Inverter/Battery Questions

[captain ron]

As many of you know I put used AGM batteries in my bus 3 1/2 years ago and they are now on their last legs. They only last about 10 to 12 hrs. I just found a few more used AGM batteries and I'm putting in a roll out rack with 12 batteries on it. My first question is, the voltage on each of my batteries disconnected and discharged to where the inverter would start shutting down is 12.38 vlts. Is that bad? The batteries I'm getting uncharged (been sitting for a while) are at 12.32 vlts. The rack holds 12 batteries so I will separate the batteries I have now from the ones I'm getting. My inverter has 2 + posts and 2 - posts. Should I run 2 seperate banks with a swich to get more usage out of them? I will also be using my newly installed 90 amp (temporary) alternator to charge banks.

[maria-n-skip]

 Charley Davidson.

I know youv'e said in the past but
Sorry I can't remember what invertor do you have? It may make a diff.

Skip

[Jerry Liebler]

At 12.38 volts you've got a good bit of battery power that you can safely use before they are down to 50 % charge.  50 % charge is real close to 12.00 volts.   Since none of your batteries are new,  I'd just go ahead and connect them all in parallel as one big bank.  Because batteries return less total energy under higher discharge current, one big bank always gives the greatest effective capacity.  Once you get them all connected you should fully charge them.  Fully charged, after resting for a couple of hours with no load or charge they should show 12.6 volts or more.  If they don't you should charge again with a good 3 state charger, then repeat the test.  If the whole bank isn't above 12.6 volts you'll have to seperate out individual batteries, charge and test to find the bad ones.
Regards
Jerry 4107 1120

[DrivingMissLazy]

If you have a charger with Quick Charge settings I would use that for a while till the overall voltage came up to about 14.5 volts. This should equalize the batteries so that they are all about the same charge.
Some good information on the Help board articles:

http://www.busconversions.com/bbs/index.php?topic=3071.0

Richard

[Tony LEE]

I think I would be charging each one up individually, letting them rest for a couple of hours and then doing a crude load test to make sure each one is reasonable before hooking them all up together. Otherwise, if one is bad, you will have to pull them all out again.

AGMs need to be charged to about 14.4V at constant current and then held at constant voltage for at least couple of hours to get them fully charged. A cheap taper charger or constant voltage converter will do a poor job.

The load test could be simple --

Charge each one fully with a quality 3 stage charger
Let rest 4 hours
Record the open circuit voltage
Hook a couple of headlight bulbs to the battery - something around 10 amps.
Record the voltage at zero time, 2 hours and 4 hours
Disconnect the load
Let rest for 1 hour
Record the open circuit voltage.


Any battery that is way out of line with the others is probably best left out of the bank.

[captain ron]

I plan on charging them all together at 10 amps till fully charged. That way they will all be equally charged and done in one day rather than one month. There are 12 batteries. I have a smart charger, actually 2 of them but one is bigger and better than the other. All of my old batteries are the same voltage now. I have several batteries to choose from of the ones I am getting. I went through them and checked current voltage and only picked batteries with 12 volts or more. I don't have time to charge them individually but can load test them after they are charged individually. I have a lot on my plate to get done in a short time. I am going to convert my bus to WVO, install new battery rack and bank, install some more cabinets I have for my bus and maybe a Proheat.

[Nick Badame Refrig/ACC]

Hi Capt. Ron,

It was a pleasure meeting you this past weekend!

The way to get your battery bank to last a long time and to be efficient, is to have all your batteries at the same state of charge and

the same capacity. Perferrably, all from the same mfg. lot too. If you are mix matching batteries, the weaker battery will either short out

first, or over heat and consume all your needed power.

Hope this helps
Nick-

[captain ron]

Hi Nick, It was a pleasure meeting you and your daughter this weekend. Nice bus, but you all ready knew that .
I am checking voltage of batteries before even considering using them. I will test each one after charging before installing them. Even if they only work for 24 hours between charges or only last a few months or a year they are worth the effort.
I have my 12 volt alternator mounted and ready for use with a few minor adjustments. It's only 90 amps but is only for temporary use. (another freebie, Thanks Gary)

[Nick Badame Refrig/ACC]

Hi Ron,

You should also use a load tester on each battery and see how far they drain. [hopefully they drain at the same rate]

This will tell you if they will charge at the same rate too.

Good Luck
Nick-

[belfert]

I hope Ron has better luck with batteries lasting than I do.  I have eight golf cart batteries and I am lucky to make it more than 15 hours before I have to charge them.  The only real load is my 110 volt fridge that says it takes 1.2 amps.  

My batteries were bought from Sam's Club and I made sure they were all made in the same month.

[lyndon]

On the topic of deep cycle batteries of all types, I was doing some web research and found an FAQ that has an incredible amount of useful information. While I can't confirm that it's all accurate information, nothing I read was inconsistent with anything I already knew (or thought I knew), and it is well written.

The link:

http://www.windsun.com/Batteries/Battery_FAQ.htm

I usually hesitate to post links because of all the spam forums receive, but let me assure you that I have no familiarity with this organization, other than finding this page in Google search results. My sole purpose is to share something I found informative and useful; I hope others will find this useful as well!

Don

[DrivingMissLazy]

On the topic of deep cycle batteries of all types, I was doing some web research and found an FAQ that has an incredible amount of useful information. While I can't confirm that it's all accurate information, nothing I read was inconsistent with anything I already knew (or thought I knew), and it is well written.

The link:

http://www.windsun.com/Batteries/Battery_FAQ.htm

I usually hesitate to post links because of all the spam forums receive, but let me assure you that I have no familiarity with this organization, other than finding this page in Google search results. My sole purpose is to share something I found informative and useful; I hope others will find this useful as well!

Don

That is one of the many Battery links posted under Favorites on the Help board here:

http://www.busconversions.com/bbs/index.php?topic=3071.msg39724#msg39724

Richard

[Ednj]

I hope Ron has better luck with batteries lasting than I do.  I have eight golf cart batteries and I am lucky to make it more than 15 hours before I have to charge them.  The only real load is my 110 volt fridge that says it takes 1.2 amps.  

My batteries were bought from Sam's Club and I made sure they were all made in the same month.

>
Ron,
It was nice meeting you finally.
The guy's you are with right now know what they are doing.
Ask one of them to turn off my fridge before it kills my new batteries please.
Thanks
Ed

[gr8njt]

Capt Ron,
It was great finally meeting you.
The music and comedy were very entertaining especially that night around the fire.
As EdNJ said: You're presently with the guys that know what they're doing.

[captain ron]

Ron,
It was nice meeting you finally.
The guy's you are with right now know what they are doing.
Ask one of them to turn off my fridge before it kills my new batteries please.
Thanks
Ed

Too late, but the bus is back on shore power for tonight at least.