2108DS Lithium install: the trip report

[tinglett]

For what it's worth, I did plug the TT into shore power right after that experiment and the TT's charger was giving them 31A. The charger is a PD4655LIV I installed a few weeks ago specifically for the new Lithium batteries. I assume the batteries would take a lot more, but this is all my setup can produce. It's interesting the current is higher than the 30A fuses on the line, but I suppose there is some percent margin there. I saw 34A for a few seconds until it walked back to 31A.

Rather than focus on tow vehicle charging, I plan to turn to solar in the spring after reading your recently-posted documents on the topic . It looks to me like a couple 100w panels will do the job nicely for me.

[DavidM]

You might try upgrading the wire size from your new charger to the batteries. You may see more current if you do this. You are only getting about 60% of the charger's 55 amp capability now.

David

[al1florida]

Originally Posted by tinglett

A follow-up. I had let the batteries discharge over the last couple weeks simply by not flipping the battery disconnect switch. It's amazing how that radio (the primary user of idle power) sucks away the juice. I hitched up to move the TT to prep for a trip this weekend and did a quick measurement via the Victron BMV to see how the tow vehicle actually charges the battery. See the numbers attached. Unfortunately I didn't take the time to check the tow vehicle battery terminals for voltage in order to see a drop. I believe I usually see something like 13.6v or 13.8v so there is definitely a drop. But I can see it's charging at approximately a 6A rate.

What was your house battery voltage before you started charging? If it was 12.8 to 13.0 and with the voltage coming from the alternator only being 13.0 you are not going to get much charging done.

The voltage needs to get up to 13.8-14.2 at the battery to do any rapid charging.

[tinglett]

Originally Posted by DavidM

You may see more current if you do this. You are only getting about 60% of the charger's 55 amp capability now.

I haven't called PD to see what they'd say about changing out the 30A fuses with bigger ones. Right now I'm just going on the assumption that it's designed to handle a total of 55A, but not all of it going to the battery for charging. But I don't really know as the manual doesn't get to that level of detail.

Of course I can't change the fuses until I upgrade the wire. For now the 30A rate is adequate but doesn't make me happy. My little honda 2200 generator could provide a lot more if the charger could send it on to the battery.

[DavidM]

I am more than a little curious why you would have wire so small that it requires a 30A fuse to protect it in a 55 amp charger circuit.

Usually that wire is at least 8 gauge which is good for 80 amps. If it is any longer than 6' from the charger to the battery, you probably want to upgrade it to at least #6 gauge and maybe bigger to limit voltage drop. Then put a 60 amp fuse in it.

You want to limit voltage drop in that circuit. If the battery needs 14.4 V to charge effectively and you have small wire, your charger could see 14.4 but the battery would only be getting 14.0 or less. Keep the voltage drop down to 0.2 V or so.

David

[thataway4]

Inteli-Power 4600 Series models can recharge the battery to 90% in 2-3 hours using our patented Charge Wizard technology.


The built-in Charge Wizard automatically selects one of four operating modes: BOOST, NORMAL, STORAGE, DESULFATION.

BOOST Mode 14.4 Volts - Rapidly brings RV battery up to 90% of full charge.

NORMAL Mode 13.6 Volts - Safely completes the charge.

STORAGE Mode 13.2 Volts - Maintains charge with minimal gassing or water loss.

DESULFATION Mode 14.4 Volts every 21 hours for a period of 15 minutes to prevent battery stratification.

The spec sheet for the converter, shows the No Load output voltage at 13.6 volts and the Maximum output voltage at >12.6 volts. Are the characteristics changed when the jumper wire is placed for the LiFePO4 battery mode?

Do you have the converter/charger set on boost?

Was the voltage when charging from the TV with the engine at an idle, or at highway RPM? I agree that the voltage of 13.04 is concerning, and would indicate very little charging--The 6 amps is noted, but at that rate, it will take close to 15 hours to reach a charge--and will not fully charge unless there is a higher voltage. A diode in the "trailer charging" circuit generally would drop the voltage by 0.3 to 0.5 volts.

Is the the 30 amp fuse and wiring it is protecting factory installed wiring? If so, it may not be sized correctly for the potential 55 amp charge. (I don't know if the "charger" function is available for the full 55 amps. Most converters are more of a trickle charger. I understand that the "charge Wizard" changes that equation to some degree.

