RC7-GS Setting Battery Capacity

[irishguy]

Hello all,

I just installed four new 6 volt Interstate deep cycle flooded acid batteries. The sticker on them states: 115mins @ 75 amp 225 Ah @ 20 hr.

So what should my RC7 be set at for battery capacity?

Should I set it at 1000 hrs since I have four 225 Ah batts?

What should I set for charge rate? 100%?, 90%

The RC7 is currently showing absorption charge mode and it states 75% state of charge. It's been that way for about an hour.

irishguy

[jacwjames]

Since the batteries are in 2 parallel sets you have 450 ah so set it at 500.
80% rate of charge is a good set point.

[irishguy]

Originally Posted by jacwjames

Since the batteries are in 2 parallel sets you have 450 ah so set it at 500.
80% rate of charge is a good set point.

Thank you Jim!

So why 80%? Is that to prevent over charging?

[Mr_D]

That last 20% takes hours to fill. Not usually worth running the generator to get to 100%.

[irishguy]

Originally Posted by Mr_D

That last 20% takes hours to fill. Not usually worth running the generator to get to 100%.

That makes sense. I'm dry camping for a couple of days so I have the generator on for awhile to make sure the new batts are charged up.

[twinboat]

Charge rate controls how many amps your charger outputs, in bulk mode, into the batteries when the they are low. To high a charge rate can overheat the batteries.

Charge rate should be set to about 15% flooded batteries AH capacity. In your case about 70 amps.

Inverter/chargers come with different capacity chargers. If yours is a 100 amp model then setting the charge rate at 70% would be right. If Its a 125 amp inverter/charger, then somewhere around 65%.

If you had a 6 or 8 battery bank or AGM batteries, then the charge rate could be set higher.

It has nothing to do with charging the batteries to 80% while dry camping.

[CountryB]

Here's the two setup choices from the manual:

[irishguy]

Thank you all for the great info!

irishguy

[Smitty77]

And irishguy, just as more info. When combing 6V's to become a 12V, your AH's C20 rating of the batteries remains the same. So for you, you now three pairs of 6V as 12V, so X's3 of the 225AH for 675AH 'House AH Capacity'. Usual rule of thumb is to live on the top 50% of house battery, so your coach would 337.5 available AH.

If you don't already have a Battery Monitor, that would be a good future addition to your rig, so you know where your battery capacity is.

I personally do not like to run down to 50% of available capacity. For two reasons: 1) I like reserve power if ever needed; 2) Shallower draw down and recharging of your battery bank, will yield longer years of usage. (It's all bout DoD Life Cycles. One draw down to 50% SOC, and then recharge to 100% = 1 Life Cycle.) I live on the top 75% of our battery bank, so it takes two full down to 75% and back up to 100% to yield 1 Life Cycle. No, will not get double the years, but I might get quite a few more years!.

And many other prefer to run down to the 50-60% SOC level. I've heard opinions from those using say Costco or Walmart/SAM's GC2 6V's, that they'd rather replace them more frequently and have 'fresher' batteries after replacement. Then having a more expensive pair of say AGM's that are not as deeply cycled, and getting more years out of them. No right or wrong on this, just choices!

Best to you,
Smitty

[twinboat]

Originally Posted by Smitty77

And irishguy, just as more info. When combing 6V's to become a 12V, your AH's C20 rating of the batteries remains the same. So for you, you now three pairs of 6V as 12V, so X's3 of the 225AH for 675AH 'House AH Capacity'. Usual rule of thumb is to live on the top 50% of house battery, so your coach would 337.5 available AH.

If you don't already have a Battery Monitor, that would be a good future addition to your rig, so you know where your battery capacity is.

I personally do not like to run down to 50% of available capacity. For two reasons: 1) I like reserve power if ever needed; 2) Shallower draw down and recharging of your battery bank, will yield longer years of usage. (It's all bout DoD Life Cycles. One draw down to 50% SOC, and then recharge to 100% = 1 Life Cycle.) I live on the top 75% of our battery bank, so it takes two full down to 75% and back up to 100% to yield 1 Life Cycle. No, will not get double the years, but I might get quite a few more years!.

And many other prefer to run down to the 50-60% SOC level. I've heard opinions from those using say Costco or Walmart/SAM's GC2 6V's, that they'd rather replace them more frequently and have 'fresher' batteries after replacement. Then having a more expensive pair of say AGM's that are not as deeply cycled, and getting more years out of them. No right or wrong on this, just choices!

Best to you,
Smitty

4, 6volt batteries.

He installed 4 batteries, not 6 of them.

[Smitty77]

Originally Posted by twinboat

4, 6volt batteries.

He installed 4 batteries, not 6 of them.

Thx's Twinboat - I did misread, thought it was 6. (The good part about my missing things now, is after about an hour - I forgot I missed something!).

So 450AH House, 225AH useable to 50% SOC.

Appreciate your polite 'Smitty - You blew it again!' post.

Best to you,
Smitty

[irishguy]

Thanks Smitty, I figured you thought I had six house batts.

Our Windsor does have a battery monitoring system which I do watch closely.

I hadn't considered the chassis batteries but from what I have read after the house batts are charged then the system charges both 12 volt chassis batteries as well.

irishguy