2003AF990 battery conversion from lead acid to LiFePO4

I think SIO2 are an option, but in a very narrow aplication. they are now the most expensive battery by ah as some LiPhO4 are dropping to a little cheeper now. they charge faster but cant handle as many amps as a regular deep cycle battery so depending on your system you may have to get a different charger anyways. there not lighter than normal laed asid, not smaller, just have a higher rate od discharge which can be overcome by adding more cheep golf cart batteries.

if you looking at replacing batteries and can do some simple soldering you can build a bumch bigger bank that charges much faster, can discharge much higher and has a much longer life for much cheeper. the only disadvantage is they need to be above 0 to charge, only to charge they still dischare with less of a loss due to cold when its cold out. but at 1/3rd the size and 1/2 the weight it isnt hard to find a interior hiding spot to put them where the furnace will keep them warm.

it all depends what your comfortable with and how much work you want to do. for my 5th wheel good quality GC batteries have lasted me 14 years, I do have to look at changing them this spring and its a toss up between normal GC batteries again or Li. the price of Sio2 is prohibitive as I would need 5 to get the same AH . I dont size batteryied to use the full range, I size them for shallow depth of discharge so I dont get 400 cycles I get much much more as I am not hitting that point where so much dammage is done, hence me getting 14 years on a set of GC batteries. my majore issue now is where to put the Li (if I go that way ) where they will be able to stay warm foe winter camping.

Steve

Hi BFL13,

Thanks for the charging info on SiO2 etc.

Absorption Stage starts when amps begin to taper from the current limit amps of the charger.

The SOC of the battery when that happens depends on the charging rate-- the amps of the charger (its max current limit) wrt the size of the battery bank in AH. Higher charging rate, lower SOC when tapering starts. It can be 65% or 95%, whatever---and that's with Wets!

At about 20% charging rate (20 amps on 100AH batt) it was 87.5% SOC when amps started to taper at 14.4ish volts with my SiO2. Battery voltage got to the charger's 14.6 volts by the time the battery was fully charged.

Since an ordinary AGM would have started to taper at more like 77% at that rate, that means at 20% rate they charge at the same "speed" (and so generator time) until about 80% and then the SiO2 is "faster" after that because it is still accepting the 20 amps while the AGM's amps are tapering. But you don't charge them to full with a gen anyway--usually to 80 or 90% to not waste gen time when camping. In that case the 80-90% of SOC would have taken less gen time. Whether that many minutes of gen time matters "depends" on the situation at each the RVer is doing a recharge. Some days it won't matter at all, others it might.

Guys who have them report Lis will not taper until in the high 90s SOC (and that is with lower charging rates) , but also since both SiO2 and Li do not need to be fully recharged every cycle to prevent suphation, and if you do stop the gen at about 90% SOC using a 20% charging rate, they would be the same "speed" in practice. The claim they go to 97% before tapering is at a lower sort of charging rate. Heck, you can charge Wets at 5% rate and not see tapering until 95% or whatever. solar is like that with its usually low amps making for a low charging rate.

You could use a much higher charging rate with Li but you still need the charger to do those high amps and a gen that can run that much of a charger. There was a graph for LFP that showed amps started to taper at lower SOCs with very high charging rates like they can take, so it is the same with them. Just with higher rates.

"Faster" charging has to be defined exactly or it amounts to bogus advertising. A 55 amp converter will not charge any type of battery at more than about 55 amps! :(

If you start the recharge at 20% SOC like you can with Li or SiO2, you get a longer Bulk stage than you can with Wets and AGMs starting at 50%.
So that is another way to be "faster". More SOC range= more AH=at the max amps of the charger. More gen time to do a 20-80 than a 50-80 of course, so it takes longer to be faster that way :)

Your battery "sales rep" will gladly tell you how much faster it all is! ("BS baffles brains"-is something in Latin for such sales talk)

FWC wrote:
If you actually want to use the full capacity of your battery you need to deal with the absorb phase every charge.

