Update of Lithium battery install

[garyb1st]

So far so good. We're still using the old WFCO converter and while it's hum is getting loud, it's still working. I can run our 12 volt refrigerator for at least 2 days on battery power alone so should have time to replace and save the content of the refrigerator if the converter goes south. The alternator also seems to be fine. There was one time I smelled what I thought was electrical wiring and don't know if the alternator was heating up or it was unrelated. Regardless, I make sure we don't let the engine idle for more than 15 or 20 minutes. Usually that's when we're deploying jacks and slides. I've seen the Victron Energy video that shows an alternator smoking because of the significant draw when charging lithium batteries. Many motorhome owners who have lithium house batteries recommend using a battery to battery charger to protect the alternator. I've read enough posts and have given a lot of thought to doing just that. But a few things I've read suggest at least in my case it may not be necessary. The primary reason for that is I only have two 105 Ah batteries. And while they can pull a lot of energy from the alternator, usually they are close to 65% or more charged. So the alternator can fully charge them pretty quickly. If we add a 3rd or 4th battery, that will change. Another reason I think my situation is different is I'm pretty sure our 16 year old motorhome doesn't have a smart alternator. While I don't understand the difference, I've read that the newer alternators can overheat when charging lithium batteries if the engine rpms are not high enough.

 

[garyb1st]

While not a deal breaker, something to be aware of. The lithium batteries are being discharged at approximately .75 amps an hour. Since we returned home Friday noon, my Victron battery monitor indicates the batteries have used about 45 amp hours. This is more than a phantom drain. Nothing is running in the motorhome. I believe it's because the lithium batteries have a continuous current well above that of a lead acid battery. Because of that, I think the motorhome sees the lithium batteries as an energy source and pulls energy from them. I've thought of adding a battery disconnect to the house batteries but would like to understand the issue before doing anything.

Anyone have any thoughts on this matter?

 

[Heli_av8tor]

Gary wrote: "I believe it's because the lithium batteries have a continuous current well above that of a lead acid battery."

That doesn't make sense to me. You would have the same draw no matter the battery chemistry.

Something is using power. You just haven't found it yet.

 

[garyb1st]

Tom, after 2 days parked at the house the chassis battery is at 13.18v. A fully charged lead acid battery at rest should be about 12.6v. Obviously something is keeping it at that higher voltage. We're not plugged in to the houses 120 and everything that can be turned off is off. The Victron monitor tells me the lithium house batteries have used 50 Ah's in those 2 days. Just seems logical that the lithium batteries are feeding the chassis battery. I'm just not sure how or why it continues to do so.

 

[garyb1st]

I disconnected the wire from the chassis battery to the house batteries. The chassis battery voltage immediately dropped to 12.79v. The drain on the house batteries dropped from .78amps to .14amps. So it looks like the lithium house batteries weref charging the SLA chassis battery. IIRC, someone pointed out why that was occurring. At the time I didn't understand the issue and since the motorhome is usually connected to the houses 120v it's not been a problem. It is when boon-docking the the batteries are linked. That's my big concern. Without a lithium converter the generator will not begin to fully charge the batteries. I had hope that with the 200 watt solar suitcase I built and my 20 amp MPPT controller I'd be able to top off the batteries when boon-docking. But with temps in the upper 90ºs to the 100º plus range boon-docking wasn't looking like much fun.

 

[John From Detroit]

Tom, after 2 days parked at the house the chassis battery is at 13.18v. A fully charged lead acid battery at rest should be about 12.6v. Obviously something is keeping it at that higher voltage.

One of the differences I'm told (Will know more next week) about LI batteries v/s Lead acid is this.
Lead acid FULL FULl FUll not Full not full dead (The upper/lower case represents voltage)(
LI is FULL FULL FULL NOT FULL NOT FULL dead
and you can use over 100 of those amp hours v/s half that for lead acid Deep Cycle of the same capacity.

The LI chemistery the voltage does not drop as the state of charge drops.. it just suddenly quits providing power

The motor home will draw power from the converter if it's the "hotter" source and if it's not the batteries will never charge.. The WFCO will not go into BULK unless those puppies are Dead and I mean Dead.. Progressibe Dynamics makes one special for LI. alas that is ALL i know about it.

 

[garyb1st]

The LI chemistery the voltage does not drop as the state of charge drops.. it just suddenly quits providing power

The motor home will draw power from the converter if it's the "hotter" source and if it's not the batteries will never charge.. The WFCO will not go into BULK unless those puppies are Dead and I mean Dead.. Progressibe Dynamics makes one special for LI. alas that is ALL i know about it.

