55 Amp Converter Charge Times

RoyB wrote:
OTRFUN - The idea is to "never never never" let your battery get below 12.0VDC... This is around the 50% charge state. If it gets to 10.5VDC it is 0% charge state.

10.5v is 0% under a modest load (5 to 25 amps?). Comes from the BCI testing standard for amp hours and reserve minutes testing. 11.89 is 0% when resting such as in storage. The RV true 0% might be somewhere in the middle due to smaller load.

No more than 50% is a full timers rule. 70% to 80% discharged is closer to the max for part timers IMO. Still get plenty of cycles to last 8+ years. Trouble is knowing how low is low so it is OK to be conservative at 50% when possible.

Just as important to get recharged asap. And 13.6v is a slow slow charge.

otrfun wrote:

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?

We don't know without measuring the OUTPUT voltage of the converter (to verify whether or not it's going into bulk stage) AND the terminals on the battery (to see how much line losses there are....still need to get that voltage into the 14 range to make any impact). Personally, I don't even bother measuring voltage when charging. I take a specific gravity (SG) reading with my hydrometer and I know instantly where my batteries are at. I don't have to guess or assume or hope. I know with 100% certainty. Now I don't take the hydrometer with me when camping because I'm not trying to charge to full at a CG (I actually don't do any charging while camping but that's for another thread). Takes WAY too much generator time to do that. Most typically run their chargers long enough to make up for most of their usage or a good portion of it. Enough to last till they get back home where the real charging starts.

OTRFUN - The idea is to "never never never" let your battery get below 12.0VDC... This is around the 50% charge state. If it gets to 10.5VDC it is 0% charge state. If they get down to 5V, 6V etc they will start self destruct mode inside and you will have to replace them.. i.e they will be hard to recover if they get that low in DC voltage...

I have a DC VOLTMETER monitoring my batteries at all times when in use and my game plan is to never let them get below the 50% charge state or around 12.0VDC... They will recover if you let them get down to 10.5VDC but that is flirting with battery death in my book...

I think most of the battery expert guys on here are in agreement with this...

You need to get a DC SHUNT installed inline with battery so you can monitor. If that is out of the picture you can pickup a CLAMP ON DC (Note I said DC) ammeter. Sears sells one for around $50 I think... The only I ever read the AV AMPS on the 120VAC side is to make sure my 2KW Honda Generator will operate my converter/charger. My PD9260C draws are 1000WATTs on the AC side when the output is loaded down to 60AMPS.

I think you really need to think about changing out your WFCO WF8955 controller/charger with a good PD or IOTA model unit.. I left my WF8945 COnverter in the power distribution panel and just turned it off. Then I mounted my PD9260C unit closer to the battery bank. I can now use either one by just flipping the correct circuit breaker. Its a backup thing. Even tho it won't go into smart charge mode it does still put out 13.6VDC and will run my DC requirements on the trailer. Just can't use it when charging my batteries.

Roy Ken

otrfun wrote:

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?

Oops. Guess I wasn't paying enough attention. Sorry about that.

This is so all so simple to VERIFY with a hydrometer. Myself, at 14.4 volts starting at that overdepleted value I would allow 12-15 hours to reach 95% state of charge.

You are dealing with a chemical reaction, not a bank account. Simple adding and subtraction is not possible. Temperature, age, length of time at less than 100% charge all factor in.

Recharge that battery to 95% SOC enough times and you're going to find yourself standing in the battery warranty return line. Or pay full-bore-for-a-new-one-line.

RJsfishin wrote:
Quote:
To see the charging amps from the converter to the battery the clamp-ammeter must be placed over the "POS"(+) post cable going from the converter/charger to the battery. Used anywhere else is an exercise in futility.
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Really, ?? Wow, after all these years I thought it would work on the neg cable just as good.

Actually it does. The sign is changed.

Quote:
To see the charging amps from the converter to the battery the clamp-ammeter must be placed over the "POS"(+) post cable going from the converter/charger to the battery. Used anywhere else is an exercise in futility.
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Really, ?? Wow, after all these years I thought it would work on the neg cable just as good.

Oops, double post :(

To see the charging amps from the converter to the battery the clamp-ammeter must be placed over the "POS"(+) post cable going from the converter/charger to the battery. Used anywhere else is an exercise in futility.

Also; if you never saw at least 14.4 volts (read at the battery-terminal) you can assume you never had any bulk charging taking place.

As for the dealers installing inappropriate chargers and batteries; they also install cheap omi-directional antennas good for 10 to 20 miles. Who camps in the city? These options look good for the ill-informed.

RoyB wrote:
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

RoyB, thank you! Some good info! I've been clear on the importance of achieving a 14.4 vdc charge voltage in terms of charging time. So, from your experience, what kind of voltage do you typically read on the terminals of a very discharged battery (less than 25%) when 14.4 vdc of charging voltage is being applied with your PD9260C? I assume the actual amount of this voltage drop is determined by the current capacity of the converter/charger (with everything else being equal)?

Anyhow, I supplied as much info as I had (using a VM and my PI EMS 120 volt current readout) which I hoped would be enough info to determine a rough state of charge. Apparently, it's not nearly enough. Guess I'm gonna have to check the SOC by brute force, with a large, verifiable load, then count the minutes till the battery voltage drops to 11.9 - 12.0 volts.