Battery monitor for Lithium

[garyb1st]

The shunt for my Victron BMV 700 broke. I can replace the shunt but have not been happy with the BMV 700. It constantly resets and shows that my batteries are fully charged when I know they are not. I've verified this by checking my batteries which have a series of lights indicating state of charge. When the batteries are about 50% charged the Victron meter says they're fully charged.

The shunt can be replaced but if there's a better unit that works well with Lithium I'd like to hear about it.

As an aside, I've read this is not an uncommon problem and the battery monitor just needs to be set for the lithium. I've used the Battle Born Lithium batteries programming but that's not working.

 

[DonTom]

It constantly resets and shows that my batteries are fully charged when I know they are not.

Did you calibrate it for full charge? If so, I don't see how you could have such an issue. My SmartShunt works perfectly on my lith battery, but mine is the one that works via Bluetooh.

-Don- Mayo, FL

 

[garyb1st]

If by calibrate you mean program, yes I did. As mentioned I used Battle Born programming. My Lion Energy batteries didn't provide any info.

Don't know why Bluetooth would make a difference. Are you able to verify that your monitor is reading the batteries correctly? A volt meter will not tell you the remaining capacity. As mentioned the only way I know is by the lights on my batteries.

 

[DonTom]

A volt meter will not tell you the remaining capacity.

Forget about volts, you want to know how many amp-hours are left. If it's calibrated, it should be 100% at YOUR AH capacity when your battery is fully charged to 100%.

I have a 300AH lith battery in this RV, which I added myself, which you can see here.

I am at 50% when I have 150 AHs left, 25% at 75 AHs left, etc.

But you first have to calibrate it for your AH at full charge.

-Don- Mayo, FL

 

[garyb1st]

Agree on both points. Problem is my Victron battery monitor resets itself to 100% full capacity regardless of the remaining amp hours in the batteries.

What battery monitor do you have>

 

[DonTom]

What battery monitor do you have>

This one.

Problem is my Victron battery monitor resets itself to 100% full capacity regardless of the remaining amp hours in the batteries.

Loose connection? Interference from something? Broken unit?

The first thing I would do is remove it and find a way to bench test it away from the RV.

-Don- Mayo, FL

 

[UTTransplant]

We have had no problems at all with our Victron battery monitor, either with our previous lead acid or the current LifeBlue brand LiFePO4 batteries. Ours is a BMV-712, values displayed using Bluetooth on our phone. We also have a Bluetooth monitor in the batteries themselves, but I have to look at each battery individually so I use the Victron instead. As Don said, you do have to calibrate your batteries on the Victron first, and they need to be 100% charged. We did it after leaving the rig connected to power for 2 days to guarantee full charge.

 

[garyb1st]

We have had no problems at all with our Victron battery monitor, either with our previous lead acid or the current LifeBlue brand LiFePO4 batteries.

Pam, I have the BMV-700 which is not Bluetooth enabled. But I doubt that is the problem. My batteries are under one of the entrance steps. I would prefer to just rely on my Victron meter, but until I get this resolved I need to check the battery capacity daily.

I keep my coach plugged in when home. But that will not get my batteries anywhere near full. Unless you have an inverter charger or converter with a lithium profile, you probably aren't getting your batteries fully charged either.

With my batteries, a series of 5 light lets me know how full the batteries are. When all lights are lit the batteries are between 75 - 100% charged. That's a huge difference and potentially 25% under charged.

But back to calibration. If I can figure out the correct parameters for my Victron, (all batteries are not the same) I should be able to set the parameters after a long drive to a campground. I'm pretty sure my Coaches alternator will fully charge my batteries. That's when I would need to program the Victron. That's what I plan on doing when I'm next on the road.

The first thing I would do is remove it and find a way to bench test it away from the RV.

Don, how do you do a bench test? Does it require any special equipment.

 

[UTTransplant]

Our Magnum converter/charger has a lithium profile, and we got the appropriate settings for it from the battery manufacturer. We have using it in that mode since Kevin installed the batteries last late spring. An appropriate charger is absolutely necessary to get the real of benefit of lithium batteries. I would update that before worrying about a monitor. Or so says Kevin the electrical engineer.

 

[garyb1st]

Does your charger also charge the chassis batteries? If so won't that overcharge them? If not, how did Kevin separate them? Also, what did Kevin do to prevent the Victron Energy smoking alternator issue?

 

[UTTransplant]

We added a separate charger for the chassis battery 3 years ago because it was easier than debugging an issue we were having with the chassis battery charging. We also have a big 160 amp alternator that most people do nothing to manage. For example, an internet friend with the same battery set up and alternator has run his for two years without any modification. But Kevin loves gadgets, so he added a 30 amp DC to DC charger in the circuit for the alternator. It is certainly true that adding a lithium battery system is more than just replacing the batteries themselves.

 

[DonTom]

Don, how do you do a bench test? Does it require any special equipment.

Just need a battery or 12V power supply and a moderate 12 volt load. The idea of the bench test is to test your Victron BMV 700 under the same conditions as much as possible, but on a bench instead of where normally used.

That way you should be able to determine if it's a problem inside your RV or if the problem is with the Victron BMV 700 itself. Don't assume either until tested on the bench.

-Don- (at Rest Stop near Cottondale, FL on I-10).