AGM Battery chargin

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AGM Battery chargin

Postby DavidB on Sun Nov 19, 2006 11:35 am

I hooked up (4) AGM 8D MK batteries for a 48V bank today. Charging by (5) KC-120's. The battery voltages when charging with 2.4A at 59.4V were:

15.4
14.5
15.0
14.8

I was concerned by the 15.4V reading and the nearly 1V difference between the batteries. I could also hear a faint noise coming from the 15.4V battery.

The temperature at the battery bank is probably around 50F.

Is this a problem? I lowered the absorb of the MX-60 to 57V.

I also noticed that my fluke measured 59.8V for the bank but the MX-60 read 59.4V.

David
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Postby crewzer on Sun Nov 19, 2006 12:42 pm

Divid,

This sounds like a mess, both literally and figuratively. A hissing AGM battery suggests the charge voltage is too high, and 15.4 V + 14.5 V + 15.0 V + 14.8 V = 59.7 V. That’s close to the total you got with your Fluke, but higher that the MX registered.

59.4 V sounds about right for the high end of a 48 V AGM battery bank at 50 F (10 F). The temp comp should be 0.03 V / C / 12 V battery X 4 each 12 V batteries = 0.03 V x 15 C X 4 = +1.8 V, and 57.6 V + 1.8 V = 59.4 V. But, if you’re measuring a higher voltage at the battery terminals, you may need to calibrate the MX’s meter. See page 26 of the rev 6.2 owner’s manual.

Back to the batteries. It sounds to me like the batteries were at various stages of discharge when they were hooked up. Since they were all being recharged with the same amount of current when wired in series regardless of their individual SOC, the batteries that started off at a high SOC may be suffering an overcharge condition while the lower SOC batteries may still be recharging..

I think the solution is to normalize the batteries’ SOC before hooking them up in series. Accordingly, I recommend something like the following:

1. Disconnect the four batteries from the MX and from each other.
2. Wire the “14.5 V” battery and the “14.8 V” battery in parallel.
3. Connect the two in parallel to the MX and reset it for a 12 V system
4. Apply a load to the batteries and take ~ 125 Ah (at 12 V) out of ‘em.
5. Fully recharge the two batteries using a14.4 V (ref 77 F) absorption setting (as measured at the battery terminals) for three hours. Use the temp comp sensor.
6. Disconnect these batteries from the MX and from each other, and than set them aside to rest.
7. Connect, discharge, recharge and disconnect the “15.0 V” and the “15. 4 V” batteries the same way as batteries 1 and 2.
8. Let all batteries rest for ~ 12 hours.
9. Each battery should be full and measure ~12.8 V to 12.9 V.
10. Assuming success, rewire all four batteries in series for 48 V, reconnect to the MX, and reset it for 48 V.
11. Discharge the 48 V bank by ~60 Ah, and then take new measurements while recharging the entire string. The batteries should all be close.
12. Check all battery connections, and re-check the the MX’s metter calibration (“Vbatt offset”).

Here's a link to East Penn / Deka / MK manual for their VRLA batteries: http://www.eastpenn-deka.com/assets/base/0139.pdf

I hope I got all of this right… Let us know!
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby DavidB on Sun Nov 19, 2006 2:46 pm

Thanks for the recommendations.. I figured I'd have to do something along those lines..

I was right there when I flipped the breaker on so that high voltage battery only made the faint sound for less than a minute before I turned the breaker back off..

I did get a more accurate temp reading of the battery area and it is 45F.
So plugging in:
temp compensation for this 48V bank =
(0.03V/C/(12V Bat) * 4 batteries = 0.12V/C

(20C - 7.2C) * 0.12V/C = 1.5V

If I follow the MK battery tech manual correctly, the MX-60 should be bulk charging at 57.6V + 1.5V = 59.1V, correct? And for one of the batteries it should be 14.4V + 0.4V = 14.8V. Float should be 13.5V + 0.4V = 13.9V (all according to the document)

It looks like all the references in the tech manual are all for 68F/20C so that's why I used 20C above.

