Victron & ripple error

[Rocketman]

Hello everyone,

On my MotorHome, I have a Victron Multiplus 12/3000 and a 544ah lithium battery (eight Lishen 272ah cells w/ Batrium BMS w/contactor).

When I startup my air conditioner Rec-Pro on the inverter & battery, I will sometimes get two warnings.

A low battery warning- I figure this is just part of the startup surge (even though Rec-Pro says there is a soft start). My CCGX display never shows the voltage getting low.

The other error I sometimes get is a high ripple warning. Is there anything I can do about that? Very occasionally the inverter will shutdown.

I never run the A/C (or heat pump) for a long time - 30-60min to cool down the bedroom because I don’t have a massive battery. (I think from full to empty I can run the A/C for about three hours).

Anyway are the high ripple warnings something to be concerned about?

 

[sunshine_eggo]

Yes. Victron indicates equipment life will be shortened.

https://www.victronenergy.com/live/_media/ve.bus:4._ripple_in_a_ac_battery_system.pdf

Section 2.6:

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

To fix high ripple in a system do the following:
• Reduce long battery cables.
• Use thicker cables.
• Check fuses, shunts and battery isolator switches for connectivity.
• Check the specifications of the fuses, shunts and battery isolator switches.
• Check for loose terminals and loose cable connections.
• Check for dirty or corroded connections.
• Check for bad, old or too small batteries.
• Always use good quality components.

 

[HRTKD]

I have a similar setup, but with no issues when running my air conditioner (15k rooftop, no softstart).

Multiplus 12/3000
Two 4s 280 Ah batteries, each with a JBD 120 amp BMS

2/0 from each battery to the common bus bars. From the common bus bars to the inverter I used double runs of 2/0.

The differences between our systems are the two BMS versus your single BMS and my doubling up of the cables.

 

[sunshine_eggo]

Dang... you effectively have thicker than 4/0 between battery and inverter.

EDIT:

Max surge: 6000W/12/.85 = 588A

Assuming a total of 6 feet one-way, you have a 2.3% voltage drop due to the cabling. Suspect bus bars are your limiting factor...

 

[HRTKD]

Dang... you effectively have thicker than 4/0 between battery and inverter.

EDIT:

Max surge: 6000W/12/.85 = 588A

Assuming a total of 6 feet one-way, you have a 2.3% voltage drop due to the cabling. Suspect bus bars are your limiting factor...

I have the Blue Seas Power Bar, 1000 amp rating I believe. The one-way run is about 3' from the Power Bar to inverter.

 

[sunshine_eggo]

by "bus bars" I meant cell interconnects...

 

[Samsonite801]

I added soft starters on both my roof AC units and very satisfied (I still can't start them both at same time due to 2800w inverter only), But either unit (only one at a time) can now start 100% of the time. Before, each one by itself would only start (without tripping the inverter) maybe 1/2 the time...

I also think it will help promote less hammering on the inverter drive circuit without the AC units dropping their full fury on them every time one of the AC units turns on...

 

[Rocketman]

Well I finally solved the issue…

I put the Micro Air EZ Bluetooth start on the RecPro 3800 air conditioner.

The first time I started it, it records the the current without it helping- 27.9amp(@120v), no wonder the inverter was giving me warnings.

After it was all setup it is now 16.5amps (@120v) for the startup surge. No warnings.

In between the original post and now, I worked on reducing the voltage drop, but I still only had a 4/0 wire between the battery and the inverter and it was a longer distance-10’+ (just the way my MotorHome was setup) and I really didn’t want to run another set.