New PowerMax Lithium Series Converter/Chargers

[HRTKD]

I had a separate converter for charging the LiFePO4 battery bank when shore power was available/needed. It worked, but I used it short term (switched, like Chris said above). When I upgraded to the Victron Multiplus inverter/charger I was glad to get rid of the converter. The Multiplus is programmable and likely a lot smarter.

 

[mercuryin]

The default 'lithium' charge voltage is too high - at least for my cells, they will hit bms over-volt. And the default 2-stage voltages are not adjustable.
In fixed voltage output IS adjustable, it works fine, but you would have to set it to a float level to set it and forget it. I'm not so sure that's such a great idea with any lithium battery. And at a lower charge voltage the differential between charge voltage and battery voltage would be so low as to be very slow charging. Constant volt charging drops current as the battery voltage rises.

Frankly I would go with the Victron, that's on the top of my list to replace my Powermax. But I am still using it, in fixed voltage set to 14.1V, with a switched power source, and I simply switch it off when charge current reaches 11A. It will put out the full 55A until very close to full, and when the CV current starts to drop then the battery is full. So far I have not had to use it, my solar panels recharge the battery to full each day, even on cloudy days with some sun breaks.

We've been two weeks out on a trip, several days travelling, then parked for several days, some cold temps, and still have not used more than half of our capacity. Solar recharges, or if we're driving then the Victron Orion supplies 18A to get it topped back up. I have it set to 13.8 boost and 13.4 float, it has a minimum 10 minute boost duration which restarts every time you start the engine, so I didn't want it over-floating the battery.

The biggest problem is there is no charge termination - it drops to float, which would be fine, but the boost voltage is too high.

We were hoping to get a full report from Time2Roll on the MeanWell charger - it had a better charge logic, but does not have a reboost function, so it resets each time you plug in, settable charge voltage, and drop to float. There is a question whether it would drop to float if there are any loads that keep the battery voltage below full charge level, so will it actually drop to float?

If you have a really big battery supplying large loads then surely you'll be looking for a high-power charging option. I find my 230A battery to be very easy to maintain. We just don't have large loads to supply.

Also, be sure to consider the input current to your converter/charger - a 100A charger is gonna pull more amps than a standard 110v 15 or 20 amp circuit can supply. The 55A charger pulls 11A at full draw. I have it on a shared 20A circuit, so that's about all I would want a charger to use. Fortunately my other circuits cover the high-amp loads, like coffee maker at the galley, microwave, AC, gas-absorption refer on AC, and etc.

Guau, thanks for such tremendous and helpful answer ! I have similar setup than yours but just 300w solar, I say had because I have nothing now excepting a Dc to Dc charger from Sterling to charge the 280Amp eve cells x 4 plus a Jiabaida 200amp BMS similar to the one you have. The flexible solar panels I have on my caravan roof are not longer working and to be honest, I haven´t used the caravan during the 2 years of Covid. Looks like these flexible panels are giving a lot of problems and lasting for just 3 or 4 years, sometimes even just 1 year. I am about to buy a new 300w flexible panel but CGIS this time and hoping to get a longer life with it. So I wanted to have quick charge for my next long trip to Spain this summer so I was thinking about this Powermax charger to top up quickly. The input here is 220v so the charger should never trip a circuit, in theory.

 

[Browneye]

I would recommend the MeanWell chargers, but would have to look to see if they have a higher capacity than their popular 750 which is 45A.
Seems like they had a 75 too.

Even at 45A, a four hour charging session would supply more than half your capacity, so might be an option.

For a single charge source the victron might be too small. On the other hand, if you plug it in overnight it would likely fully charge it. Victron has a really nice BT app interface and is fully adjustable as well. I really like my Orion charger - their stuff is really solid.

And yeah, flex PV's don't seem to get good reviews. And they're not a cheap option either.

