LiFePo4 at under $200 per 100ah battery

[Luv2Go]

Originally Posted by Bud

Is it happening?

Batteries with all the above can be purchased or built from scratch. However none can keep someone from destroying their cells by, for example, discharging them and leaving them uncharged for a winter. Of course that would destroy lead acid batteries as well.

[booster]

Originally Posted by Bud

Is it happening?

We know of one from this thread and I would bet there are others we don't know about. As with most things, when things work well, we hear about them much more than when they fail, it is human nature, I think.



The thing is, I think, as more of them get out there and as they age, the protection details get more important.


As in the example sooner or later a lot of us will mess up and inadvertently run our batteries too low which is probably what happened in the example. Chargers can mess up also as can devices that use high currents.


If users believe the "drop in" pitch of the ads or sales person they could wind up with lithium that has no protection being charged by a fixed voltage charger 24/7 for instance.

[booster]

Originally Posted by Bud

Is it happening?

We know of one from this thread and I would bet there are others we don't know about. As with most things, when things work well, we hear about them much more than when they fail, it is human nature, I think. IIRC the Fit RV had theirs overheat but the overtemp safety prevented damage.



The thing is, I think, as more of them get out there and as they age, the protection details get more important.


As in the example sooner or later a lot of us will mess up and inadvertently run our batteries too low which is probably what happened in the example. Chargers can mess up also as can devices that use high currents.


If users believe the "drop in" pitch of the ads or sales person they could wind up with lithium that has no protection being charged by a fixed voltage charger 24/7 for instance.


On edit: One major thing that hasn't come up here but has been championed by Avanti in the past IIRC, and by several others of us.


A very large amount of the more basic systems being installed appear to be using the BMS as the charge controller and not just as an emergency shutdown if something goes wrong.


I think that the BMS should be looked at as the safety backup, not the primary and only control. The charging control, temp control, etc should all be done by those components to limits inside of the BMS settings, IMO. Redundancy in areas like high amperage charging and use, along with adequate fusing, should catch a very large proportion on any problems that occur before bad things happen.


One particular area where the BMS is truly needed is if the lithium battery gets out of balance between the cells. In that case, which we have seen several examples of on the forum including ours, the BMS will cut off charging way before the normal charging setpoint for a 14.4v charge. This is because the BMS is looking at individual cells, not battery voltage and if they are out of balance it disconnects on the highest cell. I think that maybe an integrated system like a Victron setup might control off individual cells, but I don't know that. Perhaps Avanti does as his new system might. The rest of us are stuck with no redundancy on that unless we put in low voltage monitors on every cell as a standalone.

[@Michael]

Originally Posted by Bud

Is it happening?

I recall one from a thread in a different forum. My recollect is that it was a DIY setup in a camper where a cell had been loose, and from road vibration had worn through the outside case of the cell and shorted the plates against the steel frame of the homemade battery case. It got hot enough to burn down the camper, but the owner caught it before too much damage had been done.

I don't expect that to happen on properly cased cells.

[Boxster1971]

Originally Posted by Luv2Go

Batteries with all the above can be purchased or built from scratch. However none can keep someone from destroying their cells by, for example, discharging them and leaving them uncharged for a winter. Of course that would destroy lead acid batteries as well.

You can charge lead acid batteries in cold, below freezing conditions. But with lithium, of any kind, you have to heat them in order to charge them if they are at about 40 degF.

I just when from AGM to Lithium and now I see that cold weather operation with lithium is a whole new ball game. The Volta system in my new Interstate 19 will just keep heating the batteries to keep them above 59 degF. Same as an electric vehicle in cold conditions. Both will just keep the battery warm until the battery is depleted. They all need external power sources in cold weather.

[booster]

Originally Posted by Boxster1971

You can charge lead acid batteries in cold, below freezing conditions. But with lithium, of any kind, you have to heat them in order to charge them if they are at about 40 degF.

