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Charging one battery out of 16

rodwilsonsr

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Just bringing this to the top of the topics as a new thread...

I just got the right timing to do an SG test on all the cells. I put this into a spreadsheet, I attached a screenshot of my results. It appears to me that bank 1, battery 7 has 2 cells that are misbehaving.
I sent this info to Trojan support, and this was the response...
"Here is a situation where you would need a power supply that would allow you to only charge one battery or two in the string to bring the gravity up in the two low cells."
I have some understanding of what he is saying, but I am not sure of how to properly go about this since I am not grid tied and this is my primary source of power for our household.
Any suggestions on how I should proceed?

for informational purposes, I have 2 banks, 8 batteries each, 48 volt. Classic 200 midnight controller, Magnum inverter.
I have a backup generator that I could connect a battery charger to and run that dedicated to charging this one battery. But not sure what kind of battery charger to get, battery charging settings or how long to charge for?
I'm guessing, from other posts I have read, that disconnecting one bank of 8 with the questionable battery, and running with half the capacity for the house will be necessary. Would I need to make changes to the Classic 200 settings to accommodate the lessened capacity for this period of time?
Thank you for any help.
 

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You could remove one battery from each bank, making it a 42v nominal battery bank. You would need to change the settings on the midnite and the inverter.
Than find a way to charge one 6v battery. or charge 2 of them in series at 12v. But it would mean overcharging the battery which doesn't have the low Specific gravity.

Chances are you need atleast 6v 30amp power supply. I remember charging a 6v battery with my 12v victron 30amp charger. Set in powersupply mode. I believe it was charging at 8v or so. but the battery voltage was somewhere around 7volts. Not something i would do with a charger i care about (200$+)
 
You could remove one battery from each bank, making it a 42v nominal battery bank. You would need to change the settings on the midnite and the inverter.
Than find a way to charge one 6v battery. or charge 2 of them in series at 12v. But it would mean overcharging the battery which doesn't have the low Specific gravity.

Chances are you need atleast 6v 30amp power supply. I remember charging a 6v battery with my 12v victron 30amp charger. Set in powersupply mode. I believe it was charging at 8v or so. but the battery voltage was somewhere around 7volts. Not something i would do with a charger i care about (200$+)
Thanks for the response.
I got. Floor standing charger and figured out how to put the magnum in bypass so the genny is powering the house, not charging the batteries.
Disconnected the solar array.
Isolated the battery and have it currently charging at 6 volt 40 amp setting.
I'm guessing a couple hours like this but will be monitoring the SG throughout.
 
After some time learning, I came to realize that these smart battery charges, I dont believe, are doing what I need it to do. So I returned that and bought a Schumacher SC1667. This seems similar to old school manual chargers. I was able to isolate the battery and keep it charging for 6 volts at 25 amps. I did measure the voltage while charging and it was 7.6.
I left this charging for 5 hours and monitored it throughout. The SG came up a little bit.
I reconnected this battery to the bank and did a 45 minute EQ to the entire bank.
The SG went up in the 2 cells from 1210 to 1240 and 1225 to 1250.
The other 46 cells have a great SG.
Should I pull the battery again and put it on the charger longer? Or run a longer EQ on the entire bank? Or something else?
 
I've been topping off individual Lead-Acid 6v batteries in both 12V and 48V configurations with a brute-force automotive transformer and rectifier-based charger for years - there is no disconnection or isolation necessary, and no danger of blowing anything up. The two rectifiers in the charger prevent power flow in unfavorable directions. It's got an iron core center-tapped secondary copper wound transformer in it - no electronics.
 
I've been topping off individual Lead-Acid 6v batteries in both 12V and 48V configurations with a brute-force automotive transformer and rectifier-based charger for years - there is no disconnection or isolation necessary, and no danger of blowing anything up. The two rectifiers in the charger prevent power flow in unfavorable directions. It's got an iron core center-tapped secondary copper wound transformer in it - no electronics.
Thanks for the reply and your experience. Can you give me more details on the charger setup? Or the make model of charger?
 
The Schumacher one I've got isn't specifically made anymore, but Schumacher still makes current models the same way. They are identified by a steel crap-looking cabinet, simple analog ammeter, amperage/voltage multi-position switch, and a high price tag due to pounds of copper. One similar to Model SE-82-6 that's purely manual with no start/stop switch or electronics is ideal. The one I've got is an old starter version, with wheels, heavy AF and 30ish years old probably. If I had to replace it I'd spring for SC1667.

One thing I haven't tried is using a modern PWM charger on an active string of connected batteries. I have a little one I can try, for science...
 
The Schumacher one I've got isn't specifically made anymore, but Schumacher still makes current models the same way. They are identified by a steel crap-looking cabinet, simple analog ammeter, amperage/voltage multi-position switch, and a high price tag due to pounds of copper. One similar to Model SE-82-6 that's purely manual with no start/stop switch or electronics is ideal. The one I've got is an old starter version, with wheels, heavy AF and 30ish years old probably. If I had to replace it I'd spring for SC1667.

One thing I haven't tried is using a modern PWM charger on an active string of connected batteries. I have a little one I can try, for science...
I ended up getting the sc1667...guess I was on the right track of thinking, with being a beginner with this stuff. How long would you charge a single battery for? I have 2 cells on a 6 volt that read 1240 and 1250 for SG.
 
Okay, so that model you got is very strong. You'll need to watch the amperage because it can push a Lead-Acid battery well past equalization territory and not even care. The 50 amp and 225+ amp engine start settings are more than you need to pull up a low cell. Start small and watch it, measure, etc. That unit will last you the rest of your life.
 
Okay, so that model you got is very strong. You'll need to watch the amperage because it can push a Lead-Acid battery well past equalization territory and not even care. The 50 amp and 225+ amp engine start settings are more than you need to pull up a low cell. Start small and watch it, measure, etc. That unit will last you the rest of your life.
Thanks for that.
I put that charger on the battery at 6 volt 25 amp. I left it on for 5 hours. I was thinking about repeating the process and leaving it on for 8ish hours.
The charger only has one 6 volt setting.
Is it possible to use a 12 volt setting on one 6 volt battery? Or would I need to charge two batteries for 12 volt so I could use the higher amperage setting?
 
It works but noticed it detected the battery as 12V instead of 6V. It's pushing amps, so that's a win.

View attachment 241923

The reason that the P20 didn't select 6V is that it only does 12 or 24:

"🚙 [Widely used] Intelligent automatic recognition of 12/24V battery,"

It sounds from the thread that you are now using a different charger anyway.

Be careful and don't turn your back on it. FLA are very forgiving of charging mis-steps, but it's still possible to F them up.
 

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