 

[Browneye]

I had a separate converter for charging the LiFePO4 battery bank when shore power was available/needed. It worked, but I used it short term (switched, like Chris said above). When I upgraded to the Victron Multiplus inverter/charger I was glad to get rid of the converter. The Multiplus is programmable and likely a lot smarter.

I need to look into the multiplus - they seem quite popular and well liked.

I'm just blown away with how well the lifepo battery performs - amazing. I'm also surprised that I get any charge current out of the solar panels under full cloud cover - we're sitting here in WA right now under rainy skies getting 3A of charging. Not much, but at least it's a trickle. Low temps last night was probly 45deg, had 89% SOC this morning. The furnace blower pulls 12A when it runs! Fortunately, unless it's REALLY cold, it doesn't run that much.

 

[triplethreat]

I would recommend the MeanWell chargers, but would have to look to see if they have a higher capacity than their popular 750 which is 45A.
Seems like they had a 75 too.

Even at 45A, a four hour charging session would supply more than half your capacity, so might be an option.

For a single charge source the victron might be too small. On the other hand, if you plug it in overnight it would likely fully charge it. Victron has a really nice BT app interface and is fully adjustable as well. I really like my Orion charger - their stuff is really solid.

And yeah, flex PV's don't seem to get good reviews. And they're not a cheap option either.

Hey Chris....Mean Well does have a 1200W and a 1700W version of the NPB-750-12. And speaking of the MW 750, I ended up buying one and just got it installed a couple of days ago. I'm still in the testing stage with seeing how it works, but of course I discovered an issue with the factory wiring causing a .6 to .7 voltage drop from the charger terminal to the battery. I've got some new larger cable coming, a new battery disconnect to replace the OEM switch....it's dropping about .2V just across it. Hopefully, when the stuff comes in and I get it hooked up, I can do a bit of testing. When I first turned it on, my battery was down to about 84% SOC so I started charging with it. I was seeing a pretty constant 38 to 38 1/2 amps, which wasn't too terribly bad since the actual voltage arriving at the battery was 13.5 to 13.6 during CC or Stage 1. The output from the charger was dead on at 14.2 and once it finally got the battery charged, it's been sitting at a constant 13.41V....at the charger terminals.

 

[triplethreat]

A bit of an update. So the final part came in that I ordered and I got it installed and the Mean Well NPB-750-12 is charging away on my LFP. A couple of days ago I hooked up a 12V 200W heating element to discharge the battery and get it down in the upper 40s SOC. Now, with the upgraded cables, a new battery disconnect and a shorter run of heavier cable, I'm letting it charge and seeing 42.8/42.9 amps going into the battery...via the Victron BMV 712. I also took a voltage reading with my Fluke meter and the voltage drop that WAS .6 to .7 volts from the charger to the battery is now down to a .1 voltage drop measured at the same places. The NPB-750-12 is rated to output 43 amps, so it just doesn't get much better than 42.8 or 42.9. I'm very happy with the results, and since I don't have anything 12 volt running in the trailer, the charging will finally get down to the 10% level and switch over to 13.4 float voltage. I'm timing the charge time and estimating that it is going to be just over 4 hours....so I thought I'd drop the update for y'all that have or have been thinking about the Mean Well NPB charger.

 

[triplethreat]

