Lithium swap anyone?

[bobojay]

There are several Travato owners in the Facebook group that have replaced their OEM group 31 AGMs with Battleborn "drop in" replacements that are very happy with their decision.
Battleborn says the stock PD AGM/wet cell converter/charger and Zamp solar setup is OK to use with the drop ins.
On the other hand, other lithium knowledgeable owners say the converter and solar controllers both should be replaced with lithium capable units for best battery life. (Both PD and Zamp make lithium capable replacements)
This probably doesn't help your decision making, but I thought I'd throw it in here

[israndy]

Are the Travato batts kept indoors or out? My Serenity has a bay on the outside of the vehicle so no amount of heating the interior will get to the battery bay.

-Randy

[Twinbridges]

A couple years ago I swapped out 350 ah agm for 600 ah Relion lithium. Did new big cable to carry current. Reprogrammed Xantrex inverter to recommend charging profile with no float. Charge with 220 amp alternator. Has worked perfectly.

[Twinbridges]

I do have remote thermometer in insulted battery compartment I can monitor on my iPhone. Have been in mid twenties outside and bay is about ten degrees higher.

Just make certain to not charge if batteries are below freezing.

[Jostalli]

Originally Posted by israndy

If the built-in BMS doesn't cut them off what's going to stop the batts from charging when frozen? That's a situation that will KILL a lithium battery.



-Randy

All the so-called “drop in” lithium batteries have similar BMS’s, which cut charge when temps drop too low. Same when temps get too high. It isn’t going to damage them.

This is why Battleborn increased their warranty. The BMS keeps the battery safe from harm.

[Twinbridges]

That’s correct. Lithium changes the experience in some very good ways. With “stuff” running I can boondocking for 3.5 days. And then they charge really fast from driving, generator or plug. I only have a bit of solar due to space limitations but with a roof full you could go a long time.

[bobojay]

Originally Posted by israndy

Are the Travato batts kept indoors or out? My Serenity has a bay on the outside of the vehicle so no amount of heating the interior will get to the battery bay.

-Randy

Outside, right in front of the rear axle on trays.

If I were to do this, (drop ins) I'd do the these, or maybe just one, which is virtually the same available amperage as 2 group 31s, then change out the converter and solar controller...

https://battlebornbatteries.com/shop...cycle-battery/

[stanw909]

If current setup has worked for 8 years , why switch to lithyum batteries ?

[Winston]

Originally Posted by hbn7hj

Elitepowersolutions.com (is that your vendor) says 15.2 volts is the maximum for a 4 cell pack. Ours wouldn't even charge (at least very slowly) at the voltages you use.

Originally Posted by booster

From all the information we have been seeing lately, lithium batteries should not be held at a fixed voltage or floated . . .

Originally Posted by Jostalli

Here is my favorite source for accurate information on LiFePO4 batteries. Read and learn: https://marinehowto.com/lifepo4-batteries-on-boats/

Jostalli, we agree. This guy seems to have spent years using and testing lithiums and his comments are logical and scientifically sound. We, too, recommend this article as a 'must read' for those using or contemplating lithium. On the question of charge voltages . . . we remember in an earlier 'edition' of that article in which the author said something to the effect that "if you never charge above 13.8 volts you'll be happy."

To address Booster's comment, that same author also questioned whether lithiums should be floated. But he did concede that at or below 13.4 volts, possibly they could be . . . although noting that he had seen no "white papers" analyzing low-voltage lithium floating and that he had no data on which to form an opinion.

Some people - - in fear of 'floating' their batteries - - turn-off their chargers (after charge) and power their system (even though still having shore power available) from the batteries - - turning the charger 'on' again only when the batteries have been 'used' (discharged) to some lower target level.

We look at our charger - - not as a charger, but as a power supply. When a load is dropped onto our 12v system, we see no reason to 'exercise' our lithium batteries, instead, we prefer our 'power supply' pick-up the load. In short, we have chosen not to continuously cycle our batteries when shore power is available.

Step One was to determine at what SOC charge we wanted to maintain our lithium pack? We picked something in the order of 80% SOC as a compromise between fully charging and possibly 'stressing' the pack (as cautioned by that same author) on one hand, and obtaining most of its AH capacity on the other.

