Basic Set Up for DIY Marine LiFePO4 System

[areddon]

If have a LFP system on my boat, made from bare cells. I have separate load and charge busses, a REC BMS for cell balancing, high/low voltage alarms, high/low temperature shut down, and very high/low voltage disconnects.

I have a completely separate charger control that enables charging (below 20% state of charge or when charge cycle is triggered manually). The charge controller disables all charging when LFPs are fully charged based on voltage and residual current. Existing charge sources are engine alternator, shore power charger, and wind generator. They are all configured to deliver maximum current up to 14.1 volts and then hold that constant voltage as the current declines. The charge controller disables all charge sources (safely) when the charging current falls to a defined level. All good so far.

I now want to add a solar charging source. Like the other charge sources, I want the solar to deliver maximum current up to 14.1v, then hold the voltage at 14.1 as current declines until the charge controller shuts down all the charge sources.

I guess I really just need a 14.1 volt solar regulator or a charge controller with 14.1volt absorption phase and no float phase at all.

Question #1 - Does such a thing exist? Can such a regulator be MPPT without any charge control?

Question #2 - I have four 12 v, 100 watt Bouge RV CIGS Panels and one 80 watt Lensun 18 volt panel. What is the best way to set these up for the charging behavior I am looking for?

Thanks for any advice

 

[Rocketman]

This is one way of doing it (I am sure there are others…) I know Victron stuff - so that’s what you get from me

#2 Hook the four 100w panels (probably in 2s2p) into a Victron mppt 100/30. Hook the 80w panel into a Victron mppt 75/15. Use LifePo4 settings with a 14.1v absorbing and a float (just in case the connection in #1 comes out) of 13.5v or 13.4v.

#1 since you want external control of the mppt’s and don’t want them to do their automatic thing, there is a Victron cable

VE.Direct non inverting remote on/off cable - Victron Energy

Remotely control BlueSolar and SmartSolar MPPT charge controller models using the VE.Direct non inverting remote on/off cable. Find a dealer near you.

www.victronenergy.com

The mppt’s will run when the signal on the yellow wire is high and will turn off when no power is in the yellow wire. (That’s all I know - in fact I learned that as I was looking for the on/off switch - evidently the on/off switch is on larger models).

You may have to play with some of the other settings so the mppt’s want to go into float at about the same time as your system controller directs them to cut off.

Good Luck

 

[areddon]

Thanks very much for that.