Converter Size Tactics Question

[BFL13]

This will not be of concern to most, but may be of interest. I am not certain of my plan, so any comments welcomed.

The problem arose when I stuffed my 100amp PowerMax adjustable voltage (called a PMBC-100) converter/power supply in the old truck- camper to be its "converter" set at 13.8v when away from home. The locations for that camping have 15a 120v shore power connections on long wire. It usually all works great.

However, it happened that the power went out at one of those places in a wind storm (trees fell on lines) so by the time power was restored, the batts were down, and the converter kicked on (100amper although PF corrected) and so did everything else come on all at once, which popped the breaker up where the 15a shore power was coming from.

So, since around here that can happen again, I decided that the 100 amper is too much for this role, even when set at 13.8v. So I decided to get a 55amper instead. I think it (non-PF corrected) will pull fewer VA than the PF-corrected 100 amper --but not by much?)

So my choices are now--

A. Yank the 13.8 fixed voltage 7355 converter (lower portion) from the 5er and stick that in the TC, and use the PMBC-55 adjustable voltage as the 5er's new converter, or

B. Just put the new PowerMax 55amper PMBC in the TC, set at say, 13.8v (the "converter" set-up in the TC is portable, so I can still use it in the 5er or garage as required)

I just don't know if it would still pop a breaker up at the "pedestal" either way, where the 100amper did. (Some kind of surge with the high amps at first I figure, since it is rated for a 15a circuit)

At home on shore power, the TC just needs a battery maintainer, which can be my 2 amp 13.4v job, which works great, or any amps size of fixed voltage converter (I have used the adjustable voltage 100 amper for this too) but the 2amper is useless as a converter away from home, where as soon as you turn on a light (3 amps) it (2 amps) falls behind.

So I am looking at having a 55amp, fixed voltage "converter" for when on shore power away from home, but where it might get cut off once in a while, and I don't want to pop the "pedestal" breaker when power comes back on.

So, what would be the way to go? Thanks.

PS. I was also hoping to use the PMBC for its 16.5v to equalize my T-1275s, but I am told they have put a new board in those, which has a lower max voltage range to maybe 15.8v (Web-site specs to be updated on that)

[MEXICOWANDERER]

One of my Cheapowatts does -just fine- floating at 13.2, taking a prolonged power outage break then picking up the pick and shovel after a power outage. Thirty one amperes. Above Lifeline's 20% minimum.

Wish I had the room to mount the 11uf run capacitor. It definitely helps the PF although by how much is anyone's guess.

DPDT 120vac latching relays are the hot setup for alternative charging sources. "Boing" go the lights. Click goes the relay. Your big mamma be off line until you reset the relay. The red headed stepchild takes over until the latching relay button is pressed again.

I tried that top rated battery floater. Two weeks of hilarity then a pitch into the useless drawer. Connected the Cheapowatt and set it to 13.20 volts.

As long as the beater does not try to make the barge hit eighteen knots going up the Nile, the Cheapo does fine. I.E. Make a wake - attend a wake (The Cheapo's). 350 watts is 350 watts.

Whatever doesn't recycle the lead, Fred...

Best series of twenty-two dollar purchases I ever made.

[BFL13]

pianotuna wrote:
Hi Bfl,

Why not just set the fridge to the propane only setting? That will save 325 watts or 2.7 amps.

After the batteries are not so hungry switch back to the auto setting.

Agreed if it is the 5er, but the TC has a 120v-only small fridge. It is all too complicated! Anyway I am getting the PMBC-55 and will still have some options on which rig to use it in for each occasion because I will have it portable.

I was hoping to also use the 16v plus to equalize my T-1275s, but that is now in doubt at 15.8v max (if mine will--it might be spec for 15.5, we'll see) I remember some years back here, a guy said to use the Honda's DC for equalizing and I tried it out, getting over 16v, so I can revisit that if need be.

I am also confused whether it is the 55 amps I want or just the VA intake amount. I think the 75 amper with PF correction would be about the same as the 55 non-PF corrected for that, but then maybe I only want 55 for voltage drop reasons on the wiring. Too complicated--I already ordered the 55 and that's that! Can't keep second-guessing myself. You guys can do that! 🙂

[time2roll]

BFL13 wrote:
I do know I need a better "converter" for being on 15a shore power on a long wire (low voltage) than the 2a 13.4 maintainer,....

This would be an interesting experiment. I am thinking 80% chance of success.

Then you could still play mad scientist when you get home and do your top charge and hydrometer routine.

[pianotuna]

Hi Bfl,

Why not just set the fridge to the propane only setting? That will save 325 watts or 2.7 amps.

After the batteries are not so hungry switch back to the auto setting.

[landyacht318]

I cannot see any writing on the one side of the Black thing, if it is the thermistor, on my Friend's unit.
I assumed it was so because it is close to the 120v input side and had obviously been changed.

