First time to 50% SOC

[mena661]

DW and I pigged out on amp hours on our last trip to the beach a week ago. According to the Victron, we used 364 Ah in 3 days. Oddly, the Iota did not go right to 14.8V like it did when I first connected it. It did do the full 55 amps right off the bat though. When I checked it a few hours later (not sure how long), it was at 14V even. I'm going to put in an on/off switch on the output of the converter to make sure it's off completely. I'll be honest, I'm not liking this converter so far. I used the BD1093 to top off the batteries this time. Only needed to run the EQ on it twice (checking SG after each run) then a connected the Iota for 8 hrs. Checked the SG again and it was right at 1.285 in all cells (58F/14C).

For those interested, here's some pics of the CG.

[mena661]

MEXICOWANDERER wrote:

If you do your recharging in your driveway or RV park overnight, a slower rate is easier on the batteries. The question is "Where Is The Break Even Point?" I suspect in your case you may have an acceptable setup. Going camping for an extended period would jumble this all around however.

When I top charge a single 29, I start at around 12.65 and it takes 4 - 5 hours at 2-amperes to reach 15.0 volts. For the first half hour the amperage is in the 6 - 8 amp range.

I'm not much into acceptable. 🙂 Should I throw in another charger even though I'm doing this on shore power or is 55 amps ok for that?

BFL13 wrote:
I didn't see in the OP whether the Iota stayed at 55 amps for a long time before going into Absorption.

The Iota blurb says it will go straight to Absorption (what they call their 14.2v level) but do 55amps at first at that 14.2. My 7355 will too but at 13.8v instead of 14.2 whoopee-do! 🙂

So just because it did 55a does not mean it was in bulk. You want to know if battery voltage ever got up past 14.2v. It looks like the OP did not get back to see what was happening and it could have done either, where it was at 14 by the time he got back to it?

It was 38 amps when I checked (@ 14V). Was about 4 hrs or so when I checked. I really don't know if it climbed into boost or not. I should've checked more often but I didn't have time to do that.

smkettner wrote:
I suggested to wait more than a week to check specific gravity to allow IOTA at least one destratification cycle before you worry about the finish charge. I think you will find that the batteries are fine with just the IOTA. Or the data point would be interesting if finish charge still seems needed.

14.7V won't finish charge these. At least not in a reasonable amount of time. 15V @ 8 amps on the HF manual gets it done in about 2 hrs, sometimes 3 AFTER the converter (old Paramode) or my portable reaches their respective "full". The BD's EQ setting takes longer than the HF manual but it uses a lower amp rate (4A). I do typically leave the batts on the converter for a week before I do any finishing charges just to see if they get them up to baseline SG but the converter (Paramode) only seemed to accomplish that if I kept SOC above 85%. I don't know if the Iota would do it at 85% SOC or not.

EDIT: MEX, if we ever do more than a weekend of camping, I'll probably get at least one of those adjustable voltage Powermax 100 amp converters that BFL has.

[time2roll]

I suggested to wait more than a week to check specific gravity to allow IOTA at least one destratification cycle before you worry about the finish charge. I think you will find that the batteries are fine with just the IOTA. Or the data point would be interesting if finish charge still seems needed.

[BFL13]

I didn't see in the OP whether the Iota stayed at 55 amps for a long time before going into Absorption.

The Iota blurb says it will go straight to Absorption (what they call their 14.2v level) but do 55amps at first at that 14.2. My 7355 will too but at 13.8v instead of 14.2 whoopee-do! 🙂

So just because it did 55a does not mean it was in bulk. You want to know if battery voltage ever got up past 14.2v. It looks like the OP did not get back to see what was happening and it could have done either, where it was at 14 by the time he got back to it?

[full_mosey]

mena661 wrote:

full_mosey wrote:


364/3 = 121/day. That is about my daily draw from a 189AH bank. With 300W solar, I get about 90AH/day back at a net loss of 30AH/day. 3days x 30AH = 50%SOC. I do steal some AH from my 68AH starting battery with the 7-pin cable.

You're a heavy user too! After that last trip, I just might get two 230W panels instead of one (thanks KJINTF!).