I did check the Btmp value in the Misc menu and it read 175 which is about 45F, so that matches atleast..

My resistance between all interconnecting terminals is 0.3ohms using a copper busbar and stainless steel bolts.
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MK Gel & AGM Batteries Not Team Players

Postby cjl on Sun Nov 19, 2006 4:04 pm

DavidB, I installed a 48 volt system with 4 MK 12-volt gel batteries (4 in series) in 2002 and added 4 more (4 pairs in series) in 2003. One battery went dead in 2004 and I replaced it. The charger was a 16 kW Onan generater controlled by a Trace 5548 using a temperature sensor/compensator. All the batteries were completely cross-strapped with 4/0 cables. Over the tenure of those batteries, I observed the same variations batery-to-battery as you have, but mine became more severe. Sometimes, one battery would be at 14 VDC while another was at 10.5 VDC (officially dead) only to have the situation reversed at the next charging. The Trace 5548 kept the bulk/absorption voiltage under the limit voltage of the mid-range of that suggested by MK/Deka/East Penn adjusted for the difference in the Trace reference of 20 degrees C and the MK spec of 25 degrees C.

I spent many unsatisfying hours on the telephone with MK "technical support" and with the parent company, East Penn/Deka engineers. They disavowed that any such thing should happen.

I swapped batteries in the configuration, removed cross-strapping, called in an independent expert and used various resources on the Internet. I even contacted the technical director of Sonnenschien, the holder of the gel patent that is licensed to East Penn - they just messaged East Penn and told them to handle it. East Penn never contate me.

The upshot of the Internet inquiries (which included an input from an old U-boat designer) was that gels do not work well as team players. That is certainly my experience.

Also, I use (single) gels for my telephone/ship-to-shore (independent) power, Onan generator starter, and starters on two separate boats where they perform superlatively AS INDIVIDUAL BATTERIES.

My solution was to bite the bullet (as MK/Deka would not stand behind their product) and replace all eight batteries with Surrette/Rolls Lead Acid 12 CS 11PS batteries with an aggregate 714 Ah capacity. Quite an expense, but the tuition in the school of hard knocks is high.

On balance, I would like to note that, in Canada, Pow-R-Surge lead acid batteries are made by East Penn/Deka and are very highly rated and seem to perform quite well in array applications that my neighbors have - go figure.

Good luck - keep us informed.

PS: There is an Equalization process for AGM batteries that MK describes, but does not call it equalization. The call it "Optional Accelerated Finishing Stage." (http://www.mkbattery.com/images/AGMBatteryCharging.pdf)
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Postby crewzer on Sun Nov 19, 2006 4:15 pm

David,

Good move cutting off the breaker. Your numbers all look good for 45 F batteries and the 68 F ref Voltage of 2.4 V/cell. I tend to use the 77 F standard for my calculations (in part because it's the MX' ref point for temp comp), and I think that MK's upper end recommendation of 2.43 V/cell at 68 F (20 C) converts to ~2.40 V/cell at 77 F (25 C).

I hope you're able to sort this out soon!

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby crewzer on Fri Nov 24, 2006 8:49 am

David,

Any luck?

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby DavidB on Fri Nov 24, 2006 12:47 pm

I just finished hooking all 4 batteries back up today.
I only addressed the second battery which was listed at 14.5V in the original message at this time. I see I will have to spend more time and mess with these batteries. In float for a couple hours at (around 0.5A) and they now read:

15V
13.5
13.8
13.8

This is still not good.. I had drained the 13.5V battery a couple days ago so that it read around 12.5V after about 14 hours rest. Then charged it yesterday back up so that this morning it read around 12.7V and it still is the low one in the series. It had been receiving almost 30A at times when it was charging.

If I'm not mistaken this seems to be a major disadvantage to the AGM batteries not to be able to equalize. I could see that this could be the problem why some think an AGM battery bank does not last as long as a flooded lead-acid. If you don't check what the voltages are on each battery you could have one way out of whack relative to the others and be the death of the entire bank. I can't imagine if I had a LARGE AGM bank consisting of 2V or 4V batteries.