Step Two was to ascertain what 'resting' terminal voltage corresponded to that SOC. The table in our earlier comments represents the resting voltages at each SOC (resting being defined as the voltage across the battery after 10 hours of resting - - meaning, after 10 hours of no charge and no discharge). 13.36 volts approximates an 80-90% SOC.

Step Three is to set our charger/power supply to that voltage. The Engineering Principle here is: If a Power Supply of exactly the same voltage is placed across a Battery, the Battery won't know the Power Supply is there. Until an external load is applied, no current will enter the battery, and none will leave.

Now some will say this is "Floating". But it is not. And if it is, since the Battery doesn't know the Power Supply is connected, this form of Floating is completely harmless.

The advantage is . . . when a load is applied, it is the Power Supply that will take-up the slack . . . pretty much like it is your alternator that supplies your headlights while you're driving down the road.

hbn7hj, yes, ours is an Elite Power Systems product, although it is sold by Starlight Solar. We're uncertain whether Starlight adds anything to the Elite product. But did you really mean 15.2 volts, or was that a typo. Starlight/Elite was clear that 14.2 volts was the max and the number that should be used for equalizing cells.

You are correct, though. At these conservative (13.4volt) charge levels, charge currents can be low, particularly as the pack nears the target SOC. For that reason we have adopted a 'split-duty' arrangement where the Magnum 2812 charger/power supply and MidNite Solar controller are both programmed to 'maintain' the 80% SOC and are set to 13.4 volts (as close to 13.36volts that these devices allow) and use our 280amp 2nd alternator to do high level, fast charging. Ordinarily the 2nd alternator is disabled, but if we have been boon-docking and need a fast charge, that alternator is programmed to 13.8 or 13.9 . . . which provides a reasonably high rate of charge without overheating the alternator.

[hbn7hj]

"But did you really mean 15.2 volts, or was that a typo."

4 times 3.8 is 15.2. Packs are 4 cells and maximum voltage per pack was stated as 3.8v

[Santiago]

Originally Posted by hbn7hj

4 times 3.8 is 15.2. Packs are 4 cells and maximum voltage per pack was stated as 3.8v

I have the Elite power battery as well though not in service yet. I do plan on following Winstons sound and experienced advise (two years on the road now with his Elite). I have a lot invested in my Elite house battery and I don't wish to see it experience a premature death.

This is similar to a Porsche the factory red lines it at 7800 rpm. That's "max". Other than doing so now and then for fun, who thinks its wise to drive it at 7800 rpm all day long?

Santiago

[stanw909]

Let's try this again . If your current battery set-up has worked for 8 years , why change now ?

[stanw909]

If current set-up has worked for 8 years , why change it ?

[Winston]

Originally Posted by stanw909

Let's try this again . If your current battery set-up has worked for 8 years , why change now ?

Seems you've answered your own question. As is often said: "If it ain't broke, don't touch it." As we were starting from scratch, our lithium decision was based on technical benefits.

And for those benefits we could see someone with 8 years of success making the 'upgrade'. It's like our TV . . . we finally replaced our old 'tube' 4:3 standard definition set with an HD flat-screen - - the old one had worked for years . . . but we just wanted the benefits of the new technology.

[kite_rider]

Since the question of 'why lithium' seems to keep coming up; I'm adding lithium (in parallel to my existing AGM) to get additional energy capacity with small space that I have available.

The coach AGM battery on my van was mounted under the van near the rear axle, but it was only about 1/2" above the low axle height. Since I take my van off road and through deep snow this was a concern for me. On my last test camping run, I was really happy to have all my batteries inside rather than being dragged through the deep snow ruts.

Winston: I like your charging charts but am not clear on your criteria for a 'resting voltage'. On my Lithium battery, I notice that the voltage drops quite a bit within minutes after charging. How do you define your 'resting voltage'?

I've been testing my 'DIY' Lithium battery for about a week of camping in sub-freezing temps (between 14-23F). So far I'm really happy with the results. I'm charging the battery from the 220A alternator and noticing a peak of about 75A, but an average charge of around 55A. I've got my PowerMon monitor programmed to disconnect the battery after it reaches 14.4V for a continuous 3 seconds. The it will re-connect at 14.0V. Overnight power consumption has been between 25 - 40Ah of energy and the charge cycle (when driving) usually lasts between 25 to 40 minutes before the PowerMon disconnects the battery. The Low Voltage disconnect is set for 12.8V for a duration of 5 seconds; but so far this hasn't occurred. The closest I get is when the microwave oven is running, but it doesn't trip the LVD.


