question

njoynthewater avatar image
njoynthewater asked

Problems setting charge controllers foe Lifeline AGM batteries

.The following is a description as to what is going on. I will try to keep this as short as possible:

Replaced Lifeline AGM 100 amp hour battery bank with same 5 batteries so 500 amp hour

Also purchased Dongles and attached to 2 only 100/30 MPPT controllers which are supplied by 2 only 350 watt panels.

Lifeline recommends 13.25 float voltage which wouldn't work as was told in previous post that it needs to be higher, suggested 13.5 Lifeline say's overcharging, bad for batteries.

Lifeline also recommended using a fixed absorption time of around 2.5hrs with controllers going into float when batteries accepting 2.5amps. Set up fixed time and it seemed to work for awhile but after some time when checking app history absorption time had inexplicably climbed to near 5hrs.

Reset to adaptive and somewhere in the process set up temperature compensation at Lifeline recommended 14.27 and enabled temperature compensation

Maximum voltage on history dropped to around 14.08, absorption time dropped to near 30 minutes (Lifeline says batteries not being fully charged) and slowly over days battery monitor SOC percentage would slowly drop down from 100% with a corresponding drop in early morning SOC. Previously on old batteries we would consistently charge on solar to 100% and overnight would drop to around 88%. Original batteries failed suddenly after 4 years near to the day which, based on our charging history surprised Lifeline. Was suggested that early failure was from overcharging at 13.5 float voltage.

2 days ago I reset the parameters back to 14.4 absorption voltage and disabled temperature compensation. I split the difference on the float voltage at 13.35 and it seemed to work yesterday but only got an absorption time of 1hr 29 minutes and it looked like the batteries were still accepting more than the 2.5amps. We are moving today so alternator will do some charging so will continue to monitor once back on only solar charging.

Through this I have tried everything I can think of but cannot get the 2 controllers to network on the app. Uninstalled and re downloaded the app but no connection.

AGM Battery
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3 Answers
gazza avatar image
gazza answered ·

No doubt you have looked at the Lifeline tech manual but I notice that they quote quite a range for Float voltage based on Temperature? https://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101G_Lifeline_Technical_Manual.pdf

I assume both controllers are on the same firmware version? Have you tried just using one of the controllers to troubleshoot (by elimination) networking issues?

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njoynthewater avatar image
njoynthewater answered ·

I have not tried that. Currently I have a dongle attached to each controller and each controller shows the same settings and data when I check them. This is day 2 since I reset the settings and I have a new twist. My monitor is showing 100% but my controllers are showing absorption and inputting around 10 amps but there is current draw but it won't be 10 amps.

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crispyc avatar image
crispyc answered ·

I have a marine setup and Lifeline AGMs. How are you monitoring the batteries? I am pretty sure Ive got good settings from the Lifeline manual for both the MPPT and BMV712 monitor. But they are 255 Ahr batteries x2.

Not sure why someone would say that you need 13.5 V for float. Thats not true for Lifeline.

Here are the settings Im using with the MPPT and the BMV 712, all extracted from the Lifeline tech manual (set up for my system, 2x 255 Ahr):

-12V 255 Amp.Hr x2

-Absorption 14.3 v +-.1

-Float 13.3 v +-.1

-Temp compensation -.013v/battery (-13mV/deg F per 12v battery). -26mV/bank

-Tail Current 0.5% of battery rated capacity= 1.275A x2= 2.55A

-Current Threshold- 0.1A

-Charge efficiency- 0.97

-Bulk finished SOC- ?

-Victron Priority Charge Float - .2

-Peukert 1.12


I dont worry to much about the time it takes for the different charge stages. I pay more attention to the Volts and Amps being accepted by the battery. You can actually see the charge stages by the V and A graphs on the battery monitor.

Hope it helps

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