Is it normal for a new FLA battery to discharge this quick?

neogeo · 05-21-2021, 02:04 PM

Put a new 12V 145AH battery into our camper. We previously had a much lower AH in the camper - we are looking to upgrade to lithium but wanted something to get us through short term over the summer. So, we know how our old battery did and we could boondock in sunny weather for a few days with no problem.

My question - we just installed this battery (its a US Battery) and we were camping this week. We were hooked up to shorepower but wanted to test the battery so tried to run on battery only. It had been installed for a week prior, controller showed fully charged (13.4 volts approx) and we had been in and out using the lights, slide... for a bit on and off during the prior week with no issues.

When we disconnected the battery from shorepower (solar had approx 5 amp coming in), we ran 4 led lights, a propane fridge was on, bath vent fan on med and charging one cell phone on USB charger. So all of that was approx 5 amps per hour draw. The battery though, fell from 100% to 69% in less than 10 minutes. At that point, it stopped falling and charged back up to 90% over the next few hours while we had good solar. But as soon as the sun started to set, the battery again started to fall quick. Within 20 minutes of losing some of our sun, the battery was back down to 73%.

Now - we went back to the place we charged the battery and they looked at the setup and the battery and shrugged and said everything looked fine and the battery was reading fine (they did test it with their tester). I also called US Battery and they said sometimes its not really charged and it has to be discharged and recharged.

Is this normal? Does it take some cycles to reach its potential? Because right now, I don't think this battery would last an evening.

Thanks!!

OYO · 05-21-2021, 03:15 PM

There must/could be a draw you're unaware of.

I'm not an expert, but you'll probably be asked about how you are getting your measurements. Are you using a voltmeter or a true battery monitor that will give you a true state of charge (SOC), draw etc?

neogeo · 05-21-2021, 04:24 PM

Thank you for the reply.

We have a GoPower controller which we know has limitations so we also double check with a multimeter. The voltage reads the same. And we are going to buy a hydrometer to check as well.

We are fairly certain there is no additional draw. The battery percentage / voltage doesn't change until we start turning items on. We left it for 15 minutes with nothing on and it stayed 100%. As soon as we turn on the lights, fan... it starts dropping quick.

TitanMike · 05-21-2021, 04:54 PM

If battery voltage drops quick when loads are applied, using the onboard battery "indicator" it's one of two issues. First is the battery not being fully charged or defective (high internal resistance). Next is loose connections between battery and power distribution center. This can be the battery terminals, connections at inline circuit breaker, connections at power center, or the most often overlooked ones, the ground connections at the battery (neg cable to chassis, both ends) and the connection to the chassis near the power distribution center.

A great investment is a GOOD battery monitor that doesn't just show a stack of LED's or Voltage, but actually measures current out and current in, taking into consideration the inefficiency of Lead Acid batteries (Peukert Factor). These monitors show you when the battery is actually fully charged, not just when voltage is giving a false reading of charged when it's just a surface charge.

lbrjet · 05-21-2021, 05:44 PM

13.4 volts is the voltage coming out of the controller, not the battery voltage. Take it off the controller and measure it the next day at the battery terminals. 12.6-12.7 is fully charged. It sounds to me like the battery is not fully charged up and after it comes off the controller, and stabilizes, it is showing you the real reading. Also 5 amps is only 60 watts. Seems like everything you had going was more than 60 watts.

neogeo · 05-21-2021, 06:49 PM

Quote:

Originally Posted by TitanMike

If battery voltage drops quick when loads are applied, using the onboard battery "indicator" it's one of two issues. First is the battery not being fully charged or defective (high internal resistance). Next is loose connections between battery and power distribution center. This can be the battery terminals, connections at inline circuit breaker, connections at power center, or the most often overlooked ones, the ground connections at the battery (neg cable to chassis, both ends) and the connection to the chassis near the power distribution center.

A great investment is a GOOD battery monitor that doesn't just show a stack of LED's or Voltage, but actually measures current out and current in, taking into consideration the inefficiency of Lead Acid batteries (Peukert Factor). These monitors show you when the battery is actually fully charged, not just when voltage is giving a false reading of charged when it's just a surface charge.

Thanks for the info - agree on the battery monitor - its definitely on the to buy list. In talking to customer service at US Battery, they suggested using a hydrometer to test the state of charge so doing that tomorrow. We had the place we bought it from look at it today, and they ran some tests, looked at the terminals and couldn't find any issues. Thanks again for the response - appreciate it!

neogeo · 05-21-2021, 06:57 PM

Quote:

Originally Posted by lbrjet

13.4 volts is the voltage coming out of the controller, not the battery voltage. Take it off the controller and measure it the next day at the battery terminals. 12.6-12.7 is fully charged. It sounds to me like the battery is not fully charged up and after it comes off the controller, and stabilizes, it is showing you the real reading. Also 5 amps is only 60 watts. Seems like everything you had going was more than 60 watts.

Hoping that it just needs to fully charge is the case! It is new, so customer service said it may not be fully charged. Bought a hydrometer and testing tomorrow to see. With the multimeter directly reading the battery terminals it is reading fully charged but going to cover all bases!

It definitely seems like those would be more than 5 amps lol but LED lights so only 3 watts a piece and the iphone charger is approx 10 watts, and the fan is approx 20 watts on med.

kcmusa · 05-22-2021, 08:21 AM

Try a dc clamp meter, clamp on the battery wire and see how much your drawing.

https://www.amazon.com/KAIWEETS-Mult...xpY2s9dHJ1ZQ==

Larry-NC · 05-22-2021, 01:54 PM

Quote:

Originally Posted by kcmusa

Try a dc clamp meter, clamp on the battery wire and see how much your drawing.

https://www.amazon.com/KAIWEETS-Mult...xpY2s9dHJ1ZQ==

An easier way: With your multimeter set on the 10A scale and the leads plugged into the COM and 10A terminals. disconnect one lead from the battery. Put one lead on the battery terminal and one on the cable(s) and measure the current. (That is, insert the meter in the circuit between battery and trailer.)

Make the measurement with everything off and with again with what you believe to be a 5 amp load.

mnoland30 · 05-23-2021, 06:44 AM

You should be aware that when under load, the voltage will show lower. When you take the load off, it will go back up. The radio and CO/Propane detector will draw enough power to run down a battery in a week or two just by themselves. It could be your battery wasn't fully charged. The heater fan can run down a single battery in one cold night. A hydrometer (a pain to use) or battery monitor with a shunt is the only way to really know what is going on.

With solar working, and no load, you should be above 13v. Your controller doesn't tell you the charge, just the voltage. You might want to check that your controller is set for the type battery you have.

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