long as possible but this regime does not suit lithium batteries. You don't hold lithium batteries fully charged for long periods, they don't like it at all, they love to either work or go into hibernation at around 50% SOC if the lay up is going to be for more than a few mths.

T1 Terry

[tarbaby]

Better tell us a bit about your setup to get the best advice.
Are they LiFepo4 batteries or AGM?

Ahh sorry Bruce, should have explained. I have one lonely AGM battery left, the other karked it recently. Hence I am looking to install lifepo4s and ditch the AGM. I am in the process of working out what I have to do to manage the lifepo4 batteries, hence my questions. There will be more...

I have a Dingo 20 regulator, with 450 watts of solar, looking to double this soon. I have the above mentioned Projecta 35 amp charger. I have installed a shunt and rejigged the wiring so that I can measure state of charge. All this is in a 22 foot Evernew caravan of 2006 vintage.

Welcome to the forum, if you do go lithium there is a mod we do to the charger to adapt the lithium control system to control the Projecta IC series chargers as well. With lead acid batteries you could leave it connected on what ever chemistry setting you are using and it has an automatic charge, maintain and top up function that it goes through to keep the battery in top condition for as long as possible but this regime does not suit lithium batteries. You don't hold lithium batteries fully charged for long periods, they don't like it at all, they love to either work or go into hibernation at around 50% SOC if the lay up is going to be for more than a few mths.

Terry, am I likely to overcharge the lifepo4 batteries if I leave the 35 amp charger hooked up in power supply mode, or even gel mode for a day or so? I can't imagine that I would, because 13.8 volts/4 cells equals 3.45 volts/cell, which should be good.

The reason why I ask the question is because I don't have or know of an automated switch to disconnect the charger when the batteries are fully charged. I plan to rely on me looking at the Dingo SOC, thinking "Hmmm, 100%, time to switch the charger off". Not foolproof by any means.

[T1 Terry]

In a word.... Yes. 13.8v = 3.45v per cell.... if they all come up together and remain in balance at the top end of charging, 3 cells at around 3.2v and one cell at 4.2v also equals 13.8v and one very damaged cell, so relying on battery voltage alone will not protect the cells from damage.
Once a cell goes over voltage it will continue to increase its voltage and reduce the voltage of the other cells in the pack simply because it is full and has no method of displacing the energy that is flowing through it, so the voltage continues to rise, the total can not exceed 13.8v so the voltage of the under charged cells will continue to fall as the high cell goes even higher, this is known as the death spiral.
It has been 5 yrs now and quite a few $$ in R&D expense fine tuning our control unit to make it compatible with just about every form of charger and 4 levels of control to protect the battery from damage, human error is the hardest to protect against but I think we have been able to even do that now I did manage to severely damage one of my battery packs via the human error path so the final level of protection became a must have rather than over kill.

I guess everyone thinks they have built the best battery management system, but ours does have over 5 yrs of runs on the board and around 200 systems out there doing their thing with very little trouble. I back every system I install with phone and email support so the problems are quickly sorted no matter where they are located.... about all I can say really....... am I going to get banned from yet another forum for self advertising Please delete it if I've gone over the top Bruce

[BruceS]

All good! A lot of valuable information there for people to ponder.
Very important to keep the warning out in front of the eyes & mind to help save cells from getting pregnant.

[homeless]

Getting pregnant is easy if you don't know what you are doing it is the cost of child birth that is the expensive part

[Mrcoolabah1au]