Update...Part 2: So the battery finished up charging and it took 4 hours and 10 minutes. I started out with a SOC at 44.7%, and this is on an EVE 302 AH battery that showed I have right at 305 AH. The Mean Well consistently was at the upper 42A range during the CC part of the charge and finished off showing 14.1 volts at the battery.....which is exactly my .1V loss from the charger to the battery. I turned off my 300A battery switch and took a voltage reading at the charger, which was then in the float mode (3 stage charging setup on mine via the DIP switches on the front of the charger) and the charger output voltage was 13.41V.....pretty darned close to the rated 13.4V. I had one cable in the charging circuit that was slightly warmer to the touch than the rest of the cabling, and it was the 2/0 cable that goes from the 300A switch to my 300A Pos. buss. I'm going to take that off and recheck the crimp and the connections at the buss to see if I can get some improvement there. Overall, I'm very pleased with the way it turn out and the Mean Well is SO much better than the OEM WFCO FLA charger/converter that was in the trailer. The relocation of the Charger/Converter to the baggage compartment of the trailer also allows for that shorter run of cabling to the battery and extremely easy access to the C/C. The OEM C/C location required that I remove a slide rack in my storage compartment that was bolted down to the floor, then disassemble the left and rear wall of the compartment to even get to it, and the end result was a total pain in the bottom. Now, it's a matter or opening a compartment door for access. I'm getting too damned old to be a contortionist and crawling around inside the baggage compartment. I may, at some point in the future, add a switch to pins #7 and #8 to be able to remotely turn the unit ON/OFF from inside the trailer.....we'll see if that is really need though before I make that decision.

UPDATE to the update.....When my battery was fully charged (14.1V showing at the battery) the variance between cell voltage was only 42 milli-volts....which is pretty good in my opinion (please comment if you feel otherwise). Once the cell voltage gets in the 3.4V range, all the cells stay within about 2 milli-volts and at least part of the time I was watching while I was draining the battery down to the 44.7% SOC, I would see all four of them at the exact same voltage.

I had a lot of advice on this battery build by some well known members here, and I truly appreciate ALL of the advice/offerings that I received. This build was my first ever and even though I had watched some videos and had a general idea of how to do this, the expertise that was added from these members surely went a long way to help me build a successful battery on my first attempt. That same expert advise and discussion in this thread also led me to the Mean Well NPB-750-12 charger that I successfully installed and made it work for my application. And BTW, the new NPB, via the DIP switches on the front of it at set for FLA batteries because the 14.2V bulk/boost setting and the 13.4V float setting seems like a much better choice to me for the LFP batteries than pushing them to the very, very top voltages and stressing the battery needlessly. Thanks again to everyone that contributed and offered advice and knowhow to this topic.....y'all Rock!

 

[Browneye]

That is how I would set it, I don't push my pack to the high-knee either, they start to get out of balance as individual cells hit full capacity. At 14.1V the jbd is actively balancing cells. Once charging terminates and the pack settles, all cells come into perfect balance, less than 3mV variance, all the way down the discharge cycle.

The main concern for NPB was the charge termination at 10% of charge current if it was also servicing a load. Seems as long as the battery reaches the rated charge voltage to 10% of the current it will switch to float.

There is also no re-boost IIRC, so the charge cycle is restarted when the unit is power-cycled, which is probably fine for most cases.

We just spent two weeks living in the RV on a 2500 mile trip. Between solar and dc to dc charging, the pack reached 98-99% each day. Our loads, even overnight with the furnace running, some inverter use for electronics charging and TV/tuner, we never got below 50% SOC. My calculation of about 100-120Ah of capacity was spot on, the 230A pack serves perfectly. Very happy with the performance, and I too am very pleased with advice here on how to make it all work.

I never did use the Powermax converter-charger. At least not intentionally. The cats hit the 'on' switch twice, I was surprised when the battery voltage was spiking and the solar controller was loafing. Sure enough, the converter got turned on. I have it set to CV at14.1V for a manual boost if/when needed when on generator or shorepower. I taped down the switch so it couldn't get turned on inadvertently. I'm going to install a proper guard so it can't. But it's there if we need it.

We start out early in the day when traveling, usually before sun up, and the Victron Orion was a nice augment to charging - it would supply it's 18amps when the engine started. Solar topped the pack up in the afternoon at high-sun. If we had a lot of cloudy days we could run the generator and the Powermax to do a quick re-charge. At 55A, a couple of hours would replace what we use overnight.

