Batteries self discharge to dead even with voltage cut off in place

[Emtmark]

I have three of the valance Wil P specials in parallel for my camping trailer. It serves the fridge and my cpap needs a few led strips and charging phone duties. I have an aili shunt for external monitoring, a Victron solar charge controller for field recharging and a renogy dc/dc for tow charging. At home I have a ctek life charger that I can plug in for driveway duty. Everything is off when I’m home as in the fridge is unplugged and the power ports are switched off. The only draws are the Victron battery protect which sits between battery bank and 12 station distrib panel and the Victron solar charger which some load circut is the fridge (unplugged).

Issue:

I’m trying to calibrate the aili shunt. The batteries die even with the cut off voltages set at 11.5volts.

Method:
Charge fully the pack with the ctek until it’s not taking any more charge per the aili shunt and the farthest green light on the charger is lit

Plug in fridge: onboard fridge disconnect is set at 10.7, Victron load cutoff set at 11.5v, battery protect not in fridge circut but it’s cut off is set at 12. Theoretically my cpap will stop before the fridge does making fridge the priority. The renogy dc/dc is off and no power fro
Tow vehicle it’s just sitting there.

I’m trying to discharge to disconnect or 11.5v with the shunt set to 500 amp hours to see how many amp hours I have to play with to set the shunts counter at for an accurate displayed percentage and graph.

This is the second attempt to do so with the first cut off set to 10.7 mimicking the fridge cut off. I came home after a few days and the valance bms had cut power itself and batteries showed 1.5v post to post. Mild panic, woke up batteries with 12 volt 2amp to 12volts post to post then on ctek charger to full. Then repeat discharge with above numbers. Again found pack dead as shit aili meter off everything dead. Currently waking up my pack again as we speak.

Wtf!?

 

[Emtmark]

More

 

[Emtmark]

Battery + to resettable breaker to dogbone, connections to dogbone are all pos shunt, Victron solar charger batter lead, Victron battery protect and pos to distribution block, pos ctek cable, pos dc/dc renogy cable

Other Pos is from Pv goes to Victron and pos to fridge from Victron

Neg batt to shunt, dog bone ground for everything except pv (goes to Victron), fridge (goes to Victron)

 

[Emtmark]

Charged with dumb charger 12v at 10 amps until batt pack was at 12.02 volts. The ctek finally didn’t error out and it’s charging it’s built in profile at 4.5a. So I’ll bring it back from the dead and try it again with the new batt cut offs at 12volts for solar load circut (fridge) and vict batt protect (everything else)

 

[HRTKD]

I'm confused on what your problem is. I'll try to summarize what I think you're worried about: The Valence batteries aren't cutting off discharge when you think they should.

 

[Emtmark]

Yes, that and when I think I’ve set the equipment to stop delivering power, cut off the loads, the battery with no load keeps discharging. As for the confusing part, yes, full responsibility, that’s why I’m in the. EE guy section so I can learn how to assess evaluate and speak more articulately about my set up and problems.

 

[MisterSandals]

Do the batteries hold a charge on their own (nothing attached)?

It looks like there are a few little draws left on your system, like the cig lighter port has an led, the SCC is alive an probably has Bluetooth running or listening for a connection, the Ali shunt uses a smidge…

Running 24/7 on a battery at less than 5% SoC, it’s not that surprising the BMShits lvd.

Maybe you have other things like a CO2 sensor, radio, tv,… powered off but listening for remote control input. These draw something even when turned off.

Sorry I f I am misunderstanding your situation.

 

[Emtmark]

Do the batteries hold a charge on their own (nothing attached)?

It looks like there are a few little draws left on your system, like the cig lighter port has an led, the SCC is alive an probably has Bluetooth running or listening for a connection, the Ali shunt uses a smidge…

Running 24/7 on a battery at less than 5% SoC, it’s not that surprising the BMShits lvd.

Maybe you have other things like a CO2 sensor, radio, tv,… powered off but listening for remote control input. These draw something even when turned off.

Sorry I f I am misunderstanding your situation.

Cig port is controlled by a switch so what minimal draw there is zeroed, the two Victron components have Bluetooth which historically is ultra low draw there is nothing else connected when in driveway so no draws there that I can see. I will charge up the pack until there are no amps going in from ctek charger and then trip the breaker. I’ll wait an hour to check voltage then wait a week to see if the voltage has changed. The last time I did this it was the same 13.87 to 13.80 over the week for the three batteries. But stuff may have changed.since

 

[HRTKD]

When the CTEK is finished, what is the voltage at the battery?

 

[Emtmark]

When the CTEK is finished, what is the voltage at the battery?

Last night the last light on the ctek was lit it’s a green battery icon. The pos input on the charger showed no amp movement and the aili showed no up arrow the battery pack measured at 14.0 volts. I unplugged the ctek from the shore line and trailer was now stand alone no power going in and only draw being the two Victron blue tooth capable devices. After about an hour voltage was down to 13.85 there was a micro draw measured at 0.08a on the battery pos cable I’m assuming that is the two Victron devices running their led lights and blue tooth’s circuits. I’ll measure voltage again tonight

The three batteries in parallel should be 120 ah, when I set the aili at 500 and monitor the charging current via shunt it’s counting up to 402 amp hours!?

 

[Emtmark]

 

[Emtmark]

According to the Victron it’s charging up to 14.47 and resting at 13.6

I can un plug and see if it drops

 

[Emtmark]

I'm confused on what your problem is. I'll try to summarize what I think you're worried about: The Valence batteries aren't cutting off discharge when you think they should.

