Battery / hydrometer readings

Re: Battery / hydrometer readings

Yes they could be a bit low, depending on temperature (and in some cases altitude).

Take a look at the Battery FAQ's to begin with:
http://www.windsun.com/Batteries/Battery_FAQ.htm

Normally we expect SG to be 1.265 to 1.275 in a fully-charged battery. What are your charging specs? As in Absorb Voltage, Absorb time, Float Voltage and Equalization Voltage/time.

I have a similar set-up (except for the batteries - yours are better and will be what I put in next year). My MX60 is set for maximum Absorb time, so that whatever "runs up on the clock" is the net time. I've got the Absorb Voltage set to 28.4 (temperature compensated; do you have a remote battery temp sensor?) and Float is at 27.6 Volts. I Equalize at 31 Volts. To equalize I run it for an hour, then wait an hour and re-check the SG. If it's still uneven, I do another EQ cycle. I don't think long EQ times are good. When you stop seeing any improvement from the 1 hour cycle, that's the end; any more will just 'boil away' electrolyte. You should also not have any load on the batteries when EQ'ing. These L16's are 'tall' batteries and need a good amount of current to 'remix' the electrolyte. Otherwise it 'stratifies'.

Re: Battery / hydrometer readings

You really only need to EQ if there is a significant difference in SG between cells - as in your case. Then you should 'keep at it' until there's no further improvement.

Something a lot of people never find out: you should fully charge and equalize brand new batteries, then let them rest 3 hours and take a 'base' SG reading of each cell. You can pretty much assume that at that point they are as good as they'll ever be, and all subsequent readings are in reference to that initial sampling. You might have a slightly out-of-spec hydrometer that reads 1.280 for good. As long as you use the same hydrometer and compare to the base reading, you'll know how the batteries are performing.

I think you should re-program your FM 80 for longer Absorb time. The general consensus of opinion is that Absorb can't be too long or too high as long as you're not losing significant amounts of water. But different batteries behave differently, of course! These are big batteries, and need a lot of current even if you don't significantly deplete them each day.

Do you not have the Outback temp sensor? Or have they changed the design since the MX60? Mine is a little green 'stick' that glues on the side of the battery and tells the CC (& through the HUB the FX) the relative temp of the batteries.

I'd also raise the Float Voltage. Same criteria; as long as the batteries aren't 'boiling' it's best to keep the Voltages high. (Note that a lot of people overcharge the batteries by carrying this advice to the extreme!)

Re: Battery / hydrometer readings

If you've done a lot of equalizing, that may account for the water loss. It's hard to say what is "normal" water loss for a set of batteries, because the more they're used the more they need recharging and the more loss you can expect. Since usage generally isn't consistent, you have to play it by ear. As long as the electrolyte level isn't dropping below 1/4" above the plates you should be okay. Levels should also be consistent from cell to cell; too much loss in any given cell compared to others indicates an imbalance.