A few more gadgets I really liked on this trip - one was a wireless thermometer with two sensors for the gas-absorption refer, one for freezer and one for fridge. I had doubts about it's performance after 17 years of service. But at the middle temp setting it stays between 3 and 10 degrees in the freezer, and 33 to 38 in the refer. Very happy about that. We didn't have hot days though, but one near 90 and it was still holding down temps. When it gets warm the ARP board activates a fan in the vent chimney to help move heat up and out from the cooling coils.

The other gadget was the inverter, was awesome to have 110 when we needed it. We had a lot of idle time without shorepower.

And third, the Ecoflow Delta Mini. Since my Xantrex 650W inverter won't power the coffee maker, we would just plug it into the Delta. It would use about 15% of it's capacity for a pot of coffee. Based on that you could get nearly a week of morning coffee before recharging it. In hindsight I would have installed a larger inverter and transfer switch to the circuit that supplies the galley area. Oh well.

And finally, the 12V compressor mini-cooler. I got the BougeRV one, and set to 33 degrees, it kept the beer at 33-37 the whole trip, and just sips power, via cigar plug or power supply plugged into the inverter. Nothing like an ice-cold brew at the end of a day of driving. Happy campers!

Oh, and the new 'toad' is also just fantastic. We towed a chevy colorado 4x4 for 7 years - nice truck but it's heavy, about 4500lbs with a couple of bikes and gear in it. So last year we bought a chevy spark - it's half the weight, and you don't even know it's back there. The motorhome has a gas GM 8.1L V8 and gets about 8.5mpg. Yes, we used a lot of gas, well, a lot of expensive gas anyway. The cheapest we paid was $4.79 in Oregon, but usually it was mid-five dollars. A gas stop was $300 - we did that numerous times. OUCH!! We passed a lot of CA stations that posted up to $7.39/gal. Wow!

 

[triplethreat]

That is how I would set it, I don't push my pack to the high-knee either, they start to get out of balance as individual cells hit full capacity. At 14.1V the jbd is actively balancing cells. Once charging terminates and the pack settles, all cells come into perfect balance, less than 3mV variance, all the way down the discharge cycle.

The main concern for NPB was the charge termination at 10% of charge current if it was also servicing a load. Seems as long as the battery reaches the rated charge voltage to 10% of the current it will switch to float.

There is also no re-boost IIRC, so the charge cycle is restarted when the unit is power-cycled, which is probably fine for most cases.

We just spent two weeks living in the RV on a 2500 mile trip. Between solar and dc to dc charging, the pack reached 98-99% each day. Our loads, even overnight with the furnace running, some inverter use for electronics charging and TV/tuner, we never got below 50% SOC. My calculation of about 100-120Ah of capacity was spot on, the 230A pack serves perfectly. Very happy with the performance, and I too am very pleased with advice here on how to make it all work.

I never did use the Powermax converter-charger. At least not intentionally. The cats hit the 'on' switch twice, I was surprised when the battery voltage was spiking and the solar controller was loafing. Sure enough, the converter got turned on. I have it set to CV at14.1V for a manual boost if/when needed when on generator or shorepower. I taped down the switch so it couldn't get turned on inadvertently. I'm going to install a proper guard so it can't. But it's there if we need it.

We start out early in the day when traveling, usually before sun up, and the Victron Orion was a nice augment to charging - it would supply it's 18amps when the engine started. Solar topped the pack up in the afternoon at high-sun. If we had a lot of cloudy days we could run the generator and the Powermax to do a quick re-charge. At 55A, a couple of hours would replace what we use overnight.

A few more gadgets I really liked on this trip - one was a wireless thermometer with two sensors for the gas-absorption refer, one for freezer and one for fridge. I had doubts about it's performance after 17 years of service. But at the middle temp setting it stays between 3 and 10 degrees in the freezer, and 33 to 38 in the refer. Very happy about that. We didn't have hot days though, but one near 90 and it was still holding down temps. When it gets warm the ARP board activates a fan in the vent chimney to help move heat up and out from the cooling coils.

