running two chargers

[jbeliera]

Here is a technical question. Let's say you want to charge your house batteries on your RV quicker. If you have two 12 volt batteries in your battery bank would you charge that battery bank quicker if you put two 25 amp battery charges on at the same time. Would that be possible to increase charging amps and less charge time or would it fry your batteries

[MEXICOWANDERER]

Here comes the Horsee...

• Some pairings of chargers work, others no
• Look for a clearly worded confirmation from a trusted source
• I coined a term "Saturated Voltage Charging" to describe a charging intensity that instantly or close-to-thereof reaches the charger voltage limit setpoint
• AGM battery charge time benefits most from saturated charging
• Not all batteries, even those of a dedicated purpose have similar charging acceptance
• This is a valid way to tell the difference between a bargain basement flooded golf car battery and a quality battery like a Trojan
• Heads up testing between group 31 AGM batteries, the first a new Lifeline, the second being a new Odyssey, revealed the Lifeline accepted 13+ amps more initially the remained above the curve all the way to the end of the charge cycle
• Total time difference to full charge @ 44-minutes
• Returning to charging
• A valid comparison is the number of minutes it takes a charger to start the reduction of amperage due to Voltage Absorbsion limit
• If it takes 60 minutes to reach this milepost, then total charge time versus initial saturated voltage acceptance will be excessive
• i.e. sixty minutes of extra generator run time
• Meanwell RSP power supplies in excess of 1000 watts have a paralleling Hirose connector port. Load sharing
• Megawatts cannot be paralleled unless an isolation rectifier pair is used. Bad news. The Beta unit shuts off completely.

[ktmrfs]

ScottG wrote:

2oldman wrote:
OK, yes, parallel batteries might do better separated. Series, no.

Remember, the discussion is about using two chargers. Trying to use two smart chargers for either parallel or series batteries never works well if the two chargers are in parallel.

Uh,..... need to tell that to my two PD chargers. I have a 55A and a 65A PD, one replaced the WFCO and the other is in the pass through.

For 8 years now I have often used them both in parallel to charge the 4 GC batteries wired in series/parallel when I have enough generator or shore power to do it. I get 110A for an hour or more into the bank, and then it tapers. quickly charges the battery bank.

And I don't seperate the batteries, just stuff the current to them. And the batteries are now 8 years old, probably 200+ discharges down to 30% SOC or more and doing fine.

Now if the chargers are different mfg, may be an issue. And I'm not the only one who has done this. IIRC there are several folks that have 2 or more of the great BD 40A chargers they use in parallel on batteries.

[theoldwizard1]

2oldman wrote:

theoldwizard1 wrote:
If they are both smart chargers, separate the batteries and charge them independently.

You don't really have to separate them.. do you?

Read this DC-DC battery charging

[full_mosey]

In a way, all chargers have a bulk stage when they are at maximum Amps while raising the battery Volts to the constant Voltage limit/cutoff. Abs is when the Amps taper due to Voltage regulation. On a bad solar day, I have seen my MPPT stay in Bulk all day.

I remember that ice cream post!

HTH;
John

[BFL13]

I had a 4455TC in 2011 and reported some results with it on here back then. Unfortunately it got fried later that year by accident, my fault I think.

Anyway, it only became a two-stage if it had the TC option, otherwise it was a single stage 13.6. It did 14.2 in "boost" The TC was based on a "nominal" temp of 60F ISTR. Randy had a bunch of graphs etc linked for it. It did a good job recharging my 6s, can't remember about bubbling amounts.

I posted about playing with the TC sensor in ice cream to get the voltage higher. It did 61ish amps (rated 55) with short fat wiring to the batts, as seen on the Trimetric. I did crank up the pot to make boost 14.8, which also made float go up, so I had to use my OEM 7355 for Float. Drove Salvo crazy when it (at 14.8) did as well or better than his beloved Iota 55 amper 🙂

I ended up with PowerMax as a replacement (adjustable voltage ones)

[full_mosey]

BFL13 wrote:
The newer Parallax ones have PF correction though. They cost more than some others ISTR. Also they have voltage settings in the low 14s unless that has changed.

I don't know if they are newer. 5400 series are PFC, the 4400 like the 4455 at bestconverter are not.

Are the 5400TC models more expensive than other converters with temp-comp? 5475TC @ Amazon

I don't see any Voltage settings. A while ago, someone said it is a no-float charger, bulk and Abs only. So basically it is a temp-comp power supply. It likely would not be able to bubble an FLA. I would think it would be OK with an AGM. Temp-comp Voltage control should be the exact Voltage needed for batteries spec'ed at 14.4V Abs.

