3 tons wrote:
“ Do you think it would be more accurate if the meters counted Amp hours?”
A few post back I added links to two engineering discussions on this very matter that helped ‘wash my mental windows’ Well worth one’s investment of time to gain a ‘beyond novice’ understanding of the difficulties in determining SOC of LFP’s - trust, not really a ‘one solution fits all’ situation...I offer this mostly to the broader audience...
3 tons
3 tons wrote:
“Who was it that told me” ??...It was first hand knowledge, and be advised that I’ve mentioned this before - It was my Xantrex meter... Try as I might, once below about 60’ish %, regardless of what settings I used it would not track LFP SOC with any accuracy, nor does the owners manual specify LFP...However, the Xantrex worked flawlessly for 11 years with my former GC 6v...
3 tons
Freep wrote:
So 3 tons, who told you that the Xantrex LinkLite SOC meter wasn't accurate and the Victron is? From everything I can see, all three products do the same thing with regard to determining state of charge.
What am I missing?
Edit:
Do you think it would be more accurate if it counted Ahrs?
Freep wrote:3 tons wrote:
“ But a cheap coulomb counter is fine with me because it's an inherently unnecessary device.”
Ok, but for clarity it should be noted here that a meter that only counts coulombs is not structly compatible with LFP, though it may be fine above 50% SOC - in practical terms with LFP, SOC only begins to get important below 50%...
As has been already noted here several times, computing SOC with LFP requires a sophisticated algorithm including a ‘look-up’ ledger which is necessary when below a 50% SOC...This is due to the extremely flat voltage curve characteristics of LFP, and why (as previously stated) I had to ditch my former meter...
This is interesting. There are a lot of people using the AiLi for their LFPs over at diysolarforum.com and I've never heard this before. I'll go ask the gurus over there and see if I can get some clarity. I've been using it for almost a year now and it has usually agreed with the BMS on SOC.
Edit: To be clear, a Coulomb counter does not rely on voltage.
StirCrazy wrote:Gjac wrote:StirCrazy wrote:So $600 CAD is about $580 US if I converted right. I realize everyone has different electrical requirements but 2 Sam's Club 6vGC batteries are still under $200 in us dollars so I don't see a similar cost. I'm not sure what you mean by high quality deep cycle batteries, but I paid $74 apiece for my 2 GC batterers from Sam's Club 14 years ago and they are still doing fine and I only dry camp. If they failed tomorrow I can still buy them for $90 apiece, so I don't see a cost comparison that is close yet. I understand the weight is a lot less as well as the foot print and in time with all the EV's coming out they may be cheaper.Gjac wrote:
Jayco creek said: With the price getting so low for Lifepo4,I can't see a reason not to switch when there about the price of a quality lead acid...JMHO,.. So what is the current price comparison?
for making your own you can build a 280 usable AH for about 600 bucks now. to get that in deep cycles batteries you probably over 1000 for high quality and about the same in cheep on sale (these prices are CDN).
other advantages besides price now days is weight that would be about 46LB and it would give me more capacity than the 240lbs of 6V I have now that only have 235AH usable. also the size, this one Li battery is the side of one of the 6V batteries. so 1/6th the weight and 1/4 the size.
Steve
your kinda off on your conversion 600 cdn is a little over 478.00 US and you need 6 of thoes batteries to get 280 to 300 usable AH.
I dont use cheep batteries, my GC batteries in my 5th wheel are 325 CDN each for 235AH and are 14 years old and just showing signs of needing replacment. so for me to get the same power I would need 4 to 6 batteries so eaven at 4 that is over 1200 bucks for less usable AH
Gjac wrote:StirCrazy wrote:So $600 CAD is about $580 US if I converted right. I realize everyone has different electrical requirements but 2 Sam's Club 6vGC batteries are still under $200 in us dollars so I don't see a similar cost. I'm not sure what you mean by high quality deep cycle batteries, but I paid $74 apiece for my 2 GC batterers from Sam's Club 14 years ago and they are still doing fine and I only dry camp. If they failed tomorrow I can still buy them for $90 apiece, so I don't see a cost comparison that is close yet. I understand the weight is a lot less as well as the foot print and in time with all the EV's coming out they may be cheaper.Gjac wrote:
Jayco creek said: With the price getting so low for Lifepo4,I can't see a reason not to switch when there about the price of a quality lead acid...JMHO,.. So what is the current price comparison?
for making your own you can build a 280 usable AH for about 600 bucks now. to get that in deep cycles batteries you probably over 1000 for high quality and about the same in cheep on sale (these prices are CDN).
other advantages besides price now days is weight that would be about 46LB and it would give me more capacity than the 240lbs of 6V I have now that only have 235AH usable. also the size, this one Li battery is the side of one of the 6V batteries. so 1/6th the weight and 1/4 the size.
Steve