I don't sell solar, but I am sold on it. 🙂

LOL! Can I use that in my sig when I get some solar? 🙂

Here's a hoot. We went to the TX RGV and stayed at an RV resort for two months, Jan & Feb. Our metered electric bill total was $25 at .1622/KWH. The tree over half of our site budded out and shaded our panels until 1PM for about two weeks!

If you like the sig, it is yours.

You will get that warm fuzzy feeling like hugging a teddy bear when your panels are busy charging. So peaceful and quiet.

HTH;
John

[MEXICOWANDERER]

Mena with a pair of 316 A/H L-16's it would take about 88 amperes charge rate to start at a charging potential of more than 14.0 volts. You just nudged the exact reason why too small of charger on a generator (not your case) is going to cause a lot of hours to pass before the batteries can gain a decent charge.

When I configured a system to be used with a generator, I placed enough generator charger on line to immediately gain 14.8 volts corrected to 20C. This is voltage limited (read it it's different than regulated) charging and is the cheapest and fastest way to recharge batteries.

It used to be viable to have a 12-turn diesel genset charge the batteries at 20% amp hour rating to afford maximum battery life. With the advent of greed in speculation meaning three dollar plus per gallon fuel, this is not possible anymore. Charge a pair of L-16's at 20% on a generator rather than a voltage limited regimen and those two batteries are going to eat more than a thousand dollars DIFFERENCE in fuel. Unless you live on Palmyra Island or Ulan Baator, fuel costs over ride battery prices. Down here a fuel load costs the eqvt of a hundred dollars to deliver. "For what I'll save in fuel alone I could have replacement batteries FLOWN IN" was a remark I heard last month.

Saddlebag Lake CA. "My motorhome generator is charging the batteries at 30 amps. For what it costs to go buy fuel ($5+ gallon) I could go buy a NEW battery"

Calculators don't fib.

If you do your recharging in your driveway or RV park overnight, a slower rate is easier on the batteries. The question is "Where Is The Break Even Point?" I suspect in your case you may have an acceptable setup. Going camping for an extended period would jumble this all around however.

When I top charge a single 29, I start at around 12.65 and it takes 4 - 5 hours at 2-amperes to reach 15.0 volts. For the first half hour the amperage is in the 6 - 8 amp range.

[mena661]

smkettner wrote:
When you first connected the IOTA I assume the battery was near full charge. IOTA will hold the max voltage for about 15 minutes before it cancels boost mode and settles into absorbtion at 14.2 according to the specs.

When the battery is low, especially a large battery, the IOTA will remain in boost mode for an extended period until the max voltage is reached. This can easily take 3 to 5+ hours depending on discharge and capacity. With 364 Ah to replace and 55 amps you just will not get there in 30 minutes. All converters and chargers work this way. For faster charging you will need more amps. But since you are not really running the generator to charge, the added amps to reduce time is unnecessary. The slower charge is actually better as long as you have the time.

Assuming you plug in at home I would wait a couple weeks before you check specific gravity and decide to recondition with the portable.

Thank you for the explanation smk. Good to know my observations were incorrect. I am plugging in at home and definitely not in a hurry to charge there. And from what I understand, slow charging is better. BTW, finishing charge in this case would be the proper term but I'm using the EQ feature of the BD to do it as it requires some 15+V to perform that. I normally use the manual charger but didn't have time to babysit it and I didn't want the batts to sit a week at low SG. It actually took that 8 hrs for the SG to "catch up". When I stopped the 2nd EQ, SG was at 1.265-1.275. BFL describes this as "SG lag". I wonder if it has to do with the amount of amps used on the finishing charge as I don't remember any lag with the manual charger (it uses 8 amps vs 4 on the BD).

Good to see those L16 finally earning their keep.

It was actually a little exciting to see them get some use.

full_mosey wrote:


364/3 = 121/day. That is about my daily draw from a 189AH bank. With 300W solar, I get about 90AH/day back at a net loss of 30AH/day. 3days x 30AH = 50%SOC. I do steal some AH from my 68AH starting battery with the 7-pin cable.

You're a heavy user too! After that last trip, I just might get two 230W panels instead of one (thanks KJINTF!).