Furthermore you will greatly decrease the life by not performing a full charge. Say you plan on using 80% of the capacity of your battery, with a full charge you will cycle between 20% - 100% SOC and should get about 1500 charge cycles. If you stop the charge at the end of the bulk phase, you will be cycling from 0% - 80% SOC and only get the mythical 628 cycles out of your battery. Which would you choose?

pianotuna wrote:
FWC yes, with SiO2 you have to deal with an absorb phase, once every 30 days. I'm sorry you see that as such a hardship.

For those of you who really want Li at an extremely competitive price surf here: https://ablithium.com/

$400 for 100 amp-hours, drop in with BMS. Plus shipping.

My own opinion is that SiO2 have never caught on due to their high price. Some how Li has circumvented that.

As to Li such as battleborn, they are really a 120 amp-hour battery with a BMS that cuts off the bottom 20 amp-hours. I wonder how that will work out as the batteries age?

And where did you see absorb starts at 80%? For ordinary flooded it starts at 85%, with 12.5 amps per 100 amp-hours of capacity. Are you saying SiO2 are worse than flooded? For AGM absorb starts at about 90%. I'd love the information on the state of charge where absorb starts, for SiO2. I'm hopeful that it will be at 95%.

Please quote correctly from the web sites you may access. It is 620 cycles to 0 volts at which time 80% of OEM capacity is still available. I suggest that the number of cycles on an AGM to 0 volts is a heck of a lot less than 620.

SiO2 outshine AGM at peak demand, even with telcom jars that are intended for high amperage discharges. i.e. over 300 amps from a single 100 amp-hour battery.

There is no question that I could use AGM used telcom batteries for less money overall. But I wish to never buy batteries again. So I'll spend a bundle on SiO2 after I'm vaccinated.

I am needful of being able to boondock and run an O2 concentrator overnight. I will NOT run a generator while sleeping. My existing battery bank can no longer support the concentrator overnight.

Even for a full time person 1500 cycles is over four years. I expect

I will be oversizing the battery bank to give me 480 usable amp-hours (or 5.7 kwh). That compares to just 278 from the telcoms (or 3.3 kwh).

My other "need" is a battery to allow me to use the remote start on my generator. I've already managed to "kill" three brand new AGM batteries. My hope is that SiO2 will recover from my abuse.

I'm finding your posts quite aggressive. Perhaps that's just me.

I apologize to the OP for this reply being off topic.

BFL13 wrote:
I am glad he mentioned them in the first place though, or I would never have heard of them, and they happen to be just right for me. I might be the only Rver in the world that they are just right for, can't say :)

BFL13,

Nope The owner of the sanidumps site has them--and has posted a review about them.

And they are just right for me, too especially now that I'm back to very much part time.

FWC wrote:

BFL13 wrote:
"Anyway, this has been pointed out several times, but the same claims still get made. In general, if you want cheap then go with flooded lead acid, if you don't want maintenance, go with AGM, if you want the best lifetime value and performance go with LiFePO4. If for some reason it is really important for you to charge at -37C then go with SiO2"

The OP just wants more AH in the battery space available than he gets now with his Wets. Li and SiO2 will do that.

As will plain old AGM, for much less money than SiO2. I cannot see any reason to go with SiO2 in this application, but they seem to be recommended for every application.

A. You can operate SiO2s down to lower SOCs and get away with it more often than with ordinary AGMs, plus the voltage stays up at the lower SOCs so your inverter alarm will not go off so soon. You will not get as many cycles when going lower in SOC to get more AH, but that only matters if you would ever use the rated number of cycles in your lifetime or the lifetime of your RV. You get way more cycles as rated with SiO2 than with ordinary AGMs, so even if you lose a bunch of cycles you could have had, you might still be ahead on cycles than with AGMs. Depends.

B. PT should limit his recommendation for SiO2s to particular scenarios, and not tell everyone to get them as the be-all and end-all.
Agree with FWC on that.

