Ampster
Renewable Energy Hobbyist
I realize that is a simplified diagram but typically there would be either a contactor for a BMS or a FEat based BMS in that path. The BMS protects the battery from overcharge or over discharge and cell imbalances.
Battery monitor not showing any charge has occurred. Bad Batteries?
- Thread starter Soggy Man
- Start date
I realize that is a simplified diagram but typically there would be either a contactor for a BMS or a FEat based BMS in that path. The BMS protects the battery from overcharge or over discharge and cell imbalances.
mikefitz
Solar Wizard
- Joined
- May 28, 2020
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Thats good, but check where the chargers are connected. Its possible some/all the charger negatives are connected direct to the battery.
Mike
I see. So maybe once I correct the charger connection to the shut/buss bar for the negative and the positive from the charger to the positive of the battery..it should show the correct ah in the battery bank?
sunshine_eggo
Happy Breffast!
As long as what you describe puts the shunt between the charger and the battery, yes.
The shunt is just a calibrated resistor. It's voltage changes as current passes through it, typically ±0.075V per 500A. A sensor check for the voltage drop across the shunt, and it determines the current passing through it.
If all loads or sources do not pass through the shunt, it can't calculate the correct net current flow.
mikefitz
Solar Wizard
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- May 28, 2020
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It's not simplified, the op is using 4 ready built lithium batteries, the BMS in inside the battery case, one BMS per battery
Ampster
Renewable Energy Hobbyist
Sorry for the insult. The diagram does not show where the charge source is connected. That is the only reason I called it simplified. Perhaps I could have said that the diagram did not show connection to charging source. If I understand the discussion that may be the fundamental issue causing the battery to appear to be depleted.
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Geokilroy
New Member
If I read his OP correctly he has the charger on just the terminals of the same battery. I think he should leave the positive charge cable on that battery and change the neg charge cable to the shunt output or to the neg buss bar. Only needs to change one cable. (Need pics to verify how he is hooked up now)
I did have the charger on the battery terminals. I can't reach the shunt/buss bar at this time. Soon I'll be back at the shop where I can remove some things and connect the charger positive to the first battery in the bank and connect the negative to the negative buss bar.
I still don't under stand why the monitor is not showing the correct amp hours in the bank if the battery bank is fully charged. I removed the charger and according to the victron charger info the bank is charged. but the amp hours have not changed on the monitor The voltage is showing 13.1 but amp hours showing 65ah. How am I to know what is left in the bank?
Ampster
Renewable Energy Hobbyist
As mentioned earlier the shunt did not see the current that went into battery. It may take a charge cycle for it to reset. The shunt apparently does not use voltage as the only measure of SOC. If it sees current going into battery and voltage reaches setting it probably will reset to 100 percent. Try using battery for a little while then see if a short charge will reset it.
Geokilroy
New Member
As I stated before: If your charge leads are not hooked up properly, the shunt cannot read your charger input. Only need to change the NEG charger lead to the Neg output of entire battery pack after the shunt. Your battery pack is an entire package not just one cell or one battery. The shunt is only a counter to count amps either in or out. All of the power from or to the battery goes thru the NEG terminal. The charger must be after the shunt!!!! This is so the shunt can read amps in and out of the battery. If you do not put your charger neg after the shunt it cannot read the input charge to your battery. This is why your system is only counting amps out and not counting amps in (charging). See your manual.
I think I understand it now. I'll get it connected correctly and give a it a go. Thanks very much.
Ok. So I have corrected the connection of the charger. Positive to battery positive terminal and negative to negative buss bar which has the shunt as well. It started charging at 25 amps and the amp hour reading on the monitor which was showing 55 ah started to increase almost immediately. It had increased to 77ah after about 1.5 hours. I disconnected each battery from one another before connecting the charger. I left the charger on through the night. This morning it shows 66ah and 13.1v.
I'm stuck again. Should I try to rest the monitor back to 400ah or ignore it or what? The point of having the monitor ..I thought, was to have an idea of what is left to use if I'm camping somewhere.
I'm stuck again. Should I try to rest the monitor back to 400ah or ignore it or what? The point of having the monitor ..I thought, was to have an idea of what is left to use if I'm camping somewhere.
Solar Guppy
Red Cobra Guppy
Yes,
Once you have completed a full charge, reset the monitor to something a bit less than the rated Ah of your battery pack, and moving forward it should track the Ah in and out showing net remaining capacity.
Keep in mind, the monitor can't account for self discharge, efficiency losses of charging and discharging at rates other than the stated capacity which is typically a C rates of 10 to 20.
As your learning, Battery monitors are not gas gauges, they are at best a rough idea of capacity and will drift significantly over time and will need to be periodically reset.
