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joe19 avatar image
joe19 asked

Constant voltage drop loop

  1. Hi,

I have gone through the posts, but were unsuccessful in finding an answer. If I missed something, please direct me.

My victron system charges the 400A freedomwon lithium upto 14v/100%. As soon as it reaches 100%, the voltage drops to about 13.4v/99%, and the process repeats itself.

The orion b2b however, charges the battery to 14.2v and keeps the voltage constant-no voltage drop.

Freedomwon has checked on their side, and can find nothing wrong. Any ideas?

The system is on a sailboat. We have three methods of charging: shore power, solar and the b2b connected between starter battery and lithium.

How can I get the system at a constant 14.2v without the endless loop of discharging and charging?

Any help would be greatly appreciated.

Thanx in advance.

battery system voltage
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2 Answers
delf67 avatar image
delf67 answered ·

Why do you think your system needs to be at 14.2V? A fully charged battery will read 13.2-13.4V (it's nominal voltage). You are seeing a higher voltage with the b2b because it is constantly applying a charging voltage to the battery. For lead-acid batteries a constant trickle charge was needed to keep the battery topped up. As far as I know you don't need to do this with lithium. As soon as they are fully charged the charging voltage is removed and the battery settles back to it charged voltage. I would say the charging profile on the b2b is treating your battery like a lead-acid one, not lithium. Are you sure your system is configured correctly for the type of battery you are using?

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joe19 avatar image joe19 commented ·

Thanx. I'll double check the b2b settings. The real issue for me is the fact that the battery is discharging (although there is a constant power supply) to 13.4v and charges back up to 14v/100%. As soon as 100% is reached it discharges again to 13.4v. And this repeats constantly.

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delf67 avatar image delf67 joe19 commented ·

When the voltage reduces to 13.4 it is not "discharging" as such, it is the battery voltage settling back to nominal voltage because the charging voltage has been removed.

I take it you do not have the batteries BMS communicating with the Victron equipment?

So no Cerbo GX etc?

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joe19 avatar image joe19 delf67 commented ·

Thanx for the feedback. When the system was first commissioned, the system charged to and stayed on 14v. Unfortunately I can't remember when it started with the "discharge/charge cycle" .

The bms is connected to the victron system with a cerbo gx that links to a colour controller

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Albert de Jongh avatar image
Albert de Jongh answered ·

What victron product are you using to charge the battery with?

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joe19 avatar image joe19 commented ·
4 x 100/30 mppt's

1 x orion smart b2b 30amp

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