Beginner battery questions

HeyMrsMal · 01-06-2021, 02:49 PM

We have a 2003 Minnie Winnie and we recently changed out the house AGM battery for 2 battleborn lithiums. On the old AGM we could really only boondock for a day before the battery died. After switching to lithiums the house battery still dies after a day/day and a half at similar minimal use. I'm thinking I need to upgrade the charge controller? Any other thoughts about how to let my system access the power of the new batteries? Appreciate it, y'all.

DavidM · 01-06-2021, 03:20 PM

I would first install a shunt based battery monitor and collect some data. Renogy makes a decent one.

A day and a half worth of use before running down 200 Ah lithiums sounds excessive. Do you have a compressor fridge? That will do it.

Are you starting with a full charge? The standard converter will only get it up to maybe 80% unless you leave it on for a long while.

David

al1florida · 01-06-2021, 05:14 PM

Without a battery monitor like a Victron 712 or Trimetric, or the Renogy you really don't know the charge status of your batteries. Do an internet search for the devices noted above.

You could have excessive draw of battery power from something.

Compressor fridge is a problem.

HeyMrsMal · 01-07-2021, 09:43 AM

The fridge switches to propane while we aren’t plugged into shore power, so while it might be drawing a little, I don’t think it’s the main issue. We should be starting with a full charge after being on shore power for a few days.

BobC · 01-07-2021, 12:08 PM

Quote:

Originally Posted by HeyMrsMal

The fridge switches to propane while we aren’t plugged into shore power, so while it might be drawing a little, I don’t think it’s the main issue. We should be starting with a full charge after being on shore power for a few days.

A refrigerator on propane won't draw too much power. Are you running anything off an inverter? And how about heat? Your propane furnace will be a significant draw.

You didn't say what size Battle Borns.

al1florida · 01-07-2021, 03:14 PM

A gas/elect fridge operating on propane only pulls a max of about 0.2 amps. That is about 0.1 amp while not cooling and another 0.1 amp to activate the solenoid for the propane to flow to the burner.

al1florida · 01-07-2021, 03:21 PM

Quote:

Originally Posted by HeyMrsMal

The fridge switches to propane while we aren’t plugged into shore power, so while it might be drawing a little, I don’t think it’s the main issue. We should be starting with a full charge after being on shore power for a few days.

Yes, you "should" have a full charge after being on shore power for a few days.

What method do you use to actually know your batteries fully charged?

Do you have a battery monitor that shows how many Amp Hours (AH) are going into your batteries?

Do you use a multimeter to measure the voltage at the battery while it is being charged and also when you believe it is fully charged? If so what are those voltages? Note that trying to use the voltages just gives a guesstimate of the state of charge (SOC)

If you have not used either of those above methods to check your battery charge you really don't "know" if your batteries are charged.

BobC · 01-07-2021, 06:02 PM

Quote:

Originally Posted by HeyMrsMal

I'm thinking I need to upgrade the charge controller? Any other thoughts about how to let my system access the power of the new batteries? Appreciate it, y'all.

What kind of controller do you have now?

thataway4 · 01-10-2021, 07:10 PM

I suspect the the Li batteries. are not fully charged. You mention a "Charge Controller". This implies that you are using solar power to charge the batteries. What size solar cells? Are they located in full sunlight all day long?

If it is a 2003 RV the Converter (110V AC to 12V DC) will not be set up to charge a Li battery. On my boat I have two 100 amp hour Battle Born batteries. These will run two chest refrigerator / freezers for 24 hours, plus our cooking on an induction burner thru a Victron multiples 2000 PSW inverter/80 amp battery charger. I charge either with this 80 amp charger or a DC to DC 12 volt to 12 volt (LiFePO4 profile) charger.

You need to put in a shunt monitor, which shows power in and out (as noted the Victron etc) and use a battery charger which is made for the LiFePO4 battery. If you are depending on solar only, then you need to re-evaluate the output of the solar panels, and the type as week as the size of the Solar charging controller.

The Voltage of the BattleBorn battery should be about 13.5 to 13.6 Volts resting voltage--no charge/no discharge for 2 hours. The AGM battery would have been 12.7 to 12.8 Volts resting. Voltage alone is of little value with the Li batteries. They hold high voltage until almost 90% discharged.
"

AKBruce · 01-10-2021, 07:30 PM

I'd definitely look into the power center and charge controller. On a 03 you've got some Flintstone charging technology. I just changed out the controller on my 05 Minnie with a Progressive Dynamics controller. Replaced the original lo-tech Chinese stuff in the Parallax 7300 power center. Not too difficult of a job, good instructions included from PD.

CWHTRAINS · 01-10-2021, 07:34 PM

How did you determine that your refrigerator is running on propane? Do you have a 120 V AC inverter? If you have your inverter on, it is possible that you are running the refer on AC power from the inverter (that is what my unit did, many automatically switch to AC operation when 120 V AC is present) which would run down your batteries easily in a a day and a half. Another way to tell is to look at your propane burner on the refrigerator and see (or listen) to determine if it is burning during operation. Many propane refrigerators also allow you to set it to run only on propane, which you could do as well while you are researching this battery usage issue. Your refer user manual will tell you how to do this.

If the inverter is left on and the unit is only on battery power, the inverter will be using some of that battery power the entire time the inverter is on, even if all other items are turned off.

If you do not have an inverter, then do a count of lights bulbs (inside and out), furnace usage, fans running, TV time, computer and phone charging time, etc and try to estimate the amount of amp hours you are using as compared to the battery capacity you have. The power has to be being used somehow, just got to find out what your power draws are and make decisions from there about usage and necessary generator charging times required each day.

Good luck.