discharge level Image

discharge level

Using "battery protect" product to prevent battery bank over discharge by inverter

I have a very modest 480W solar 12V PV system, using MPPT charge controller, AGM batteries and a small (300W ) inverter (no victron products in use, unfortunately).

Like most similar systems, small DC loads can be managed (shut off, timed etc) by using the load output terminals of the solar charge controller.

To further protect the battery bank from over discharge, can the battery protect product be used to prevent the DC inverter draining the battery bank down to the inverter cut off voltage (10.5V)?


Many thanks

Grahame

artyjones12 asked
Matthias Lange - DE answered ·

1 Answer

BMV712 shows minus current when charging

Hello brains trust,

I have a BMV712 for a dual battery system in my car and I’m using an enerdrive 40amp dc2dc charging unit.
I have connected all cables, one coming off the neg of the 2nd battery to the battery side of the shunt and then on the load side I have a cable going to a bus bar and a cable going to the neg of the charger.
Could anyone help with why the BMV would be showing a minus amps (-2.3amps for example) when the charger is charging?
I have no loads connected to the bus bar and the battery is at 100%. The 2 other cables coming off the neg post are a temp sensor for the charger and a earth to the chassis.

TIA,

David

[image]

davidtm274 asked
klim8skeptic commented ·

1 Answer

Max discharge current for AGM Battery bank

Hi All

I have a 6ooAh AGM batt bank on a sailing boat (3 x 200Ah)

What is the max safe current drain for said bank, especially with longevity in mind?

Reason:

I have a 1,6kW 230V AC watermaker and would like to run it off the batt bank through an inverter for about 30min at a time. (and some other power tools on the odd occasion)

I do have a generator so that watermaker can be run for longer periods but for 30min (making 50L of water), it would be very convenient to not use the generator, not to mention saving petrol, fumes, and noise.

I have 640W solar and 300W wind gen which should be more than enough to deal with the discharge, I believe, on a sunny day.

So, is there a rule of thumb for a max safe discharge current for (AGM in my case) Lead Acid Batteries?

My gut feeling is that 300A for an hour on a 600Ah bank should be safe. But then my 2nd gut will freak out when it sees 200A of discharge on the BMV.. Even 100A is a hell of a lot in my mind.

Regards

christo asked
Bill Nichols edited ·

7 Answers

Battery Cycling Recommendation - 2xPylontech US3000B

I have 2x Pylontech US3000B batteries totalling about 7kwh of storage. I also have grid-assist via a ET112 meter. All connected to a:

venus GX;

multiplus II 3000VA;

MPPT 150/45 with 2000w PV array

MPPT 150/35 with 1500w PV array

Currently: I cycle them ONCE daily, discharging down to 50%SOC around 4am, with a scheduled charge from 6am-4pm. This means the batteries are not discharged during this period ALTHOUGH they are usually as 100%SOC by 10am via solar charging.

Question: Is it advisable to allow a 2nd discharge during the middle of the day to assist the grid during water heating, say at 1-2:30pm?

Regards

bonie-wanda asked

0 Answers

System battery flat, shouldn't the BMV712 relay prevent this?

I did my monthly visit my motorhome in storage. It has two 12V AGM batteries in parallel that are about a year old. When I arrived, the battery bank was discharged and the BMV-712 wasn't lit.

I ran the motorhome's generator (puts out about 30A) and the Victron app was showing an oscillating +0.2 A/-0.2 A line so I'm assuming they were too discharged to be detected by the motorhome's charger. The bank showed a SOC of 100% and voltage of 5.21 after two hours of generator time.

I have the relay setting at 77% to prevent this much of discharge while in storage. Shouldn't this setting cut off all power draws so the battery bank doesn't get this low?

mbutts asked
Justin Cook - Bay Marine Supply USA commented ·

3 Answers

Calculating Starting Battery Size

Hi All,

I have a requirement to supply 3 battery banks to start 4 engines.