[Old Navy]

My Minnie has 6 gauge from the WFCO 55A converter to the battery, and I suspect the micro minnies are the same. There is still significant voltage drop when you start pushing 30A. In my trailer, I suspect I have at least a 40' run from the converter to the battery, via the battery cutoff switch and the frame conn box/30A breaker.

[tinglett]

My TT also has 6 AWG wire. The 12v fuse panel with the 30A fuses came with the PD4655LIV. This fuse panel replaced the WFCO panel which had 40A fuses. Note that the PD4655LIV is specially made for Lithium charging only. It has a big warning sticker on it to the effect. I purchased it through Battle Born on their recommendation as a replacement for the WFCO 55A charger.

We did go out this weekend for some late autumn camping in MN (brrrrr..). This time we let ourselves be a bit sloppy with power usage, and it was also colder, so we used up 103Ah over the course of about 2.5 days. I took a screenshot of the Victron BMV both before and after connecting to the tow vehicle for the return home. See attached.

I thought it very odd the batteries were down to 10.27V. I'll call Battle Born about that unless you guys have an explanation. I have 200Ah of battery (two 100Ah) and wasn't expecting a voltage drop quite like that. In that first screenshot I haven't yet hit the battery disconnect switch, so there was pretty much only parasitic draw left.

In the second screenshot you can see the tow vehicle connected and idling. I was pretty amazed at this 17.88A of current. I didn't have a DVM with me. The tow vehicle has a voltage gauge but it's pretty worthless for accurate reading.

By the time I got home about 1 hour later is when the third screenshot was taken. So it put about 10.6Ah into the battery over 1 hour.

The fourth screenshot shows the readings moments later after I pulled the tow vehicle wire. Voltage dropped a little and we are back to a parasitic draw.

Finally, the fifth screenshot shows shore power connected and the PD charger back on duty. I find it interesting it can run 37A through those 30A fuses. I looked a few minutes later and it was down to 34A. My experience is that it hangs out around 30A until it's mostly charged and then current drops rapidly.

On the plus side, my Victron BMV didn't "reset" like it did last time. Changing the settings fixed that (see earlier in this thread).

Summary of attachments:

1. Just before attaching to tow vehicle after a weekend of drain (10.27V) 12:50pm
2. Just after attaching to idling tow vehicle. (11.81V) 12:56pm
3. After towing for an hour (13.06V) 2:10pm
4. After disconnecting from tow vehicle (moments after #3) (12.95V) 2:18pm
5. After connecting to shore power (13.47V) 2:21pm

[al1florida]

Wow, you took your batteries down to 10.27V. I wonder what the cut off low voltage is in BMS system in the Battle Born batteries? Note that the cutoff voltage is a safety thing, not something that is recommended to normally discharge your batteries to. Anyways the batteries were down to zero percent capacity.

Do you know what your battery voltage was a couple of hours after arriving at the campground? I assume your tow vehicle did some charging on the way to the campground. So I say a couple of hours after you arrive to allow the batteries to stabilize for a good voltage reading. (you probably only need 10-15 minutes to stabilize)

I thinking your batteries were not charged to 100% full to start with.

In display #5 when you are connected to shore power, a voltage of 13.47 is way to low to efficiently charge your batteries. I am assuming you checked the voltage very shortly after connecting to shore power. Do you know if the voltage went up an hour or so later?

Your charging voltage should be over 14.0 volts and perhaps as high as 14.5-14.6 volts. Is there info in your charger documentation showing what the lithium battery settings are set for?

Whenever we dry camp, I frequently (several times a day) check the SOC of my batteries. I don't have the ability to use a smart phone to check, but do have a display panel in the bedroom. So most every time I go into the bedroom I glance at the display.

For what it is worth, I limit my charging voltage to 14.2-14.3 volts, but I don't have Battle Born. I also limit my float voltage to about 13.4V and leave my batteries at about 40% to 60% full when on shore power. 40-60% is the typical recommended battery storage capacity.

