I certainly recommend that you upgrade your battery bank; this may end up being required if, after a battery test, you discover that you need a new battery. Had an old Plymouth. No 12-volt battery will remain at over 14 … Sounds like the supply wire - either positive or negative - has a bad connection, probably at the panel. I recently bought a new battery (200Ah) Wich I have cycled a couple of times now and when I have no load and fully charged it sits around 13.1V. I cycled it around 8 times with 7A because it sitting in the shelf a lot and now it stays idle 13.5V. I was just wondering if from experience that big a volt drop is usual for 21 amps load or a sign of an undersized cable. Don't get excited about V at this point, just try to remain aware of how much you're taking from the batt. Voltage drop under load 08-25-2018, 09:43 PM I have a front wheel drive electric diy bike running of 4 12v battery in series (soon to be 8 12v battery 4-4 in series) it runs quite well getting up to about 40kmph just by itself but the voltage seems to drop from 51volts(fully charged) to 46 volts when any throttle is applied. If the voltage is below 12.6v it indicates that the battery isnt fully charged or has a fault. I turned them off as I heard dropping before 12.30 could damage the battery. Title says it all. That's normal at AGM. I've read that 11.9v is a good minimum voltage to stay above. Multiplus II BMZ ESS Low Battery Shut down. If it is without the controller applied then the question should be how long has the battery rested before taking that reading. Make sure its fused. JavaScript is disabled. You're trying to find where the voltage has a large drop on the way towards the stereo.-Don- Reno, NV Should I stop at 11.9v under load, or will I be able to go lower than 11.9v if it's under a load? Is it just this pump, circuit or do you loose 12.4 V throughout the vessel? You can put the battery under load test and it should return back to the proper voltage in the green range after the load test. I used it a couple of times to test it. Well, this is 50% less than what the transformer is rated to handle. If we follow the paper it claims this battery would be at approx 13% SOC under a 20 hour load at 11.7V. Think like an electron, if you can't get though, you don't.. A forum community dedicated to Sailing enthusiasts. A good fully charged battery should only drop about .2-.4 volts under the load and hold at that level. 1. And oh, I note you have User-defined your V charge settings to higher levels. I’ve just installed a 300w solar panel and 100/20 MPPT smart to my van with a 12v 95ah class A AGM battery. It's worth questioning if "when not in use" means resting though or just not pulling a load with the controller applied. My question: I know that battery voltages drop when under a load. I checked the open voltage at the supply wire before splicing it to the pump's wires, and it reads 12.4V. The batteries are of unknown age and rated for 550 CCA. Start with the battery, checking for full voltage. Didn't get a chance to test it yesterday as I'd hoped, but just a little more info: I'm inclined to think it's an issue with the panel the pump and tillerpilot are connected to. Do this 3 to 4 times and your battery will get better. If the voltage across the battery is good, move on down the circuit (wires) until you get to zero. Had this problem 2x now. At 9V it will drop right away under the same loading current. I think I have been over thinking this. For a better experience, please enable JavaScript in your browser before proceeding. @Sampeett I agree that your battery resting voltage appears high; normal resting voltage of an AGM battery is typically around ~12.8v. At its 12V mark, you can see there is a "tipping point" where the voltage goes from relatively constant to plummeting. I have a pair of 12 volt deep discharge batteries wired in parallel that drop from 12.6 to 11.6 volts at their terminals while supplying about 140 amps to an inverter to run a microwave for 20 seconds. I'm using a 12v AGM deep cycle battery. At 11V it is almost going straight down. 3.9K views Bad connection(s) somewhere along the way most likely. Connect the multimeter probes to the car battery. Resting fully charged 12-volt batteries are around 12.8-12.9 volts, and flat dead ones are at 12.0 volts, so 12.4 volts on a resting battery means it's about 50% charged. I'm replacing my broken freshwater pump (now realizing the breakage was probably related to this until now undiscovered electrical problem). Current Visibility: 4eb7bd94-abd0-4c22-8c91-1c8fffabdd1d.jpeg, Viewable by moderators and the original poster, Please help us Answer the Unanswered Questions. The best is, wait for a sunny day and then pull some amps to discharge and let it charge up again. With a float voltage of 13.8v that reading of 13.77v where ever it was taken is very close to the target float voltage. Had to leave before it was dark enough to see if those lights are working, which might confirm my panel wiring theory. For your battery to pass a load test, the multimeter must read between 9.5 to 10.5 volts straight for 30 seconds when the battery is tested. Using the above example of a 50W light we now know it draws 4.17A, so if we were to use a 0.5mm² cable which has a resistance of 0.037 W /m and its total length from battery positive back to battery negative was 5m, then the voltage drop would be: V drop = … The battery needs to be fully charged to perform a load test accurately. Battery terminal would pass small amps and big amps but horn was just the right draw to sizzle. As a battery is charged the indicated voltage increases and, as discharging occurs, the indicated voltage decreases. You can get it tested like this with these at most repair shops. sorry for all these questions, I am very new to this. Yours is just rolling out of bed.. :). Akin to an athlete running a race, but limbering-up beforehand. But don't go beyond 10.5V. I did read an article saying 13.8 was the float state of charge? Battery voltage drop under load? Best was to isolate the ground is to pull a temporary new ground wire to the pump, If everything's hunky