National Luna Split-Charge System Charging Issues?

[remote camper]

dstock

It looks like you have the backing of the NL folks and your measurement didn't produce anything alarming for parasitics. I'm going to say that the NL system is not contributing to the problem for the time being. If it does turn out to be a problem, they'll stand behind you.

I recommend you focus on the getting the batteries replaced next and hope that goes well. An imperative here is that for maximum life, the Platinums must live above 12.84 volts. You don't have to keep them on a charger full time. But it is important that you apply a suitable charger (temperature compensated at the battery, min 14.7 absorption, 13.6 float) if voltage falls below that when the vehicle is not in use. For best results, resting voltages should be taken with no load and no recent charge on the battery. Six hours is often recommended as a resting time, 2 hours might give you something to work with. Since the aux is likely cycled more deeply, I certainly recommend the Ultimizer.

One difference outside the NL system between yours and mine is that mine are always in parallel. When I run accessories, a fridge or whatever they run off of BOTH batteries at the same time. As a result both batteries are (minimally) drained at the same time and recharged at the same time. One battery is never seen as a load to the other. The other difference is that charger I mentioned in the earlier thread. Ever since I've had the Platinums, when the vehicle is not in use for a few days, those batteries are floating at 13.6 volts. I can remove the charger and voltage will remain at 12.9 for some time. When it drops to 12.7, I put the charger back on it. I'm even floating both while in parallel. While the charger is not approved by Odyssey, it's voltage profile is correct, it's temperature compensated (at the battery) and according my discussions with Odyssey engineering, it should be OK for my application.

With your aux setup if I understand it correctly, the aux battery is isolated from the starting battery with the key off. This focuses the loads you apply solely to the aux. When the vehicle is started, NL system reconnects the aux battery and the alternator attempts to charge both batteries simultaneously. The starting battery is likely in the circuit with the engine running, too and wants to help. Whenever the aux battery isn't at parity with the starting battery, it will be chronic load on the charging system and the starting battery when they are hooked up together. The lower the discharge on the aux, the bigger the load it is on the system. That's what I suspect anyway. (As a side note, it would be interesting to see the difference in voltage measurements for the aux and starting batteries after running the fridge and any other usual accessories on your outings before you pack up and leave. It probably won't be practical to obtain resting voltages. My bet is that there could be a significant difference between the 2. That's the difference the alternator (and possibly the starting battery) tries to make up when you leave.)

The other condition here is that a normal vehicle's alternator system is not designed the recharge these AGMs they way they should be. I believe you are going to have to look at the Ultimizer to keep these batteries in tip-top shape. I have been getting away with a much lesser charger, but that's been because I don't deep cycle them. You might also be able to get an alternator/regulator with a profile that more closely matches the Platinum/Odyssey needs and is better suited to the demands of a dual battery setup.

I believe lack of an adequate charging system for the Platinums to ensure they stay above 12.84 volts, combined with the discharge of the aux battery to be a deadly combination here for the long term.

I expect some blowback here on my theory of what's contributing to the demise of these batteries. Even if I'm wrong about the aux/starting scenario, I am not wrong about keeping those batteries above 12.84 volts even if others are happy with the 12.4 or so volts they are experiencing. We buy the Platinums for a reason. For the most part, it is expected they will be used in automotive systems and cycled. We need a charger that can meet their unique charging needs and supplement the inadequacies of a vehicle charging system.

It will likely be 2 or more years before you see the difference.

 

[Equipt]

Thank you Remote Camper for your comments. They do shed some light on the characteristics of the Platinum batteries and also where there might be some contention between the batteries and the NL system.

The NL system connects the batteries when the voltage available from the main battery is above 13.1V. This is traditionally when the vehicle starts up, but it doesn't necessarily have to be. And the system isolates the paralleled batteries when the combined voltage dips below 12.7V. Traditionally when the vehicle is turned off, but they can stay connected with the vehicle off as long as the combined voltage stays high.

In light of the voltages you mention, it would appear that the batteries would stay connected most of the time. 12.84V is above the disconnect level for the NL system. It is unfortunately not a variable that can be adjusted. So consequently the solenoid is energized to keep the batteries in parallel, and as noted earlier in the thread it creates a draw to the batteries to do so. Over time, the draw would lower the batteries until hitting that 12.7V threshold, opening the solenoid contact and removing the draw. So that may be why dstock has seen his battery level at that 12.7V level for quite some time.

Cheers,

 

[remote camper]

Thank you Remote Camper for your comments. They do shed some light on the characteristics of the Platinum batteries and also where there might be some contention between the batteries and the NL system.