Originally I was concerned about my battery separator keeping my coach and chassis batteries connected, but now I'm less concerned. I listen to a lot of satellite radio on these long cold nights (powered off the chassis battery). The power draw for this hasn't been excessive and I'm now thinking it's a good thing to keep my chassis battery topped up while out in the boonies camping.

[Winston]

Originally Posted by kite_rider

Winston: I like your charging charts but am not clear on your criteria for a 'resting voltage'. On my Lithium battery, I notice that the voltage drops quite a bit within minutes after charging. How do you define your 'resting voltage'?

All batteries voltage 'sags' after charging. All batteries voltage 'recovers' (increases) when loads are removed.

Our concept of 'resting voltage' is to determine what the voltage is AFTER these temporary sagging/recovery effects have 'run their course'. We find that the pack voltage will 'recover' slowly for several hours after each discharge segment. We consider the recovery to have 'run its course' when the pack voltage no longer increases - - generally we require several hours of 'no (voltage) change' before taking our reading. To be on the safe side, we've been letting our pack 'rest' for 10 hours after each discharge segment.

As we seek to create a chart/table correlating pack voltage as a function of State of Charge . . . and since, for any given SOC, the pack voltage can vary dramatically depending on whether the battery is, or has been, under charge or is, or as been, under discharge . . . we believe that 'resting voltage' provides a meaningful and repeatable standard for battery voltage measurement.

[Santiago]

Tracking voltage while battery is in service (charging/discharging) throughout the day is pointless. I agree that for voltage reading to be meaningful the battery has to have sufficient time to rest and that means no loads or charging for an adequate period of time, aka resting voltage reading.

While monitoring charging and static voltage is still great data, battery ampere "level" tracking is more meaningful especially in light of lithium's flat voltage curve, unlike what we are accustomed to with lead acid chemistry.

My planned house power design will follow Tom's (TGregg) battery tracking method that he's been using for some time with his lithium bank. That is to measure battery's in and out current similar to a water tank level gauge only more accurate and periodically recalibratable to ensure accuracy as battery capacity changes, monitor errors creep in, etc.

While in service, no need to charge 100%. Setting ampere flow monitor to stop charging when battery ampere capacity level is 90-95% full is safe and will ensure long lithium life. A lower limit setting restarts charging. I like his method.

Santiago

[avanti]

Originally Posted by Santiago

Tracking voltage while battery is in service (charging/discharging) throughout the day is pointless. I agree that for voltage reading to be meaningful the battery has to have sufficient time to rest and that means no loads or charging for an adequate period of time, aka resting voltage reading.

That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.

[booster]

Originally Posted by avanti

That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.

What I have read, but have no idea if it is gospel, is that the rest time in lead acid batteries is needed to allow the electron migration through the battery to finish and be uniform. It was referred to as surface charge in reverse, as it gives a similar false actual voltage, but in the opposite direction compared to surface charge. I don't know it it also applies to lithium, and if it does, would it take as long with their high charge and discharge rates?


If discharge rate were stable over time, and you had a conversion chart to what the rested would be for that load, I would think then that the loaded voltage would be a decent reference. Many users do have relatively steady use for fairly long periods, so there are probably lots of users that kind of instinctively know where they are based on loaded voltage and past experience. Personally, I prefer to just look at the battery monitor and know for sure, instantly, what my SOC is.

[Bud]

Originally Posted by avanti

That is an interesting claim. I do not know whether it is strictly true or not. My understanding is that the reason for the "rest" period is simply that it provides a standard condition for measurement. It is not clear to me that some other standard condition (i.e., with a fixed load) would not be just as valid (but with different quantitative standards). If THAT is true, then over a long enough period of time, continuous measurement averaged across the whole range of usage might well be meaningful.

I honestly don't know, but it is an interesting question.

Hi avanti,

Recently you may recall me writing that SOC is determined by me without AND with loads is all I use. 12.13 volts means something different concerning SOC depending on length of resting vs. using a 200 watt appliance. Yes, Mr. booster stated that I had trained myself like a puppy or something like that. Hey, I'm a full grown dog now, just took some time.

Bud