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.

[BFL13]

I Googled "stacking inverters" and got the info on that. Never mind.

[pianotuna]

Hi Mr Wizard,

Yes, for most of the thread, and that is usually safe to do.

MrWizard wrote:
PT
he is talking about stacking 'converters' aka chargers, in series
like solar panels in series

NOT inverters

[BFL13]

Naio wrote:

DrewE wrote:
you would get faster charging by rewiring the batteries in parallel and operating the two converters in parallel

Most of this discussion is over my head, but in case it is useful I will mention that you probably don't have to rewire to do this.

I have 2x12v gel cells running the 24v motor on my ice machine, and I have hooked them up to 2x12v chargers, one charger on each battery, a few hundred times over the past 10 years, without disconnecting the batteries from each other. Batteries are still perky.

When using non-identical chargers, I do swap which charger goes on which battery.

Ok, back to regularly scheduled :B

That works of course. Good point. It does by-pass the Trimetric monitor though, if that matters.

[westend]

BFL13 wrote:
So it's not that horrendous in price to get a 24v inverter that would run the microwave, etc. (Not recommending, just noting the price)

http://www.boatandrvaccessories.com/powerbright-ml2300-24-inverter.html

Ask Bob in Denver about that inverter brand, they are Chinese junk.

Probably cheaper to go the higher amp DC-DC converter route and keep what you have: Victron DC-DC converter

[MrWizard]

PT
he is talking about stacking 'converters' aka chargers, in series
like solar panels in series

NOT inverters

[BFL13]

So it's not that horrendous in price to get a 24v inverter that would run the microwave, etc. (Not recommending, just noting the price)

http://www.boatandrvaccessories.com/powerbright-ml2300-24-inverter.html

[pianotuna]

Hi BFL13,

You want to let the magic blue smoke out? Some inverters can be "stacked". Some can be in series, but most stacking is in parallel. The few I've seen require a sync cable to do so.

BFL13 wrote:

The big inverter is still an issue. Hmmmm can you use two 12v inverters as a 24 somehow? I have a 2000w and 3000w same brand MSW I could combine if so. Then just run a 12v converter (got some) from the inverter "bank" to make 12v for the rig.

[BFL13]

Thanks Mr Wiz. So everyone seems to agree, and I got my answers. Thanks everyone! Happy New Year!

[MrWizard]

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)

yes provided the generator can supply it and the batteries will accept it

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)

Yes .. same answer

[BFL13]

"Actually the 75 and 100 may work in series (24v) as each will only be at max 75 amps output. This is similar to the 155 amp 12v that seems to work."

That's what I have been trying to figure out from some calculations previously posted. The PFed 100 doing 75 should pull less VA than the non-PFed 75 doing 75. I figure 1279VA vs 1693 and total is 2972 doing 75 on 24v, much lower than the 3293VA total doing that 155a on 12v.

I'm kind of curious now to see if this would work, even though I am not planning on going 24v for now. Never know. It would save getting a new 24v converter if you could use the 12v chargers you already have.

The big inverter is still an issue. Hmmmm can you use two 12v inverters as a 24 somehow? I have a 2000w and 3000w same brand MSW I could combine if so. Then just run a 12v converter (got some) from the inverter "bank" to make 12v for the rig.

[time2roll]

BFL13 wrote:
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 agree the PF correction is helping with the 55 - 100 combo. If it does not overload in parallel it should not overload in series.

Actually the 75 and 100 may work in series (24v) as each will only be at max 75 amps output. This is similar to the 155 amp 12v that seems to work.

[pianotuna]

And we will be seriously grateful.

BFL13 wrote:
If I have to go out there, draw my battery bank down to 50%, swap it around to be 24v, then run my chargers in series, watch the Trimetric for amps, attach my Kill-A-Watt to each different charger to see what it is pulling from the gen, I will be seriously annoyed.

You guys are supposed to know what will happen and just tell me. That is what this forum is for, so I can just sit inside where it is warm. Get with it you guys! 🙂

[MrWizard]

Time2roll

At this moment all his testing is 'Parallel' chargers on parallel batteries

This 24v thing is 'what if' conjecture and questions

[BFL13]

If I have to go out there, draw my battery bank down to 50%, swap it around to be 24v, then run my chargers in series, watch the Trimetric for amps, attach my Kill-A-Watt to each different charger to see what it is pulling from the gen, I will be seriously annoyed.

You guys are supposed to know what will happen and just tell me. That is what this forum is for, so I can just sit inside where it is warm. Get with it you guys! 🙂