HTH;
John

[BFL13]

It is not so simple. My Kill-A-Watt readings on a PF corrected 100 amp PowerMax being run from a Honda 3000 with unloaded voltage of 126.8v:

122.7v, 15.57a (I was lucky not to fry the KaW limit of 15a) 1854w
But was 1910VA, and PF 0.97

In contrast the non-PF corrected 75 amper(their ad is wrong about the 75's PF correction--it isn't) was:

123.8v, 13.64a, 1241W, 1693VA, and 0.73PF. (Note the higher "loaded voltage" from the 100 amper's)

BTW their efficiencies comparing input and output (work not shown) was low 80s for the 100 and high 80s for the 75, leading one to suspect there is a trade off in efficiency to obtain the PF correction.

When on generator VA, obviously you want the lower VA and hang the efficiency percentage.

On starting in-rush-- that may be what happens with the Honda gen when starting cold and not given time for the engine to warm up a bit.

I have had it conk out with the 100 amper loaded too soon. Trick is to leave the Honda in "Eco-off" and let it run for a minute, then connect the 100 amper. Now it won't conk out and you can then turn Eco on. That is with the 3000w, good for 2800VA and the 100amper wants 1910VA when running.

[full_mosey]

You don't recall correctly. There is no mention of a 20A socket with the 5475. The 5490, 90A model is the one you are thinking about. The 4400 series have the usual poor PF.

You will see the specs in the link I provided. It says 15A socket( as in 1875W @ 125V).

5475TC wrote:

Specifications

AC Input :
105-130 60Hz
AC Input Watts:
1260 <--------The 5475 benefits from an extremely efficient feature of operating on a standard 15 amp outlet.
Amps:
75 amp
Dimensions:
3-5/8”H 8-3/8”W 11”L
Listed:
ETL Listed
Special Features:
TempAssure standard, standard 120VAC 15 amp line cord, steel enclosure with durable powder coat finish
Replacement Upgrade?:
Yes
Series:
5400 Series
Temperature Compensation:
Yes
Type:
Deckmount Converter
Weight:
7.75 lbs

Why can't you divide 1260W by 110-125V? to arrive at Amps?

1260/110 = 11.4A, or 1260/125=10.1A; within the range of a 2000W genny(1600VA).

The 5400 series are PFC which should be very close to VA=Watts.

HTH;
John

[MEXICOWANDERER]

Do your homework on INRUSH. Then MUSE the effects of inrush amperage PLUS system burden with converter developing energy product simultaneously with inrush.

i.e.

You may be dismayed if you couple a larger converter or charger to a smaller generator without penciling this out...

[Sam_Spade]

Cydog15 wrote:

That's just not true.

Unless and until you can show some charging CURRENT charts with two chargers versus one charger.....over the same period of time......with batteries at about the same depleted SOC when starting out.....

I contend that it IS true. Prove me (us) wrong.
Simply stating your opinion over and over does not make it true.

And just to clarify a bit:
I am NOT saying that having two chargers connected and running at the same time will cause any problems.....probably.....but that it will not GAIN you much or anything in total charging capacity.

[time2roll]

Xantrex white paper on power factor

[BFL13]

The newer Parallax ones have PF correction though. They cost more than some others ISTR. Also they have voltage settings in the low 14s unless that has changed.

[ktmrfs]

full_mosey wrote:

ktmrfs wrote:

Dirtpig wrote:
I feel like it would be much less of a hassle to just upgrade your converter/charger to a 75amp/100amp model. No Mickey mousing clamping or disconnecting batts. Just my 2c.

well, since I have a 2000VA generator, it will NOT run a 75 or 100A charger. so, I have a 55A charger in place of the WFCO and a 65A in the pass through. when only on one generator, on goes the pass through 65A. when I have shore power or two generators then I crank them both on and get 110A or so for quite a while.

So, there are reasons to have two chargers rather than one.

and there is no mickey mouse stuff, I just turn one or the other on or both on. both are connected to the same battery bank in parallel.

75A on 15A line, 1260W.

Any good?

HTH;
John

look at the current draw which they don't specify, not the watts. Since most converters have pretty bad power factors, the actual current draw is higher than the watts calculation would indicate. Now powermax does make some power factor corrected converters. but they are the only one with a 100A power factor corrected converter.

In reality once you take into account the terrible power factor of most all converters, the current draw is well over the watt calculation rate. my PD65A measured draw at 60A is in the 1300VA range, comfortable for the honda 2000. IIRC The 75A has a 20A plug, won't even plug into a 15A circuit because the VA draw is so high and is marginal at best with a honda 2000. anything more and it's overload time.

[brulaz]

Like others, we routinely parallel two chargers (solar or shorepower). They are set to the same absorb set point.

During bulk phase their amps add together and get the batteries up to about 80-90% SOC quickly.

But during the absorb Constant Voltage phase one eventually cuts out, perhaps because of a slight difference in temperature adjusted V? And/or as long as just one can provide all the amps the batteries will accept at that point?