Jim, I am curious what your volage readings are on your AGM's while charging.. are they all about equal?

I must also comment that because of the poor accuracy of the MX-60 voltage reading it probably isn't the best choice for charging AGM's.. I have had to adjust the battery voltage anywhere from +.2V to +.5V while still set for 48V..

David
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Postby crewzer on Sat Nov 25, 2006 1:39 pm

David,

I’m encouraged by three of the four voltage readings. The two batteries that read 13.8 V while in FLOAT mode look good. The 15 V battery has me worried. Let’s come back to that one.

The 13.5 V battery’s reading of 12.7 V after a recharge and rest indicates to me that it wasn’t quite full when it was returned to service. In my old 12 V configuration (four each size 4D’s wired in parallel), my batteries typically ended up at @ ~12.85 V when full and rested, and the East Penn / Deka (MK) manual suggests full to be “12.80 V or higher”.

30 A charge current into a single 8A battery doesn’t sound at all abnormal to me. 30 A is just 12% of the battery’s ~250 Ah capacity, and that’s a perfectly OK value.

The 15 V battery issue caused me to do a bit of on-line research yesterday. There’s some literature that suggests voltage equalization balancing can be a problem with VRLA batteries (AGM or gel). I have to admit that while these imbalances may be possible, I’m not sold on the impartiality of the reports, as they seem to be related the companies behind the Powercheq and BattEQ battery battery balancing gadgets.

Here’s a link to a variety of reports: http://www.smartsparkenergy.com/press.h ... hitepapers

Another reason for my skepticism is that a 12 V battery is really just six 2 V cells wired in series, and I’m not aware of large cell-to-cell imbalances being a consistent problem. At the extreme, GNB’s Absolyte AGM batteries are assembled of 2 V blocks wired in series, and they seem to work just fine. Concorde’s Sun Xtender AGM batteries are also available in large individual 2 V cells that are the size of regular Group 24 and -27 batteries.

So, I recommend you check to make sure all of the batteries are the same mfr date, and then contact your dealer and/or MK Battery for possible warranty assistance on the 15 V sample, as that one suggests to me that the internal resistance is a bit high.

What was its V measure at rest, BTW?

But... Although my batteries’ voltage readings are generally fairly consistent, there's a quirk evident during the ABSORB mode. My batteries are wired in a series-parallel configuration. Two series-pairs are wired in parallel (Series #1 and Series #2), and each series pair consists of Battery A and Battery B.

Here’s a summary of various readings over the past day:

Late Fri. afternoon (11/24), discharging, light load:
1A: 12.64 V
1B: 12.65 V
2A: 12.66 V
2B: 12.63 V

Early Sat. morning (11/25), discharging, light load:
1A: 12.34 V
1B: 12.35 V
2A: 12.35 V
2B: 12.34 V

Late Sat. morning, Bulk / MPPT charging:
1A: 13.75 V
1B: 13.75 V
2A: 13.76 V
2B: 13.74 V

Early Sat. afternoon, early Absorb stage (14.1 A):
1A: 14.84 V
1B: 14.76 V
2A: 15.05 V
2B: 14.55 V
(all of these values dither a bit as the MX makes “constant voltage” adjustments vs. increasing battery bank SOC)

Mid Sat. afternoon, late Absorb stage (6.3 A; reduced battery bank total voltage is an artifact of active temperature compensation):
1A: 14.74 V
1B: 14.66 V
2A: 15.05 V
2B: 14.35 V
(all of these values dither a bit as the MX makes “constant voltage” adjustments vs. increasing battery bank SOC)

Mid Sat. afternoon, F-MPPT stage, no significant load:
1A: 13.15 V
1B: 13.15 V
2A: 13.16 V
2B: 13.14 V

Mid Sat. afternoon, Snoozing, no significant load (shadows cut off the PV array 2 minutes before the end of the Absorb stage):
1A: 13.04 V
1B: 13.03 V
2A: 13.04 V
2B: 13.03 V