Whenever we come off of shore power to dry camp or boondock, I bring my charging voltage up to about 14.2V for several hours to get my batteries up to 90% full or more. I do have 650watts of solar and my solar controller is set for 14.2V charging. So while traveling I get some good charging if it is a sunny day. Solar is my prime source of charging.

The good thing about your setup, is you are not going to overload your alternator. With 25 feet or more of #10 wire (could be #12 wire) going from the alternator to the trailer batteries you won't be able to get a high current flow.

On your trip home, you show that your charging current was about 17amps. The current probably dropped as the battery voltage increased. With a battery voltage down to about 10.3V that is probably the max current you will ever see, based on the small wire size coming from the alternator.

[al1florida]

Below are a discharge and a charging curve chart for LiFePO4 batteries. These are from the website from the mfg of my batteries elitepowersolutions.com.

The numbers along the left side are the cell voltages (4 each to make up a 12V battery) and the numbers along the right side are the corresponding battery voltages.

The numbers, such as 0.5C, are the charge/discharge current as a percent of the total battery capacity (C). So for a 200AH battery pack, 0.5C would be a charge/discharge current of 100amps.

[creativepart]

I can’t make sense of those BMK readings especially the 10.2v. That number doesn’t seem possible for a LiPo battery bank.

It also sounds like your Converter/Charger isn’t taking good care of your batteries. Treating them like FLA batteries with that charge profile.

I’d call Battleborn and have a long talk with their Techs.

[tinglett]

Originally Posted by creativepart

I’d call Battleborn and have a long talk with their Techs.

I called BB and they are confused as well. The first concern was if the Victron BMV settings were right (not sure how that could impact voltage) and we ruled that out. They also wanted me to check with a voltmeter to verify the BMV is correct so we look into fixing the right thing. I personally doubt the BMV is reading wrong as the jack operated sluggish while at 10.27v and pepped up dramatically after plugging into the TV.

I didn't snap a screenshot when I started the camping trip, but I know I did look and the bank (remember it is 200 Ah with two BB batteries) was totally full. Here's a screenshot of the battery bank 1 hour after I pulled shore power this morning, and also a screenshot of the battery bank on late Saturday afternoon.

Right now I have both MaxxAir fans running, the range hood, and some lights and I'm drawing down at a 9A rate. I'll let it chew away some charge for a few hours then will take a voltage measurement and maybe call back BB. I did suggest maybe I should try one battery at a time to see if there is an issue with one battery. They said that's a good idea, but I don't think they are thinking there's a problem there.

[tinglett]

Originally Posted by al1florida

Wow, you took your batteries down to 10.27V. I wonder what the cut off low voltage is in BMS system in the Battle Born batteries? Note that the cutoff voltage is a safety thing, not something that is recommended to normally discharge your batteries to. Anyways the batteries were down to zero percent capacity.

I am not going to claim a defective battery yet, but I wonder if this kind of behavior could happen if one of my two BB batteries is "not good?" I plan to separate them late today or tomorrow as an experiment.

Originally Posted by al1florida

In display #5 when you are connected to shore power, a voltage of 13.47 is way to low to efficiently charge your batteries. I am assuming you checked the voltage very shortly after connecting to shore power. Do you know if the voltage went up an hour or so later?

Your charging voltage should be over 14.0 volts and perhaps as high as 14.5-14.6 volts. Is there info in your charger documentation showing what the lithium battery settings are set for?

The voltage does indeed drift up, but I haven't taken enough readings to make a graph. For sure it lands at about 14.5v when it hits 100%. I'm not sure my charger has settings. It's the "LIV" version of the charger which is Lithium-only according to the huge warning label. I'll ask BB about this (I bought it from them) after I figure out the voltage issue.

Originally Posted by al1florida

For what it is worth, I limit my charging voltage to 14.2-14.3 volts, but I don't have Battle Born. I also limit my float voltage to about 13.4V and leave my batteries at about 40% to 60% full when on shore power. 40-60% is the typical recommended battery storage capacity.

I'm curious how you do this. Do you flip the battery disconnect switch? I should probably start doing that when I have the rig plugged in at home.

[tinglett]

I should also point out my own installation work could be "defective" somehow. I'll look it all over carefully this afternoon sometime when I take voltage readings to cross-check the Victron BMV. For example, I'd think we'd all agree this behavior would be expected if only a single 100Ah battery was actually in the circuit. Then making it to 103 Ah would be considered a feat rather than a fail.

