AGMs went from fully charged to 89% in 7 days

[Toy4Rick]

I installed 2 new 125Ah AGM batteries (12v) in parallel 2 weeks ago, ensured they were fully charged...

Came home last week and they were still fully charged (Victron 712)

Battery disconnect turned off and 7 days later they are down to 89% (12.83v)

Just checked again and nothing is turned on, battery disconnect is off...

Where to start with finding this much draw on 250Ah battery bank in 7 days?

2021 Sunseeker 2250LE

I can hook up to shore power at home or even put out the solar panels but 7d, geez

[NavyLCDR]

To completely disconnect the battery from the trailer you need to remove the negative cable from the battery. Just make sure to reconnect it before you move the trailer.

[Toy4Rick]

It could very well be how I had the batteries wired... they were in parallel but with the pos and neg to the coach coming from the same battery. I moved all positive cables from battery 2 to battery 1, left the coach negative cable as is as well as wired in parallel.

I'll get them charged back up and watch them over the next few weeks, should be better, at least I hope so

[RedLdr1]

Originally Posted by Toy4Rick

Where to start with finding this much draw on 250Ah battery bank in 7 days?

Sunseekers can have several items wired directly to the batteries from the factory. The LP / CO Detector is normally direct wired on all units. Some folks have reported the house radio being direct wired, probably to support the clock function. One of our Sunseekers had the dash entertainment center (radio /GPS / DVD player) direct wired. None of these items are a huge draw but they add up.

[dmctlc]

Parasitic draws are normal for any RV. Only way to stop them as mentioned is to completely disconnect the battery. I'd charge them fully then disconnect and check in 7 days I bet you'll see very little if any change then.

[ScottBrownstein]

I lose a little less than 1% a day on my 4 6-volt deep cycle house bank. I installed a disconnect on the ground connection and can cut that to self discharge of about 4 to 6 percent per month.

[Theo]

Toy4Rick -

Before you installed the 2 new AGMs, was the BMV-712 working properly? Have you changed any of the BMV parameters with the new AGM install? To what percent is your "discharge floor" parameter set?

[camaraderie]

Originally Posted by Toy4Rick

I installed 2 new 125Ah AGM batteries (12v) in parallel 2 weeks ago, ensured they were fully charged...

Came home last week and they were still fully charged (Victron 712)

Battery disconnect turned off and 7 days later they are down to 89% (12.83v)

Just checked again and nothing is turned on, battery disconnect is off...

Where to start with finding this much draw on 250Ah battery bank in 7 days?

2021 Sunseeker 2250LE

I can hook up to shore power at home or even put out the solar panels but 7d, geez

Ummm check what you posted 12.83 V is MORE than 100% charge and indicates a surface charge still on the plates. 12.7 or perhaps a very little bit higher is 100% for most AGM's.
If that is correct... and not a typo...you have no drain. You do have a problem with your initial set up parameters which you should re visit.

If it is a typo ...the next step is pulling all your dc fuses one at a time while watching the CURRENT drain on you meter. when you eliminate most of the drain...you've found your culprit. If you are down to 89% in a week you'll be down 44% in a month when with disconnected AGM's you should be losing less than 5% max.

Also making sure...you do have your cutoff switch on the negative battery terminal right? And no other negative wires other than the one to your shunt are on the batteries right? You're not just using the mfr battery cut off switch right?

Good luck!BTW...who makes 125amp hour AGM batteries?

[Delco Bobby]

The Magnadyne radios used to be a big draw on batteries in Sunseekers.

[Toy4Rick]

Originally Posted by Theo

Toy4Rick -

Before you installed the 2 new AGMs, was the BMV-712 working properly? Have you changed any of the BMV parameters with the new AGM install? To what percent is your "discharge floor" parameter set?

712 was installed at the same time as the new batteries and setup all parameters per the guide for AGMs. The discharge floor is set to 50%

[TitanMike]

Originally Posted by Toy4Rick

712 was installed at the same time as the new batteries and setup all parameters per the guide for AGMs. The discharge floor is set to 50%

It may be possible the SOC percentage is affected by the discharge floor you have set.

I recall reading something to that effect when I set up my Victron BMV. Check the printed manual as well as notes in app when in settings and adjusting the discharge floor

Also, when yours was installed did you perform a "zero current calibration" and when batteries were fully charged a 100% SOC sync?