I just when from AGM to Lithium and now I see that cold weather operation with lithium is a whole new ball game. The Volta system in my new Interstate 19 will just keep heating the batteries to keep them above 59 degF. Same as an electric vehicle in cold conditions. Both will just keep the battery warm until the battery is depleted. They all need external power sources in cold weather.

Yep, cold weather sucks if you have lithium as it puts you into having a couple catch 22 things. It is a given that they need heat if you are in cold weather and you have to park outside. How you do it gets more complicated.


Many of the batteries are mounted inside the van so they keep warm, but that is only when you are using and and/or heating it. They are normally not insulated as they also want them not to get too hot from use when inside.


But when you are parked how do you heat them? If uninsulated it will take bigger heaters if they are inside the batteries and you can control them and much bigger heaters if they are just under or between the batteries. Heating the interior of the poorly insulated vans seems like not a good thing to me.


Many of the setups that are "drop in" or close to it retrofits are leftovers from lead acid and designed to float the batteries but you don't want to float lithium per most current sources, I think. That means you heat has to not come from shore charger unless it can run without the battery reference and thus floating the batteries. 110v heaters would work for shore power at that point with charging system off, but when in use you would either need to run the inverter to run them or have duplicate 12v heaters. It would be interesting to see if anyone puts a watt meter on their outdoor stored, lithium equipped, vans to see how much actual power gets consumed over a winter when stored outdoors in a cold climate, especially in Canada.


I probably would not have done the lithium swap in our van if we had to store it outside here in Minnesota as it would make it more hassle than it was worth as the AGMs we had worked quite well for a long time. The lithium do some stuff better, but there the tradeoffs also, and temp stuff is one of the largest IMO.

[peteco]

Assuming you have 12v heaters and 120v availability at home, why wouldn't you just plug in at home if you don't have indoor storage. I guess you need to have a way to not overcharge the Li batteries, but I would think the system could be setup to handle this issue. (Note: these comments coming from a Li battery hope-to-be-someday).

[Urlauber]

Luckily I live in an area where it rarely freezes, unless I go up North or into the mountains.

I imagine one would certainly need a way to NOT heat the batteries all the time. If you don't use the camper, and don't leave it plugged in, turn everything off until the next outing. Just make sure before you do that the batteries have enough juice left to be able to unfreeze themselves and not run empty while doing so.

Maybe I am simplifying things...
But in my simple mind all there is to it is some extra battery capacity to account for the heating process. More if you are in Minnesota.

[avanti]

A couple of thoughts:
1) I think having an uninsulated battery box makes little sense under any circumstance. Such a setup does little to keep your batteries cool--just as likely to make them warmer. Plus, a little muffin fan can negate the effect of any insulation very easily and effectively. You don't need a fancy setup like mine.

2) I would think that you would always want 12/24V heating pads, not 110VAC, for the sake of flexibility. If you don't like running your converter, a little power brick will do.

3) I think it is very important that your charging setup be capable of powering your DC loads without charging the battery. High-end systems can do this, and lower-end ones can pretty easily be wired to do so, perhaps with a switch or relay.

4) People have been talking about avoiding "freezing", but that is only important while charging. When in storage, it is only necessary to prevent very low temperatures (typically spec'd at 0-degrees F). This is a much less frequent situation, and really isn't that hard if you are plugged in. If you are not plugged in, you need a fancier setup that probably includes remote engine or genset starting as a last-resort. The latter is somewhat daunting, the former is not.

On my still-new rig, I am getting through this winter via shore power keeping my Victron system running but in "no-charge" state, and with a 12V thermostatically-controlled battery heater inside an insulated compartment. This works fine, although it is not particularly energy-efficient (the Victron reports consuming around 50W of shore power). As I flesh out the systems, I will address the energy-efficiency in several ways, and also likely provide for disconnected storage.

[booster]

Originally Posted by avanti

A couple of thoughts:
1) I think having an uninsulated battery box makes little sense under any circumstance. Such a setup does little to keep your batteries cool--just as likely to make them warmer. Plus, a little muffin fan can negate the effect of any insulation very easily and effectively. You don't need a fancy setup like mine.