This is the reason using a volt meter to measure the remaining charge of a Li battery doesn't work. It will read about 13.2v until almost dead. Using a battery monitor like the Victron which shows the number of amp hours used works for me. That way I know approximately how much charge remains.

That's true about the WFCO. I've looked at the Progressive Dynamics as a possible alternative. They have a unit with a switch that can be used for either Li or Lead Acid. But that also has limitations. From what I've read, the best solution is a combination of a regular converter (not lithium) and a solar charge controller for the Li batteries. But that means some solar on the roof which I don't have.

 

[Lou Schneider]

First, you have to remember unlike lead-acid batteries, lithiums are perfectly happy to sit at less than full charge. It does them no harm whatsoever.

I have a pair of Lion Safari UT1300s in my Safari Trek and still have the stock inverter/converter (Magnum 1000). It's 13.5 volt output will charge them to about 80% and I've let them sit at that level for a couple of months - no harm done.

When I start the main engine, the alternator supplies about 14 volts and within an hour or so of driving charges them the rest of the way full.

Eventually I will install some solar (I have most of the parts) but I haven't gotten around to it yet.

The Progressive Dynamics and WFCO first generation lithium converter/chargers put out a constant 14.6 volts. Battle Born says this is the upper limit for their batteries and is now recommending a more conservative limit of no more than 14.1 volts for extended periods, with 13.6 volts preferred for continuous charging.

I predict you'll soon see multistage converter/chargers for lithium batteries with settings just a few tenths of a volt different than what we now use for lead acid batteries. Maybe with an external button like the PD Charge Wizard to let the user manually start a high voltage charging cycle since lithium's constant output voltage doesn't provide an easy way for the charger to sense the battery's state of charge. High voltage (14.6 volts) for fast charging, then throttling back to a lower maintenance voltage (13.5 volts) once the batteries are full.

The lithium landscape is changing as people gain more long term real world experience with them and the biggest take-away is they're not nearly as finicky as was first thought.

 

[garyb1st]

Lou have you experienced the same problem I have with the Li batteries somehow charging the chassis battery? In 2 days my Li batteries were drawn down about 50 Ahs. If not, any ideas why it's doing that in mine.

 

[Ex-Calif]

What is the technology of the battery paralleling device?

Automatic charge relays generally sense the voltage on both sides. If one side shows a voltage high enough to be considered a "charging" source they are paralleled.

If the resting voltage of the Lithium batteries is 13+ volts I am guessing most charge relays will put the batteries in parallel.

If you chassis battery is lead acid then the problem would appear to be that the lithiums and LA are trying to reach equilibrium meaning the lithiums will keep charging the LA until it get to 13+ volts (which it wont') or the lithiums drop to 12.6 (which they eventually will).

A quick solution is to wire in a 1-2-all manual switch and manually disconnect the batteries when parked up and you have no shore power. That will allow you to leave the house batteries energized for boondocking.

 

[John From Detroit]

From what I've read, the best solution is a combination of a regular converter (not lithium) and a solar charge controller for the Li batteries.

My Solar Charge controller is due in Thursday
I'll get a solar panel on Friday more than likely (50 watt as the battery I have is only 20 AH) and give it a workout Sat/Sun (Field day) at least that is the plan..

 

[solarman]

the issue with "drop in replacement lithium" batteries is a chemistry difference, both partial and full SOC is different from lead acid. they are only drop in when used exclusively. Mixing different chemistries is bad, even mixing SLA and FLA is a bad choice.
the difference in voltages between the two are causing your issue.
DO NOT mix battery chemistries.
a solution to your problem exists, it's called a DC to DC charger/isolator.
Victron has the "Victron Energy Orion-Tr Smart" unit and Renogy has the DCC12 unit.
this device will isolate the two systems and permit charging from alternator too.

 

[Lou Schneider]

Lou have you experienced the same problem I have with the Li batteries somehow charging the chassis battery? In 2 days my Li batteries were drawn down about 50 Ahs. If not, any ideas why it's doing that in mine.

No, my chassis battery is completely separate from the house system except when the engine is running and it closes the charging solenoid. If anything, my chassis battery loses some charge from the engine computer's parasitic load when I'm parked but it's not been a problem so far. My radio is on the house system so it's not a load on the starting battery.

The problem with using a DC-DC converter in an RV is the jump start feature (where you can use the house batteries to jump start a dead chassis battery) has to be disabled. I had a complete failure of the starting battery halfway through a trip and my pair of UT-1300s easily started my engine (gas) until I was able to get to a Walmart instead of having to pay more for a battery out in the boonies. The failure was an internal open between the cells and one of the battery terminals so the battery was completely out of the circuit. BTW, the battery that failed was an Interstate installed by the previous owner, I've never had a failure other than from old age from any Walmart battery.