I have a 400ah lithium bank...4 100ah batteries connected in parallel. All connections were verified by an electrician. I do not have solar installed yet. I have a renogy 40amp dcdc charger connected to the bank. I have a victron ip67 25amp charger connected as well with a Renogy battery monitor. I had sat parked for about one week and depleted the bank down to around 100ah. I started on a short drive with the monitor showing about 85ah remaining in the bank. I drove about three hours with the dcdc charger on. I currently have a reading on the monitor of 75ah/19% remaining. I connected the victron charger and it was set to a lithium profile but now after over 18 hours the charger has switched into storage mode and the monitor shows no change in the remaining amp hours. The charger started in bulk for about 2 hours then switched to absorption overnight and then to storage. The bank does not appear to be taking any charge. Could I have bad batteries or a bad bms in one or all of the batteries? Obviously I can't power a refrigerator or much else with 75ah on a 400ah bank. I am not sure what to do to check things out. Any ideas?
Battery monitor not showing any charge has occurred. Bad Batteries?
- Thread starter Soggy Man
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John Frum
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This one https://www.renogy.com/500a-battery-monitor-with-shunt/ ?
Has this setup ever worked correctly in its current configuration?
I wonder if your charge sources have bypassed the shunt.
What is the battery voltage?
Has this setup ever worked correctly in its current configuration?
I wonder if your charge sources have bypassed the shunt.
What is the battery voltage?
Yes that is the monitor.
The monitor appeared to be correct showing 400ah and correct voltage upon installation
The shunt is connected at the first battery and the charger is connected at the last battery. I don't know how the chargers could have bypassed the sources...but not sure. I do know that when the dcdc charger is on that sometimes the monitor will flash and show a plus sign but also when the dcdc is on and there is a load such as the refrigerator running it will not flash.
Both the monitor and the charger show 13.7v.
The shunt is on the neg of the first battery then the shut connects to a neg buss bar.
Solar Guppy
Red Cobra Guppy
The charger has to run through the shunt, meaning it connects to buss bar (negative ) and battery positive. The battery negative connects to the other end of the shunt.
The way you have it wired, the charger current is not seen by the monitor, just the current being discharged by the battery.
The way you have it wired, the charger current is not seen by the monitor, just the current being discharged by the battery.
John Frum
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Please provide pictures of your batteries and busbars.
Solar Guppy
Red Cobra Guppy
I have one of these on my golf cart, they use a Hall Sensor and it is installed on the positive of the battery bank, with both the load and charger going though the same direction to the battery.
John Frum
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Interesting, the one that I linked has a shunt.
Solar Guppy
Red Cobra Guppy
Ampster
Renewable Energy Hobbyist
Is it LFP or another Lithium chemistry that has a higher resting voltage? That voltage would be 3.4 volts per cell which is resting for LFP but depleted for other Lithium chemistries.
When you say the charger is set to a Lithium profile do know what that charging voltage is? Did you see what the charging voltage was when in Absorb?
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I see. I have to change it around. It's hard to access now without disassembly of other parts surrounding the electrical set up.
Even if the charger is not connected too the shut would the monitor not still show the amp hours in the battery bank. The monitor is still showing only 75ah.
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It is LFP. The Asorb charging profile is 14.2. I believe the bulk voltage was 13.6
Ampster
Renewable Energy Hobbyist
The good news is 13.7 is the resting voltage for LFP so if I understand your earlier comment correctly to mean the voltage of the batteries is 13.7 volts, the batteries are full and rested at that voltage. Perhaps something has gone wrong with the guessometer, or as @Solar Guppy suggested, it is wired wrong.
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Would the voltage of the batteries be the same if they are all connected in parallel or if one was bad or low would that cause the entire bank to show a lower voltage.
The renogy monitor shows 14.1v but it shows 75ah for the battery amp hours. So could the monitor or shunt be bad?
The renogy monitor shows 14.1v but it shows 75ah for the battery amp hours. So could the monitor or shunt be bad?
Ampster
Renewable Energy Hobbyist
I changed my post to reflect that it was @Solar Guppy who suggested the wiring was wrong and might not be picking up the charge current. Presumably it is showing discharge which is why is is showing a low SOC. I have never seen a shunt or monitor fail where is only shows either discharge or charge. Sometimes they are wired backwards where discharge shows as charge but that does not look like what was happening here.
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I wired my parallel lithiums with shunt on one battery negative and the positive to the other battery. In your case I would have wired the monitor to the away side of the shutnt (even to the busbar) and ran the pos to the furtherest battery. Is this how yours is done? Also when setting up the shunt you either have yo have each battery fully charged or discharged. If fully charged (do one battery at a time) you can set the monitor to the full amperage..400 in your case and at 100%. If totally discharging it pays to monitor the amperage put back into the battery and total this up for all batteries Just because a lithium is advertised at, say 100a/h, doesnt mean it will discharge/charge 100a/h. My ITech batteries 120a/h are only good for 95-100 USEABLE A/H (OVER 12 VOLT). hOPE THIS HELPS.
sunshine_eggo
Happy Breffast!
No. the shunt calculates the net current in and out of the battery. It does not use voltage as that's notoriously inaccurate.
If you only pass the current leaving the battery, the shunt will only show that. It must also see the charge current to determine how many Ah are actually in the battery.
I have the neg on the first battery wired to the shunt B- and the pos on the last or fourth battery wired to the main disconnect switch. The small pos wire on the shunt is wired to the first battery positive terminal. I started with a batteries fully charged and the monitor registered 400ah. I checked all four batteries before install to be 13.1v.
