Series 12v Chargers ?

[BFL13]

Bestconverter ad says,

"The PD9100L Series can be wired in parallel to charge at much higher current rates. They can also be wired in series/parallel to charge 36, 48, 60, 72 and higher voltage battery packs at high charge rates"

I keep thinking about going 24v battery bank. I have several 12v converters (PowerMax brand) Reading the above, I am wondering how that would actually work.

Say I put my adjustable 100 amper and my adjustable 55 amper in series to make a 24v charger. I would want the voltage to be 2 x 14.8, so I would set 14.8 on each.

How many amps would that make to the battery bank? I am thinking 55 where you get the lowest amps (like with solar panels in series?) but that 55 with 24v is like 110 amps with 12v, so that is not too bad?

Is that how it works? Or what? Thanks.

[time2roll]

Anytime you expect more amps than the charger rating the voltage sags. So if the 100a starts pushing more than the other charger is rated the other charger voltage will drop off and limit the amps.

Basically if you have the 55 and 100 in series then anything above 55 amps will cause the output voltage to sag from the combined set point (29.2v) to something less as dictated by the battery.

This is exactly the same effect as when charging at 12 volts. If the battery wants 100 amps but you only have 55 the voltage sags and we call that bulk as the charger is maxed out.

Or another way to look at it is that anything above 55 amps the 100 amp charger is on it's own and of course set at 14.8v those extra amps go nowhere into a 24 volt battery.

[BFL13]

CA Traveler wrote:

BFL13 wrote:
No, this is with the battery bank as 12v. The 55 and the 75 run perfectly from the Honda 3000 individually, but add one to the other and it pops the Honda's overload, but the engine keeps running. Then you have to shut down the generator's engine and start over as how to reset it.

Something is not right. Those two chargers by themselves are no where near the gen capability.

So bad gen, connection problem, bad charger, other loads, cockpit problem or something else???

Not understood. The gen is rated for 2800VA continuous. The 55 pulls 1383VA by itself and the 75 pulls 1693VA by itself. Together that would be 3076VA, which is above the Honda's rating. (actual Kill-A-Watt measurements)

It is more surprising IMO that the gen can run the 55 (1383VA) and the 100 (1910VA) together no problem (3293VA)

PT suspects the PF correction of the 100 is the reason, but that doesn't change the VA figures above.

I have tried it several times with different choices of receptacles on the gen but it still does it.

[BFL13]

Mr Wizard, do you agree with the others like PT who say the 55 amper will be at 14.8v (as set) doing 55 amps while the 100 amper will be at 14.8v(as set) also doing 55 amps? (output 55 amps on 24v same as 110 amps on 12v)

And if I swapped the 55 out and put in the 75 amper, it would do 75 amps and now the 100 amper would also do 75 amps? (output 75 amps on 24v same as 150 amps on 12v)

I agree I have no clue how it works internally. Can't seem to get my mind around it.

But I don't need to know why it does whatever it does; I just have to use the information to stay within the VA limit of the Honda 3000 (which seems to be a bit more than its rating of 2800 at sea level)

[CA_Traveler]

BFL13 wrote:
No, this is with the battery bank as 12v. The 55 and the 75 run perfectly from the Honda 3000 individually, but add one to the other and it pops the Honda's overload, but the engine keeps running. Then you have to shut down the generator's engine and start over as how to reset it.

Something is not right. Those two chargers by themselves are no where near the gen capability.

So bad gen, connection problem, bad charger, other loads, cockpit problem or something else???

[MrWizard]

Bro you are con fussing yourself

50 amps at 14v is 700w

To charge two batteries at 50 amps 24v is 1400 watts

The 75 is not just a pass thru switch it has to produce and carry 50 amps to make the total 24v st 50 amps or nothing works get charged

The power to charge two batteries in series is the same as the power needed to charge to equal batteries in parallel

You trade 100 amps at 12v for 50 amps are 24v
Same amount of power

In parallel you double the amps two for one
In series you double the volts each battery will see 12v at 50 amps
Just exactly like running two six volt in series

Or six , 2v cells

Your confusing your self over stacking the chargers in series
Both have two produce exactly the same amount of power
Each one produces the same amps at 1/2 of the total voltage

[BFL13]

time2roll wrote:

BFL13 wrote:
The no go with 55 and 75 is a puzzle. It pops the breaker(s) immediately.

is it a load issue or a GFCI issue?
Set the voltage same as the battery (26v?) and try again.

No, this is with the battery bank as 12v. The 55 and the 75 run perfectly from the Honda 3000 individually, but add one to the other and it pops the Honda's overload, but the engine keeps running. Then you have to shut down the generator's engine and start over as how to reset it.

