batteies

Cptnvideo wrote:
StirCrazy, my Victron 150/100 MPPT controller lets me set all the settings you are talking about. In fact, so does my GoPower IC3000 inverter/charger. However, the charger portion of the GoPower is always off unless I've had 3 really bad days of weather and need to run the generator.

ya my renogy MPPT will also, lots of solar controllers will, but I have never investigated a combo charger/inverter as myself I wouldn't buy one, just because there more expensive to replace if something breaks. but it is something to look into.

StirCrazy, my Victron 150/100 MPPT controller lets me set all the settings you are talking about. In fact, so does my GoPower IC3000 inverter/charger. However, the charger portion of the GoPower is always off unless I've had 3 really bad days of weather and need to run the generator.

otrfun wrote:
For folks like yourself who monitor their battery & converter closely, this risk is lower. However, I would surmise most folks would prefer not to be babysitting converters and batteries while they're on vacation---I know we'd prefer not to.

In any event, NONE of the above risks exist when charging with a 2-3 stage converter (with the proper voltages)---even if the converter and lifepo4 battery are left unattended for weeks, months at time. It negates these risks by automatically activating a completely safe, lower float voltage as soon as the lifepo4 battery is fully charged.

I can agree with this, although I don't monitor it that closely like some people do. only when I am wondering about something. I guess what I could say is I built my own and selected my BMS for features I wanted that would let me use the BMS to compensate for a single stage converter as there really weren't any Li dual stages that I had found when I was buying equipment, well affordable anyways haha. and like I mentioned if you buy an off the shelf LFP battery you don't know exactly how it works or what the settings are unless they tell you.

Now I built my camper battery out of eve cells, and they actually spec charging at 14.6 until the cell voltage is at 100% (3.65) then turning the charge off. so what I did is set up my BMS to do this when I am on my balancing cycle, for my normal camping cycle I charge at 14.6 but shut it off when the battery capacity reaches 90%. The only time I must interact with this is when I change that 90% to 100% to do the balance and all that is, is opening my cell on the morning, I decide to do the balance and click my second profile. Then I set a reminder to put it back after it gets dark. which is probably still more than most would want to do.

so, I guess it's the difference of how you look at it, and what you learn when you build vs buy. I had the opportunity to select my accessories to operate it the way I wanted to. I still think a two or three stage charger would be good if there were decent ones out there... Maybe I am just being picky, but I would like the ability to adjust the voltage of each stage independently and be able to switch stages based on voltage feedback from the battery bank. it would be nice if we could turn the equalization cycle into a balancing cycle also, so every so many days (you set it) it does a full charge with the extra time for balancing then automatically goes back to your regular setting. any converter companies watching this haha I wonder if I could make something like this with an Arduino.

This may help:



https://onlinelibrary.wiley.com/doi/abs/10.1002/er.5298

Grit dog wrote:
And to think, the OP just wanted to know if he could put Li batteies in his camper…..:S

Actually the OP (ck1246) only had a question about using his current converter. Everything was reasonably on topic until these last two posts about thermal runaway.

ck1246 wrote:
My house batteies went bad this winter. Can replace with lithium batteies. Will they work with my converter?

And to think, the OP just wanted to know if he could put Li batteies in his camper…..:S

MrWizard wrote:




Over voltage is dangerous it can cause Thermal Runaway and fires,

If we are talking older forms of LI and not LiFePo4 I would tend to agree with you, LiFePo4 is highly resistant to thermal runaway and is hard to get to do it.

I am reading a study right now where they took a 202ah battery and put a 900 watt heating element on each side and ran full boar until the safety valve popped and it went into a thermal runaway state. It took a battery internal temperature of over 160 degrees Celsius to do it and the maximum temperature achieved during the runaway was 202 degrees Celsius. Another they did with only 1 heater but put the battery into a sever overcharged state first and then heated it until it started to run away. so while it is possible to get thermal runaway it is very hard under normal conditions, you would need the charger to fail, the BMAS to fall in a manner that still allows charging, and possible some external heat source to aid the process as the charge rate most of us will have on their batteries wouldn't be enough to spike the internal battery temp high enough.

just for a bit of context the batteries they use in teslas that people were getting cells from and putting them in their rv's will thermal run away much easier and will reach 600+ C temps when they do.

StirCrazy wrote:
. . . maybe you can explain this, is why it is such a big deal to have a second stage. When I am camping in the bush the charge isn't running, so it's no big deal. With LiFePo4 everyone is so adamant about not storing them at a full charge so we shouldn't be leaving them on charge anyways when we are not using the unit. and the final category if you camp in power sites mostly, well then why did you spend money on LFP? and if you only camp with power once and a while, just turn off the charger breaker and you don't need to worry about it

StirCrazy wrote:
. . . No, not necessarily do you need 14.6v, for instance my BMS will start balancing at higher than 13.6V but for me the cell manufacture recommends charging at a constant 14.6 and then cutting the voltage when the state of charge is reached. Considering they are one of the biggest prismatic cell manufactures, I would assume they know what they're talking about and that is how I set up my system. I do play with it to see how it behaves in different situations though . . . .