The NL system connects the batteries when the voltage available from the main battery is above 13.1V. This is traditionally when the vehicle starts up, but it doesn't necessarily have to be. And the system isolates the paralleled batteries when the combined voltage dips below 12.7V. Traditionally when the vehicle is turned off, but they can stay connected with the vehicle off as long as the combined voltage stays high.

In light of the voltages you mention, it would appear that the batteries would stay connected most of the time. 12.84V is above the disconnect level for the NL system. It is unfortunately not a variable that can be adjusted. So consequently the solenoid is energized to keep the batteries in parallel, and as noted earlier in the thread it creates a draw to the batteries to do so. Over time, the draw would lower the batteries until hitting that 12.7V threshold, opening the solenoid contact and removing the draw. So that may be why dstock has seen his battery level at that 12.7V level for quite some time.

Cheers,

Yes and while the thought ocurred to me, it didn't stay with me as I wrote that piece. The NL system disconnects when the battery voltage drops below 12.7. That's OK for a flooded battery where a near full charge is at 12.65 or so and is OK for that type of battery. It's too low for the Platinum/Odyssey long term, although voltage might come back up to 12.84 on a newer battery after the disconnect occurs. The issue is just aggravated because of the alternator not being able to fully recharge the Platinum, so it ends up living in the inadequate zone.

It would seem that for the time being, if dstock were to connect the proper charger after the disconnect occurs, that might be the way to go don't you think? Does the solenoid reconnect the 2 batteries in the Key Off position if voltage goes back up? I don't suppose that would be an issue if it did with an Ultimizer as the charger. My charger wouldn't work though. While the voltages are correct it will likely detect the solenoid load and show an error LED when trying to keep both batteries floating at the same time.

 

[dstock]

Thanks for your reply and kind words. We try our best to make things right. Things happen. It's how you handle them that matters.

The National Luna Dual Battery System is a very solid product. Equipt and National Luna will both stand behind this system, so if anyone is having an issue with their system please contact us directly and we will help you find a solution. Whether it comes out to be something on our end, an installation concern or a use issue. We're here to help, and get you back up and running. The title of the your thread had me quite concerned. The concept of automating the connection and isolation of 2 batteries in a vehicle is pretty straight forward, but can get really complex under the surface. Charging rates, discharge rates, connection and isolation values, draws on batteries, alternator output fluctuations on connection, new electronically managed alternator output, different vehicle manufacturers, battery capacity and design, different batteries, climate, use, and the list goes on. The National Luna system does a good job at managing all this, and is the messenger for the system too. All too often the finger gets pointed at the messenger. I am just here to have the messenger's back.

As most know, I am not on this forum as much as I should be. Often there are just too many balls in the air to see everything. I do remember a couple guys that were at the Overland Expo in 2013. They were driving a couple Disco IIs and one was having a real issue with his vehicle and the NL system, and their deduction was that high heat was making the NL system fail. I understand he wrote a thread on this as well. Anyway, it just so happened that the owner of National Luna had come over from South Africa to visit the show and these two gentlemen came through our booth with some questions. We all went out to the north 40 to diagnose the issue on the vehicle. Heat turned out to be a factor, but the NL battery management was working perfectly. The issue was that the there were a lot of demands on the system at any given time. Radios, lights, fridge, interior charging, stereo, etc. But the biggest culprit was the climate system constantly bumping on and turning off to keep the interior cool. The compressor kicking on is a significant hit, and with all the other systems taking their bite as well, the charging system was fighting to offset the draw and would at times drop below the 12.7V cutoff while the vehicle was running. At least that is the gist of what we found. We tested the NL system to connect and disconnect correctly, and it was working fine. I am not sure those findings were forwarded to the thread or not. A long story here for a short point. It is often the case that when the NL battery charging system is acting strangely, it is trying it's best to tell you something else with the system is not functioning properly.

I will try to reach out to KellyM and see what we can do for him. Thanks for the heads up. Does KellyM drive a Jeep as well? Forgive my ignorance here. I'm a Toyota guy. But I understand that the Jeeps have come out with an electronic charging system in their vehicle. Is that correct? The solenoid concerns seem to be originating on Jeeps specifically, and I am interested to know more about that system.

I had another thought on your reduction of resting voltage. Seasonal temperature change can effect the voltage capacity of a battery, especially as it ages. Are you in a climate that is going down in temperature as winter sets in? I am back in Utah, and know first hand that the winter cold can have an effect.