2) I would think that you would always want 12/24V heating pads, not 110VAC, for the sake of flexibility. If you don't like running your converter, a little power brick will do.

3) I think it is very important that your charging setup be capable of powering your DC loads without charging the battery. High-end systems can do this, and lower-end ones can pretty easily be wired to do so, perhaps with a switch or relay.

4) People have been talking about avoiding "freezing", but that is only important while charging. When in storage, it is only necessary to prevent very low temperatures (typically spec'd at 0-degrees F). This is a much less frequent situation, and really isn't that hard if you are plugged in. If you are not plugged in, you need a fancier setup that probably includes remote engine or genset starting as a last-resort. The latter is somewhat daunting, the former is not.

On my still-new rig, I am getting through this winter via shore power keeping my Victron system running but in "no-charge" state, and with a 12V thermostatically-controlled battery heater inside an insulated compartment. This works fine, although it is not particularly energy-efficient (the Victron reports consuming around 50W of shore power). As I flesh out the systems, I will address the energy-efficiency in several ways, and also likely provide for disconnected storage.

Nothing wrong with going with 12/24v heaters but you have to have system that can handle that, such as a charger that can run and hold voltage without a battery reference which will be shut in cold weather normally and you wouldn't want to float if it wasn't. As mentioned, a separate power supply/converter might be a good option with the appropriate controls of when it should run or be out of the system.

Being able to power the van is similar to the heaters running with the batteries disconnected and is certainly a nice feature that most people don't and won't have unfortunately. We have a moderately high end collection of good charging equipment and none of the three sources will run without a battery reference in the system. This can be a problem if the batteries shut down or are too cold to come on line and charge. We are lucky in that respect as our system is two parallel alternators that run both the coach and the starting battery with a disconnect between them so we always have a battery reference and ability to run the coach. Standalone second alternators don't have that ability unless a jumper switch to parallel the starting battery is in place.

I have mentioned several times in the past that the sharp cutoff temps at 32* and -4* for charging and discharging for lithium are very highly likely to be arbitrary "best compromise" temps to try to balance damage vs usability vs sales success. Based on the literature I have been able to find the best charging and using temps are quite a bit higher and some mention negative effects happening at anything under about 50* for both charging and discharging. It is probably an unknown (to us) curve that shows more damage with colder and with more time at any given temp. The net damage would be an integration calculation of the whole area under the curve. I hope no one really believes the batteries at 33* are getting any real amount less damage than they would at 31* for instance as I bet they are very close to the same.

I also think that in vans that sit outside all year, they may actually get as much problem with too hot of storage. The literature is also starting to lower that number, with a significant number under 100*F, and 95*F getting pretty common. Very tough if you live in a hot climate when the days are hotter than that most of the summer, and even in the more temperate areas, vans get hot in the sun. Keeping the batteries cool might be tougher and harder on them than cold is to handle. I think the Fit RV lost their first set to the heat, but it was over 100* IIRC.

[@Michael]

Originally Posted by booster

It would be interesting to see if anyone puts a watt meter on their outdoor stored, lithium equipped, vans to see how much actual power gets consumed over a winter when stored outdoors in a cold climate, especially in Canada.

I ran a 15w heating pad wrapped around a 100Ah Battleborn, with minimal insulation wrapped around the battery. The results are here:

https://www.classbforum.com/forums/f...tml#post124258

Originally Posted by @Michael

Where the insulation is poor I see +30F temperature difference. Where the insulation is not-so-poor I see at least +45F above ambient.

My conclusion is that with better insulation (I.E. 1" of well-fitting XPS) the 15 watts of heat is more than adequate to keep the battery above freezing under most circumstances and above the low limit of -4F under nearly any condition.

Even with as little as 1/2" of well-fitting XPS I believe that the 15 watts of heat would keep the battery 40-50F warmer than ambient, adequate to prevent damage under discharge pretty much anywhere in North America, and above freezing in most of the continent.