dory then its the ground path. This behavior is significantly less when using an LFP battery, but still present - it's simply how a battery behaves. Many batt makers actually publish info saying that full rated batt capacity isn't developed until subjected to quite a few cycles. If the battery begins to hold and then steadily drops in voltage, there is a problem. Therefore when measured at the output, although the output might show a full 310V (due to the 12V peaks), but under load this might quickly drop to 150V, since the average supply at … Sounds more like a dead battery. This applies a load to the battery. In this example, one digital multimeter would display the voltage loss between the battery and the load, the other would show the voltage loss from the ground side of the load to the battery. Battery voltage drop under load - posted in ATM, Optics and DIY Forum: Hi, I have a CCD in which the cooler draws around 3.6 A (@12 V) for a short time every second (e. g., the camera cooler remains idle for lets say 0.7 s and then draws 3.6 A for 0.3 s). For example, for a 10% drop below the bulb's rated voltage, the current only drops about 5%. Now,the multi-meter will display the battery voltage under loaded condition. Percentage of Charge 12 Volt Battery Voltage Specific Gravity 100 12.70 1.265 Dropping under load, however, is exactly how it works... when you apply a load to a battery, the voltage will drop. And your tiny Wh history isn't helping do that. I suggest reaching out to your battery manufacturer regarding this, or taking the battery and having it tested. The voltage doesn’t have to differ much from 12.6v for it to indicate a discharged battery. Circuits on one of them work fine (cabin lights, nav lights, depth, radio, accessory sockets). It looks like your battery has lost a serious amount of capacity to drop that much voltage with a load that small. If there was that high a resistance in the conductor, the fuse should blow (if there is one) or if it's a 20amp fuse on a 5amp pump or that last strand should melt. Conducting a Voltage Drop Test. So far, so good. Note: If you are using a smart or automatic charger and your Step # 1 voltage reading is below about 6.5 volts, then you will need to hook up the battery in parallel with another battery … It is a 5% drop between the intake voltage source and the load point, not 5% drop between unloaded and loaded voltage. When used, the SmartShunt measures about 900W (and a healthy 86A) but the battery voltage drops down to 10.5 under that load. Chesapeake Bay Eats restaurant review spreadsheet, https://m.youtube.com/channel/UCqO0_5ifYcTzOP477-Su6Fg, VerticalScope Inc., 111 Peter Street, Suite 901, Toronto, Ontario, M5V 2H1, Canada. Since 10.5V is the lowest the cells could handle before taking damage (Discharged my little one to 9V accidentally but charged it directly). I certainly recommend that you upgrade your battery bank; this may end up being required if, after a battery test, you discover that you need a new battery. If the battery has not passed the load test, remove the load, wait ten minutes, and measure the state-of-charge. A 12W, 12V incandescent lamp makes a good 1A load, since its resistance drops as the voltage drops, tending to keep the current more constant as the battery discharges, and as a bonus, it gives a visual indication of the discharge state. Voltage when the car is starting A good fully charged battery should read ~12v and not drop below 10v over the period of 15sec while cranking. It only takes one strand of wire connected for the voltage to pass, but it will not carry the required current for the pump to run. ... switch or connection. 12-08-2012, 01:05 PM Hi Everyone, I just got my system up and running two days ago so I … A small inverter plugged into the 12v cig lighter with its thin wire, will show a big voltage drop under load, but the same inverter with the same load, clamped right to the battery will show much less voltage drop under load. I did not measure the voltage at the supply, just at the load point. Both the pump and the main feed from the battery. If old syle fuses corrode emery cloth both the ends and replace in scraped cleaned fittings ,.Crud under screws need cleaning too. Hey, 13.8V at idle of a completely new battery is fine. (Your battery should have a minimum of 12.4 volts.) With experience, one can accurately determine state of charge using a voltmeter. So, in summary: Battery voltage dropping under load is normal and expected. Try to charge the battery with the 12 volt charger. Unexplained Voltage drop in my system under no load, need some advice. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more! Poor grounds can be confusing. I have, I guess two problems, one being the voltage seems very high (13.77) when not in use? \$\begingroup\$ @Karn The two quantities are interlinked, the voltage will drop as you use up the battery's stored energy. So you have to know the circumstances. Second, when I first installed the system the battery seemed to sit at 12.8 but after loading the system for 30mins it dropped to 12.6 then by one hour 12.40 to which I turned the load off! Notice 100% is given as an open cell voltage and all other as under load. It is very strange as the battery is brand new, any ideas as to why is drops so fast under load? If that doesnt work take a new Pos wire to it. One more thing to check is the fuse. Your high battery resting voltage is probably not normal, so please check with your battery manufacturer regarding the expected resting voltage of your battery, and then -unless they say that ~13.7v is normal- go have that battery checked. See photos. At 12.2v the battery is in effect 50% discharged. I don’t really understand how the MPPT works. 1) With the voltmeter connected to battery, and key and engine off, record a "base" voltage reading. Original wire on my boat, can't blame it for dying after nearly 40yrs. 85% SoC – 5.25A Load – Volts =12.52V It said the current was 1.9amps be pulled. I have had a partly blown fuse which gave the same symptoms had me tearing my hair out for hours. Turned out to be corrosion under the connection to the ground bus.