I use the Sears Diehard Platinum batteries, and often suggest them to customers. I think they are a great value. I put one into use in my 4Runner about 1.5 years ago when I put my NL system in. It's paired to the Panasonic battery new with the vehicle. I have a resting voltage of around 12.4V and honestly haven't thought much about it. It was higher when I bought it new, and expect it to decrease as the battery ages. I use the secondary battery quite a bit too, but charge it up well on the long distances I travel. I guess what I am saying is that I personally don't think 12.4V resting is out of range for a couple year old battery. You could drop by Sears and have them stress test them. Their warranty is one of the main reasons I use this battery. They could tell you if the batteries are fine or not, and may be able to test for parasitic draw. Great piece of mind.

Thanks,

Thanks Paul, I'm going to go down the path with Sears and see what I can learn, and I will update as I go.

KellyM has a either a 2012 or 2013 JK and I'm pretty sure his system was installed by AdventureTrailers.

I sorry I don't know more about the electronics in the JK but I am also beginning to wonder if it is specific to the vehicle. Granted, I have never seen the voltage drop below the 12.7 cutoff while running. I have an Aeroforce gauge which operates off the OBD 2 port and I keep the voltage display as one of the permanent settings so I always have an eye on what the alternator is putting out. Granted, this is what the computer is saying the voltage is, maybe that's not what is actually occurring at the battery? I have not seen it drop below 13.8 even in traffic, A/C running full blast etc. When the previous high heat issue would occur with the solenoid cutting out, the DBC would still show the main battery as fully charging. It was a bizarre issue for sure and as much as I wouldn't wish problems on anyone, I'm relieved a bit to see KellyM is having the same issue.

I appreciate the support, and will update once I have more info on the battery front.

 

[dstock]

The 2013 JK keeps power to the radio, windows and other things after the engine has been turned off until one of the doors is opened. So typically you will hear the solenoid disengage within a minute or two if you are still sitting in the vehicle. Currently, it disengages almost immediately after turning off the engine. I doubt I ever had the full 12.8 resting voltage but it would for sure be at the 12.7 reading on the DBC even after overnight on the main and the aux if the fridge was not connected.

Is the solenoid re-connecting itself during the night? I tend to not think so but I will give it a couple checks tonight at different times to see if there is any fluctuations in charge level.

 

[Equipt]

Yes and while the thought ocurred to me, it didn't stay with me as I wrote that piece. The NL system disconnects when the battery voltage drops below 12.7. That's OK for a flooded battery where a near full charge is at 12.65 or so and is OK for that type of battery. It's too low for the Platinum/Odyssey long term, although voltage might come back up to 12.84 on a newer battery after the disconnect occurs. The issue is just aggravated because of the alternator not being able to fully recharge the Platinum, so it ends up living in the inadequate zone.

It would seem that for the time being, if dstock were to connect the proper charger after the disconnect occurs, that might be the way to go don't you think? Does the solenoid reconnect the 2 batteries in the Key Off position if voltage goes back up? I don't suppose that would be an issue if it did with an Ultimizer as the charger. My charger wouldn't work though. While the voltages are correct it will likely detect the solenoid load and show an error LED when trying to keep both batteries floating at the same time.

The NL system bases it's actions on voltage level only, not by the switch on the vehicle. And the connection of the two is based solely on the main battery voltage increase, not from the auxiliary battery. So an increase to voltage above 13.1V to the aux. battery would not activate the IS to connect the two together. Say, in the instance of connecting a solar panel to the auxiliary. It would be possible for either battery to come back up to the 12.84 level after the IS opens the contact, and since it is under the 13.1V reconnecting voltage that the IS is looking for, they could theoretically do that. dstock had noted that his resting batteries were in that 12.8-12.7V range, so apparently that is a possible outcome.

One possible option for charging is to connect the charger only to the main battery, and run it at a voltage above 13.1V. That would call the IS to action, connecting the two batteries and would then charge them in parallel. As you mentioned, if the charger is smart enough to know there is that connection it might be an issue. It would be worth a try. Or you could charge the aux. battery by itself to any voltage level you choose, since it won't back charge through the IS.