Sat. evening, Sleeping mode, no significant load, the middle of each series string connected:
1A: 12.87 V
1B: 12.87 V
2A: 12.87 V
2B: 12.87 V

The absorption mode reading for batteries 2A and 2 B perplexes me a bit. I’m going to consider three options:

1) Tie the “12 V” midpoints of the two series together after they’ve discharged a bit (done late Sat. afternoon)
2) Reduce the absorption voltage (28.8 V -> 28.4 V ref 77 F) but increase the time (3 hrs -> 4 hrs)
3) Check into a pair of the Powercheq balancers

I must also comment that because of the poor accuracy of the MX-60 voltage reading it probably isn't the best choice for charging AGM's.. I have had to adjust the battery voltage anywhere from +.2V to +.5V while still set for 48V..

There may be two issues at work here. As you suggest, one is the MX60’s meter accuracy. FWIW, my MX’ meter reads 0.1V high, so I used the OPTIMIZATION (now called ADVANCED) menu to insert a -0.1 V offset.

What’s ultimately important to me is that the battery bank voltage, as measured at the battery terminals, be correct near the end of the Absorption stage. Therefore, another possible issue could be a voltage drop in the cables, connectors, shunt, fuses and/or breakers between your MX60 and the batteries.

This is easy to check by measuring the voltage drop between the MX and the batteries, and there will likely be two sources of losses: one between the MX60’s Bat+ and the battery +, and the other between the MX60 Bat- and the battery -. I had several tenth’s of a Volt drop in my original system, and converting to a higher voltage (less current), heavier cable and bigger breakers took care of all but 0.1 V of that problem.

I think that was a long was of saying there was a 0.2 V difference between my MX’ meter and my measurement at the battery terminals. I cut that to 0.1 V by inserting a -0.1 V offset in my MX’ Vbatt calibration.

These losses between the charger and the battery bank are indeed annoying, and they are a reason why I like the battery sense feature found in other controllers (hint, hint, Outback). By measuring battery voltage at the batteries instead of at the controller terminals, the controller can maintain a very accurate charging voltage, especially in configurations involving high current and/or a wide current range, as these conditions can lead to large and/or varying voltage drops.

This all reminds me of a “law” I leaned many years ago in a program management seminar: “It takes 90% of your resources to get the first 90% of the job done, and another 90% to complete the last 10%”.

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby DavidB on Sat Nov 25, 2006 6:12 pm

Jim,
The batteries came on the same pallet and have the same date code (J6). The 3rd and 4th battery do seem to be equalized with each other now.. and am keeping the busbar attached between them while messing with the first two.

The first one I did remove about 12Ahr's and did float the 2nd battery again separately.. Now stringing the 1st and second battery together for a 24V bank and floating, the 2nd battery was about 15V and the 1st at 13.5V. I will see what they are in the morning after rest and probably will have to charge the first one alone again.

I had attempted to charge the 1st alone again after seeing that 13.5V result above and the MX-60 would try bulk charging first but immediately say the battery was full and go to float.. but then float it with around 7A's going into it..eventually dropping to about 2A. I also checked that the VBat compensation was adjusted to get it close to what the fluke was measuring. :-k I will reconnect the two in the morning and see what I get.. and make sure I'm not confusing myself.. :roll:

It was really amazing that I was just thinking what a good idea it would be for someone to have a product that made sure the batteries were all equal within a string and lo and behold you mention Powercheq (which I never heard of before).. I also thought it might be worth it to get some of those if they were about $50.. and I was able to find a place so far that sells them for $58..

I am wondering how widespread of an issue this is in the RE field? I don't recall ever seeing it mentioned in Home Power or any of the numerous RE websites about checking the voltages of batteries in the same string.. They always mention worrying about differences in voltages between two separate strings. Considering how expensive a battery bank can be you would think there would be more monitoring options available in the RE field besides the total bank voltage when just one battery could ruin the entire bank.