Yes spot on, and furthermore the Victron low voltage shut off is not shutting off when the input voyage gets to 12 volts either?

The SCC had a load output shut off set to 12 volts it’s only job is to run the fridge. The low volt cut off supplies the fuse panel and it is also set to 12 volts.

When I leave everything on fridge and battery heater. The voltage slowly drops over the week. I expect that the low voltage would trigger the shut offs. When I see the trailer dead I plug in the shore line to start sharing it back up. However the shoreline charger the ctek won’t charge because the batteries are all sitting at 8-10 volts and won’t accept the input. I have to place the pack on a 12v 750mA dumb charger to bring up the pack to 11volts before the ctek will take over and begin charging the batteries.

So batteries are continuing to discharge past the low voltage cut offs to the point that the BMS will not allow them to charge.

I’m trying to set it up so that I won’t ever have to have the 750mA charger to “wake up” my valance batteries.

 

[HRTKD]

I looked at your wiring again and I don't see anything that I can blame for the voltage dropping so low. But you didn't show a picture of your battery bank. Can you show that?

Post a picture of the VictronConnect screen where it shows the Load Output parameter settings. If you have access to the BMS, show the low voltage disconnect parameter there.

Assuming that the solar charge controller and the BMS are working properly, the only thing I can come up with is that here is a load that doesn't go through the load port on the solar charge controller or some load is bypassing the BMS (unlikely).

If you have a DC clamp-on ammeter, connect it in different places to see if you can find a parasitic load.

 

[Emtmark]

I looked at your wiring again and I don't see anything that I can blame for the voltage dropping so low. But you didn't show a picture of your battery bank. Can you show that?

Post a picture of the VictronConnect screen where it shows the Load Output parameter settings. If you have access to the BMS, show the low voltage disconnect parameter there.

Assuming that the solar charge controller and the BMS are working properly, the only thing I can come up with is that here is a load that doesn't go through the load port on the solar charge controller or some load is bypassing the BMS (unlikely).

If you have a DC clamp-on ammeter, connect it in different places to see if you can find a parasitic load.

looked at your wiring again and I don't see anything that I can blame for the voltage dropping so low. But you didn't show a picture of your battery bank. Can you show that?

Picture of bank added, they are wired in parallel with the positive on the right most battery and the negative on the left most connecting it to the 100a breaker and shunt respectively.

Post a picture of the VictronConnect screen where it shows the Load Output parameter settings.

Will do I’m at work right now.

If you have access to the BMS, show the low voltage disconnect parameter there.

I don’t they were ebay buys and the cables were cut pta

Assuming that the solar charge controller and the BMS are working properly, the only thing I can come up with is that here is a load that doesn't go through the load port on the solar charge controller or some load is bypassing the BMS (unlikely).

Every thing I have goes through a positive bus bar then through the LVDC or SCC

If you have a DC clamp-on ammeter, connect it in different places to see if you can find a parasitic load.

I do have one I will play with it tomorrow morning when I’m home.

 

[HRTKD]

It's probably not the problem but keep an eye on that 100 amp breaker on the battery. It may be an audio quality breaker. We've seen fuses similar to the one you have that don't hold up. In one case, the fuse holder melted.

The way you have the three batteries wired in parallel isn't optimal. The middle battery may not get charged to the same state of charge s the outer batteries. Keep an eye on it. Access to the BMS would help confirm if there is (or isn't) a problem. Since you don't have that, check it with the voltmeter.

 

[Emtmark]

It's probably not the problem but keep an eye on that 100 amp breaker on the battery. It may be an audio quality breaker. We've seen fuses similar to the one you have that don't hold up. In one case, the fuse holder melted.

The way you have the three batteries wired in parallel isn't optimal. The middle battery may not get charged to the same state of charge s the outer batteries. Keep an eye on it. Access to the BMS would help confirm if there is (or isn't) a problem. Since you don't have that, check it with the voltmeter.

Check on it-> disconnect all batteries and test individual batteries to verify similar voltages? Confirm if that was the instruction please.

Also what configuration would be optimal?

I have no inverter to run everything on the trailer is 12 volt. Would one more or less battery be better than the three I have?

I guess I’m searching for the whys here.

Thank you

 

[HRTKD]

Check on it-> disconnect all batteries and test individual batteries to verify similar voltages? Confirm if that was the instruction please.

Also what configuration would be optimal?

I have no inverter to run everything on the trailer is 12 volt. Would one more or less battery be better than the three I have?

I guess I’m searching for the whys here.

Thank you

You can test the voltage of each battery without disconnecting the cables. Place the voltmeter probes on the battery terminals (under the cable lugs).

The "Why" is explained in this thread. The gentleman that created the thread used math to determine the optimal wiring configurations.

Calculation of parallel string battery currents

Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current...

diysolarforum.com

 

[Emtmark]

great thread, I'm goin going to reread it again im sure they covered a three battery set up in there somewhere and I'll have to redo my battery wires.

Forgive the naiveite of this question. I'm truly seeking to understand. If i contact the positive and negative posts on a battery with my multimeter it will only read that particular batteries voltage. Despite that the battery being measured is connected to another batteries positive and negative posts via conductive cables.?

To my mind the electricity from the other battery would be conducted to my test leads from the other battery unless i severed the connection by removing the cables from each battery but i am willing to try and report back.

 

[Emtmark]

ok, i re read the thread I have to move my load connections to 1/3 the distance on the diagonal as long as all the connecting cables are the same and the same length. got that. this is getting juicy now

maybe this will explain why the aili amp meter is not reading the correct amps as well.

Excited to mess around tomorrow i hope i have the time lol