The other gadget was the inverter, was awesome to have 110 when we needed it. We had a lot of idle time without shorepower.

And third, the Ecoflow Delta Mini. Since my Xantrex 650W inverter won't power the coffee maker, we would just plug it into the Delta. It would use about 15% of it's capacity for a pot of coffee. Based on that you could get nearly a week of morning coffee before recharging it. In hindsight I would have installed a larger inverter and transfer switch to the circuit that supplies the galley area. Oh well.

And finally, the 12V compressor mini-cooler. I got the BougeRV one, and set to 33 degrees, it kept the beer at 33-37 the whole trip, and just sips power, via cigar plug or power supply plugged into the inverter. Nothing like an ice-cold brew at the end of a day of driving. Happy campers!

Oh, and the new 'toad' is also just fantastic. We towed a chevy colorado 4x4 for 7 years - nice truck but it's heavy, about 4500lbs with a couple of bikes and gear in it. So last year we bought a chevy spark - it's half the weight, and you don't even know it's back there. The motorhome has a gas GM 8.1L V8 and gets about 8.5mpg. Yes, we used a lot of gas, well, a lot of expensive gas anyway. The cheapest we paid was $4.79 in Oregon, but usually it was mid-five dollars. A gas stop was $300 - we did that numerous times. OUCH!! We passed a lot of CA stations that posted up to $7.39/gal. Wow!

My testing so far has been with basically nothing else 12V related, on in the camper, so it switched to float as it should. I have NOT tried the charging with enough 12V stuff on that it would impact whether or not the charger went to float voltage.....but honestly, I don't see how it could because it is sensing total output current, not just charge current. I don't really expect that it would drop to float voltage if I have other 12V devices running that would cause it to be more than 4.3 amps....but I'm OK with that for sure.

Second "Bolded" sentence......I agree, I do not believe it would "reboost" unless it is power cycled....but at the minimum, it is still going to be putting out 13.4V float voltage which would put some charge back in the battery, just not enough to completely charge it. The charger does come with the little 14 pin plug that you could use to add an external ON/OFF switch for doing the power cycling of the unit. In my case, if I decide to go that route, I will likely be using one of these remotes to turn it ON/OFF from the comfort of my recliner....

https://www.amazon.com/dp/B083P75T63/?coliid=I3ED4IVRC8AVCC&colid=3OCCIL325J3O8&psc=1&ref_=lv_ov_lig_dp_it

Third "Bolded" area.....I have wireless temperature sensors with a display panel for my fridge also. They are very useful and informative and that is what make me realize that my Norcold absorption fridge was not worth a plugged nickel for us. Thus the trip to Shipshewana, IN and having JC Refrigeration convert our 18 cu ft. unit to the twin 12V compressors. Power consumption when both compressors are on is right at 12.6 amps and on a 6+ hour drive, we consumed a bit over 37 AH....BUT, that was with a pretty much empty fridge and nothing to help keep the temperatures regulated and cold. I'm sure it will do better and run a little less when it's loaded up with food/drinks/freezer stuff. It is almost like having a "home" refrigerator in the trailer.....18 cu. ft. 4 doors, and cooling that is done by actual refrigeration compressors.....ala 12VDC though.

 

[Browneye]

A 12V compressor conversion is definitely on my shortlist should the Norcold quit working well enough. They're a good price too.
Why should a RV refer cost over two grand???

 

[triplethreat]

A 12V compressor conversion is definitely on my shortlist should the Norcold quit working well enough. They're a good price too.
Why should a RV refer cost over two grand???

Chris....here are a couple of pics of the backside of our Norcold (formerly an absorption fridge, but with all of that stuffer removed during the conversion mod by JC Refrigeration). Twin 12VDC compressors.....the larger one takes care of the freezer section and the smaller one takes care of the fresh food compartment. Two totally separate thermostats so you have complete control over what temperature each compartment (fresh food and freezer) can be set to....

