Adjustable Voltage Boondocker Converter Question

So what you're saying is, by running the pm for 15 minutes, with no load attached, could cause the thermistor to warm up enough that when the load is applied, the thermistor could blow? That would not be good :(

However, when the 15 minute thing ends, the unit actually stops outputting for a couple seconds, and then resumes. I always know when this has happened because the Honda's eco-throttle reacts accordingly. This does not blow the thermistor... so perhaps it is only a disruption in the 120Vac power that causes the thermistor to blow???

I would think it would be no different than the converter sitting idle, while plugged in to 120Vac pedestal power, and then suddenly having to output whatever current necessary to meet whatever 12v load is applied; be it the battery bank, or a 12v appliance.

I would be nervous about starting the PM3 or even a PM4 and then connecting it to the battery though. That is at least one factor in causing the in-rush thermistor to fail. They say that problem has been fixed in the newer models but I would still be nervous.

They are working on a new design that will not have an in-rush thermistor at all, but not there yet.

On cold start of a Honda and heavy load-- to run my 100amper, I have to start the Honda 3000 first and let it warm up before plugging in the charger or it will conk out if ambient is cold too. It warms up faster if you start it with eco-off. Plug in the charger with eco-still off and after the grunt, now you can put eco to on.

That is another way to blow the thermistor. The charger gets started before the Honda conks out and now you restart the Honda which restarts the charger, so you have a "hot restart" on the charger while its thermistor is still warm, so it fails.

The thermistor fails by having a crack through it but it keeps working, so you might not notice unless you have the lid off and look carefully. After a few hot restarts and more cracks in it, eventually it burns through and pieces fall off. At some point you will notice even with the lid on--see the smoke or the unit won't start.

Replacing the thermistor is fairly easy, but getting the board out takes a while unscrewing it all. You drill through the board from underneath where the thermistor RT1 legs go in the old solder, poke the new thermistor legs through, solder them a little above and below, and snip off the legs underneath. Pull on the thermistor to make sure it is not loose. Put the unit back together, say a prayer, and plug it in for a bench test.

BFL said,

"but if there is an engine battery and house batteries, maybe he could put the rig's house on the engine battery for 15 minutes or so, while the charger gets through that phase."

My concern is not limited to the fridge's control board, and such. I also do not like the idea of hitting the batteries so hard from the get go. Perhaps there is no problem with doing so, but I prefer the 'soft start' approach, rather than suddenly hitting them with say 15.8v, right out of the gate. So either way, I would prefer not to subject the bank to that 15 minutes of higher (+1v) voltage.

Yeah, with the eu2000i's eco-throttle feature, it's good to let it warm up and find its happy place. I'm curious to see how it will handle the pm3-75. It has never been subjected to anything heavier than that of the pm4b-45.

Think of it as necessary....

Exercising The Generator

Take my word fo it - water cooled diesel gensets need startup pampering. Got the Woodward to 1-minute at 1000 RPM Then advance to 1200 RPM for 10-minutes before going online.

Disconnecting the house bank will pose no problems for me. When charging via genset, I just run pretty much everything off the genset, anyway, along with the charger. The few things that are run directly off 12v, can certainly be powered down for 15-20 minutes without any worries.

(EDIT: ok, coffee finally kicked in :)... there will be no down time if I simply disconnect the bank from the charger. 12v power will still be available.)

And with summer on its way, Solar will likely be all that is needed. It won't be 'til the cold weather returns that the gennie will be used to any extent. Thus the generator warm up time will also serve as the 15 minute down time. A simple solution to simple but annoying problem.

Bottom Line------------------------

The B.S. DETECTOR by Francis Freas

Inarguable. Absolute.

scrubjaysnest wrote:
It's to bad no one makes a converter to charge batteries per the battery manufacture's specifications.

Your TS-45 should be very very close to perfect.
Anyone charging off grid should have similar before worrying about the converter.

I don't have the details of the OP's rig, but if there is an engine battery and house batteries, maybe he could put the rig's house on the engine battery for 15 minutes or so, while the charger gets through that phase.

I have a 12v battery I am keeping alive for the time I intend to put the main bank on 24v configuration for a test on solar using 24v batteries. The spare 12v battery will run any 12v demands while the main bank is disconnected.

The same principle applies here. If the main battery bank is disconnected, any old 12v battery could hold the fort for 15 minutes or so.

Yes, my pm3 has the 15 minute thing. :(

Do to such high shipping costs, I decided to just keep both units, and do whatever mods were necessary to make them as user friendly as possible. Your idea of simply waiting 15+ minutes before connecting the bank may be the best solution... and would save me the hassle, and cost, of getting the pots replaced.

My plan was to add a switchable fuse between the charger and the bank, anyway, so disconnecting the bank will be easy enough.