[Toy4Rick]

Originally Posted by camaraderie

Ummm check what you posted 12.83 V is MORE than 100% charge and indicates a surface charge still on the plates. 12.7 or perhaps a very little bit higher is 100% for most AGM's.
If that is correct... and not a typo...you have no drain. You do have a problem with your initial set up parameters which you should re visit.

Per the AGM battery Mfg, anything over 13v is fully charged. Also, I have checked the settings more than once, per the Victron docs, and everything appears to be set correctly.

If it is a typo ...the next step is pulling all your dc fuses one at a time while watching the CURRENT drain on you meter. when you eliminate most of the drain...you've found your culprit. If you are down to 89% in a week you'll be down 44% in a month when with disconnected AGM's you should be losing less than 5% max.

TY, great suggestion

Also making sure...you do have your cutoff switch on the negative battery terminal right? And no other negative wires other than the one to your shunt are on the batteries right? You're not just using the mfr battery cut off switch right?

Not sure I'm following. Are you referring to the Battery Disconnect Switch? If so that is a positive lead and not a negative lead and yes, it's all FR wiring.

All I installed was a neg to neg, pos to pos and a neg from battery 2 to the Victron shunt. Attached is how it's wired

Good luck!BTW...who makes 125amp hour AGM batteries?[/QUOTE]

Here are the batteries - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Toy4Rick]

Originally Posted by TitanMike

It may be possible the SOC percentage is affected by the discharge floor you have set.

I recall reading something to that effect when I set up my Victron BMV. Check the printed manual as well as notes in app when in settings and adjusting the discharge floor

Also, when yours was installed did you perform a "zero current calibration" and when batteries were fully charged a 100% SOC sync?

I'll review the discharge floor setting, it's currently at the default

Yes I did a SOC sync, no did not perform the zero current calibration, will do that tomorrow

Edit: Performed the zero current calibration. After doing a bunch more research, even on the victron forum, the settings are all over the place... uggggghh

Attached is what I have set currently

Thank you

[Theo]

Rick -

What is below is applicable to flooded lead-acid batteries (FLA). Your AGMs are sealed lead-acid (SLA) batteries so the parameters below should be similar. The parameter info will help to make sure that the BMV is automatically synchronized properly and that the SOC reflects an accurate percent.

To make sure your BMV settings are accurate, you will need to consult your charger's specifications. Typically, chargers have three phases: bulk, absorption and float. Each phase sends a different voltage to your batteries. Your "Charged voltage" setting should be set to the voltage coming from your charger after it transitions to the float phase (battery is fully charged). If your float voltage is 13.2V, typically the "Charged voltage" would be set to about 13.0V (or about 0.2V below the float voltage). In your thumbnail, I believe your 14.1V is your bulk voltage, not your float voltage.

Also, the "Tail current" should be set to the percent of your 250Ah capacity that represents the float current value shown on the BMV when you have entered the float phase. Remember, it is expressed as a percent of your 250Ah battery capacity, and is typically somewhat less than 1.0A. I have a 208Ah battery bank and my tail current is about 0.7A. However, the lowest the tail current percent parameter can go is 0.5% which, for my battery, is calculated to be 1.04A; this works pretty well for my case. But, YMMV, so the best way to set this parameter is to watch the charging current on the BMV about 10-min after your charger switches into the float phase and then do the percent calculation. In your thumbnail, your tail current of 2.00% (or 5.0A) seems high.

Finally, you should adjust the "Charged detection time" parameter. This parameter specifies how long BOTH the "Charged voltage" AND the "Tail current" parameters MUST be met (simultaneously) for the BMV to consider the batteries fully charged and, therefore, automatically synchronize the SOC to 100%. I have mine set to 5-minutes, which seems to work reliably. Your charged detection at 3-minutes seems about right.

I found the following video by Johannes of Victron to be invaluable in setting and explaining the BMV-712 parameters for both FLA and LiFePo batteries:

https://www.youtube.com/watch?v=mEN15Z_S4kE&t=759s

HTH!

[Toy4Rick]

Quick update...

After nearly 2 weeks now, battery level is at 95%, not on shore power, BDS off.

I believe my issue was 2-fold

1. For batteries running in parallel, all positive cables goes to the first battery in the group, ground connects to the last battery in the group. (I had both on the same battery)

2. Minor tweaks to the Victron app and setup

Thanks everyone for the great support and suggestions

Happy trails