Immediately to the left of the larger compressor (in the first pic) is the InkBird digital temperature controller for the freezer section.

 

[Browneye]

How is that MeanWell charger doing?

House guests arrived yesterday and wanted to use the 'west wing' - the RV in the driveway, so I got the AC going and turned on the Powermax converter to pump up the battery a bit as I have my 'storage' settings on the SCC which lets it rest at about 50%.

Well gee, it just bounced all over the place, 2-3 amps then off, then on, the green led light blinking. Disconnected it, turn it on, tested with correct voltage, but would not charge the battery. Turned the battery off - Powermax would support 12V loads, but would not charge the battery when connected.

I'm done. Not even going to mess with trying to claim warranty coverage. Ordered a Meanwell NPB450-12. 25A charging on shorepower is enough juice for the 230A lifepo4.

I looked at the Victron IP one in 30A, but it's another $80, so screw it. ?‍

 

[triplethreat]

How is that MeanWell charger doing?

House guests arrived yesterday and wanted to use the 'west wing' - the RV in the driveway, so I got the AC going and turned on the Powermax converter to pump up the battery a bit as I have my 'storage' settings on the SCC which lets it rest at about 50%.

Well gee, it just bounced all over the place, 2-3 amps then off, then on, the green led light blinking. Disconnected it, turn it on, tested with correct voltage, but would not charge the battery. Turned the battery off - Powermax would support 12V loads, but would not charge the battery when connected.

I'm done. Not even going to mess with trying to claim warranty coverage. Ordered a Meanwell NPB450-12. 25A charging on shorepower is enough juice for the 230A lifepo4.

I looked at the Victron IP one in 30A, but it's another $80, so screw it. ?‍

Chris.....I am 100% satisfied with the MeanWell so far. It does everything it is supposed to do. When I'm parked at home, I turn the battery main disconnect switch off (300A Blue Sea) and just let the MeanWell provide the DC for lights, A/C control power etc. In my case, with the Lippert 6 point hydraulic leveling system on the trailer, I always need to make sure that the battery disconnect is in the "ON" position before trying to use the hydraulics. I did make a little plastic flap that goes over the controller for operating the landing gear that simply reads "300A Switch???". That is my reminder to myself to make sure that the battery disconnect is on before trying to use the hydraulics. That pump motor will draw ~70A when running, and that would certainly overload the MeanWell that I have. I've got the NPB 750-12 which will put out right at 43A and that is obviously not enough for the hyd. pump motor. I also have a note inside the trailer by the switch for the main slides in/out because they too are hydraulically operated and the same pump motor is used for them too......so just another warning for me to make sure that the battery disconnect is on before anything hydraulic operates. And the obvious reason for leaving the battery disconnect in the off position is to not keep the LFP battery fully charged when not using it.

 

[Browneye]

Sounds good.
My jacks run off the starting/chassis batts, and generally the engine is started before operating all the heavy loads - slide-outs, power awning and step, and the jacks.

LFP has been working great. I just can't figure out why the powermax won't charge - I think it just fried itself. I should try calling them, but I'm tired of the rigmarole.

Speaking of jacks...mine are hydraulic cylinders with 17K lbs of lift - the controller operates two at a time, either side, or front or rear. The unit weighs about 20K lbs so they'll lift it completely off the tires if you run them all the way down. Well, they all started leaking last year, so I tried a stop-leak product and low and behold they quit. But then on our trip north this May, the second night one of them blew out the lower seal and leaked fluid all over. Since it did retract, I left it up and went without them for the duration of the trip.