Engine 1: 24VDC, 2 x 7.5kW Starters (330ah Victron AGM Battery Bank, Skylla TG 100Amp Charger)

Engine 2: 24VDC, 1 x 6kw Starter (330ah Victron AGM Battery Bank, Skylla TG 100Amp Charger)

Engine 3: 24VDC, 1 x 5.5kw Starter (165ah Victron AGM Battery Bank, Skylla TG 50Amp Charger)

Engine 4: 24VDC, 1 x 5kw Starter (90ah Victron AGM Battery Bank, Skylla TG 35Amp Charger)

I have purchased batteries to suit those recommended by the engine supplier however I need to prove that the batteries are large enough to cope with the starting currents of each engine.

Each engine needs to be able to crank for maximum of 10 seconds for 6 start attempts.


How do I calculate this?


I also need to prove the batteries can be recharged in less than 6 hours.

I calculated the charger size with the following formula:

ah of battery * 40% charger losses / charger current


Many Thanks,


MarineUK





marineuk asked
ripper edited ·

1 Answer

Does MPPT 100/20 load output allow bidirectional current (from AC charger)

Hi,

I have a solar array in my rv charging a deep cycle battety through a smartSolar 100/20 charge controller. I also have a Progressive Dynamics PD4000 battery charger/power distribution block installed. I would like to use the load output to avoid over-discharge of my battery. However, I also would like to be able to use the PD4000 to charge the battery when AC power is available. My question is, can I connect the load output of the charge controller to the battery terminals of the PD4000? Under normal operation current will flow from the load output to the DC distribution block of the PD4000 and on to the various load circuits. When connected to AC power, current could flow in both directions, from the PD4000 charger to the battery through the load output or from the battery to the load. Can I do this or do I need to use the load output to control a relay/SSR connecting the battery to the PD4000?

smbnnt asked
markcx answered ·

3 Answers

BMV shows discharge while charging

Have connected a 5KW Honda generator and after the power line on a Multiplus 48/5000, and in both cases, the batteries start to discharge. Have checked all connections of Multiplus and BMV with the suppliers and, everything seems normal. I'm off-grid and have 8 Vicron 220AH batteries. Can someone help? Thanks.

bernie-bare asked
Daniël Boekel (Victron Energy Staff) commented ·

3 Answers

REC-BMS for Victron / Multiplus 24/3000 / Control Load busbar

Hi,

I'm pretty new to LiFeYPO4 (coming from normal batteries) and I want to build a Victron system using Winston LiFeYPO4 batteries with REC SI BMS for Victron. I intend to build a 2p8s system which is connected to the BMS.

REC BMS communicates with Victron via CAN and CCGX will be configured with DVCC to let the BMS decide the whole charging thing.

My issue is regarding the LOAD:

In all Lithium Victron diagrams (e.g. here) a Smart Battery Protect is used to switch loads on and of. SBP is controlled by VE-BUS BMS via the load disconnect signal. But with REC-BMS I have no clue to accieve this...

Is it possible to use the alarm relay of CCGX? REC BMS also has an optocoupler but the manual says this is only for charging...

My questions are:

Is it correct that in case of undervoltage the inverter of the MPII is switche off via CAN?

Has anybody an idea how to switch of all 24/12v loads in a Victron environment using REC BMS for Victron?

Any ideas appreciated.

Thanks
Peter

pegi asked
nebulight commented ·

2 Answers

Can I control the discharge current from the batteries to load output on my MPPT 100/20 Charge Controller?

I have a MPPT 100/20 Solar Charge Controller connected to Lithium batteries. The load output is connected to my load (a pump).

In the settings I already limited the charging current to 5A. Can I also limit the discharge current from the batteries?


