Starting my LFP build.
- Thread starter Hayden Watson
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,160
You think it looks like a model?
You been reading the wrong magazines....
Battery Magazine
Model Magazine
Oh... figure of speech... Never mind.
Looks very futuristic. And the data says it is working.
You been reading the wrong magazines....
Battery Magazine
Model Magazine
Oh... figure of speech... Never mind.
Looks very futuristic. And the data says it is working.
No, Model. From design to reality. Remember I are an engineer.You think it looks like a model?
You been reading the wrong magazines....
Battery Magazine
View attachment 206626
Model Magazine
View attachment 206627
Oh... figure of speech... Never mind.
Looks very futuristic. And the data says it is working.
And I get reprimanded for thread piracy....
Anyway, 'Splain to me Paco.... I don't get the bus bars for lack of a better term. On one side of the battery all the cells are included. On the other side of the battery there is a gap of one cell - or so it appears. It's asymmetric. Why?
Anyway, 'Splain to me Paco.... I don't get the bus bars for lack of a better term. On one side of the battery all the cells are included. On the other side of the battery there is a gap of one cell - or so it appears. It's asymmetric. Why?
This is not piracy. The point of this thread is discussion of my build. Yes, the correct term is buss bars. In the final build I used flexible buss bars that have a hump in the center to allow them full freedom of movement.
This is a 2p4s 12v battery made up of eight 280Ah cells that each produce 3.2v that are connected in parallel (2P). those pairs are cells 1-2, 3-4, 5-6, 7-8. The parallel connection adds the Ah and keeps the voltage, so each pair is 280Ah + 280Aah = 560Ah at 3.2volts.
these four 560Ah pairs are then connected to each other in series where the Ah remains the same but the voltages are added (560Ah at 4x 3.2v - 12.8v at 560Ah.
If you look at the model, you can see a red "+" sign on each of the cells. 1, 2, 5, 6 are on the far side and 3, 4, 7, 8 are on the near side.
Good question.
This is a 2p4s 12v battery made up of eight 280Ah cells that each produce 3.2v that are connected in parallel (2P). those pairs are cells 1-2, 3-4, 5-6, 7-8. The parallel connection adds the Ah and keeps the voltage, so each pair is 280Ah + 280Aah = 560Ah at 3.2volts.
these four 560Ah pairs are then connected to each other in series where the Ah remains the same but the voltages are added (560Ah at 4x 3.2v - 12.8v at 560Ah.
If you look at the model, you can see a red "+" sign on each of the cells. 1, 2, 5, 6 are on the far side and 3, 4, 7, 8 are on the near side.
Good question.
By the way, I think my battery is pretty sexy. Does that make me old?You think it looks like a model?
You been reading the wrong magazines....
Battery Magazine
View attachment 206626
Model Magazine
View attachment 206627
Oh... figure of speech... Never mind.
Looks very futuristic. And the data says it is working.
Sue thinks I am pretty sexy for building her a battery that will power her fridge, freezer and hydronic heating system and allow us several days on anchor without any need to make power. Does that make me young again?
Just checking in on your build, @Hayden Watson , any updates?
I confess I'm jealous. I would love to duplicate what you've done.
jv
I confess I'm jealous. I would love to duplicate what you've done.
jv
I have been using it for the past week and so far I am delighted. It is not poured in place but close to it.
The only thing left for this phase is to make a cutout in the heat molded acrylic lid for the two negative wires to pass through.
I have not gotten the PWM control to work on the alternator yet but have been able to throttle the output by putting two 100W 0.5 ohm resistors in series into the field wire which gets me 60A max output.
The time on the boat has been put to good perpose.
The only thing left for this phase is to make a cutout in the heat molded acrylic lid for the two negative wires to pass through.
I have not gotten the PWM control to work on the alternator yet but have been able to throttle the output by putting two 100W 0.5 ohm resistors in series into the field wire which gets me 60A max output.
The time on the boat has been put to good perpose.
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Very nice. I don't suppose you'd make these parts available?
I'm curious about not getting the PWM alternator controller working properly yet. Any ideas as to what the problem might be?
I can ask my bother-in-law if he would be willing to sell the spacers. I am not sure why the PWM is not working but it is probably my lack of understanding. I did not have time to mess with it before our cruise which began yesterday.Very nice. I don't suppose you'd make these parts available?
