Adjustable Voltage Boondocker Converter Question

You can take the lid off and read the numbers letters on the thermistor. You can find the specs for that thermistor on the www and also post that here. Salvo and others can comment on whether it is a good fit.

You can also ask PM tech support if that is the upgraded size for the 75 or not.

My 100 amper may have less margin for chosen thermistor than the 75 and its chosen thermistor so the 75 may be less trouble there anyway.

Yes I was able to replace the thermistor myself but that doesn't mean anybody could! :)

A little off topic, but I've been wondering if a small charger, like one of these would raise Vbatt fast enough to then power up the Turnigy 1080w, without it going into protection mode?

750 mAh maintainer/charger

The Turnigy goes into what I believe is 'fold-back' protection(?) when first powered up. But if Vbatt is already above its (adjustable) starting voltage, then it starts fine. I used the gophert 1620 (20a) power supply and that worked very well. I set it at 14+(?)volts and 20amps, and within seconds, Vbatt was up high enough to get things going. The Turnigy goes from about 12.8v to about 18v, IIRC. So, as long as Vbatt is above that ~ 12.8v, I can do a soft start with the Turnigy, by slowly turning up its voltage. But I'm not sure if a small charger, with much less current, will push Vbatt up fast enough to make it a practical solution?

I'm basically looking for something compact, inexpensive, and easy to pull out and put away, after only a few minutes. I have lugs inside the inverter cabinet, adjacent to the battery cabinet, that I can easily attach a small set of clamps to.

Yeah, that thermistor issue has added more grey hairs to my beard (if that's even still possible?) than the 15 minute +1v 'boost' thing ever could. I'm at a complete loss as to what to do about it? I could send both units back for an upgraded T, but there goes at least $70 in shipping. And a 15 minute delay-on timer (about $100 delivered) would mean I would have to wait a half hour to start charging (15 min delay-on followed by 15 min wait 'til v drops to Vabs). And if I wasn't there to throw the CB, boost would still kick in once power was restored by the delay-on timer. Actually, in either case, power back on means that +1v boost thingy, so both issues are a real pita! At least on gen power, I have some control, but when on shore power... forget about it!

It seems the only inexpensive fix will be for me to replace the T's myself, like BFL did. If I'm not mistaken, BFL replaced his pm's T with a better one? One capable of better handling hot starts?

I am more inclined to have the PD9245-14.8 than worry about thermistors in the PMax.

"So my take is that Either Randy is unaware he is selling 75 amp models as 100 amp versions or is ignorant of it. Telling me that two depleted group 31s AGM's could not accept more than 75 amps infuriated me and made me lose all respect for him. Simple dishonesty or complete ignorance, one or the other, nothing else."

That is disturbing. I caught a flagrant error of his and politely inquired how he arrived at his conclusion. An answer never came.

My SINGLE group 31 Lifeline required 93 amperes to reach 14.2 volts with a absorb max setting of 14.4

Perhaps these abnormal facts are the product of a tinkerer playing the part of expert. Claiming what he did about charge acceptability of a pair of AGM batteries is a product of ignorance or being disingenuous re his products. Either way debunking this is absurdly easy and only compounds the accusation with a charge of lack of intelligence. A cruel conclusion on my part but par for the course for what I did for a living.

I was at my brothers the other day, charging with the pm4b on shore power. My brother was trying to cut some wet lumber with a skill saw, and power to the garage blew. Power went off in the camper, so I knew what had happened. So there I go, running out of the camper, yelling "don't turn the power back on, yet!" Well stupid me, I suffer from a complete and utter 'brain fart', and instead of disconnecting the pm from 120v, I throw the CB between the pm and the bank. My brother restores power, and then I realize what I had done. Good news is, no smoke! (Although I do plan on pulling the unit out and inspecting the thermistor for any damage).

But with it being a 4B model, the T issue may not even exist??? I'm still not sure, exactly, which units have the upgraded T? When the original pm4b-60 I ordered let out the blue smoke, it was assumed it was the T, but alas, I will never know. I'm just glad I wasn't using the pm3-75 at the time, as I'm pretty sure that one would have fried.

