Multimeter and charge controller show different voltage

[Boisblancboy]

Definitely new to this whole world but want to be sure I’m not damaging anything. Just received a 75/15 victron charge controller and a 200ah Lifepo4 battery. Got it all hooked up and slowly charging it with a 200 watt panel. Currently at the battery terminals with a multimeter it reads 13.50 volts and the charge controller reads 13.44 and still in bulk mode.

In the history section of the controller it shows the batter over the past 3 days has hit a max battery voltage of 13.68.

So I’m hoping everything looks good. If not hoping someone can lend me some pointers. Thanks!

 

[DougfromdaUP]

Six hundredths of oF a volt isn’t much. Many pieces of equipment -and voltmeters- are off by more than that.
Don’t worry about it.

 

[Boisblancboy]

At what voltage should I expect it to transition into absorption?

 

[wpns]

At what voltage should I expect it to transition into absorption?

First that’s 0.5% error, so that’s OK.

What does the battery want for settings and what’s your SCC set to?

 

[Boisblancboy]

I used the preset setting in the controller.

 

[wpns]

So why wouldn’t you configure the SCC to match your battery requirements?

 

[Luk88]

You know the saying. A guy with a watch knows the time, a guy with two is never sure.

Same is true about voltmeters. I have one quality HP "bench multimeter" I trust and I have various other portable multimetersshow errors of up to half a volt.

If you're interested in getting a really good portable multimeter instead of building used equipment on ebay (that's how I got my bench top HP). Eevblog.com forum has a huge excel spreadsheet of multimetersshow to conpare.

 

[Boisblancboy]

So why wouldn’t you configure the SCC to match your battery requirements?

So which settings should I change cause in the user defined area it doesn’t give me any other parameters to alter than what I posted?

 

[wpns]

 

[seneysolar]

Definitely new to this whole world but want to be sure I’m not damaging anything. Just received a 75/15 victron charge controller and a 200ah Lifepo4 battery. Got it all hooked up and slowly charging it with a 200 watt panel. Currently at the battery terminals with a multimeter it reads 13.50 volts and the charge controller reads 13.44 and still in bulk mode.

In the history section of the controller it shows the batter over the past 3 days has hit a max battery voltage of 13.68.

So I’m hoping everything looks good. If not hoping someone can lend me some pointers. Thanks!

Seems like you are in float, which is good if the battery is fully charged. Have you discharged the battery since hooking it all up?

The preset on the victron should be ok. They seem to be set for a universal average of LFP batts and a tad on the safe side for voltages.

 

[Boisblancboy]

Seems like you are in float, which is good if the battery is fully charged. Have you discharged the battery since hooking it all up?

The preset on the victron should be ok. They seem to be set for a universal average of LFP batts and a tad on the safe side for voltages.

No I haven’t. According to the battery manual it is shipped not at full charge. Initial voltage was 13.26.

The controller has just always said “bulk” so I figured that it hadn’t finished its process.

 

[seneysolar]

No I haven’t. According to the battery manual it is shipped not at full charge. Initial voltage was 13.26.

The controller has just always said “bulk” so I figured that it hadn’t finished its process.

Ahh, it may take a while to get full. Sometimes even a few days to get cells balanced.

Are there any other loads that may be slowing down the charge process?

How many hours does your panel get sun?

In bulk, yes you should eventually get into the 14's

 

[Boisblancboy]

Heck I know it’s not getting but only a couple hours of full at best. Plus I’m in Michigan and some trees shade it. No loads at all hooked up yet.

I’m not worried about how long it takes. Just learning the process and making sure I’m not doing something wrong.

 

[wpns]

So which settings should I change cause in the user defined area it doesn’t give me any other parameters to alter than what I posted?

Gee, I dunno, what parameters that you posted do you think you should set to match your battery requirements?

 

[740GLE]

Until the battery terminals hit 14.2v, why worry?

How far away from the battery terminals is the SCC?

What’s the connecting conductor between batteries and SCC?

 

[Bob142]

At what voltage should I expect it to transition into absorption?

I used the preset setting in the controller.

If you look at your first screenshot, you will see that the Victron preset for the LFP setting that you're using has Absorption voltage set to 14.2V.

THAT'S the voltage you should expect it to transition into absorption.

So which settings should I change cause in the user defined area it doesn’t give me any other parameters to alter than what I posted?

In your second screenshot, the battery indicates you should set your Absorption voltage setting to 14.4V.
Looking back at your first screenshot, I believe you can click on Absorption voltage and adjust it (I'd check on one of mine but I'm out of range and quite comfortable)

If you want to make changes to the three items below Absorption Voltage in your second screenshot, you'll need to activate the Expert Mode slider seen in the first screenshot.

Start with trying to modify Absorption voltage while using the Victron preset. If that doesn't work, report back cuz you'll need to switch your Battery Preset to User Defined. There's more work there...

 

[Boisblancboy]

If you look at your first screenshot, you will see that the Victron preset for the LFP setting that you're using has Absorption voltage set to 14.2V.

THAT'S the voltage you should expect it to transition into absorption.


In your second screenshot, the battery indicates you should set your Absorption voltage setting to 14.4V.
Looking back at your first screenshot, I believe you can click on Absorption voltage and adjust it (I'd check on one of mine but I'm out of range and quite comfortable)

If you want to make changes to the three items below Absorption Voltage in your second screenshot, you'll need to activate the Expert Mode slider seen in the first screenshot.

Start with trying to modify Absorption voltage while using the Victron preset. If that doesn't work, report back cuz you'll need to switch your Battery Preset to User Defined. There's more work there...

I appreciate the explanation. Thank you

I have been doing a bunch of other research and some of what I’ve come across says 14.2 can lead to a little less capacity but more lifetime cycles. If that’s true, I like the sound of that. Unless there is a drawback I haven’t come across

 

[740GLE]

What brand make of battery?

 

[Boisblancboy]

What brand make of battery?

Litime 200Ah 12v

 

[740GLE]

IMO I’d keep the victron settings that’s 3.55v per cell plenty to keep cells balanced.

How is the battery going to be used? Most of its life at float with very little % used or will you be rocking the thing from 80%-20% daily and it’ll never see 100%?

I feel that 14.4 is needed for cell balancing which is good for the battery, it if done properly you can get the same effect with 14.2 or even 14.0.

 

[Boisblancboy]

IMO I’d keep the victron settings that’s 3.55v per cell plenty to keep cells balanced.

How is the battery going to be used? Most of its life at float with very little % used or will you be rocking the thing from 80%-20% daily and it’ll never see 100%?

I feel that 14.4 is needed for cell balancing which is good for the battery, it if done properly you can get the same effect with 14.2 or even 14.0.

It’s going to be used sparingly for back during power outages.

 

[time2roll]

A low battery in the multimeter can cause a high reading. Consider replacing with a known good battery and check again.
Otherwise it is what it is.