Yes, the heat is bad. I was at the storage lot today diagnosing one of the axle hubs on my trailer.
JBD-SP04S020-L4S-120A-B-U Help
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Yes, the heat is bad. I was at the storage lot today diagnosing one of the axle hubs on my trailer.
Acho_303
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Just John - Currenty I am using the canned lifepo4 lite settings so I just want to confirm the setting is the balanced turn-on voltage, correct?? Also would 8t be okay to just set it without top balancing? I am in the mountain and didn't plan to go back to town where my charger etc is until friday
Acho_303
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I have been thinking about adding a mini split to the back of my sprinter, now that I have the juice lol... Just not sure how it will look.. the pioneer units are 31 inches wide which is about the same as one of the back doors... but honestly anything above 85 is brutal in the city, even with two sirocco fans on high and two maxxair fans running... its hard to sleep.
Yes, stop telling it to balance at 3.2v. That setting is destroying your top balance. Above 3.4v per cell, you will always have a "runner" cell. It is normal. Certainly you can try to get every cell to 3.65v, but that is not what the manufacturer defines as a standard charge. A standard charge will have the cell settle within 2 minutes to 3.4v. After an hour (again, part of the standard charge procedure from the manufacturer) they will settle to 3.375v. What is the obsession with 3.65v?
Preliminary data:
| EBC-A40L .25 amp cutoff | EBC-A40L 14 amp cutoff | EBC-A40L 3.4v with absorb 2.5v discharge | EBC-A40L 3.4v with absorb 3.0v discharge | EBC-A40L 3.4v with absorb 3.1v discharge |
278.4 | 277 | 276.9 | 269.2 | 264 |
278.8 | 277.5 | |||
278.9 | 277.4 | 276.8 | 268.5 |
First column is what you would normally do to top balance, charge to 3.65v until current drops under .25 amps. Capacity is measured to 2.5v.
Second column is a "standard charge" defined by Eve, charge to 3.65v and stop when current drops under 14 amps. Capacity is measured to 2.5v.
The following columns, 3.4v with absorb means charge to 3.4v and stop when current in drops below 1 amp. I'm trying to dial in the settings that will give the best battery cycle life (Eve says 80%, but doesn't tell you what voltage or current to use). So the last three columns I'm testing cut off voltages. Below 3.1v discharge, the cells start to warm up, not badly, but it was 118 here today, I don't want a 5 degree Celsius rise in cell temperature. 3.1v discharge at 40 amps gives a 2 degree Celsius rise.
Real data. Stop trying to charge to 3.65v, you really and truly are getting so little gain, and shortening cell cycle life.
My 16 (commodity) cells (notice less than 2 amp hours difference). Each of these test takes a day, so 32 days worth of testing here. The first column is what you are trying to do, the second is what the manufacturer recommends.
| EBC-A40L .25 amp cutoff | EBC-A40L 14 amp cutoff |
278.4 | 277 |
278.8 | 277.5 |
278.9 | 277.4 |
270 | 267.8 |
277.9 | 276 |
271.8 | 269.5 |
278.3 | 276.4 |
278.7 | 276.8 |
278.1 | 276.1 |
271.5 | 269.4 |
275.2 | 274.1 |
276.2 | 275.1 |
278.7 | 275.9 |
276.8 | 274.6 |
278.4 | 276.3 |
274.1 | 271.6 |
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Acho_303
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Lol no obsession, I just get worried when there is a high voltage difference and want to stop that. Since it's summer I have been running into that several days in a row. I set the balance turn-on voltage to 3.4 instead of 3.2 for both packs
Hardware overvoltage protection - 3.65
Hardware undervoltage protection - 2.5
Balance turn-on voltage - 3.4 (I personally turn it off)
thegoogler
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Put the positive meter lead on the BMS ring and also test it from the copper lug. Don't use the grub screw, they are used to secure your lug but the real voltage transfer happens between the lug and the metal ring at the top of the battery not the screw. Also if the screw is a different material (zinc or SS) than the battery (aluminum) it may have slightly higher resistance.
Hard to tell if that is just a reflection or a star washer between your BMS lead and the copper lug? If it's a star washer it needs to go on top
Are you sure your meter is correct? Do you have access to another meter to confirm whether the BMS or the meter is correct.
thegoogler
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Someone else can chime in here but I don't think you're using that busbar correctly. These are designed so each of those lugs gets bolted to its own screw. I don't know that it will matter with the battery cut-off sandwiched between the battery lugs but YMMV, particularly if the lugs aren't perfectly flat.
Side note: I looked at buying these but ended up just making my own from some smashed copper pipe.
Acho_303
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So originally I had the lugs on their own bolt, but I found one battery would pull more ah than the other... it got to a point it was one battery would be 25 or more ah less than the other. I read a post from another member having that issue and the event was corrected by using the same bolt for both leads. I then changed my setup so the order is one battery, the lead to the power draw, and the other battery, basically a oreo cookie... where the white is the power pull and the black is the leads to the batteries. Since then my battery packs are within 2 or 5ah of each other.
Acho_303
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No washers, the nuts have a flange to them
thegoogler
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Interesting. I would've thought if it was BATTERY -> SWITCH -> BATTERY -> UNUSED it would've been balanced. BAT -> BAT -> SW does seem like it could end up unbalanced.
I have 3 leads on 3 different screws, but I used 3/4" type-L copper pipe, and the 3 leads are all going between the battery box post and either the BMS or the positive battery terminal. In fairness my smaller 10-ga lugs on the other side of the BMS and fuse are all stacked directly on the battery terminal like yours is (mainly for space reasons). Basically I'm saying I wouldn't think any of this would actually matter, it's just something that looked odd.