Same thing with the 75 (non-PF) and the PFed 100.

When you add the non-PFed 55 to the running 100 it just revs up the gen a little more and you see 155 on the Trimetric, no sweat. Seems that is about max in VA for my Honda 3000 (14 years old at sea level)

[time2roll]

BFL13 wrote:
The no go with 55 and 75 is a puzzle. It pops the breaker(s) immediately.

is it a load issue or a GFCI issue?
Set the voltage same as the battery (26v?) and try again.

[BFL13]

pianotuna wrote:
Hi BFL13,

The Honda can only do that "over" wattage for 30 minutes--then it may shut down to protect itself. It can do that because the no load output is 127 volts.

It won't do the 75 and 55 because neither is power factor corrected?

I don't have any data for testing that 30 minute idea. Longest run in notes at constant 155 amps on six batts was 25 minutes before tapering, but that was from getting close to Vabs. I need more batteries! Then I can see about going past 30 minutes 🙂

Nothing in the manual about the 30 minutes idea. Maybe a Yamaha thing? (I have no battery in the 3000 either as it happens)

The no go with 55 and 75 is a puzzle. It pops the breaker(s) immediately. It shouldn't be the PF unless somehow PF correction reduces starting surge because the VA is higher with the 100 and 55 than with the 55 and 75 even with the PFed 100.

I am suspicious of the receptacle inter-play. It seems you get different total amps if you plug one charger into the duplex 15 and the other into the adapted 23.3 (30 twist) and when you use a splitter (triple end #12 cord) in just the one 23.3.

I do have to adjust the charger voltages better to get the highest amps, fine tuning, but that doesn't explain it all. One day I will spot something.

Supposedly, you can do anything amongst the receptacles as long as you stay under 23.3 total, but each may have some own limit at play. I don't do it the same way each time and can't remember which way I got the most amps last time. Got to camp in the winter more often! J

[pianotuna]

Hi BFL13,

The Honda can only do that "over" wattage for 30 minutes--then it may shut down to protect itself. It can do that because the no load output is 127 volts.

It won't do the 75 and 55 because neither is power factor corrected?

[BFL13]

time2roll wrote:
Yes put the 75 and 55 in parallel and that group in series with the 100 amp.
This will get you 100 amps at 24 volts.
I can't wait for the testing 😉

I still recommend matching the chargers or even better just get a 24 volt converter.

It's all your fault for putting me onto this multiple chargers trick in the first place! 🙂

On the above, I would need more generator. I could then use both my 100s and get 100 that way too.

It would be fun to run some tests of all this for sure. All put away for the season right now though.

[time2roll]

Yes put the 75 and 55 in parallel and that group in series with the 100 amp.
This will get you 100 amps at 24 volts.
I can't wait for the testing 😉

I still recommend matching the chargers or even better just get a 24 volt converter.

[BFL13]

PT---we need a press to talk button! 🙂


Working on the VA if I swap the 55 out for the 75, taking advantage of the 100 only doing 75.

Kill-A-Watt on the 55 doing 56.8a is 1383VA, 980w, PF 0.70

If that 55 were PF corrected (o.97 vs 0.70) then VA would be about 1010 but now with the 75 PF corrected that is 1241/97 = 1279

Meanwhile the Kill-A-Watt on the 75 is 1693VA (1241w. o.73OPF)

1693 + 1279 = 2972 VA ---Honda rated at 2800---but will do the 55 and 100 at 155 which is about 1383 + 1910 = 3293 (don't know how it can do that but it does---perhaps because the total is less than the sum of the parts due to the lower loaded voltage when both on there)

(It won't run the 55 and 75. 1383 + 1693 = 3076. Don't know why not.)

[pianotuna]

If you use the 75 amp in series with the 100 amp then:

75 x 14.4 = 1080 / pf 0.7 =~1542 watts
75 x 14.4 = 1080

So the total would be about 2623 watts.

[pianotuna]

Hi BFL13,

Assuming no losses the 55 amp and the 100 amp operating in series would draw

55 x 14.4 =~ 792 / pf 0.7 =~ 1131 watts
55 x 14.4 =~ 792

total about 1924 watts

[BFL13]

2oldman wrote:

BFL13 wrote:
If in fact the 100 is adding its voltage, but no amps, what would its draw on the generator be?

I'd have to say (55 x 12) watts.

OK, so you agree the 100 will be doing 55 amps. To clarify, in that case its draw (in VA) would be a little more than its output of 55 x 14.8 = 814w. Actually it would then be drawing less than the 55 amper also doing 55, because the 100 is PF corrected.