Inverter Charger

[Herman]

Dam well that has thrown a spanner in the works

My QPX600D power supply is having a dummy spit which is the only way I can charge my 48 VDC NiFE bank, so I am definitely on the look out for a good inverter charger the ones i have been looking at are the SP PRO INVERTER MODEL  SPMC481 bit to pricey I think and I am concerned that it wont get the voltages I need to charge the NiFe cells from what I have heard, the next option is the Out Back VFXR3048E better price but again will it get up to 66.6 VDC with out going into over volt, I am just finding it confusing as my charge voltage can be as high as 1.65 V DC - 1.75 V DC per cell with a flat of  1.45 V DC per cell, (quick education on NiFe each cell is 1.2 Volt they can take overcharge and deep discharge and virtually indestructible) so as you can see most chargers go into over volt at about 64 volt and very few claim they can get up to 68 V DC and none I have see get anywhere near 70 V DC.

Any constructive thoughts would be helpful as I have made one wrong decision with a installer and I am cringing at making another bad decision without any study.

[Westbranch]

Herman, can you refresh our memories....  how  many cells make up your 48volt bank, seems to me I remember you might have dropped one cell from the bank....??

thanks

[mike90045]

Wintertime, I just get by with the 64V the XW6048 puts out, and when the sun comes along the solar tops it off.   Otherwise the generator run time to get the cells up to full, would be much longer than it is.   And the lower charge won't hurt the NiFe like it kills lead acid.

[Herman]

Hi

I use 40 Cells as I cannot see the reasoning in dropping one or two cells so that you can charge, the reasons are you only need voltage as high as 1.65 V DC per cell (66 V DC) as a charge voltage and 1.45 V DC per cell (58 V DC) as a holding float voltage, I do not think it would be necessary to run a equalization using those voltages.

That is the main reason for looking for and inverter that can handle at least 68 V DC.

Unfortunately i have a very short sunlight window here and because where we live in the subtropics have a lot of cloudy days some times it is near impossible to get a decent charge into the cells and that I blame myself for not knowing better at the time and the dodgy installer salesman for who under sized every thing and poor workman ship and ethics.   

[russ_drinkwater]

Two options Herman.

One. Send the nickel irons up to me in Qld until you get something sorted

Two. There are made in taiwan inverter/chargers that a mate of mine uses and he swears by them.
They are not expensive and he states do a fantastic job. One of those will get you out of trouble until you sort something more long term out.

What is the unregulated output of your arrays?
Can you use the panels without a reg to give them a charge up and monitor them while having a few light beers?

[Herman]

Hi Russ

If it is a Power Master I have a inverter from them which goes into over volt at 64 V DC and I have a Power master MPPT as well which does not like NiFe cells unfortunately, because I have Two banks of Batteries I am using the Power Master MPPT on the Lead acid which is 24 volt and I cannot fault it, the inverter I use on the NiFe cells just not happy with it as it cuts out at 64 V DC but am getting around and I agree with your mate the Taiwanese mad stuff is good.

Solar Panel I am using TS CIGS SERIES, TS-160C2 as per the specs on the attachment.

The Way my batteries are set up I am running my 24 Volt system during daylight hours via a transfer switch which is disconnected when the 24 volt bank is at 25 V DC and will stay on the LA Bank till evening when it drops to 24.2 V DC when the Transfer switch becomes active and switches to to 48 Volt NiFe bank, so as a rule we have no real power problems during good long sunny days, at the moment because of the shorter days and the rotten east coast weather  I have had to run the generator to top up both banks of batteries.

Due to the power supply issue I have been running the generator from about 1600 - 1800 for the 24 V DC LA bank only that way I avoid an early transfer from LA bank to the NiFE bank keeping as much power in the NiFE cells for night use this seems to be working on clear days and as the TS CIGS are working during cloudy weather the NiFe are getting partial charge but the LA are not getting much at all.

[Herman]

Hi Westbranch

I have done a bit more research and found from Encell the reason for the cell drop was that when working with specific inverter's, it is recommend using one fewer cell in series.  This allows us to achieve the higher per-cell voltages without going over the inverter limits.  As NiFe batteries perform at up to 118% of rated capacity, the nominal loss of a single cell does not affect total capacity.

In layman terms you can charge the cell up to 1.65 - 1.75 V DC for a 48 Volt bank 66 - 70 V DC most invertes go into over volt at 64 V DC and a few are rated at 68 V DC which would be ideal for NiFe Cells. In general, these cells like to be worked!  Charge them up and push your batteries hard with a heavy load.  You will find that your battery performs better with heavy use than if you let it sit in float charge.

As I am running 2 Banks of batteries one LA and the other NiFe I can run the La during the day turn the Inverter off for the NiFe and punch in a higher charge with no damage (apart from my man pride when i forget to trun the inverter back on  ) this has been working quiet well until the power supply had a hissy fit.

I will keep you posted on the outcome

[russ_drinkwater]

Mate, the offer still stands to look after those edison's until you get things sorted!
Good luck!

[RossW]

i have been looking at are the SP PRO INVERTER MODEL  SPMC481 bit to pricey I think and I am concerned that it wont get the voltages I need to charge the NiFe cells from what I have heard

Love mine, does (just about) everything I want except ethernet connectivity and integrated webserver.
Just went and checked on mine, and maximum charge voltage looks like 64.8V

[Herman]

Thanks Ross

I think that is what the SP PRO is at 64. 8 V DC not what the spec sheet says 68 V DC.

Russ I did consider your offer for a milli second 

[russ_drinkwater]

Bugger!
Just hang out for spring Herman as we are past the shortest day of year already!
I have some 18 volt voc panels here.
4 x 2 of those without a reg allowing for losses would probably give those edisons a good charge.

[Herman]

Herman, can you refresh our memories....  how  many cells make up your 48volt bank, seems to me I remember you might have dropped one cell from the bank....??

thanks

Hi Westbranch

I think that may be the easy answer at the moment as the best charging voltage is 1.65 V DC if i use 40 cells that pushes me over the inverter high volt alarm @ 66 V DC if we drop two cells keep it at 1.65 V DC keeps me well below the high volt alarm @  62. 7 V DC from my understanding that it makes little or no difference to volts or AH but I may be wrong will keep you posted.

[mike90045]

There are 2 things to consider before dropping a cell out of a bank, to work the remaining cells harder.

1) 40 cells gives you the higher voltage.  I rely on my solar to charge the batteries above the point the inverter/charger can manage.

A single 1.22V @ 400Ah = 488wh, half of which is usable (244wh).   Can you, by booting the cells up to higher voltage, gain back what you loose by having the extra cell?    And then you need a maintenance program for the 1 odd cell.

[Herman]

There are 2 things to consider before dropping a cell out of a bank, to work the remaining cells harder.

1) 40 cells gives you the higher voltage.  I rely on my solar to charge the batteries above the point the inverter/charger can manage.

A single 1.22V @ 400Ah = 488wh, half of which is usable (244wh).   Can you, by booting the cells up to higher voltage, gain back what you loose by having the extra cell?    And then you need a maintenance program for the 1 odd cell.

I see where you are coming from and fully agree and have gone back to 40 Cells as I am not impressed with the voltage loss

[Herman]

Quick Update

As you said Mike the voltage drop was hard to sallow so I am back to using 40 cells and charging 63.9 V DC which seems to be working fine and I have the luxury of independently charging it up to 1.65 V DC per cell with a separate supply for the house during good sunny days for an Equalize.

Cheers