55 Amp Converter Charge Times

RoyB wrote:
I go by this brochure report published by Progressive Dynamics on how long it takes to re-charge deep cycle batteries.

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

This is just about what I see here in my setup when doing the same thing.

I use a home made BATTERY MONITOR PANEL to watch my batteries very close when camping off the power grid. Then when the battery banks reads around 12.0VDC I will hookup my trailer 30AMP Shore Power cable directly to the 120VAC receptacle of my 2KW Honda Generator using a RV30A-15A "long" adapter. This will power up my trailer on-board PD9260C Converter/charge and will re-charge my three 85AH Interstate deep cycle batteries in a 3 hour generator run time. I measure my DC AMPS being drawn by the battery bank using a DC CURRENT meter setup between the converter/charger and the battery bank.






Roy Ken

RoyB, very cool, informative info here! If I ever get serious about doing some serious boondocking this info will certainly come in very handy. Thanks!

BTW, do you have any idea how many amps your converter/charger is drawing from the 2kw Honda generator when you're charging these three 85ah batteries, at the same time, in 3 hours?

If your 55AMP converter/charger is the WFCO WF-8955 then just note not many folks can get those to go into the BOOST 14.4VDC charge mode. I never could get my WFCO WF-8945 to do it so I replaced it with the PD9260C 60AMP converter/charger. It works everytime now...

If you want to get it charged in a three hour time span then you have to use 14.4VDC with a current capacity of around 20AMPs. When the GP24 Interstate battery sees 14.4VDC it will start drawing around 20AMPS DC from your converter/charger. The 14.4VDC will stay up around two hours and then switch down to 13.6VDC for an additional hour. Then you will be at your 90% charge state.

If you are only putting 13.6VDC on the battery terminals it will take those times listed in the PROGRESSIVE DYNAMICS Brochure report listed under the 13.6VDC side.

The battery will determine how much current it wants to draw. You just have to have that much current available to use to get the times noted in the report.

Roy Ken

MNtundraRet wrote:

otrfun wrote:
Well, decided to run a realworld, worst-case test. Discharged the battery to approx. 11.90 volts with the converter OFF. Then, turned the converter ON.

------------

Zero Hour:
Converter (110 volt) input current: 9-10 amps
Battery voltage (at battery terminals): 13.02 v

1st hour:
Converter input current: 5 amps
Battery voltage: 13.38 v

2nd hour:
Converter input current: 3 amps
Battery voltage: 13.56 v

3rd hour:
Converter input current: 1 amp
Battery voltage: 13.64 v

-----------

I've noticed I usually read approx. 13.70 - 13.75 volts at the battery when it's fully charged with the converter ON, and 12.75 volts with the converter OFF and no residual charge voltage remaining. Tried reading the battery voltage in a static state with the converter OFF, but I couldn't get the residual charge voltage to subside enough by the time I made this post (continued to hover above 13 volts).

Am I correct in assuming the above "3rd hour" battery voltage reading of 13.64 volts is very close to a 90% charge?

Thanks!

Did you get to 90% charge? NOT EVEN CLOSE!

First of all you bought the wrong type of battery. The marine battery you purchased is a hybrid between starting battery and deep-cycle battery. Worse than a starting battery and worse than a deep-cycle battery.

Your 55 amp 3-stage charger is gross overkill for your single battery. As you already saw your charger never went into "Bulk" stage charging at 55 amps. For an acid/lead battery a smart charger will limit the charge rate to around C/5 (15 amp-rate for 75AH battery).

If your group 24 battery was 75AH, charged fully, dropping voltage to 11.9 volts would be a 40% charge (30 amps left/ 45 amps used).

Since you used some sort of amp-meter you must realize that the reading is a rate similar to your speedometer. If you don't go 60 mph for the full hour, you did not drive 60 miles.

Your readings only total 19 amps charging. Since the amps tapered lower each hour deducting 25% will leave the real charge around 14 amps out of the 45 amps needed.

You should have purchased a larger AGM battery capable of faster charging rates, for your purpose.

For your testing you should have taken an amp reading about 10 to 15 minutes after starting the charge. The 3-stage charger will start in "Absorption" mode (10 to 15 amps) to test the battery-bank and then go into "Bulk" mode (55 amps) if the battery(s) can handle it. You may have missed the "bulk" mode if it happened at all.

MNtundraRet, I didn't purhcase this battery. It came with my brand new toy hauler. FWIW, nearly every RV center I visited in several states during my long search for a toy hauler install these Interstate Marine/RV batteries things as OEM. I'm sure they're on par with the choices a typical TT manufacturer makes for everything else they install--which isn't saying a whole lot--lol!!

The charging current you are quoting is the 120 volt INPUT CURRENT to the converter while it was charging my battery (with no parasitic loads). As I mentioned to Tenbear, even assuming terrible converter efficiency, I would assume my battery was seeing a whole lot more than 19 amps during those 3 hours.

Again, I'm not after fast charging times, just trying to get a rough idea of how much my battery charged in those 3 hours. With all the different perspectives in this thread so far, it looks like I'm probably going to have to do it by brute force. Just see how long my battery powers my 600 watt PSW inverter under full load :)

Good point that the reason it didn't go into boost might just be from the charging rate being too high, and not from the wiring between converter and battery being too long /thin. Of course you can have both problems at the same time :( You have to do some PITA work to find out all the aspects for your rig and what can be done if needed.