Thank you!

ana-carvalho asked
wkirby answered ·

1 Answer

Help getting the best out of my sodium (salt water) batteries

The System 5.2Kw PV with a Fronius Primo 4-1 inverter interfacing with a Victron MultiPlus 48/5000/70-100 an a CCGX Gateway, 2 x Aquion S30-0080 48v batteries.

I'm new at this. The batteries have only been up and running for 2 months so I'm learning about them every day. I'm trying to get the most out of them, that is charging to 100 % and discharging to near zero every day. However the Victron unit is, I'm sure, preventing this as It's not designed to work with sodium batteries.

My problem is that unless the batteries have a 100% SOC for at least an hour during the day they will only discharge to a relatively high percentage SOC.

In the summer where the batteries have a 100% SOC every day the batteries will discharge to about 11%. ( I was hoping for lower)

At this time of year I'm rarely getting a 100% SOC via Solar and so have to use scheduled charging. However as soon as the charging is finished the discharging starts . But only to about 60-70%.

I'm beginning to think that there is a battery life protection built in to the Victron unit even though it is disabled in the CCGX.

My options/questions:

How do I enable scheduled charging and get the SOC to remail at 100% for at least an hour?

Is there a battery life protection built in within Victron?

Can I turn off battery life protection within the Victron?

As you can see in the first image, as soon as the SOC is 100% for about an hour (10-1100 )the battery will discharge more, down to about 40%. the other attachments show what happens if I can't get that magic hour of 100% the discharge is between 60 to 70%.

If the battery doesn't achieve 100% SOC the I'm left with about 80% SOC

I am planning in the winter to charge the batteries with cheap grid electricity at night, but if I cannot get the !00% SOC to last for more than a few minutes the batteries will never discharge fully, which is one of the reasons I chose the sodium batery.

Any advice gratefully received.

Thanks,

Chris

[image]

[image]

[image]

screenshot-20191020-194346.png(61.5 KiB)

cmorewood asked
cmorewood edited ·

4 Answers

PYLONTECH battery Low Voltage shut down - Multiplus

Good Day

I have a PYLONTECH 8kw 48V battery setup with a Victron Multiplus on ESS, connected to Solar.

One issue I have is that when the mains supply fails and am running on batteries at night, I cannot limit the level of discharge (batteries discharge below 80%).

I tried adjusting the dc input low shutdown on the Multiplus but did not work.

Please advise. I would to limit the battery to lowest 85% discharge level.

moodlyd asked
Guy Stewart (Victron Community Manager) converted comment to answer ·

3 Answers

battery protect BP-220 low voltage disconnect but dont reconnect need help

Hello,


Im new for a solar setup. I managed to do a tesla battery setup work great except for the battery protection.... i set it to 19v disconnect so its the setting 2C, it work so much that it stay disconnected when i take off the 2-1 pin it show E3 even at full battery so i have to disconnect the cable and put back them on it and it work fine... until it reach again low voltage i hope some one can help me. this week end i tought it was the inverter so i changed it.... this morning still same problem

ho yes the inverter has a low disconnect at 19.6v


[image]

[image]

stickygreen0 asked
nebulight commented ·

2 Answers

Battery will not discharge beyond 65%

I have a 24kwh battery built from a Nissan leaf. I have added a Batrium BMS system. My battery will not discharge beyond 65%. The settings in the ess are set to 20% in the discharge setting.

Anyone help. It's rather frustrating.i have been over and over the settings


crop1 asked
crop1 commented ·

2 Answers

Can I revive a "Deeply Discharged" 200Ah 12V Smart Lithium Battery?

I have the 200Ah LiFePO4 as the house battery on my bus conversion. It is connected to a BMS 12/200. I was out of the country for 5 weeks. After a couple of weeks it was clear that the location was not getting enough solar to keep up with the charge on the system, so I had someone go into the bus and turn off all of my main disconnects for the battery itself, the MultiPlus inverter/charger, the BlueSolar MPPT charger, and the connection to the starter battery for alternator charging. It only had about a 13.5V charge on it when I had them cut everything, or so I thought, they didn't fully disconnect everything as I had asked.