I am glad he mentioned them in the first place though, or I would never have heard of them, and they happen to be just right for me. I might be the only Rver in the world that they are just right for, can't say :)

BFL13 wrote:
"Anyway, this has been pointed out several times, but the same claims still get made. In general, if you want cheap then go with flooded lead acid, if you don't want maintenance, go with AGM, if you want the best lifetime value and performance go with LiFePO4. If for some reason it is really important for you to charge at -37C then go with SiO2"

The OP just wants more AH in the battery space available than he gets now with his Wets. Li and SiO2 will do that.

As will plain old AGM, for much less money than SiO2. I cannot see any reason to go with SiO2 in this application, but they seem to be recommended for every application.

"Anyway, this has been pointed out several times, but the same claims still get made. In general, if you want cheap then go with flooded lead acid, if you don't want maintenance, go with AGM, if you want the best lifetime value and performance go with LiFePO4. If for some reason it is really important for you to charge at -37C then go with SiO2"

The OP just wants more AH in the battery space available than he gets now with his Wets. Li and SiO2 will do that.

In my case with the previous TC, I just carried more batteries than would fit in the TC battery box, by putting them in the truck bed in front of the wheel wells and running wire inside. I would do that with the camper part way into the truck when loading and unloading the camper.

In my case the two batts had to go inside so that meant no Wets.

I did get two SiO2s for this camper, but for a reason not mentioned above. I use high amps for microwave etc with a big inverter. That takes four batteries and in a bigger RV they can be Wets, no problem. No reason at all to get Li or SiO2 if you can fit four Wets outside or vented.

With space for only two batts, you can't run the high amps with either Wets or ordinary AGMs. That leaves SiO2 or Li. I chose SiO2 because I can't afford Li, but could spring for the SiO2. I also don't like the whole BMS thing that Li has, but that is just me, so not a factor for others I suppose. I don't have to consider their weights in my scenario. The low temperature advantage of SiO2 might be a good thing where we use the TC in the winter, not sure- mostly it is above freezing here in winter but not by much at night.

On life span of the battery by number of cycles, both SiO2 and Li would be way more than we will ever do, so just not a factor. If you are 30 years old and will keep your RV for 30 years and camp often, that might be worth a look compared with Wets or AGMs, but I doubt most will ever realize that "advantage" if that is why they are buying Li. (Seems more like it is just to "keep up with the Joneses" in some cases reading rv.net posts---but some folks do have good reasons as they have explained)

So you do have to work your way through the choices to see what you need and can afford, as mentioned by FWC above, but there are more scenarios for juggling all the factors than mentioned.













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If you actually want to use the full capacity of your battery you need to deal with the absorb phase every charge.

Furthermore you will greatly decrease the life by not performing a full charge. Say you plan on using 80% of the capacity of your battery, with a full charge you will cycle between 20% - 100% SOC and should get about 1500 charge cycles. If you stop the charge at the end of the bulk phase, you will be cycling from 0% - 80% SOC and only get the mythical 628 cycles out of your battery. Which would you choose?

pianotuna wrote:
FWC yes, with SiO2 you have to deal with an absorb phase, once every 30 days. I'm sorry you see that as such a hardship.

For those of you who really want Li at an extremely competitive price surf here: https://ablithium.com/

$400 for 100 amp-hours, drop in with BMS. Plus shipping.

My own opinion is that SiO2 have never caught on due to their high price. Some how Li has circumvented that.

As to Li such as battlebord, they are really a 120 amp-hour battery with a BMS that cuts off the bottom 20 amp-hours. I wonder how that will work out as the batteries age.

FWC yes, with SiO2 you have to deal with an absorb phase, once every 30 days. I'm sorry you see that as such a hardship.

For those of you who really want Li at an extremely competitive price surf here: https://ablithium.com/

$400 for 100 amp-hours, drop in with BMS. Plus shipping.

My own opinion is that SiO2 have never caught on due to their high price. Some how Li has circumvented that.

As to Li such as battlebord, they are really a 120 amp-hour battery with a BMS that cuts off the bottom 20 amp-hours. I wonder how that will work out as the batteries age.