I'm curious about not getting the PWM alternator controller working properly yet. Any ideas as to what the problem might be?
We had 17 house guests for the 4-day 4th weekend so not much time for R&D. It might be a DOA, or a bad board because I mis-wired it they first time around. I plan to test it and a spare at home with a case fan until I get the control to work on that.
So far, we have gotten to full charge on both days. I did find that the diode battery combiner does not work well due to the large voltage drop on the LFP side and small drop on the AGM side. I will need to upgrade that to a FET based combiner to eliminate that problem. For this cruise, I have come up with a good workaround of just using my emergency back combiner to get the same voltage on both banks.
The 1.0ohm 100W resistor pulls the output down to about 60A. That output had the alternator temp between 195º and 200ºF which is ok but higher than I would like to see. Then I notice that I had the buildge blower turned off. Once that was on, it dropped down to about 180º which is probably about right given that I have a 180º Tstat in the engine.
Yes, I have been charging directly from my 105A Ample Power "hot rated" alternator. I have been told that it is built for 100ºC 100% duty cycle. It is currently using my old Xantrex InCharge regulator, but I added a 10-Ohm 100W resistor to the field wire so that it puts out a max of 60A and the alternator temp stays below 85ºC. Currently my bilge blower inlet is not long enough to reach inside of the box of soundproofing I installed so it is not doing the best job of pulling out the hot air. I am going to add some more duct to get the hot air out of the engine enclosure and see if I can turn it up a bit more. I am also thinking about adding a "push fan" to supplement the pulley fan to increase the airflow.
We have been cruising with it since 7/6 and if we travel a couple of hours each day, we are topped up. This is with 12v icebox conversion, 12v 54qt freezer, hydronic heat in the morning and evening to heat domestic water and all of the lights and electronics.
Today we sailed most of the day, so we are stuck with "only" 81% of our 560Ah in reserve. Not sure if 453A will be enough to get through the night! Tomorrow we will need to motor 30Nm home given the forecast of 3knts of wind. That ought to top us up.
Attachments
Is the BMS turning off the alternator when the bank is full? Are you charging to 100% when you charge?
Thanks,
jv
What is 100%? On the LFP, that it not a requirement so I leave some headroom. 3.65v is the max cell level voltage so with a perfectly balanced pack, you can go to 14.6v but I do not have much faith in a perfect world. I charge (CC) to 14.0v or 3.5v per cell. and then absorb for 30-minutes. My active balancing begins at 3.45v so it is balancing during the absorb phase.
FWIW, LFP are very happy to be at less than 100% SOC and should be stored anywhere in the 30% - 70% range. When I got back from my cruise today, I was at 98% and the resting voltage was 13.38v and below the 3.40v balaance voltage.
Here is another screen shot taken a bit earlier which shows SOC @ 94% and still taking 50A and not at balance voltage. This thing just sucks up everything you send at it with almost no change in voltage.
This shot was taken 3 hours earlier. In those three hours, I motored at 2100rpm, added 140Ah and it raised the battery charging voltage by 0.16v. All I can say is WOW!
The battery itself is 8½"W x 9¼"H x 25½"L but the #2 wires that I used and the 225A Class-T fuse at the end made it wider and longer. It was a tight fit into the C30 Mk2 battery box which is 9½"W x 10¾"H X 27"L. It fit is without binding but cannot move in any direction by more than 1/8".
Thank you! Ugh, the height might prevent me from implementing this on my Tartan 3800. This boat was designed as if all that anyone needed was a couple of group 27 FLAs - and even those were a tight squeeze! I might have to start looking for an alternate location for the batts. It will be tough to find a place that will handle the size of your pack.The battery itself is 8½"W x 9¼"H x 25½"L but the #2 wires that I used and the 225A Class-T fuse at the end made it wider and longer. It was a tight fit into the C30 Mk2 battery box which is 9½"W x 10¾"H X 27"L. It fit is without binding but cannot move in any direction by more than 1/8".
Do you happen to know what it weighs?
Thanks,
jv
Wow, that's awesome. I mean, the battery system, and your reporting on it!
My "dream" system would have a way I could tell the system to go to storage mode, and somehow burn Ah's to get to 85%, or 50%, or whatever I tell it - maybe hearting water - like the ocean?