I came back to find the battery at 8.73V, with the cells at 2.29V, 1.84V, 2.14V, and 2.46V.

I thought the BMS would protect from over-discharging... but that's a different question.

Is this battery a lost cause, or would it be possible to revive?

shiftynick asked
adev commented ·

3 Answers

Uneven Battery Bank Discharge Current

I have two battery banks of different sizes, the first supplying a DC panel with 2 X 100AH gel batteries and a Skylla 24VDC 50A charger, the second supplying a DC panel with 8 X 100AH gel batteries and a Skylla 24VDC 100A charger.


Coincidently, the larger of the two banks has the least working load at 17A and the first and smaller bank has a larger working load at 22.5A.


There is a consumer which is supplied a main supply from the first panel and a backup from the second panel. Both supplies are terminated and "on" at the same time through separate breakers. When I measure the DC discharge current at this consumer at each breaker I thought I would see an even load as the end consumer load is the same but this is not the case. The higher capacity battery bank and charger is supplying this consumer with 11A and the smaller capacity battery bank and charger is supplying the same consumer with 6.5A.


The only conclusion that I can infer from the tests I have done is that the larger capacity bank will supply the load unevenly and greater than the smaller capacity bank. Could someone confirm that, possibly show a formula that one could calculate these differences?

almcluckie asked
almcluckie commented ·

3 Answers

Overload issue: 125 amps/3400 watt drawn from a 1200 watt/45 amp oven

Hallo !

I have a 1200 watt oven that has drawed that (almost 1200 watts and approx. 45 amps) every time I have switched it on. (I bought the oven new last summer)

However, the last three times I have used the oven has used almost 3600 watts at about 125 Amps (!!).

-I get an "Overload L1" message followed by "Recovery" every time (VE.Bus).


[image]



What could be the cause of this?

I dont understand how or why this could happen (the only other appliance i a fridge that pulls about 70 watts for a few minutes every hour).


(I have an offgrid Easysolar 3kVA (24/3000 - 150/70) with 10 kW lithium ion and 1,8 kW panels.).


Alittle disturbing that my system draws almot three times more amps than I expect, so would greatly appreciate views/solutions to this.


Eric




eric-heiberg asked
eric-heiberg commented ·

2 Answers

BYD batteries losing charge?

Hey all

So over the last couple of nights, my BYD B-Box 10.24kwh has started losing charge overnight.

A view over the last 7 days clearly shows this.

[image]


Victron 48/5000/70-100, running with a CCGX and a SmartSolar MPPT. ESS is running in Optimised mode with BatteryLife, Min SOC at the moment is 70% (Last night it was 65%)

Also noticed that I put nearly 7kwh of solar into the battery today for only a 29% climb in battery SoC.

[image]

[image]

There's no DC consumers on the system.

Batteries are 3 weeks old now.

[image]

Is this normal behaviour or do I have a possibly faulty battery/bms?


Thanks

sinbad asked
sinbad commented ·

2 Answers

Set a SOC for the morning consumption

I have an ESS and I would like to set a specific SOC at 07:00 so the batteries are able to supply the loads before the PV can do it.

I have constant loads during the night and I would like to tell the battery: Keep 70% for the morning, and the remaining 25-30% can be discharged equally during the night.

Is there a possibility of doing that? I have seen the charging schedule, but this way I won't be able to supply a part of the night consumption.


Thanks and regards

luis asked
boekel commented ·

1 Answer

Discharge level for generator to start charging

Hello. What is the optimum level of discharge of batteries to set for auxiliary generator to automatically start charging?

matt-b asked
matt-b commented ·

1 Answer

23 Posts
48 Users
0 Followers

Topic Experts

There are no topic experts for this topic. Participate in the posts in this topic to earn reputation and become an expert.