I noticed that on the wish list for Bogart Engineering's Pentametric is the ability to measure battery voltages other than the entire bank's voltage.

And thanks for the info and comments.. I find this exercise quite interesting.. :wink:
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Postby sparky on Sat Nov 25, 2006 9:03 pm

I do not think your problem is widespead. Sounds like defective product.
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Battery balancers

Postby abrahamsolar on Wed Nov 29, 2006 11:12 pm

Prior posts in this thread have mentioned the BattEQ(TM) equalizers from Smart Spark Energy Systems. As Smart Spark's designated distributor into the alternate energy & electric vehicle markets, I can address technical questions that may arise in this forum. Disparate monobloc voltages within a single series string are a common problem with serious consequences for battery health. BattEQ and the competing PowerCheq product from powerdesigners.com both address this problem by pumping energy out of the high increments and into the weaker increments until the voltages match. PowerCheq works on 12 volt string segments and is current limited to 2 amps. The smallest BattEQ device is similar, but these "baby balancers" are for small batteries only. Bigger BattEQ devices are now shipping which can balance "home power" sized battery banks in 6 volt increments--these are my personal favorites when designing battery systems. Soon to arrive is a BattEQ that can balance a string of four 12 volt batteries exactly like the out of whack AGMs described in a prior post on this thread. 24/7 battery balancing is the new wave in battery health care. Mick Abraham, Proprietor, http://www.abrahamsolar.com
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Postby crewzer on Fri Dec 01, 2006 2:56 pm

I ordered a pair of the Powercheq equalizers earlier this week, and they arrived today. I'll install 'em tomorrow after I pick up the ring terminals I need, and I'll try to report on their effect on Sunday.

More later...
Jim /crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby DavidB on Fri Dec 01, 2006 3:12 pm

Mine as well! :lol: Unfortunately installed too late for the sun..
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Postby crewzer on Sat Dec 02, 2006 1:32 pm

OK... I installed two of the Powercheq equalizers, one for each series pair of batteries. Here are today's measurements:

Early Sat. morning (12/2), Bulk / MPPT charging, no load:
1A: 13.09 V
1B: 13.09 V
2A: 13.09 V
2B: 13.09 V

Late Sat. morning, Bulk / MPPT charging:
1A: 13.50 V
1B: 13.46 V
2A: 13.46 V
2B: 13.50 V

Early Sat. afternoon, early Absorb stage:
1A: 14.67 V
1B: 14.58 V
2A: 15.58 V
2B: 14.67 V
(all of these values dither a bit as the MX makes “constant voltage” adjustments vs. increasing battery bank SOC)

Mid Sat. afternoon, late Absorb stage:
1A: 14.58 V
1B: 14.57 V
2A: 14.59 V
2B: 14.56 V
(all of these values dither a bit as the MX makes “constant voltage” adjustments vs. increasing battery bank SOC)

It would appear that the little "equalizer" bricks seem to work. The worst-case 0.70 V spread observed last weekend was reduced to 0.09V -- a reduction of 0.61 V, or 87%.

The green LED indicators blinked on and off, and "ON" time appeared to never exceed ~33%. The blink frequency is an apparent indication of when the bricks are actually shuttling current, and the frequency dropped as the batteries filled and the absorption current declined. Based on today's results, the two units appear to be large enough to handle my four batteries (12 V x 200 Ah each).

So far, so good! :grin:

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby DavidB on Sat Dec 02, 2006 2:56 pm

Thanks for the results Jim.. Here's my report.

This morning with 3A going in during Absorb stage (there are flurries out) and battery area at 39F :roll: :

1: 15.03
2: 15.08
3: 15.11
4: 15.16

I can't take 4 measurements at once (yet!) and the voltages are fluctuating quite a bit (+/- 0.1V with all the activity from the MX and PowerCheq's.

#4 has the positive cable connected to it. Each PowerCheq has a green and red led on it. When it blinks green it is transferring energy from or to the other battery connected to it. You can watch as the green leds light from the PowerCheq connected between 3 & 4 down to the one connected to 2 & 3 then to the one on 1 & 2.


