- Neither the Meanwell S-350 or the SP-320 are rated or certified for parallel operation.
Agreed...The bigger ones are..at least some of them...the 1.5 or 3 kw versions certainly do have a parallel facility
Kingfish wrote:The S-350 isnâ€™t being driven to full potential. We can see that with the input current in comparison with the spec. Given the amount of time it takes to charge at voltage, we can also ascertain that the unit is underperforming, significantly â€“ possible greater than 50%. Imagine itâ€™s pulling 1.5A @ 120V; how does 180W of VAC magically translate to 350W at 63V? What have I missed?
I am thinking maybe be what you have missed, and I also missed, ( and this is possibly borne out by what you say later), is that maybe the current limit is one of the 320 units that you have in parallel.
You next say
Kingfish wrote:Adding the 3rd SP unit confirms that I did not have bad SP units; that the performance was exactly the same.
If adding the third unit made no difference..then maybe you only have one of the 320's taking al the load and that is the one limiting the current
Kingfish wrote: In addition, I was able to glean in detail the performance during the final 0.2V of the charging cycle. The final test with just one SP unit confirms there is contention between the paralleled units in the sense circuitry during the termination phase. Do you agree?
Yes, I have noticed that with two S-350's in parallel, they only stay in balance and equally sharing the load at a particular voltage...above and below this they do drift out...but not by enough to be too concerned
Kingfish wrote:With regard to the SP-320 & Imbalance, I can see and accept your point easily; that seems quite reasonable, and would explain the artifacts of the observation. But then consider that if the stock POT is so delicate and difficult to bring into balance â€“ then the entire assembly comes into question and is hardly road-worthy.
Ah...I was not implying that the stock pot is delicate, it is just that the adjustment is very coarse because it is less than one turn...maybe 270 to 300 degrees so it is therefore difficult to adjust accurately, so setting an accurate voltage and matching it to another can be tricky. Consider then a 16 turn pot, ...same value 2k or 5k whatever..but adjustable over 16 turns...far finer control is possible.
I have two meanwells...each with 4 pots all 16 turn cermets. I replaced both the stock VR1 and also added SVR2 the current limit pot. The reason I have 4...they are switchable, so I can have two preset voltage limits, and two preset current limits. My set up consists of two S-350-48's 8 cermet 16 turn trimmers, and two 4 pole change over switches, so i can switch between parallel and series, and also switch between two voltage/current settings.... 41.5 volts and 8.5 amps and 36 volt and 9.7 amps. When I have it switched to 41 volts, I also switch them in series for bulk charging direct to the pack. Or in parallel a the lower voltage to run the charger for a balance charge
Kingfish wrote:In fact Neil, you have stated clearly a trait that should have been mentioned back when people first began tinkering with these components: It takes a skilled technician with professional equipment to properly dial these devices into balance.
have to disagree there. Correct that they are not designed for parallel operation, but if I can get them running balanced in parallel, anyone can. With the 16 turn pots and two cheap 10amp DVM's I can easily get mine in balance. I bought 4 of the el cheapo DVm's from e-bay for $0.99 . They are only 10 amp, but for my 350's 10 amp is fine. All I did first off was ran all 4 of them in series, with my pack and the Meanwells, and chose two that gave he same current reading. The put them in sereis with each parallel PSU output, load up the pair of them with a battery, and then adjust the voltage of one or the other to equalise the current between the two
Kingfish wrote: I could not ask for any better validation. You Sir deserve a gold star! (sincerely)
Very kind, but hardly deserved.
Kingfish wrote:In other words, the modest tools at my disposal, with the resolution and measurement that I have, it is still not enough to bring these simple low-cost devices into balance;
get a few of those cheap DVM's, they are good enough for this job..
unless someone can come up with a â€œunifiedâ€ sense circuit like in the HRPG, PSP, RCP, RSP models, and so forth.
Now, that is the real answer.
Much earlier in this thread, you mentioned using the thermistor and the pot mod for the fan control. Far better is bridging the collector-emmiter of the Q5 transistor. I put a switch across mine, so I have always or full auto.
Well which ever way you decide to go with those other supplies, let us know.
It is a shame you are limited over there to what is it? 110 or 120volt AC in the household supply