I also ran a 300Ah SFK battery with internal heating pads. The results are here:

https://www.classbforum.com/forums/f...nts-13794.html

Originally Posted by @Michael

With ambient temps inside the camper at -5F, the 80 watts of heating pads run with about a 50% duty cycle, so there is plenty of headroom for either colder temperatures or lower wattage heating pads.

In the first case, I ran the heating pads from the AGM batteries, then kept the AGM's charged via shore power using a normal charge curve. In the second case, I set the shore power charger (Victron IP-22) to maintain a constant 13.2v and ran the heating pads from the battery.

My original plan was to make the lithium battery removable. After a bit of experimentation, I do not think that's needed as long as I have shore power. If it's well below 0F and my house has no power for a long enough time to freeze my battery, my $1500 lithium battery will be the least of my problems.

I don't camp in hot weather, so I'm not concerned about overheating the battery. If I were, I'd simply make the insulation removable.

[booster]

It is good to see some real work numbers. The 80 watt heater in a 300ah battery is quite large. Even at 50% duty cycle I think that would eat over 100ah of battery capacity a day on a 600ah bank or two batteries. It would take more solar that you could put on the roof to get that much recovery per day in the great white north areas where the days are short and the temps cold, I fear.


It is certainly showing that for lithium and cold weather outside storage, shore power to heat the batteries is nearly mandatory.


I have often wondered why we have not seen anybody either DIY or a company manufacture a cooled pet crate for traveling pets that might need to be left in an RV in hot weather. Based on what we see with Danfoss powered DC refrigerators a crate could be cooled to acceptable levels with very small amounts of energy used, especially when compared to AC for the whole RV. If the van was ventilated you could keep it near ambient to minimize the needed cooling.


That leads to the possibility of doing the same thing for lithium batteries in very hot climates. Just the inverse of heating pads in the north. Lithium is getting less expensive, but still not cheap for a relatively large bank, so might be worth doing a truly temp controlled battery box that includes both heat and cooling so you could be anywhere, anytime and not have to mistreat your batteries to do it.



As lithium becomes much more common, it will be interesting to see if battery life is better or worse or similar between different parts of the country, especially in outdoor stored vans.

[avanti]

Originally Posted by booster

Nothing wrong with going with 12/24v heaters but you have to have system that can handle that, such as a charger that can run and hold voltage without a battery reference which will be shut in cold weather normally and you wouldn't want to float if it wasn't. As mentioned, a separate power supply/converter might be a good option with the appropriate controls of when it should run or be out of the system.

For me, using 12V heaters was a very important design decision. The reason is that it makes it possible to recover from a "battery below Zero (or whatever)" condition without the availability of shore power. Specifically, I have the ability to switch the van's entire 12V power system to the chassis power system (which has two batteries). If the heaters were 120VAC, there would be no recovery mode absent shore power. It is true that I also have a DC-AC-DC setup, so I have a redundant alternative, but most will not have this.

Being able to power the van is similar to the heaters running with the batteries disconnected and is certainly a nice feature that most people don't and won't have unfortunately. We have a moderately high end collection of good charging equipment and none of the three sources will run without a battery reference in the system. This can be a problem if the batteries shut down or are too cold to come on line and charge. We are lucky in that respect as our system is two parallel alternators that run both the coach and the starting battery with a disconnect between them so we always have a battery reference and ability to run the coach. Standalone second alternators don't have that ability unless a jumper switch to parallel the starting battery is in place.

But, one doesn't lose battery reference at 32-degrees. That doesn't happen until Zero F (I am using these exact temperatures simply as shorthand for the two distinct thresholds -- no charge and no-discharge). I don't know about other systems, but the Victron BMS/Multibus system can continue to stay powered up below freezing--it just won't charge. I admit I don't yet fully-understand its behavior, but so far I have seen no issues operating below freezing. I simply need to heat the batteries via one of my several redundant options before I can charge them.

As I said above, it is important to distinguish the "can't charge" state from the "can't use at all" condition. That latter is also allegedly a "can't store" condition, so it needs to be avoided at all costs.

