Lithium Battery Question
I am thinking about converting my 2020 lance to Lithium batteries. I want to do it as inexpensively as possible. (Battle Born ain't gonna happen) Can anyone tell me what specifications I should look f...
Forum Discussion
http://liionbms.com/php/wp_soc_estimate.php
Looking at that paper again, and how the Charge Wizard works.
If the bank is at 70% and you do a recharge, AFAIK the PD by itself will not go into Boost, but remains at 13.6v. If the bank is more like 50% it will. But then it will drop to 13.6v after two or three hours depending on how long it takes to get to about 97% where it drops. (still not full)
If you use the Charge Wizard, no matter what the SOC you get four hours of 14.4v on the timer and then it drops to 13.6v. If not yet full, you hit the boost button and get another four hours. If you get to full after an hour into the second go, you can use the Charge Wizard to drop it to 13.6v yourself.
I don't have a PD, so if that is wrong, please correct that!
So the flat part of the Li voltage vs SOC I imagine would fool the PD so it never went into Boost even at 50%, but maybe at 25%? So you must use the Charge Wizard and have the fixed four hours at 14.4.
That might mean it stays at 14.4 three hours after it gets to full after one hour depending on the situation. So is that three hours too long? If it is, you must be there to manually drop it to 13.6 when the time is right. If it is not too long, you can leave it to drop by itself later.
Back to the paper and a new set-up IMO you should observe what happens closely taking notes and make a rough graph to find the point at the high end where the voltage spikes/drops and note the AH count.
First get the bank full at 14.x where amps flow has tapered to near zero and stop. Set the AH counter to zero. Start a load at the 20 hr rate (10 amps for a 200AH bank) and watch the voltage drop, taking note every few minutes for your graph and note the AH. When you see the voltage flatten out, you have enough info.
So now you know how many AH out of supposed 200 it took to get to where it flattens, so you know the SOC when it did that--might be 90% or whatever.
So what good is that info? You can use the AH counter from then on to get your SOC and never mind the voltage. You know that 20 AH is 10% so at 90% you are down 20AH. At the bottom where voltage drops off, it would be at say 180AH, so stay above that. You can tell how much you have left before you are as low as you dare to go.
Say you are using about 50AH a day as you see from experience. One morning you see the AH count is 140 down. So by tomorrow morning it will be about 190 down. Oops too far. So recharge today. Stop the gen when it gets back to 20 down just as voltage starts to spike ( about 90% SOC if that was the number when you did your testing)
On top-balancing each recharge--do you need to? I got the notion that you only need to be top-balanced when first building the bank to get your high voltage cut-off marker, but after that you don't care? Not clear on that. Li guys will know.
Looking at that paper again, and how the Charge Wizard works.
If the bank is at 70% and you do a recharge, AFAIK the PD by itself will not go into Boost, but remains at 13.6v. If the bank is more like 50% it will. But then it will drop to 13.6v after two or three hours depending on how long it takes to get to about 97% where it drops. (still not full)
If you use the Charge Wizard, no matter what the SOC you get four hours of 14.4v on the timer and then it drops to 13.6v. If not yet full, you hit the boost button and get another four hours. If you get to full after an hour into the second go, you can use the Charge Wizard to drop it to 13.6v yourself.
I don't have a PD, so if that is wrong, please correct that!
So the flat part of the Li voltage vs SOC I imagine would fool the PD so it never went into Boost even at 50%, but maybe at 25%? So you must use the Charge Wizard and have the fixed four hours at 14.4.
That might mean it stays at 14.4 three hours after it gets to full after one hour depending on the situation. So is that three hours too long? If it is, you must be there to manually drop it to 13.6 when the time is right. If it is not too long, you can leave it to drop by itself later.
Back to the paper and a new set-up IMO you should observe what happens closely taking notes and make a rough graph to find the point at the high end where the voltage spikes/drops and note the AH count.
First get the bank full at 14.x where amps flow has tapered to near zero and stop. Set the AH counter to zero. Start a load at the 20 hr rate (10 amps for a 200AH bank) and watch the voltage drop, taking note every few minutes for your graph and note the AH. When you see the voltage flatten out, you have enough info.
So now you know how many AH out of supposed 200 it took to get to where it flattens, so you know the SOC when it did that--might be 90% or whatever.
So what good is that info? You can use the AH counter from then on to get your SOC and never mind the voltage. You know that 20 AH is 10% so at 90% you are down 20AH. At the bottom where voltage drops off, it would be at say 180AH, so stay above that. You can tell how much you have left before you are as low as you dare to go.
Say you are using about 50AH a day as you see from experience. One morning you see the AH count is 140 down. So by tomorrow morning it will be about 190 down. Oops too far. So recharge today. Stop the gen when it gets back to 20 down just as voltage starts to spike ( about 90% SOC if that was the number when you did your testing)
On top-balancing each recharge--do you need to? I got the notion that you only need to be top-balanced when first building the bank to get your high voltage cut-off marker, but after that you don't care? Not clear on that. Li guys will know.
