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zeitfest
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Joined: 31/07/2019
Location: Australia
Posts: 684

Posted: 01:13pm 28 Jun 2026

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What is recommended for charging 12v LiFePo batteries from solar panels ?

I have a dinky trial system, LiFePo battery nominally 12V, "Powerhouse" mains charger (Jaycar), Anko inverter rated at 300W / 600W peak, several 230v LED strips from Aldi. Worked fine to provide lights during a power cut off overnight for street pole replacements.

Also have a panel that can put out 17 - 18 v and 10-14 amp + at the limits.

The panel has a "charge regulator" but it is intended for lead-acid and is
basically PWM, but the panel can deliver 18 V so I am wary of connecting it to the LiFePo. The LiFePo has a BMS (battery management system) but I doubt if a stream of overvoltage PWM is going to be OK.

(added)
The Powerhouse charger is good, I guess I could run it from the inverter but the
inverter output is "modified sine wave" which may not be suitable. Also the efficiency of the chain will not be great, and it leaves the question of the rapid intermittency
of the panel output impacting the charging assumptions.

I am wondering if a jobber battery is needed, something that will absorb intermittent
charging without problems and then provide it as clean power to charge the main store.
Edited 2026-06-29 03:35 by zeitfest

Solar Mike
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Joined: 08/02/2015
Location: New Zealand
Posts: 1218

Posted: 12:16am 29 Jun 2026

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Need to know the AH rating of your Lifepo4 12v battery, that determines the amount of current you can charge it. As your PV can output 10-14 amps, you would ideally require a battery around 20 - 30 AH minimum for long term operation.

With a PWM charger, when turned on the PV panel voltage will be pulled down to the battery voltage, with current as whatever the PV can output at the time. Then it turns off as the battery volts increase. The pulsing current wont really upset the battery and its inbuilt BMS; providing the AH rating is high enough.

Hopefully you can set the charger voltage Bulk and float end points to something like 14.2 for bulk and 13.2v for float. Turn off any higher Equalizing setting as that will really stuff up the BMS.

If the battery is only used very intermittently, once its charged up I would remove the charger until you put some load on it, as it will hold its charge for 12 months or more, depending on how much standby current the internal BMS uses.

Cheers
Mike

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