Acho_303
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I think another forum member stated the Terminal connectors I have are cheap metal... and that might have played into the battery ah balance issue... I ordered and installed before searching, but over the winter with my espar running all day the 25ah+ difference was a issue so that's when I stumbled upon another member with the same issue... it might not have been the order of the lugs but the cheap metal, either wY now with the lugs sandwiched together my packs stay within 5ah of each other
Acho_303
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The offgrid solar guy just posted a video detailing how he fixed his imbalances. It looks like he set the float and absorption to a high voltage and set the absorption time to zero minutes.
I thought I might try that, so I set absorption to 14 and float to 13.9... with zero absorption time (my Orion would not take zero and defaults to 1 hour)
Thoughts???
I thought I might try that, so I set absorption to 14 and float to 13.9... with zero absorption time (my Orion would not take zero and defaults to 1 hour)
Thoughts???
thegoogler
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It's a hack. I think it depends a bit on how much you need to recharge the battery each day. If you need a lot of amps to get back to near full then you want more absorption time, but if you don't drain your battery much and you have decent sun then you might be OK with a lower voltage.
I tested on a day with full solar starting with a 280Ah battery at 87% and if I set my absorption on my Renogy Rover Elite to 13.6V I was seeing about 3-4A. I changed it to 13.8V and I was seeing ~6A. Bumped to 14.4V and I got almost 12A being delivered. I needed ~36-37A so at 14.4V I should be able to recharge in ~3 hours, but at 13.6V it would've taken 9-12 hours. Now if my battery was at 50% I would've needed to get 140A into it to fill it, and even at 14.4V/12A that's >12 hours so in that case high voltage (high absorption) is critical to get you close to full and then you could float from there.
The more I've researched this the more I'm convinced if your goal is to stay 10-90% SoC you need a controller which understand tail voltages . Here's why:
You need to find a target voltage in which the battery will settle at about 13.4V (3.35V/cell). If you charge at 13.4V/cell, it's going to take FOREVER for you to get to 90% because the current will taper off. So what you really want is to charge at 14.4V/cell (which ensures you get a lot of Amps) but once the battery hits ~13.6V you want to turn off charging, at which point the battery will settle to around 13.4V. To my knowledge there are only 3 ways to terminate charging before you hit the target voltage though:
1. Manually shut off the solar charge controller
2. charger automatically switches from absorption to float after a period of time (typically 3 hours)... but if you start the morning at 80% then you may well overshoot and end up close to 100%
3. smart charging system which detects the "true" battery voltage, basically by watching for a current drop and then shutting off charging... tail voltage.
I think Victron does #3.
Now if you don't care about hitting 100% charge then set it to 14.4 or 14.5V and don't worry about it.
I tested on a day with full solar starting with a 280Ah battery at 87% and if I set my absorption on my Renogy Rover Elite to 13.6V I was seeing about 3-4A. I changed it to 13.8V and I was seeing ~6A. Bumped to 14.4V and I got almost 12A being delivered. I needed ~36-37A so at 14.4V I should be able to recharge in ~3 hours, but at 13.6V it would've taken 9-12 hours. Now if my battery was at 50% I would've needed to get 140A into it to fill it, and even at 14.4V/12A that's >12 hours so in that case high voltage (high absorption) is critical to get you close to full and then you could float from there.
The more I've researched this the more I'm convinced if your goal is to stay 10-90% SoC you need a controller which understand tail voltages . Here's why:
You need to find a target voltage in which the battery will settle at about 13.4V (3.35V/cell). If you charge at 13.4V/cell, it's going to take FOREVER for you to get to 90% because the current will taper off. So what you really want is to charge at 14.4V/cell (which ensures you get a lot of Amps) but once the battery hits ~13.6V you want to turn off charging, at which point the battery will settle to around 13.4V. To my knowledge there are only 3 ways to terminate charging before you hit the target voltage though:
1. Manually shut off the solar charge controller
2. charger automatically switches from absorption to float after a period of time (typically 3 hours)... but if you start the morning at 80% then you may well overshoot and end up close to 100%
3. smart charging system which detects the "true" battery voltage, basically by watching for a current drop and then shutting off charging... tail voltage.
I think Victron does #3.
Now if you don't care about hitting 100% charge then set it to 14.4 or 14.5V and don't worry about it.
Acho_303
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Sorry, setting both the absorption and float to 14.4?? And zero absorption time?
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thegoogler
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What's your goal? Are you trying to fully charge to 100% and maintain at 100%, or are you trying to stop at ~90%?
If your goal is 100% charge, then:
- Set "bulk" to 14.4V (if you have a bulk setting)
- Set "absorption" to 14.4V (if you have an absorption setting)
- Set "float" to 13.6V
- Disable equalization or set to 13.6V if you can't disable it
- Set "bulk" (if you have a bulk setting) to something between 14.0V and 14.4V (depending on how much charge you need to recover... assume you'll run in this state for 2 or 3 hours)
- Set "absorption" (if you have an absorption setting) to 13.8V or 14.0V (again depending on how much charge you will need to recover
- Set "float" to 13.4V
- Disable equalization or set to 13.4V if you can't disable it
- Set "bulk" and "absorption" to 13.8V (or 13.6V if you want to be very conservative)
- Set "float" and "equalization" to 13.4V (if you can't disable them)
I would very much agree.
You want as many amps as your charge controller can put out going in, until current begins to drop.
Like you say, once it begins to drop then you can set your float to about 13.4v - 13.6v.
Finding a charge controller intelligent enough to do this is a challenge, I don't currently have one.
I will say that the larger the gauge wire, and the shorter the wire length, obviously the more amps you can push without higher voltages. But you still need an intelligent charge controller, and it's best if it can read the actual terminal voltage (not through the charging cable).
