End amps float and stuff

Chuck46

If I am undwerstanding this right the end amps are the amps when absorb stops and the CC goes to float using those amps to maintain the batteries! Right or wrong?

Chuck

stephendv

Re: End amps float and stuff

End amps is a trigger value that will switch the controller from absorb mode into float mode. As soon as the controller sees values less than [end amps value], then it'll switch from absorb to float.

Float is a constant voltage phase, the amps used to maintain float will vary continuously with the loads and have nothing to do with the end amps value.

Chuck46

Re: End amps float and stuff

Thank you for some reason I keep getting those things mixed up. Im using Crown L-16 395 ahr batteries in 4 in series and 3parallel, based on the manuf specs Bulk is set to 29.0, absorb is 28.8 and float is set to 26.8 end amps is set to 18 which is 2% of total amp hrs. The batteries are a little over 2years old and 8 of them are using masive amounts of water (1+ gals per week). I am not under charging them and this is driving me nuts. I talked to the Crown folks and they said my setup is good. Cabling is 2/0 bettween batterys and 4/0 to inverter all cables are the same lenghts and the inverters are hooked up to the center string. Any sugestions?

jcheil

Re: End amps float and stuff

How are you setting a BULK, ABSORB and FLOAT voltage on an FM-80?
To the best of my knowledge (and I have one) you can only set ABSORB and FLOAT. (someone please tell me if you can otherwise)

Perhaps you have it set somehow to 29.0 as ABSORB and 28.8 as FLOAT which in the case of the latter would certainly consume a lot of water floating at 28.8 all the time.

And I notice in your SIG that you also have a wind generator. Perhaps the settings on the charge controller for the wind generator is what is causing the overvoltage and thus water loss?

Blackcherry04

Re: End amps float and stuff

Bulk is not a Setting, it is a trigger Voltage you reach to begin Absorb cycle.

Cariboocoot

Re: End amps float and stuff

Outback chargers do not have a 'Bulk Voltage' setting. Sensibly they set the change-over and maintain Voltage for Absorb and Float. You haven't accidentally got and EQ mixed in there somewhere?

The thing that usually causes too much water usage is too high a Voltage and/or for too long. You should definitely have a remote temp sensor on the batteries, as the Voltage may be too high for them as they warm up during charging.

The other thing is; you have three strings in parallel. Unless this is done correctly (i.e. equal length wires to common connection point such as bus bars) the current between the strings will not be the same so some batteries may receive more current than others.

BTW, three parallel sets of 395 Amp hour batteries is 1185 Amp hours and 2% of that would be 23.7 Amps, not 18. What's more there's no way a single FM80 can pass enough current to properly charge such a massive battery bank.

Your signature indicates you have only two parallel battery strings, which would be 790 Amp hours and an end Amps of 15.8 not 18. An FM80 would handle this. It would be maxed out at about 2500 Watts, so you're probably wasting 500 Watts of panel with a 3 kW array.

Check the SG of each and every cell after a full charge cycle. Look for low ones which would indicate the need for equalization, and any correlation between low/high SG and the batteries that use a lot of water.

BB.

Re: End amps float and stuff

That is too much water... Are all cells using water equally, or are some cells using most of the water and some using hardly any.

Get a DMM and measure the voltage across every cell (or every battery). Look for high/low values. See what the absorb and float voltages read at the battery bank.

I like a cheap DC Current Clamp meter so you can check the current into each string.

Are the batteries getting hot (or at least some of them)?

If you are at >2% rate of charge with reasonable float/absorb voltages, your batteries may be going bad (shorted cell, etc.)... That can be an indication that the cells are about to fail spectacularly.

-Bill

Chuck46

Re: End amps float and stuff

Well as usual gray and brains dont go together. That was 29 EQ, 28.8 absorb and 26.8 float.

Bill the batteries using water are all in the same series strings, cables are all exactly the same length. I feel they are about to fail.

Cariboocoot, Since they started using water sg has been all over the place, I do have 2 FM 80s and 12 bats just need to up date that info. and I also have a temp sensor on the system.
Thanks all for the answers it leads to the same conclusion as I came to, witheverything right the batteries are bad.
Thanks Chuck

BB.

Re: End amps float and stuff

Chuck,

You have 3 parallel strings and only one or two strings are using lots of water?

If so, you may have a shorted cell--Check the charging voltage across each battery/cell. Look in the cells and see if there is one cell that is "still" (or even bubbling more than the rest). You are looking for "differences". A shorted/low voltage cell can draw excessive current in the rest of the series strings (and over charge those cells).

Do you have a hydrometer/logging the temperature corrected specific gravity?

-Bill

Vic

Re: End amps float and stuff

Hi Chuck,

Thanks for the added info.

Could not find the SG of the electrolyte used in your CR395s, but the CR390s say those are 1.275 SG. The EQ voltage seems to me to be far too low for most any Flooded battery I've seen. Normally would expect it to be in the 31+ volt range. This is NOT a direct reason for the high water consumption, however.

You mentioned that you " ...have a temp sensor on the system" So you have a Hub (think that is what does the trick), which allows sharing a single BTS among the OB hardware?

Good that you have turned off the wind turbine, at least as an experiment. Although, one might think if it was an issue of Vabsorb or Absorb time too long, that all of the batts would use about the same amount of water.

Guess that you have added an additional string of batteries recently (?). Good Luck, Vic

NorthGuy

Re: End amps float and stuff

Chuck46 wrote: »

... the batteries using water are all in the same series strings

One of these batteries might have failed. If one of the cells on the string has shorted, the rest will be overcharged and will use more water. The batteries in other two strings may become undercharged and may be damaged.

I would measure voltage on each of these 4 bad batteries individually during discharge state to see if they're all the same.