You must talk to Errin himself. He is very concerned about this kind of thing, but won't do much if the customer won't send the unit back so PM can test it for themselves to see if the customer has it right.

PM will make it right once they can see for themselves. This is no different from anybody else's warranty policy.

Till recently, the 75s had three fuses and the 100s four with a bigger heavier chassis too. Errin says the latest PMs have fewer fuses than before, but I don't have the details on that.'

Randy only shows a 75 as the biggest he sells on his site, so I don't know where he would get a 100 to sell unless he has a way that he does not advertise.

Sorry to hear.

I do not recall the conversation with Errin.

The model which was measured at 94 amps is about 1 inch longer than the first "100 amp" version and has an extra external fuse, and A louder faster fan.

landyacht318 wrote:
My Powermax story goes like this.

Ordered a 100 amp adjustable voltage unit. The UNit which came had a 100 amp sticker right on it with 3 40 amp external ATC fuses.

Once it arrived, a pair of New and fully charged group 31 AGM batteries was taken down to 50% Via a 10 amp load for 10 hours.

The powermax, when attached, and cranked all the way up, was not capable of more than 75 amps.

Randy tried to tell me that 2 AGMs at 50% could not accept more than 75 amps. Effing BS!

Then measured the unit and Randy said yes that is the 100 amp version, bla bla bla, talk to Errin at powermax.

Errin said send it back, if it tests at 75 amps we will ship you a new one and refund the return shipping.

Over a month later a PM3 100 NON adjustable voltage model arrives. It has 4 40 amp external fuses and is an inch longer. It is never unboxed as there is no adjustable voltage.
Another month goes by and the adjustable voltage model arrives, also 4 40 amp external fuses, and an inch longer than the first '100 amp' model

It tests at 94 amps and line voltage is the suspected culprit for the 6 missing amps.

So my take is that Either Randy is unaware he is selling 75 amp models as 100 amp versions or is ignorant of it. Telling me that two depleted group 31s AGM's could not accept more than 75 amps infuriated me and made me lose all respect for him. Simple dishonesty or complete ignorance, one or the other, nothing else.

I would recommend skipping bestconverter.com entirely and placing any orders directly through Errin@powermax by phone. Screw the lying or ignorant middle man. All these adjustable voltage models are special order type things, not done by Randy, but by PowerMax.

My friend whose money was spent acquiring this Powermax tried to get an electronic timer installed for all the trouble along the acquisition of the correct product path, and they said they could not make it work properly.

I have a spring loaded 12 hour timer for the 94/100 amp adjustable voltage model.

The return Shipping was never reimbursed, and the automatic model still sits on my friend's bench next to the adjustable voltage model, so the drama is not quite sorted out yet. I am not sure if his card was charged twice, or if Powermax wrote off the non adjustable model.

So I would not order any Model without a means to test its maximum output on arrival. There is some dishonesty or ignorance going on with regards to what stickers are placed on what models.

If we had no Clamp on Ammeter we would have believed the 75 amp model was the 100 amp model like the sticker says.

I think I'm in the same boat. I ordered a PMBD-100 from Randy with the adjustable voltage. It arrived, has 3 fuses, and after camping this weekend found during a camping trip it wouldn't push over 75amps into nearly 4 brand new GC2 Golf cart batteries at 50% depleted. I have a Victron power meter to see amps in/out.

I did request by phone a 100amp model, and he said he would make one for me. I paid extra over the 75amp model.

To be fair I haven't called Randy, yet. I think I'll call and find out what the deal is. Did Errin say the 100amp model must have 4 Fuses vice the 3 on the original?

Joel

BFL,

Funny you mention a fix for the 15 minute thing... earlier I was sitting staring at the components, wondering if there was something that could be done to disable the 15 minute timer. Yes, that would solve a lot of problems for me. Then I could just set it at the Vabs of my choosing, and leave it 'til an adjustment is deemed necessary.