Really interested in how this PM3 Lithium Series works for you
@Browneye. My neighbor has a Thor 24sa motorhome he is wanting to change out the Progressive Dynamics PD9260C and the 2 80ah FLA batts. There is just not enough juice when simply overnighting and running the propane heater with 12 volt fan and a few items intermittently, when not on shore power.
Considering updating to PM3 Lithium Series 55A and 2 Ampere Time 200+ batts. The 100A may be a consideration but have to look at the wiring and guess the current 60A wiring for the current PD9260C won't be enough. As the Ampere Time batts won't fit in the current location it may make sense to just upgrade the wiring when moving and upgrade to wiring that will support 100A.
I do have concerns about pulling 100 amps when only plugged into a 15amp receptacle instead of campground 30amp. Not that 15amp AC can't support 100amp DC, but if a few other items are running, will the 100amp drop to not cause issue with the 15amp AC breaker? New to modding RV systems.
I had to read this a couple of times to understand what you were saying about the 100A - so 12V charging at 100 amps, got it. Per the specs I'll link below that unit in the PM3-LK series is 15 amps 120V AC input. I get it, you plug into a 15A receptacle with an adapter - we do that a lot as well, like visiting someone's home, or even at home - I don't know why I never bothered to install a 30A outlet for the RV - it's been sitting there next to the house for 17 years!!
Anyway, a standard 120V outlet is on a 20A circuit, so the 15A your converter would pull would be fine. And no, it won't run your AC, nor probably a microwave either at the same time. You would likely pop the breaker at the source. I caught my mom turning on the AC plugged in to the standard outlet and boy oh boy does that extension cord get hot where it plugs into the RV shorepower cable. It will do it for a short while but it's a really bad idea.
Here's the spec sheets on the standard PM3 units showing AC draw:
https://powermaxconverters.com/wp-content/uploads/2019/02/PM3-Spec-Sheet.pdf
The units are 'current limiting', so I don't know if that means it pulls it's full load and then puts out what the battery needs, or if it ramps up draw based on the load, like an inverter does. Some of these guys may know for sure on that.
I can see if you're going to want to go with 400Ah of lithium that you might want a 100A charger. Especially if you don't have another charge source like solar. Also keep in mind that a drop in replacement with your alternator and isolator runs the risk of burning out your alternator. The lithium packs have so little internal resistance, unlike lead acid batteries, that they'll pull everything your alternator can put out - at idle or close it can easily overheat it. So a DC to DC charger is in order, and the Victron Orion seems to be the go-to for these, their bigger one is only 30A.
Anyway, so those are some things to consider. Your wiring should be fine for a battery upgrade, and likely for a converter upgrade for a 55A. For the 100 you would want to take a look at the connect wires - sometimes they use 6 or 8awg, and 6awg should be enough but you would want to take a look-see. If they're 8awg wires you could easily replace them with heavier gauge wire. If you're going to install a large inverter then all bets are off - you'll want to reassess the whole setup. Do you have 30A or 50A service in your unit?? I would opt for the 55A unit if it were me - makes it easier to configure, and that's still a lot of charging amps, even for a 400A battery bank.
And for sure if you're moving your bank location you're going to need new connect wires to your main power bus or switching area. I'm making up new 2awg cables for mine, which will easily carry the max 60-80A's I would ever draw from my bank, and the round trip is under 7'.
I had thought my remote positive post in my electrical bay had a heavy lead to it - the batteries are 1/0, but low and behold the feed for the main 55A 12V breaker is 6awg. Which was fine as built, with the 45A converter/charger and house loads, but then I put my new 600W inverter on the same circuit and noticed quite a bit of voltage sag. Well, that explains that. So I'm running a new 4awg feed from the main battery disconnect remote switch directly to the inverter. It only pulls 5A max at full power, but that's 50A and with 6awg wire the voltage sags quite a bit.
For your buddy with the two 80A deep-cycles, yeah, if those are 12V RV/marine type, they're not very heavy duty. And they never seem to get properly charged up and de-sulfated, so they tend to go south in a couple of years. The furnace blower is 6-8A, and if there's a fridge board and lights, could easily add another few amps, so if it's cold and the furnace runs a lot you could easily deplete the 80A usable from the two.
The PD9260C is a very good converter/charger for FLA though, so he may just need a new battery bank. If he's going to keep FLA, I recommend a pair of 220A golf cart batteries - the plates are a lot heavier and you can equalize the crap out of them to keep them de-sulfated. lf he's going to lithium like you want to, then yeah, the old chargers that auto-equalize is a bad idea for them. OTOH, the newer PD92XX units have an optional 2-stage charge profile, so that's worth looking into. It might well be fine with either type of battery option.
I just got my new PowerMax unit this week, excited to try it out. But my lithium cells won't be here for a couple more weeks, so I'm not in a hurry to install it. Plus I'm moving it from my electrical cabinet where my inverter is, over to where the new ltihium pack will be, and a direct wire to the battery.
The installation manual is a bit different than what they published prior - that I linked to above. The new one says 2-stage charging volts are 14.6 bulk and 13.2 resting. If that's the case the default setting should be perfect for my new lifepo pack.
It also accepts 4awg wire and I have some extra, so it will have heavy charge leads direct to the battery. I have to install a new 20A receptacle for shorepower/genset where it will be placed.