Solar charger for Sp140 battery

Hi - does anyone know how to charge the SP140 battery directly from solar (not via a battery with an inverter). I have big solar panels on my RV and have the Victron SmartSolar MPPT 250/70 SmartSolar MPPT 150/60 up to 250/70 - Victron Energy. Can I connect my SP140 battery directly to the MPPT to charge?

MPPT is probably a 48V unit and the battery is 86V so it may not work?

Agreed Allex - but my question is rather, even though the voltage is lower, is it still possible to charge the battery pack (maybe it takes longer to charge). The SP140 battery, which I believe is 100v nominally, is an awkward voltage. Most batteries are configure in multiples of 12 v and most chargers available work with either 12, 24 or 48 volt. Anyone with insight into this? Thanks.

12/24/36/48 is really old lead acid standard.
Now when we have Li-ion it is a bit different.
Each cell is 3,6V nominal and with 24 in series it gets to 86,4V
Even when the pack is discharged you have a voltage of around 3V per cell, this gives you 72V and is way above the voltage your MPPT can deliver. So while I am total beginner on Solar, I think you might need to have a boost, similar to:

but one that can go up to 100V to fully charge the battery.

Thank you Alex!

You must have a charging device that produces at least 100v in order to charge a 100v battery. It appears that your solar array and MPPT unit operate at voltages that are far too low to charge the SP140 100 Vdc battery. An inverter is required to raise the common battery voltages of 12, 24 or 48 up to residential AC voltages of 120 or 240; and the charger designed for the SP140 battery rectifies and reduces those voltages to produce the needed matching DC voltage. Direct connection of mismatched DC voltages is a recipe for high surge currents that may damage any connected devices, and your MPPT is not capable of producing high enough DC voltage to charge the 100V battery directly. Current always flows from higher voltage to lower voltage, hence it would flow away from the battery and back through the MPPT if they were to be connected directly.

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Yes you can absolutely do this, I have been solar charging my sp140 battery for about a year now. The charge rate is slow though could be increased because my charger is limited by heat dissipation without a fan. I will take some pictures of it tomorrow and the electrical layout and share on this page

Thank you for the info. Can you pls send me your setup - much appreciated. Also, is it perhaps possible to have two (or more) solar chargers connected in a way to increase charge time?

Hey, sorry I firgot to reply to this post.

The setup is this device.

I have the settings like so

Input Cuttoff voltage setting: 30V
CC setting: 3.1A
CV setting 100.8V

The reason the cord is there is that i wanted to be able to charge the battery on my unit while the whole thing is outside.

My solar array is 990W peak, typically pulling 500-700W.


Thank you very much for the info - very helpful. So, in essence, you are using a EPEVER 40A MPPT Charge Controller and a DC-DC converter.

No, the mppt controller is for my separate 24 volt battery system. The DC to DC converter is fed from the solar panels directly.

I see - thanks.