After 2 hrs of float (about 1A going in)
1: 14.01
2: 14.08
3: 14.11
4: 14.15

After 3 hrs
1: 14.02
2: 14.07
3: 14.09
4: 14.13

After 6 hrs: (with 1.7A going in )
1: 14.04
2: 14.09
3: 14.09
4: 14.09


The settings on the MX-60 I have at:
Absorb: 57.0V
temp comp value: 59.8V

Float: 53.6V
temp comp value: 56.4

I'm not sure I have my settings exactly correct yet but I did lower them from the default slightly until I'm sure the batteries have somewhat equalized.

These obviously made a drastic difference compared to the voltage values I posted in previous postings with none of the batteries being overcharged now. It would be more interesting to see how it behaves with large loads and a recharging the bank that's at a lower state of charge.

David
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Postby abrahamsolar on Sat Dec 02, 2006 4:27 pm

Very interesting results, Crewzer & David. Are you able to read the amperage transfer on the top & bottom wires? A clamp style DC ammeter would allow you to see how many amps are moving in real time, & I for one would like to see those numbers, perhaps integrated with your voltage numbers.

I'm also curious about the data logging system that was mentioned. Let us know what you try on this and how it works out.

I have some experience with BattEQ(TM) brand equalizers on older batteries; that's sometimes more fun than experiments on newer batteries which are easier to keep in balance as their state of health is more consistent.

The "delta-v" (or difference in voltage from high increments to low ones) tends to widen with increasing amp input or output on the battery string. Also, the delta-v widens more at the extreme low state of charge or extreme high state of charge, compared to a moderate state of charge. The combination of high amperage draw at low SOC is the worst case, in my view. As the delta-v widens, the balancer attempts to pump more power up to its limit. In the case of the PowerCheq I think there's a fuse that can blow--at least that's what some of the electric vehicle crowd has reported, so you'll want to keep an eye on that.

I believe Power Designers suggests that the PowerCheq is suitable for battery ampacities up to 35 amp-hours...check with them on this. This company and the company that I rep derive these suggestions based on typical charge/discharge rates in industrial battery application. Since solar guys often charge & discharge their batteries at a slower rate compared to lift trucks, golf carts, etc., it is sometimes fine to deploy a balancer beyond the manufacturer's suggested battery size. I call this "overclocking" the balancer. If you've overclocked too far, the BattEQ units will shut themselves off rather than burn up. I don't know for sure about the PowerCheq, but it's probably possible to parallel an additional group of balancers if you find that more balancing current is needed.

In the electric vehicle world battery owners often subject their packs to very high rates of discharge, and also to fast recharge at times. In these situations, it may be necessary to "underclock" the balancer (compared to mfr. suggestions) to ensure adequate equalization current.

Thanks again for the reports,

Mick Abraham, Proprietor
http://www.abrahamsolar.com
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Postby Ecnerwal on Sat Dec 02, 2006 7:09 pm

DavidB wrote:I am wondering how widespread of an issue this is in the RE field? I don't recall ever seeing it mentioned in Home Power or any of the numerous RE websites about checking the voltages of batteries in the same string.. They always mention worrying about differences in voltages between two separate strings. Considering how expensive a battery bank can be you would think there would be more monitoring options available in the RE field besides the total bank voltage when just one battery could ruin the entire bank.


Amplepower's complex system controller
Amplepower Enermatic controller
has an add-on unit (site battery monitor) that senses voltage and temperature for every 6V of battery. That's more of a complete system, and makes some other tradeoffs (much more engine-oriented than solar oriented, from what I can tell), rather than being an add-on unit just for balancing. But they do have some features I consider superior to what Outback offers (ie, the moral equivalent of a Mate by just plugging any terminal or PC running a terminal program into a serial port, not as an additional cost unit; firmware upgrades downloadable, rather than ship unit back to factory for firmware upgrade). But the focus is not on solar to an extent that even I (I don't expect to be fully solar for quite some time, if ever) don't think I can live with. But I could Frankenstein a great system by putting Outback and Amplepower features together...
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Postby abrahamsolar on Sun Dec 03, 2006 7:35 am

