What size battery charger??

[ssullivan]

Will respond more, but for now... I wanted to confirm:

Yes, we do use twin (qty 2) Itoa DLS-90's. These are Iota's highest power chargers, or were when I bought them. I was told you cannot hook the chargers up in parallel with each other, but should isolate them from each other. The reason was that there could be intereference between the two as their sensing circuits overlap (as there might also be some interference on the pulses of the PWM?)

Anyway, I've had the DLS-90's going for a year now. They were used every day for 6+ months at anchor this summer to bring my set of 4 Trojan T-105's back up to power. I run off a 5KW (6KW Peak) diesel genset, so power isn't an issue. I'll post more or edit tomorrow. Very tired tonight. Can't see straight.

Please ask me any questions, as I have all the info, experience for a year with this type of setup (although a little larger) and also have some graphs showing power outputs and requirements for Iotas.

[Leighton]

Sean,

Can you elaborate. Do you use both chargers at the same time, separating the batteries into two isolated banks or do you use only one of the chargers feed all four batteries?


Leighton

[Rick]

PLs see Sean's comments on "Generators, Shorpower &.." where he notes that the battery bank gets split in two with one Iota per split until the batteries are charged then combined again for when there is no generator running.

Sean, again there is no damage that will occur when paralleling the Iotas or other chargers. The only problem is, as noted, the lack of simultaneity and tracking of the regulators to give "source current sharing".

One can run an engine alternator output to a battery bank while operating a shore power charger along with a pv panel (hopefully with regulation) and several other sources all at once without hurting anything as long as no single source delivers a voltage too high thereby causing unnecessary gassing of the battery bank. The regulators internal to each source will "back off" in the presence of another source having a regulator set to control a higher voltage, even milli-volts higher. When using a DVM to verify this note that the DVM mode must be set to DC + AC to compare dc sources that have an ac component which adds to the level of internal regulation control. Even then, the meter would have to be an average ac reading function in the DC + AC mode else you will be fooled as to the actual value that an internal regulator measures since most of them are average responding and not true rms, which some good DVMs have (this will only give a slight difference in most cases).

[ssullivan]

Originally Posted by Leighton

Sean,

Can you elaborate. Do you use both chargers at the same time, separating the batteries into two isolated banks or do you use only one of the chargers feed all four batteries?


Leighton

Of course, I'll defer to Rick, since he the person who helped me to understand how to hook up my Iotas to being with.

But yes, here is how it is set up:

4 Trojan T-105's are wired up in series parallel to give 2 banks of 12VDC. I have each Iota DLS 90 hooked up to a single bank (each bank consisting of 2 Trojan T-105s). During charging, I isolate the battery banks and run both Iotas at the same time, allowing each DLS-90 to independently charge its own battery bank.

When charging is complete, I then put both banks in parallel and drain them as a single bank, enjoying the benefits of a slower drain rate since I'm drawing from all 4 Trojans at the same time.

The system has worked flawlessly for us. The batteries, surprisingly, are behaving like new still, a year later.

[Strygaldwir]

I find I get the same output as Bil on Makai. I have a Kipor 2500 watt generator, with a Xantrex Freedom 2500 watt inverter/charger. I have never seen it accept more than 80 amps while I was using the generator. This I could do if I ran an additional AC load. Otherwise, it puts in about 50 amps. I read the Link documentation, it says this is normal. It will not produce max rated output unless the generator is 3.5 Kw. It will produce 90 amps when I am on shore power (30 amp service)

The 2500 watt is a good size for us. I went that large so that I could run my microwave oven. That's a little bit of overkill because I end up not running the microwave unless I am running the generator. I find I have to run my generator about an hour a day when I am out. I also make water at the same time. Works well.

[Rick]

The Xantrex 2500W inverter/charger (modified sine-wave inverter/chargers) load a generator inductively. The smaller the generator output rating (less than 4.5kW) the more the effect will be on the charger output current regardless of a battery bank charge acceptance.

Most switch-mode chargers (and all of them that adhere to low harmonic distortion standards) do not affect a generator output (rating relative to the power rating of a charger) as significantly. Some presently manufactured and eventually future chargers will ALL adhere to standards requiring low harmonic distortion and, therefore, will not require a derating of the generator. The non-harmonic corrected chargers may load the generator output voltage such that the output battery current is effectively linearly decreased as well.

With inductive-loading chargers a generator loaded with increased resistive-only loads (such as heaters) actually ameloriate the waveform to re-establish the voltage waveform effectively increasing the voltage to the charger resulting in an increased battery current (believe it or not!).

[Thermal]

I was in the same predicament a while ago - just could not get any info on input power requirements. Wound up just guessing - I got a ProMariner 40 amp charger (only because they gave me a deal for "upgrading" my existing ancient ferro-resonant ProMariner). After putting it though it's paces, I found that it draws about 10.5A of 120v shore power and put out 42A in "bulk charge" mode. Works great with shore power, but is way more than my small honda 700 generator can do; this charger seems to be much more inefficient that I expected.