I also think that in vans that sit outside all year, they may actually get as much problem with too hot of storage. The literature is also starting to lower that number, with a significant number under 100*F, and 95*F getting pretty common. Very tough if you live in a hot climate when the days are hotter than that most of the summer, and even in the more temperate areas, vans get hot in the sun. Keeping the batteries cool might be tougher and harder on them than cold is to handle. I think the Fit RV lost their first set to the heat, but it was over 100* IIRC.

My hope is that having an insulated battery box outside the van will be optimal in high-heat situations. Under the van will, I think, almost always be cooler than the inside of a parked van, and if necessary, I can ventilate the battery compartment using outside air with just a little power to the reversible bilge fan. I have many temperature sensors throughout the van, so I should be able to gather very good data on this next summer. I already know that the van interior can easily exceed 100-degrees F in sunlight, a temperature that is unusual (but not impossible) underneath.

[booster]

Originally Posted by avanti

For me, using 12V heaters was a very important design decision. The reason is that it makes it possible to recover from a "battery below Zero (or whatever)" condition without the availability of shore power. Specifically, I have the ability to switch the van's entire 12V power system to the chassis power system (which has two batteries). If the heaters were 120VAC, there would be no recovery mode absent shore power. It is true that I also have a DC-AC-DC setup, so I have a redundant alternative, but most will not have this.

But, one doesn't lose battery reference at 32-degrees. That doesn't happen until Zero F (I am using these exact temperatures simply as shorthand for the two distinct thresholds -- no charge and no-discharge). I don't know about other systems, but the Victron BMS/Multibus system can continue to stay powered up below freezing--it just won't charge. I admit I don't yet fully-understand its behavior, but so far I have seen no issues operating below freezing. I simply need to heat the batteries via one of my several redundant options before I can charge them.

As I said above, it is important to distinguish the "can't charge" state from the "can't use at all" condition. That latter is also allegedly a "can't store" condition, so it needs to be avoided at all costs.

My hope is that having an insulated battery box outside the van will be optimal in high-heat situations. Under the van will, I think, almost always be cooler than the inside of a parked van, and if necessary, I can ventilate the battery compartment using outside air with just a little power to the reversible bilge fan. I have many temperature sensors throughout the van, so I should be able to gather very good data on this next summer. I already know that the van interior can easily exceed 100-degrees F in sunlight, a temperature that is unusual (but not impossible) underneath.

If you have the ability to connect the front system to the coach, you should be able to run the coach off the engine I would think as you could run through the inverter to heat AC heaters if you had them. Downsides to both DC and AC to some extent but I think could be workable although the low voltage wiring is much easier and safer to do in most cases.


The battery reference thing is somewhat odd in that respect and I hope somebody decides to test it some day. I don't know how any particular system is configured but how the discharge side is configured could really make a difference I think. On our batteries both the charge and discharge come out of the battery terminals, so they are one and the same at that point and go to the inverter/charger and the coach. They are also both connected to the batteries inside the battery but from two separate sets of wires to the batteries. The only way I can figure they could work would be for the BMS to switch which battery wire connects to the outside. For that to work there would have to be something like diodes to prevent the charging in the discharge line. At that point the charger would see a dead end that would accept no current, even though it would see voltage. Non power supply style chargers I think need to be able to dissipate some energy to maintain voltage. One charger I had said in the instructions that it looked for a battery in the system and did a small test current to be sure it could accept power, even before connecting. I am not sure how it would turn out in testing and may be charger dependent by brand or model, but it is probably something that would be good to know for some people when they plan battery recovery methods. It doesn't matter to us because we are full parallel capable if the separator is closed so there is always the starting battery available to allow stuff to run until the batteries can reconnect from whatever happened. All of this points to the benefits of having a converter/power supply style charger, I think, as it would give lots more options.



Totally agree that can't charge is an inconvence and no store is much more if it winds up for more than a short time, I think.