Next time I am there I'll pull the lid off and look again and take a bird's eye photo.

[BFL13]

The thermistor in the 100 amper is the 5R25 IIRC. Should be writing on it to show its size.

I can't find my long thread about the thermistors for some reason, but I had a photo of that section of the board on my prototype 100 in that thread early on somewhere. I wanted to compare it with the layout in the production model you show.

[landyacht318]

Not cheap, but 100 amps never are.

Looks like 120Amp model run off of a 15 amp household receptacle will max out the 15 amp receptacle/ circuit/breaker

[JiminDenver]

landyacht318 wrote:


JiminDenver, the adjustable voltage powermax in the 100 amp or 120 flavor would be a good option for you, if you actually get the model you order. I think this issue would have to be sorted out by now.

Not cheap but I think your are right.

[landyacht318]

We found the fan would cycle on and off floating 2 group 31 AGMS at 85F ambients, and blow out a good amount of heat.

I was surprised as the output amperage was only ~0.5 amps to float these 2 agms. The fan is loud so adding another, switched was desirable to him.

We will be relocating the POt and Voltmeter and have the unit located somewhere not so accessible for pot twiddling.

It looked as if the thermistor had been removed and replaced with a giant black honking thing about 1.5 inches across. The white immobilization caulk had obviously been scraped off.

[BFL13]

landyacht318 wrote:
BFL-13, Understood with the wife and if you are not there, but her education can save you a lot of money.

"If power goes out, turn this dial to here, afterwards, you can turn it to here."

And with the money you save you can send me beer 🙂

My Meanwell rsp-500-15 only goes down to 13.12v and if my AGM battery is low it will still do 25 amps on startup( max of 40amps ), but I know my friends 100 amp adjustable voltage Powermax will go as low as 12.0 volts.

We are going to add another fan to it for a push pull scenario:


Might also swap out to a 10 turn potentiometer as a 90 degree sweep of the provided pot goes from 12.0 to 15.5v making 14.46v hard to dial in precisely.

JiminDenver, the adjustable voltage powermax in the 100 amp or 120 flavor would be a good option for you, if you actually get the model you order. I think this issue would have to be sorted out by now.

For sure, call Errin at PowerMax to get the specs you want. The website is a bit behind the ever-moving advances for the specs! 🙂

Interesting about adding a fan. I haven't had any fan issues, but I also don't live in Death Valley. 🙂

[landyacht318]

BFL-13, Understood with the wife and if you are not there, but her education can save you a lot of money.

"If power goes out, turn this dial to here, afterwards, you can turn it to here."

And with the money you save you can send me beer 🙂

My Meanwell rsp-500-15 only goes down to 13.12v and if my AGM battery is low it will still do 25 amps on startup( max of 40amps ), but I know my friends 100 amp adjustable voltage Powermax will go as low as 12.0 volts.

We are going to add another fan to it for a push pull scenario:


Might also swap out to a 10 turn potentiometer as a 90 degree sweep of the provided pot goes from 12.0 to 15.5v making 14.46v hard to dial in precisely.

JiminDenver, the adjustable voltage powermax in the 100 amp or 120 flavor would be a good option for you, if you actually get the model you order. I think this issue would have to be sorted out by now.

[BFL13]

JiminDenver wrote:
My bank ate my Megawatt so when I get it replaced, it will be on float duty. Should be fine for that without being borged out.

Can the PMBC-100 run full out for two or three hours? I see they have a 120a model too.

It can run at full out forever. It is meant to be a power supply (such as in a car dealer's showroom), not to be a converter as such. However, I can't see why not to use it as a converter as long as I change the voltage settings to suit the situation.

As a converter my 100 stays at constant 103amps till the battery bank demands a tapering amps when the battery voltage tops out (at 14.8 in my normal setting)

Yes, I would like that 120 amper available now, instead of my 100 (biggest back then) combined with my Vec 40. It doesn't take long before you are down from 140 to 120 anyway on my size of bank (four 6s starting at 50%)

This whole deal is interesting IMO, because I am trying to find a limit on the converter, where usually people want a max.

[BFL13]

landyacht318 wrote:
Mark 12.5v on the 100 amp powermax potentiometer.

Turn it to that when the power goes out. Even if batteries are 12.2v when power comes back on, few amps will flow and not trip the 15 amp breaker.

Later, crank it up to you pre marked on the dial favorite absorption voltage and let those amps fly into those thirsty batteries.

That could work for sure. Not so sure if I am not there but DW is, where she is not 100% up on all this stuff. 🙂 Phone calls to do this and that are not the best method! 😞

Yes, I have posted before about using a "marker pen" on the casing top around the knob to mark some favourite voltages so you can set it to them without a voltmeter.

[JiminDenver]

My bank ate my Megawatt so when I get it replaced, it will be on float duty. Should be fine for that without being borged out.

Can the PMBC-100 run full out for two or three hours? I see they have a 120a model too.