Charging my Batts: Round one - "Outback vs the Hydrometer"

Re: Charging my Batts: Round one - "Outback vs the Hydrometer"

feedhorn wrote: »

Running a genny is so 'not cool', too expensive, noisy! I'd rather put more water in my batts than hear my genny run.

Noisy ?? I am old, but I can't even hear the Honda running. I have a sound enclouser, open on one end with 2" of insulation all around in a Aluminum box. Cost is $.64 cents a hour with Gas @ $4.49 on the water. You can always add more panels. I figured what I needed derated and doubled that number and ended up with 8.2 KW. Then it's the excess production that bugs you and trying to figure out out how to use the over production.

Re: Charging my Batts: Round one - "Outback vs the Hydrometer"

Today is the first day of the year I get to run my fridge on excess solar power. I set the thermostat to min and let it get as cold as I can. Saves on propane.

As for Battery Life I replaced my GC batts at 4 years figuring they had about 50% capacity left. Since we are nearing armegeddon I didn't want to end up with lame batts.
Now with the worldwide demand for ammo skyrocketing, it won't be long before the price of lead goes up too. BETTER GET YOUR NEW BATTS NOW.

Won't be long before we will be pouring new lead plates out in our backyards.

Re: Charging my Batts: Round one - "Outback vs the Hydrometer"

Well, Return Amps, aka, Ending amps is confusing because of the way different Manufacturers use the term or the way the same manufacturer will use it on two different pieces of their own equipment differently. OutBack doesn't mention any load draw and we all know that will throw it off if you do not take it into account.

Step # 3: The Return Amps must be entered.
Return Amps, ADV/ DC/CHARGE This is the charge rate that is expected to be returned to
your batteries when they are full or approaching full. This value is derived from a percentage of
the total amp hours in your battery bank. This value can be obtained from your battery
manufacturer. 2% of your total amp hours is a good default to establish our baseline. For
example, a 250 Amp-hour battery bank @ 20hr discharge rate with a 2% value of return amps
would be 250 x .02 = 5 amps.
Another more concrete method to find your return amps value would be to charge your batteries
until they are full using the battery manufacturer charging values to include specific gravity
readings if applicable. Then simply do another rebulk and absorb. If you are using an off grid
inverter simply turn off the AC source for about 1 minute, and turn on the generator again or
reconnect the AC source. If you are using a grid interactive inverter that can sell back to the grid
start a RE-BULK (push AC IN button 4 times). Then monitor the current holding your absorb
voltage by viewing the shunt activity (positive amps) returning to the battery bank with no loads
on the batteries at STATUS/DC/METER . Set the return amps to this value.
.

Re: Charging my Batts: Round one - "Outback vs the Hydrometer"

Sigh.

The ending amps are really easy to determine empirically.

1). Set "Absorb" to just about forever.
2). Every 15 minutes write down the charging current from the "Net" off a FNDC.
3). When the net current has declined less than 2% in 15 minutes, you've found the ending current.

Example -- 15, 12, 10, 9, 8, 7.5, 7.2, 7. 12/15 = 80%, 10 / 12 = 83%, ..., 7.2 / 7.5 = 96%, 7 / 7.2 = 97.2%, which is close enough for government work. Enter 7 amps as the "ending amps".

This does not work with sulfated batteries. But this does --

1). Start an EQ.
2). Let that go for a while. Even just two hours is plenty. You're doing math, not an EQ.
3). Do the steps above for a normal battery.
4). Start another EQ. You can even do this the next day, but not next week.
5). Do the steps above again.
6). Keep doing this until a few hours of EQ stops RAISING the ending amps.

So, why RAISING in this instance? Because sulfated batteries have more resistance / less active plate material and won't accept as much charge.

One more thing -- battery charging is based on probabilities and normal distribution curves. There's a lot more math than carving in stone going on. A slightly higher Absorb voltage isn't going to fry a well-maintained set of batteries. So long as water consumption is reasonable, everything should be fine. It's high voltages and long cycles that you want to avoid.

Re: Charging my Batts: Round one - "Outback vs the Hydrometer"

tallgirl wrote: »

It's high voltages and long cycles that you want to avoid.

May I ask you to explain what is wrong with long cycles and high voltages? How long should be the cycle for you to considere it harmful?