Need help upgrading DC system

[colemj]

Originally Posted by btrayfors

I've never known or experienced the "preset" 8-hour absorption time. Mine (and I have had two for over five years in 24/7 service and have installed many others) don't do that. I assume you're talking about the IQ4 models, which are the only ones which should be used for battery charging on a boat.

Also, momentary power interruption does NOT result in reversion to absorption-level voltages for another 8-hour period. I've tried cutting the AC power on mine when in float mode (which I've set to 13.8VDC) and they revert right back to float mode...13.8VDC.

Yes, the IQ4 version.

As per the Iota manual (and our experience): "ABSORPTION STAGE - This state is limited to 480 minutes (8 hours) during which the charger will operate either at Full Current output or Constant Voltage output depending on the discharged state of the battery. During Full Current output, the charger is providing its full current rating and will slowly increase the battery voltage to the “Absorption Stage” voltage. At the end of the 480 minutes, the charger will revert to the FLOAT STAGE."

Also from the Iota manual (and experience): "The FLOAT STAGE will end when either the battery voltage drops below the “Low Trigger” point or at the end of seven days when the IQ4 initiates an equalization stage to remove sulfate layers from the battery plates. In either situation, the unit exits the FLOAT STAGE and enters the BULK STAGE."

The low trigger point is 12.8V, so if you are running any DC loads when the power is cut, or the power goes out for more than a second, the charger re-enters bulk mode and quickly settles in for another 8 hours of absorption.

Mark

[btrayfors]

Mark,

I think you're reading the manual incorrectly. The 8 hours is the upper limit, i.e., the maximum time it will stay in absorption mode. It doesn't automatically go to 8 hours.

Also, your voltage should never drop below 12.8VDC or so with the charger connected and turned on.....unless you have a HUGE load more than the charger can handle or bad batteries.

Bill

[colemj]

Originally Posted by btrayfors

Mark,

I think you're reading the manual incorrectly. The 8 hours is the upper limit, i.e., the maximum time it will stay in absorption mode. It doesn't automatically go to 8 hours.

Also, your voltage should never drop below 12.8VDC or so with the charger connected and turned on.....unless you have a HUGE load more than the charger can handle or bad batteries.

Bill

I just posted the quote from the manual and our experience with the unit. 8 hours is what it does and if it is triggered out of float mode, it will do another 8 hours.

The batteries drop below 12.8V when the input AC power is lost for more than a couple of seconds or if there is a load on the batteries at the time.

Mark

[batkins61]

Actually, my initial concern is indeed dockside charging. Eventually, I will need to upgrade my alternator, but right now I need more than my Sentry 20A can provide after a day/weekend out.

[s/v Jedi]

Originally Posted by batkins61

Actually, my initial concern is indeed dockside charging. Eventually, I will need to upgrade my alternator, but right now I need more than my Sentry 20A can provide after a day/weekend out.

In that case you got some leads: Victron, Sterling, Outback. I think the whole CF community agrees with these brands.

cheers,
Nick.

[Ex-Calif]

Originally Posted by s/v Jedi

In that case you got some leads: Victron, Sterling, Outback. I think the whole CF community agrees with these brands.

cheers,
Nick.

I've learned more about charging and charge systems in the last two months than I have in the last 2 years. A lot has changed in both technology and philosophy.

I hadn't needed to think about advanced charge systems until recently. My simple alternator and iso switch was all that I needed until recently. My brothers new boat has 15 & 30 amp 240 shore power, a 2kva genset, a 24vdc alternator, 24v engine & windlass and 12v house. It has wind and solar and while the basic system is not bad, bits and pieces have been cobbed together over 15 years. Documentation is weak and just figuring out how stuff is wired together is a bit of a sleuthing exercise.

The great thing about CF is when you bear down on a topic there are some head and shoulders above the rest folks here on any topic you like.

[CharlieJ]

We have had several discussions on CF regarding temperature compensated charging sources, esp. for AGM and TPPL AGM batteries. I am a believer in including temperature compensation, others are not.

With a bit of time to kill today, I looked at the technical documents for Deka AGMs, Rolls-Surrette FLAs, Trojan FLAs and Mastervolt TPPL AGMs. In all cases, temperature compensation for charging sources was either recommended or required.

Here is the information that I found, taken directly from the tech docs on the websites:

Reqt for using temperature compensated charging sources.pdf

I hope this helps bring some clarity to this oft discussed subject.

Charlie

[btrayfors]

Thanks for that, Charlie, and Happy New Year!

I fear I may be one of those who you have characterized as a non-believer, so would like to make my thoughts crystal clear.

