jrnymn7 wrote:
BFL13 wrote:
Gutsy move! Good work!
Well you don't want more than 15.4v ever to stay inside the fridge controls limit, so it looks like you have some weird choices, but not impossible.
Set it higher so it does whatever it gets to for that 15 minutes while you have the fridge off for that 15 minutes and not need the inverter (won't run at over 15) and then get the steady state to be 14.x as high as you can. (14.8 being ideal but not compulsory.)
Once you get to 90% or so where amps are down, swap over to your finish charger that has low amps but high voltage and carry on from there if your PM's new Vabs is lower than you like. Or else just leave the PM run at the voltage you got it to do after the 15 min is up.
Very interesting! The Paramode converter also had a little pot like that and when it was jacked up it changed both its voltages higher too. Rising tide floats all boats kind of thing.
the higher voltages will work great in colder weather... and that's when i'll need a big amp charger to replace more Ah usage. so that could work to my advantage.
??? is it o.k to just turn the fridge off, or should i have it set up so i can disconnect the power to the fridge easily?
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I just turn the fridge off (it is on gas at the time)which is as easy as it gets? Nothing has gone wrong with our Norcold fridge while seeing 16v battery and being off.
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??? fridge controls aside, would rising to say 15.5v during boost, (then dropping to 14.5 Vabs) do damage to the plates? i'm guessing heat would be the biggest factor here?
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I can see why it did the 15 min on your full battery after the mod, then dropped to 14ish. However on a low battery that 15 min does not apply if the unit is running right (I don't think you ever saw it run right on a low batt? only on a fairly full batt? )
If it now does 15.x in "boost" then on a low batt you would think it would stay at that till the batts reach 15.X. I do not understand this situation. Obviously the PM4 is not a PM3! Or else there was indeed something weird about your particular unit as you suspected.
that drop you saw from 15.x on the full battery might even have been from 15.x Vabs to Float where Float also is now higher from 13.2 to 14.x I don't know.
What you want is to see it run at 75 amps on a low pair of 6s for say half an hour at 14.8 or similar voltage, so you will need the Trimetric to measure the amps.
Maybe you will be twiddling that pot some more until you get that thing under control! :)
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i think you said earlier 90% would be about 5amps per battery at 14.8 Vabs. if so, i now only have 2 batts in series, so that would be 10amps. but my gophert 16v/20a power supply will do 20amps at 14.8v, so i could switch to it well before 90%, yes? (or would the lower powered power supply not do as well as the 75amper anyway?)... that said, any idea what the amps would be at 90% at say 14.2 Vabs ? thanks!
Amps per batt at 90% at 14.2 would be lower than at 14.8, but I don't have a number.
You would normally leave the regular charger on at 14.8 (whatever)till the batts are "full" then do the overcharge at 15.x so amps per batt acceptance will be low then. You don't need to swap chargers earlier anymore now that the main charger will stay at the higher Vabs past that previous drop to 13.6 at 78% SOC. Assuming you do get that PM75 working the way you want.
Very puzzling, but you have a good grasp of the principles so please keep us posted on what you discover.