Not sure if you realize it, but all this monitoring, "cutting the voltage" and "turning off the charger breaker" that you recommend doing while using a single-stage 14.6v converter would not be necessary with a 2-3 stage converter. IMO, a converter should be able to safely and efficiently charge/maintain a lifepo4 battery for weeks, months at a time . . . with ZERO user input. This is exactly what a multi-stage (2-3 stage) converter does well.

StirCrazy, here's a simple analogy that hopefully answers your question why I feel a converter with 2-3 stages is a really a "big deal" . . . and why a single stage 14.6v converter is such a bad deal.

Using a single-stage (one voltage) 14.6v converter to charge a 12v lifepo4 battery is roughly equivalent to driving a car at redline. To clarify, 14.6v subjects the cells in a 12v lifepo4 battery to 3.650v---the Maximum Rated Charge Voltage for 3.2v lifepo4 cells . . . this is roughly equivalent to driving a car with a Maximum Rated RPM (redline) of 6000---at 6000 RPM. Sure you can drive a car at redline for short periods of time. You can also charge (float) a lifepo4 battery at its maximum rated charge voltage for short periods of time, too. No immediate damage occurs in either case. However . . . common sense says . . . "redlining" a car or subjecting a battery to its maximum rated charge voltage, for extended periods of time (accidentally or otherwise), presents a much higher risk of permanent damage occuring. If you're the set-it & forget-it type, and forget to turn-off a single-stage 14.6v converter while using FHU's for a month or so, you run the risk damaging your lifepo4 battery. For folks like yourself who monitor their battery & converter closely, this risk is lower. However, I would surmise most folks would prefer not to be babysitting converters and batteries while they're on vacation---I know we'd prefer not to.

In any event, NONE of the above risks exist when charging with a 2-3 stage converter (with the proper voltages)---even if the converter and lifepo4 battery are left unattended for weeks, months at time. It negates these risks by automatically activating a completely safe, lower float voltage as soon as the lifepo4 battery is fully charged.

Several things are well know about Lithium batteries
Batteries that are not heated or maintained within a heated compartment are not to be charged when cold, they can be discharged aka used but not recharged

They can be charged with a lower voltage and not harmed , {they will just not reach will recharge} but this for not harm Lithium as they do not develope a damaging hardening coating like lead plates,

Over voltage is dangerous it can cause Thermal Runaway and fires,

There are some LiFePo batteries that can accept normal RV converter charge voltage and are advertise as drop in replacements, no special charger needed, Battle Born might be one of them,

The good ones, charge at one set voltage do not need special charger patterns, and do not use,/,need a float voltage, just charge at the set voltage, and leave them alone or use them, then recharge

otrfun wrote:

StirCrazy wrote:

Tom_M wrote:
When I'm plugged in my battery will not charge fully but that is not a problem with lithium.

be careful saying that. yes, I agree it doesn't have to be charged fully on a regular basis, but you still have to charge it full once and a while to ensure the cells stay balanced.

You can get away with this because you let your solar charge it with proper profiles and hopefully you take it up to 100% with that once and a while and let it fully balance. My BMS has a passive balancer that would take forever to balance so I added an active balancer to mine, so it only needs 2 hours or less to balance my 300AH battery. When I am camping, I do this once a week, the rest of the time I cut off at 90% but that's the BMS controlling that.

Tom_M didn't mention what voltage his converter or solar charger is using to bulk charge with. Without this information there's no way to know definitively what's going on with his system.

Also, in a number of your posts you seem to allude that you must have 14.6v to properly balance a 12v lifepo4 battery. This is not true . . . unless the BMS's threshold voltage for balancing is set too high. A 12v lifepo4 battery bulk charging at 14.4v (equivalent to a 3.600v parallel top-balance) should be more than enough voltage delta to allow a BMS to balance in a timely manner. If it's not, then you probably have bigger problems (see next paragraph). For what it's worth, Battleborn lifepo4 batteries are capable of supporting all BMS balancing functions when bulk charged at 14.2v - 14.4v (14.4v recommended). As you know, BB does not recommend long-term bulk charging at 14.6v.

Yes, an active balancer, especially a 5-10a version, will balance rather quickly. However, if you have properly top-balanced, "matched" cells, the 100-150ma passive balancer found on most BMS's should balance in a reasonable amount of time. If the 100-150ma passive balancer is not capable of doing so, then an active balancer may be compensating for, or putting a band-aid on, the true problem: moderately to badly mis-matched cells. No amount of top-balancing, passive balancing via BMS, or use of an active balancer can correct this problem. The result, permanently reduced ah output from the battery---especially during high c discharges.

No, not necessarily do you need 14.6v, for instance my BMS will start balancing at higher than 13.6V but for me the cell manufacture recommends charging at a constant 14.6 and then cutting the voltage when the state of charge is reached. Considering they are one of the biggest prismatic cell manufactures, I would assume they know what they're talking about and that is how I set up my system. I do play with it to see how it behaves in different situations though.

I only used my active to do the initial setup. it's still attached, and I can use a switch to turn it on.. that was because someone on here recommended that for the 20 bucks I get one. That was couple years ago when I was looking into the stuff, I needed to build mine.