RoyB wrote:
13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

This is what the OP is currently looking at.

otrfun wrote:
Well, decided to run a realworld, worst-case test. Discharged the battery to approx. 11.90 volts with the converter OFF. Then, turned the converter ON.

------------

Zero Hour:
Converter (110 volt) input current: 9-10 amps
Battery voltage (at battery terminals): 13.02 v

1st hour:
Converter input current: 5 amps
Battery voltage: 13.38 v

2nd hour:
Converter input current: 3 amps
Battery voltage: 13.56 v

3rd hour:
Converter input current: 1 amp
Battery voltage: 13.64 v

-----------

I've noticed I usually read approx. 13.70 - 13.75 volts at the battery when it's fully charged with the converter ON, and 12.75 volts with the converter OFF and no residual charge voltage remaining. Tried reading the battery voltage in a static state with the converter OFF, but I couldn't get the residual charge voltage to subside enough by the time I made this post (continued to hover above 13 volts).

Am I correct in assuming the above "3rd hour" battery voltage reading of 13.64 volts is very close to a 90% charge?

Thanks!

Did you get to 90% charge? NOT EVEN CLOSE!

First of all you bought the wrong type of battery. The marine battery you purchased is a hybrid between starting battery and deep-cycle battery. Worse than a starting battery and worse than a deep-cycle battery.

Your 55 amp 3-stage charger is gross overkill for your single battery. As you already saw your charger never went into "Bulk" stage charging at 55 amps. For an acid/lead battery a smart charger will limit the charge rate to around C/5 (15 amp-rate for 75AH battery).

If your group 24 battery was 75AH, charged fully, dropping voltage to 11.9 volts would be a 40% charge (30 amps left/ 45 amps used).

Since you used some sort of amp-meter you must realize that the reading is a rate similar to your speedometer. If you don't go 60 mph for the full hour, you did not drive 60 miles.

Your readings only total 19 amps charging. Since the amps tapered lower each hour deducting 25% will leave the real charge around 14 amps out of the 45 amps needed.

You should have purchased a larger AGM battery capable of faster charging rates, for your purpose.

For your testing you should have taken an amp reading about 10 to 15 minutes after starting the charge. The 3-stage charger will start in "Absorption" mode (10 to 15 amps) to test the battery-bank and then go into "Bulk" mode (55 amps) if the battery(s) can handle it. You may have missed the "bulk" mode if it happened at all.

I go by this brochure report published by Progressive Dynamics on how long it takes to re-charge deep cycle batteries.

"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.

13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.

13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."

This is just about what I see here in my setup when doing the same thing.

I use a home made BATTERY MONITOR PANEL to watch my batteries very close when camping off the power grid. Then when the battery banks reads around 12.0VDC I will hookup my trailer 30AMP Shore Power cable directly to the 120VAC receptacle of my 2KW Honda Generator using a RV30A-15A "long" adapter. This will power up my trailer on-board PD9260C Converter/charge and will re-charge my three 85AH Interstate deep cycle batteries in a 3 hour generator run time. I measure my DC AMPS being drawn by the battery bank using a DC CURRENT meter setup between the converter/charger and the battery bank.






Roy Ken

There is a PF of maybe 0.7 adding to the converter's draw in 120v which does not translate into DC amps out using the 10 times rule AFAIK. Also there is a mystery wiring resistance in the rig (too long or thin) adding to battery resistance which is why it won't go into boost, so that may (not sure--ask somebody else!) leave the converter running harder on 120 for fewer amps seen at the battery.

You really need an ammeter at the battery. You can mark the progress of the recharge by how the battery voltage does rise. Eventually it will reach converter voltage and amps stop, so now that is when the battery is considered full (except its SG might not be up where it belongs)

If you had some sort of measuring set-up, you could make a graph of how the battery voltage gets closer to the converter voltage over time and SOCs along the way, so after that you could get your SOC from watching both those voltages. Easier to see amps tapering and have an idea of what amps the battery will accept at that voltage at that SOC.

tenbear wrote:
For a rough idea, look at the average charging current in each hour.
Started @ 9-10 A, 1 hr - 6A, average ~7A
Second hour, avg ~4A
Third hour, avg ~2A

You have put about 13 AH into the battery. Charging is less than 100% efficient, but even if it was 100% efficient you could only have replaced 13 AH, nowhere near enough to bring your battery from the 30% point to 90%.

The 9-10 amps wasn't "charging" current, that was the 120 volt input current to the converter (with NO 12 vdc parasitic loads). Even assuming terrible converter efficiency, the battery should have been receiving at least 30-40 amps of charge current at the start of the charge, right?

For a rough idea, look at the average charging current in each hour.
Started @ 9-10 A, 1 hr - 6A, average ~7A
Second hour, avg ~4A
Third hour, avg ~2A

You have put about 13 AH into the battery. Charging is less than 100% efficient, but even if it was 100% efficient you could only have replaced 13 AH, nowhere near enough to bring your battery from the 30% point to 90%.