1. I am NOT anti-temp compensation. I think that temperature-compensated charging (i.e., adjusting charging voltage to the ambient temperature of the batteries by means of a remote temperature sensor) does indeed make sense for many installations, particularly those where the batteries may be exposed to large temperature fluctuations;

2. I am also NOT anti-temp sensing of the batteries for safety purposes, i.e., charging current or voltage limitation when the battery temperature is sensed to exceed a set trigger point (e.g., the Balmar MC-612 and MC-614 regulators which do this when fitted with a temp sensor, cutting the amperage in half).

3. I'm just not convinced that temp sensors are: (a) always necessary; or (b) always accurate. In situations where the ambient temp of the batteries doesn't vary a lot, it may be OK to go with a non-temp compensated charger like the Iotas. After all, there are THOUSANDS of such installations around the world and very few if any reported problems.

And, what about the MILLIONS of batteries in automobiles, trucks, and busses? Their batteries are often exposed to huge temp variations and almost none are charged by temp-compensated chargers. Also, there have been lots of problems reported with the accuracy of temp sensors; this can result in undercharging if the sensor reads too high, and a dangerous overcharging situation when the temp sensor reads too low.

In my own experience with the non-temp sensing Iotas over seven years on a boat and at home -- spanning 10 different T-105 flooded golf-cart batteries in three banks -- the lack of temp compensation has not been a problem at all. These batteries live in spaces where the temp never goes below about 50F or above 90F, and are on charge 24/7 at dockside.

While temp compensation on the Iotas would be good, I'd sooner see the automatic repeat absorption feature (which they erroneously term, "equalization" cycle) of the IQ4 be more frequent than once a week, like every day or two. Also, a real equalization cycle with voltages on the order of 15.5-16.5VDC would be a plus.

Meanwhile, the Sterling UltraPlus line and the nearly identical ProMariner ProCharge Ultra line appear to be GREAT chargers, having just about all the features you could wish for. Just about....except for really strong output. They only have 60A maximum models, whereas lots of applications on medium- to large-size cruising boats these days could profitably use a LOT more. After all, the Victron MultiPlus inverters and others often have 120 amp smart chargers built in, and many folks (like me) wish for even more.

With just six T-105s in my house bank (675AH capacity), I could profitably use 150A or more charging capability when at anchor, and I have the generating capacity to run a charger that big. If I had AGMs instead of flooded batteries, I'd be crying for 300A charging capability or more.

FWIW,

Bill

[Paul Elliott]

Bill, it looks like you are referring to flooded batteries when you discuss the low importance of temperature sensing. What about with AGMs? And would temperature-sensing become more important if the charger were able to deliver more current?

I've got 4 8-D AGMs for the house bank on VALIS, a Freedom Marine (Xantrex) 2000W inverter / 100A charger, a Link 2000-R controller, and a temperature probe for the Freedom charger. Unfortunately, the probe is really just monitoring ambient temp, not the battery temp. This is old stuff, but it's been working well for the past ten years.

[Rick]

Hitachi alternators are excellent when altered to use an external 3-step regulator. Otherwise, they are only good to recharge the start battery. As far as a deeply-discharged battery is concerned the stock internal regulator makes the battery "feel" like it is trying to drink beer through a coctail straw.

I have not tried to alter the latest model Hitachi units and understand that they may be more difficult to externally regulate....any others have info on this? The earlier units are very easy to alter, especially since Yanmar gives schematic info on them. Externally regulated, the 55A units will deliver 67A and the 80A units will deliver over 95A cold. They hold up well considering their size....good air cooling with their relatively open frame design.

Having an externally regulated alternator is paramount for any cruising boat in order to recover deep discharge batteries and/or using heavy dc loads when underway or when raising anchor with an electric windass.

[btrayfors]

Originally Posted by Paul Elliott

Bill, it looks like you are referring to flooded batteries when you discuss the low importance of temperature sensing. What about with AGMs? And would temperature-sensing become more important if the charger were able to deliver more current?

I've got 4 8-D AGMs for the house bank on VALIS, a Freedom Marine (Xantrex) 2000W inverter / 100A charger, a Link 2000-R controller, and a temperature probe for the Freedom charger. Unfortunately, the probe is really just monitoring ambient temp, not the battery temp. This is old stuff, but it's been working well for the past ten years.

Paul,

I'd say you are probably OK with what you've got. Battery temperature changes very slowly, usually. And, with 700-800AH total capacity in the 8-D AGMs, your 100A charger isn't going to be at all stressful to them. Unless, of course, the voltage is allowed to get too high for very long and/or there is a fault in the batteries themselves.

Bill