I don't sell solar, but I am sold on it. 🙂

LOL! Can I use that in my sig when I get some solar? 🙂

[full_mosey]

mena661 wrote:
DW and I pigged out on amp hours on our last trip to the beach a week ago. According to the Victron, we used 364 Ah in 3 days. ...

364/3 = 121/day. That is about my daily draw from a 189AH bank. With 300W solar, I get about 90AH/day back at a net loss of 30AH/day. 3days x 30AH = 50%SOC. I do steal some AH from my 68AH starting battery with the 7-pin cable.

I don't sell solar, but I am sold on it. 🙂

HTH;
John

[time2roll]

mena661 wrote:
Thanks all. I was under the impression that the Iota went right to 14.8V. Didn't know it was like other converters that ramp to that voltage. That would explain the behavior. Although I do wonder why it went to 14.8 when I first connected it. About solar, it's on my list.

When you first connected the IOTA I assume the battery was near full charge. IOTA will hold the max voltage for about 15 minutes before it cancels boost mode and settles into absorbtion at 14.2 according to the specs.

When the battery is low, especially a large battery, the IOTA will remain in boost mode for an extended period until the max voltage is reached. This can easily take 3 to 5+ hours depending on discharge and capacity. With 364 Ah to replace and 55 amps you just will not get there in 30 minutes. All converters and chargers work this way. For faster charging you will need more amps. But since you are not really running the generator to charge, the added amps to reduce time is unnecessary. The slower charge is actually better as long as you have the time.

Assuming you plug in at home I would wait a couple weeks before you check specific gravity and decide to recondition with the portable.

Good to see those L16 finally earning their keep.

[full_mosey]

smkettner wrote:
I am not sure what the complaint is on the IOTA?
It will take some time at 55 amps to see 14.5+ volts.

Agree. If Volts were rising, the charger was in stage 1 bulk and working as designed.

If Volts are steady, the charger is in stage 2 absorption or stage 3 float.

HTH;
John

[mena661]

Thanks all. I was under the impression that the Iota went right to 14.8V. Didn't know it was like other converters that ramp to that voltage. That would explain the behavior. Although I do wonder why it went to 14.8 when I first connected it. About solar, it's on my list.

[full_mosey]

A generic definition of a three stage charger reads like this:

1. Bulk - all available Amps are supplied to the bank while the charger slightly LEADS the bank Voltage as needed until the absorption setpoint is reached.

2. Absorption - The Voltage is held STEADY at a 14.4V setpoint while the battery dictates the acceptance current. Absorption stops when the current DROPS to a certain value(depending on your charger settings).

3. Float - the volts DROP again and then the charger regulates a low current to hold the bank at the float voltage.

Some converters have tweaks and timers and that is what leads to endless discussions of which converter is best.

For example, my WFCO 8735 holds 13.6V in absorption for 48hrs before dropping to 13.2V in float.

[MNtundraRet]

I really think too many people get confused by not seeing the 14.4+ volts right off the bat.

What maters is the amp output. If 55 amps is the output for your charger, and you were getting that from your 1/2 discharged batteries everything is fine at that time.

The voltage reading is usually taken across the battery-terminals. That means at start of charge the voltage would have been about 12.1 volts and climbing to around 13.2 to 13.6 volts. If your are seeing about 55 amps during this period, there is no need for the charger to up the voltage to 14.4+ volts to "force feed" the battery-bank.

If your current output dropped back to the 15 amp range, without the charger going into "bulk" charging (14.4+) volts then you could have a problem.

As long as the amps are near full rated output (55 amps) on the way to around 80%soc, the charging system is working as advertised. After that voltage of 14.4+ and tapering amps for "absorption" charging, or "equalization" at about 95%soc.

If your batteries get charged to "full", per your charger, in the expected number of hours for your battery-back capacity, nothing to get excited about.

Mark B.

[time2roll]

I am not sure what the complaint is on the IOTA?
It will take some time at 55 amps to see 14.5+ volts.

[KJINTF]

Eliminate the need to worry about amp/hr usage
Plenty of room for 500 watts or more of solar

Looking forward to receiving the converter