How do I tell when my batteries are fully charged on my xantrex inverter?

[oscargortez]

Hi, I'm currently trying to charge 8 batteries for my battery bank individually since they all have a different charge. Unfortunately, I'm not fully sure how to tell once the battery is truly topped off and I can switch to the next. I'm currently using the xantrex freedom 3000 inverter/charger and don't have the optional panel yet that would normally give me that information. Also the owners manual I have doesn't really elaborate on the subject, it states that when the battery is over charged it will shut off. Does this mean I just have to barge the battery until the inverter turns off then switch it over?

[RV Wizard]

You should have all of your batteries set up in a bank and connected together in series and parallel configurations to supply the coach with 12 volts DC. There should be a cable from the common 12 volt positive terminal of the battery bank feeding through a large 300 amp fuse to the inverter 12 volt positive terminal. Another cable will fee the inverter from the 12 volt negative common post of the battery bank. The inverter will charge the entire battery bank at once. If you find that you have a bad battery in the bank, you may have to replace all the batteries unless they are only a few to six months old. The inverter is also capable of doing an equalize charging rate to de-sulphate the battery plates. Here is a few links U.S.Battery/Leader in Deep Cycle Batteries
Frequently Asked Questions (FAQ) - DC Battery Specialists
Deep Cycle Battery FAQ
http://www.rvsolarelectric.com/sources.htm
on batteries and such.

[oscargortez]

OK, we have eight batteries that are all at different charge levels so we cannot put them all on the charger at the same time. We consulted a battery expert in San Diego who told us to use our inverter/charger to individually charge them and then hook all of them together. But, none of that is neither here nor there. am very well versed in how to configure the power array.

Specifially we have a Xantrex that we do not have the external control interface for. It has three light's on it. I am simply wondering how I am supposed to know when each battery is fully charged. There is no info in the documentation on the exact process for fully charging a battery. Right now it is just sitting here telling me it is charging. This is a question about the Xantrex, not how to hook up the batteries.

[garym114]

During the bulk and adsorption charge cycle the voltage is over 14 volts. When it switches to the float charge rate, battery fully charged, the voltage drops to around 13.4 volts. Use a digital multimeter to check.

[hdossett]

You didn't mention if they were six or twelve volt batteries, but if it is eight GCs, you looking at up to 880 AH capacity. The charger should be set up to match the AH rating of the battery bank, otherwise, it will not do the job right.

If it were me, unless the state of charge varies a lot, i.e., dead to full charge, I would connect and charge all at once. Just my opinion!

H

OBTW, garym114 gave you the answer you were looking for!

[RJay]

Even though the batteries are of different charge, not sure how they got that way, if you connect them in bank(together) as RV Wizard suggests the charge on each battery should equalize and you can charge them as a bank. Garym114 gives the guidelines on how to charge them. The batteries should be all of the same type and capacity though.

[wa8yxm]

On my Xntrex prosine when you choose the 12 volt status (or the multiple status) on the display and the 12 volt amps drop to +0 You know it's fully charged, Plus a very small number is also fully charged.

Now.. Why charge them indepently? (Unless you need to test them) Let me tell you what will happen if you simply parallel (NOTE: This applies to 12 volt batteries in parallel.. TWO six volt batteries in series make one 12 volt battery and may be (Should be) treated as such)

Depending on just how different the SOC is the more charged battery may try to charge the lesser charged battery,, In this case,, If it's great enough, you may get some gassing and overheating of the patch cables.. So consider that.

However if they are all ovre 50 percent (or under 50 percent) this should not be a problem.

Assume the majority of the charge comes from the converter, Also if you can "Throttle down" the converter a bit.. My Prosine 2.0 can be set to different max charge rates up to 100 amps (It's not qutie that easy) by adjusting the "Battery bank size" setting,, You want to take this down to around 100-200 amp hours or the max charge rate to 30-50 amps.

Now,, If the converter is providing the charge.. Then the lowest battery will charge, the others will not since they need a higher voltage to charge, Till the lowest battery catches up with the 2nd lowest, then both of them will charge till they catch up with the 3rd lowest, and then ... till they are all full.

I know there are lots of myths of batteries with different states of charge.. And in fact there is some basis for them but ONLY WHEN THEY ARE IN SERIES

(If you have six volt pairs, they need to be matched that is each half of the pair needs to be matched,, However as I said above treat each pair as a SINGLE 12 volt battery, and I just explained how they do NOT have to be matched.

NOTE: the same applies to large and small batteries in parallel.. The myth is "one will charge faster (The thought being the smaller one will charge faster)

The fact is that if you measure current into the batteries the larger one (Assuming both are in good condition) will be getting the larger share of the charge.

But if you measure state of charge say every 20 mintues and plot it.. You will find they charge at EXACTLY THE SAME RATE.. for reasons stated above.. So in terms of State of charge they come up in perfect lock step and when one hits 100%, the other does as well, same second. No difference at all.

[oscargortez]

I was just at camping world. I got my answer. On thew Xantrex there is no way to know if the battery is charged or not without the remote. We don't have one. At this point I don't even have power to charge them... thanks for the help

[powerboatr]

Quote:

Originally Posted by wa8yxm On my Xntrex prosine when you choose the 12 volt status (or the multiple status) on the display and the 12 volt amps drop to +0 You know it's fully charged, Plus a very small number is also fully charged. Now.. Why charge them indepently? (Unless you need to test them) Let me tell you what will happen if you simply parallel (NOTE: This applies to 12 volt batteries in parallel.. TWO six volt batteries in series make one 12 volt battery and may be (Should be) treated as such) Depending on just how different the SOC is the more charged battery may try to charge the lesser charged battery,, In this case,, If it's great enough, you may get some gassing and overheating of the patch cables.. So consider that. However if they are all ovre 50 percent (or under 50 percent) this should not be a problem. Assume the majority of the charge comes from the converter, Also if you can "Throttle down" the converter a bit.. My Prosine 2.0 can be set to different max charge rates up to 100 amps (It's not qutie that easy) by adjusting the "Battery bank size" setting,, You want to take this down to around 100-200 amp hours or the max charge rate to 30-50 amps. Now,, If the converter is providing the charge.. Then the lowest battery will charge, the others will not since they need a higher voltage to charge, Till the lowest battery catches up with the 2nd lowest, then both of them will charge till they catch up with the 3rd lowest, and then ... till they are all full. I know there are lots of myths of batteries with different states of charge.. And in fact there is some basis for them but ONLY WHEN THEY ARE IN SERIES (If you have six volt pairs, they need to be matched that is each half of the pair needs to be matched,, However as I said above treat each pair as a SINGLE 12 volt battery, and I just explained how they do NOT have to be matched. NOTE: the same applies to large and small batteries in parallel.. The myth is "one will charge faster (The thought being the smaller one will charge faster) The fact is that if you measure current into the batteries the larger one (Assuming both are in good condition) will be getting the larger share of the charge. But if you measure state of charge say every 20 mintues and plot it.. You will find they charge at EXACTLY THE SAME RATE.. for reasons stated above.. So in terms of State of charge they come up in perfect lock step and when one hits 100%, the other does as well, same second. No difference at all.

very well stated.

[DAN L]

oscargortez,
you can measure the charged condition of batteries by measuring the specific gravity of each cell with a hydrometer, but you have to do it properly.
this resource explains how and when to check the specific gravity.

The 12volt Side of Life (Part 1)