Also agree that under the van is normally cooler when parked, unless you just stopped on hot parking lot or such but that is short term. I think the high temp hazard is worse underbody when driving because the area is hot from several sources of heat. Engines and transmissions are running at 200* or more. Exhaust pipe 500*+ in the front and cooler as it goes back to the rear. The differential may be the biggest heat source because it is very close to the batteries if they are behind it as most I have checked are in the 150* or warmer range. Of course you are also going over a road surface that can easily be over 120* or more. Or AGMs sat in that spot and were totally baffled to direct the hot air around them when moving, but not in an insulated box. I had a temp sensor on rear facing side of the batteries and it would routinely show 100-120* going down the road in hot weather. I never checked the front side at the baffles but I would bet the outer side near the differential was even hotter. I think it will be very interesting to see how warm yours get inside the box, as IIRC you not vented into the van and are using underbody air.

[avanti]

Originally Posted by booster

IIRC you not vented into the van and are using underbody air.

No. I have a reversible fan that can draw air either from under or inside the van. Once I get it configured, it will automatically choose the best direction and fan speed. Driving down the highway in summer, it will probably most often be venting from inside to outside, since the van will be air conditioned.

[avanti]

Originally Posted by booster

If you have the ability to connect the front system to the coach, you should be able to run the coach off the engine I would think as you could run through the inverter to heat AC heaters if you had them. Downsides to both DC and AC to some extent but I think could be workable although the low voltage wiring is much easier and safer to do in most cases.

Yes, but I have emphasized redundancy throughout. A 120VAC battery heater would not work with an inverter failure. 12V would have more options.

[avanti]

Originally Posted by booster

The only way I can figure they could work would be for the BMS to switch which battery wire connects to the outside. For that to work there would have to be something like diodes to prevent the charging in the discharge line.

As I said, I am pretty fuzzy about the details of the Victron setup, but it is pretty elaborate. I do know the the BMS communicates with the battery at the cell level, and sends a "don't charge" signal to both the solar controller and the MultiPlus. Also, the Cerbo display shows several states for the battery, including "charging", "discharging" and "idle". Exactly how these states are accomplished I do not know, but there is a lot of control and sensor capability in the system. You can also set the MultiPlus for "On", "Off", "Charger Only", and "Inverter Only".

[booster]

Originally Posted by avanti

As I said, I am pretty fuzzy about the details of the Victron setup, but it is pretty elaborate. I do know the the BMS communicates with the battery at the cell level, and sends a "don't charge" signal to both the solar controller and the MultiPlus. Also, the Cerbo display shows several states for the battery, including "charging", "discharging" and "idle". Exactly how these states are accomplished I do not know, but there is a lot of control and sensor capability in the system. You can also set the MultiPlus for "On", "Off", "Charger Only", and "Inverter Only".

Does the BMS itself have an "emergency" type of shutdown, like nearly all of the in case batteries have? If the BMS is communicating with sources, everything is different as it can just turn stuff off for the charging cutoff, the non communicating systems don't have that luxury, unfortunately, but with the increase in Bluetooth batteries those days are coming, I think. If the battery goes into BMS controlled shutdown in a drop in, you get whatever they use to shut down and they don't really tell you in the specs what it will be or how it will affect other components. One more reason not to use the BMS for charging control, and only for when something messes up.



Interestingly, the Wakespeed alternator like I am using is also available with a Canbus connection and can communicate with a Victron system, it appears based on all the literature. It sounds like that gives it the capability of killing the field of the alternator first, before disconnecting completely to prevent the killer spike issue. That would save having a special output on the Victron to kill the field and then a separator if you have one. If it does work that way, it would be another step in not needing a B to B charger in line to protect the coach. The Wakespeed is about the size of a Balmar regulator but could do the job of multiple B to B chargers and with 30 amps of field current probably support well over 500 amps of alternator charging out of that small box while having fully programmable charge control. I hope to get the first test on our pretty soon as most of the wiring is done far enough to test, even though not cleaned up all the way and finalized.