Thanks for the link about the AmplePower Enermatic. David Smead & Ample Power are well regarded in the marine world particularly. The ability to monitor individual segments within a battery string is interesting--particularly the temperature monitoring function. If an appropriate battery balancing system is in place, voltage monitoring of the same segments at which you are balancing is relatively less important, as the voltages should be the same much of the time. Obviously, the Enermatic does many more functions which no doubt makes it a costly part. That's dandy if the other functions are needed, but not so dandy if one only wants a datalogger.

Mick Abraham
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Postby sparky on Sun Dec 03, 2006 8:30 am

Also consider that Dave Smead and Ample Power made there name on sytems for Cruising Boats where there was little room for Gel (now AGM) batteries going bad and sending the crew to flashlight batteries in a liferaft. To be fair I am sure a few wet cells were saved by their systems!

I have been following this thread with an open mind.
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Postby DavidB on Fri Dec 08, 2006 8:30 am

I asked the company who makes PowerCheq some more info and this is what I received:

- The fuses that came with mine look like 3A fuses, not 2A fuses (has the number 3 on them)
"We have updated to 3 ampere fuses quite some time ago. The manual is in the process of being updated to show the 3 ampere devices."


- Under what conditions will the fuse blow besides a short-circuit?
“Fuses will blow if the input voltage difference exceeds 39 volts. This is usually due to a loose cable or a damaged battery. Neither of these conditions are covered by the warranty. Excessive long cables battery to battery or a switch in the cable that does not disconnect the PowerCheq will cause the charge discharge current to flow through the PowerCheq and not the main vehicle battery cables. This is again a condition not warranted.”
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Postby crewzer on Sat Dec 09, 2006 1:47 pm

David,

Thanks for the additional info. My Powercheqs also arrived with 3 A fuses installed.

Here's a quick performance update: In early absorb mode today, my four batteries were all within a couple of hundredths of a Volt of each other. The infrequent light blinks suggested very little charge current is being shuttled now that the batteries are apparently "equalized".

:smile:
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby crewzer on Sun Jan 14, 2007 9:14 am

David,

One more update: I put my new Fluke 189 DMM (a combined major birthday and Xmas present) to good use today to take 60 second average readings on my batteries with the PowerCheq's installed during an absorb stage.

Here are the numbers [battery temp = 55 F (13 C), measurements taken at battery terminals]:

1A: 14.762 V
1B: 14.744 V (String total is 29.506 V, average battery value and tolerance is 14.753 +/- 0.009 V)
2A: 14.759 V
2B: 14.750 V (String total is 29.509 V, average battery value and tolerance is 14.755 +/- 0.005 V)

I'm happy! :cool:

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby HB Phil on Tue Feb 20, 2007 8:10 pm

Hi Jim,

Would a powerchecq equilizer be useful for my bank of 4 4D in parellel, or, does it only work for batteries in series?
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Postby crewzer on Wed Feb 21, 2007 6:02 am

Phil!

The PowerCheq's seem to help with series "equalization". However, since you're planning on wiring your batteries in parallel, they wouldn't be of any use to you.

Correctly wiring your four size 4D batteries into a large 12 V house bank for your RV is nonetheless important. Use heavy and high-quality battery cables between the batteries. Also, take a look at the 12 V battery diagrams in the following link. The "3 parallel" diagram is an example of how to "diagonally" connect batteries wired in parallel to the inverter cables (using four batteries in case).

http://www.solarseller.com/battery_bank ... iagram.htm

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby HB Phil on Thu Mar 01, 2007 10:47 pm

Jim

Are you still using the equivalent of 14.3 for bulk, with the final current of zero?

Phil
Last edited by HB Phil on Thu Mar 01, 2007 11:54 pm, edited 4 times in total.
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6 each 130 Watt Kyocerra PV panels
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