In the manufacturers infinite wisdom, the cylinders were built and then welded shut. What were they thinking? The only way to fix them is to grind the weld off, replace the o-rings, and weld them back up. I'm just not good enough to try that, so I found one rebuilt one on ebay for $700. They sell new ones at e-trailer for $1300, and then there's the original manufacturer in Kentucky that will rebuild them for about $400 each. Anyway, the one rebuilt one got us going again, but now another one has started leaking again, so I sent the first failed one to them to rebuild. Once I get it back I'll send the second leaker in and have that one rebuilt as a spare. What a giant PITA. I'm tempted to remove the whole system and just do without. It was about a $4K option when the coach was new in 2005 . It sure is handy to push a couple of buttons and have the coach level, plus putting all four down takes the load off the suspension making the whole unit feel solid when you're walking around inside.

Can't wait to get the new charger - hoping it fills the bill.

 

[Browneye]

Wow - that TRC Electronics is fast. Placed my order last night at 10pm and it has already shipped. Whoot!

 

[JimmyM]

My Powermax is used in fixed voltage mode and still works fine. I'm about to switch to high voltage mode tomorrow morning.
Something must have just fried in your.

 

[JimmyM]

Chris....here are a couple of pics of the backside of our Norcold (formerly an absorption fridge, but with all of that stuffer removed during the conversion mod by JC Refrigeration). Twin 12VDC compressors.....the larger one takes care of the freezer section and the smaller one takes care of the fresh food compartment. Two totally separate thermostats so you have complete control over what temperature each compartment (fresh food and freezer) can be set to....



Immediately to the left of the larger compressor (in the first pic) is the InkBird digital temperature controller for the freezer section.

Damn. Who knew "fridge envy" was a thing. Apparently I got it

 

[Browneye]

Well...the saga continues...
Today when I went home for lunch I thought I would load my 'away' SCC parameters and let the panels charge the battery all the way up. It kicked into boost and started charging the pack at about 25A - not bad for 430 watts of solar panels.

So I thought I would switch on the powermax just to see if it was still acting up, and low and behold it's back to normal. Doubled up charging amps, both it and SCC were tapering off a bit as the pack reached 13.8 volts. For the life of me I can't figure out why it was not charging last night - just not getting this. BMS was going nuts, the power was pulsing on and off and the cells were jumping all over the place. Everything is happy today.

In the meantime, TRC has shipped me a new Meanwell charger. Going to switch it out and sell the powermax on ebay. Or bin it. Or donate it to the local high school science class. LOL

 

[triplethreat]

Damn. Who knew "fridge envy" was a thing. Apparently I got it

"Fridge envy".....LOL. I have to admit though, before I had ours converted, I had a bad case of it too....especially last fall when we did our one month long trip out west and and the Nevercold fridge never kept the kind of temperatures that a fridge should have. Although we didn't lose any food or get sick from eating anything in it, that cemented my decision to have it converted in the spring this year. Definitely one of the best mods I have done to the Toy Hauler.....and I've done a lot of mods.

 

[Texas-Mark]

I read about up to page 5 of this thread when it seemed to start getting off the topic of the Powermax. I currently have a PM3-100 It is quite a few years old and it has no external controls (no switches, pots, or LED). The label lists 3 voltages 13.2v, 13.8v & 14.6v. I always just assumed it was a 3 stage charger. I probably only used it once or twice to charge my FLAs for a few hours, and did not pay attention to the voltage.

I now have a bank of Lifepo4s and decided to mess around with the Powermax. I popped the lid off and adjusted the single adjustment pot down to 14.4v.

Reading some of the earlier posts, I have seen people say they are using a timed boost on these units. Some said it is 30 minutes. However, I have left my unit plugged in (just a meter connected) for well over an hour and the voltage is staying at 14.4v. This seems to indicate it is not really a 3 stage unit. The two page manual that came with it also talks about the 3 stage "option", which again seems to indicate some of these units were just fixed output. If that is the case, I am actually happy with it, since I will rarely use this for charging, and will simply shut it off when the current zeros out. I can also bring the voltage down a bit, but I don't think that will be necessary for the once in a blue moon I may need to use it.

So I guess my main question is, does anyone else have one of these older units that behaves this way (appears to be a fixed output despite the label)?