[Old Navy]

Originally Posted by al1florida

In display #5 when you are connected to shore power, a voltage of 13.47 is way to low to efficiently charge your batteries. I am assuming you checked the voltage very shortly after connecting to shore power. Do you know if the voltage went up an hour or so later?

Your charging voltage should be over 14.0 volts and perhaps as high as 14.5-14.6 volts. Is there info in your charger documentation showing what the lithium battery settings are set for?

Assuming the PD4655LIV was putting out 14.4V at 37A (per pic #5) through approx 30 feet of AWG 6 wire, you would expect to see about 13.5V at the battery. Ideally, the charger should be close to the battery.

[Old Navy]

Originally Posted by tinglett

I'd think we'd all agree this behavior would be expected if only a single 100Ah battery was actually in the circuit.

I would have expected the BMS to disconnect closer to 12V, but it looks like BB's BMS kicks in at 10V, so you are probably on to something here...

[tinglett]

After running about 30 Ah out of the batteries, I shut off the battery disconnect and measured the voltage while there was 0A draw. My measurements exactly matched the Victron BMV.

I decided it was time to split these two batteries apart. I removed one and it measured at 13.25v completely disconnected from anything. The other was still connected to the Victron BMV and TT, but otherwise was disconnected. It measures at about 10v!

So I called BB to see what this is about. He said that 2nd battery is in a safety mode, fully depleted, and needs to be "woke up." He avoided the question of how it might have got that way, but did give suggestions on how to wake it up. Perhaps you guys understand this, but he said the charger won't do it. I see the charger is giving it 14.5v, but it's only drawing 0.25A. Like nothing. His recommendation was to get out the tow vehicle and jump it. Yes, jump it! He said I should do that for about 15 min, and then remove the jumper cables and try charging again.


I did ask why the other "good" battery in parallel with this one didn't already do this, but he didn't have an answer. He just repeated that I should jump it. He did say that my PD4655LIV is explicitly made for Lithium batteries and there are no adjustments that can be made on that unit.


I'll do this later today. Makes me a little nervous as I've read about what these things can do to alternators. I'll be watching the BMV like a hawk. I think I'll do the first attempt without the vehicle running. I'd rather have a dead battery than a smoking alternator. He initially suggested a car battery as if I have one laying around.

[creativepart]

I wouldn't think that 15 mins shouldn't be much risk to your alternator on your tow vehicle.

Here's an article on the process on the Battery University website:

https://batteryuniversity.com/learn/...oltage_cut_off

[tinglett]

Well, jumping it didn't seem to do any good. You can see the setup below. I moved over to the utility trailer just in case "bad things" happened.

The first screen snapshot is when it was jumped to the TV. The TV produced about 13.95v most of the time and would only go to 14v if I rev'ed it a little. I let it run beyond 15min for good measure, but note that the battery was drawing no measurable amps so this did no good at all. The second snapshot is when I put it back on the TT's charger. This is exactly what it looked like before the jumping effort.

I'll leave it "charging" for a while in case something happens. At least a miniscule amount of current is flowing. Maybe it'll wake up since the other battery is not attached and willing to suck it all away.

[al1florida]

Good to see that your charger does go up to 14.3V or a max of 14.5V instead to the 13.5V when you initially started charging when you got home.

Originally Posted by al1florida View Post
For what it is worth, I limit my charging voltage to 14.2-14.3 volts, but I don't have Battle Born. I also limit my float voltage to about 13.4V and leave my batteries at about 40% to 60% full when on shore power. 40-60% is the typical recommended battery storage capacity.

I'm curious how you do this. Do you flip the battery disconnect switch? I should probably start doing that when I have the rig plugged in at home.

I have a Magnum 2012 inverter/charger I bought in about 2015. It doesn't have a lithium setting, but it does have a "custom" battery setting that allows you to vary the charging voltages.

About the voltage setting in your charger. I would expect the documentation in the owners manual would show the voltages. If not maybe a call to the mfg would be in order to find out how they programmed the voltages. Not that it is hugely critical to know, but I always want to know how things work. Knowledge is important when things don't work well, or as well as expected.