Just as a bit of extra information on the NL system. When the IS recognizes a voltage above 13.1V available from the main battery, it starts a timer. The "Timer Active" light on the IS starts flashing, and it keeps the batteries isolated for the first 5 minutes of the increased voltage in an effort to recoup the charge to the main battery from the discharge of starting the vehicle. After about 5 minutes, the IS closes the solenoid contact connecting the batteries in parallel and the "Timer Active" light goes to solid green. Behind the scenes, the IS then starts a separate 3 minute timer where it ignores the input voltage to allow the vehicles charging system fluctuate for a bit to compensate for the added charging load. In the 3 minute window, I believe manual override of the battery connection (the right button on the DBC) is suspended as well. The point here is to allow the charging system to go lower than the 12.7V if it needs to in that 3 minute window without opening the solenoid contact due to low voltage readings. It smooths out the fluctuations possible from the vehicles charging system.

Cheers,

 

[Equipt]

The 2013 JK keeps power to the radio, windows and other things after the engine has been turned off until one of the doors is opened. So typically you will hear the solenoid disengage within a minute or two if you are still sitting in the vehicle. Currently, it disengages almost immediately after turning off the engine. I doubt I ever had the full 12.8 resting voltage but it would for sure be at the 12.7 reading on the DBC even after overnight on the main and the aux if the fridge was not connected.

Is the solenoid re-connecting itself during the night? I tend to not think so but I will give it a couple checks tonight at different times to see if there is any fluctuations in charge level.

My 4Runner acts the same way. All the toys are available until I open a door. That is usually right at the time I am trying to roll up a window, stopping it half way up. My solenoid usually waits to open until something makes a draw to lower it's voltage, like opening the door.

I don't believe the solenoid is re-connecting during the night. The only way it could is if the main battery voltage raised and stayed above 13.1V all on it's own. Then it would have to stay there for 5 minutes, connecting them together. But it would isolate them again when the batteries dipped below 12.7V. So dropping the voltage to 12.4V wouldn't be possible.

Thanks,

 

[Equipt]

Thanks Paul, I'm going to go down the path with Sears and see what I can learn, and I will update as I go.

KellyM has a either a 2012 or 2013 JK and I'm pretty sure his system was installed by AdventureTrailers.

I sorry I don't know more about the electronics in the JK but I am also beginning to wonder if it is specific to the vehicle. Granted, I have never seen the voltage drop below the 12.7 cutoff while running. I have an Aeroforce gauge which operates off the OBD 2 port and I keep the voltage display as one of the permanent settings so I always have an eye on what the alternator is putting out. Granted, this is what the computer is saying the voltage is, maybe that's not what is actually occurring at the battery? I have not seen it drop below 13.8 even in traffic, A/C running full blast etc. When the previous high heat issue would occur with the solenoid cutting out, the DBC would still show the main battery as fully charging. It was a bizarre issue for sure and as much as I wouldn't wish problems on anyone, I'm relieved a bit to see KellyM is having the same issue.

I appreciate the support, and will update once I have more info on the battery front.

Thanks for the comments. I will talk to guys at the AT shop to see what their installation procedure is, just to see if any external activities may be triggering this. I could be way off base here, but what I have heard is that the newer JKs have an electronically managed charging system that is not like the traditional alternator system. I am curious about this system, wondering if for some reason that there might be a millisecond of voltage reduction that would trigger the IS to drop out. Something that would not be detected by us looking at the DBC or your Aeroforce monitor. It's just a theory right now, but I do think it is odd that the solenoid issues are only on the JKs.

Thanks,

 

[dstock]

I don't believe the solenoid is re-connecting during the night. The only way it could is if the main battery voltage raised and stayed above 13.1V all on it's own. Then it would have to stay there for 5 minutes, connecting them together. But it would isolate them again when the batteries dipped below 12.7V. So dropping the voltage to 12.4V wouldn't be possible.

Thanks,

Agreed, I saw your post which reminded me about the 13.1v re-connect and I am sure that's not happening.

I'm debating whether to pull the NL system out before I head over to Sears, or to just remove one battery at a time and take them there, as my guess is they are going to want to charge them and keep them overnight. I do not want Sears, (or anyone else for that matter) monkeying around under my hood.

Any issues with the NL if I leave it all connected and they run their stress test? What do you suggest?

Thanks.
-Dave

 

[dstock]

Thanks for the comments. I will talk to guys at the AT shop to see what their installation procedure is, just to see if any external activities may be triggering this. I could be way off base here, but what I have heard is that the newer JKs have an electronically managed charging system that is not like the traditional alternator system. I am curious about this system, wondering if for some reason that there might be a millisecond of voltage reduction that would trigger the IS to drop out. Something that would not be detected by us looking at the DBC or your Aeroforce monitor. It's just a theory right now, but I do think it is odd that the solenoid issues are only on the JKs.

Thanks,

It's a good theory, because if it happened repeatedly, that would also continuously reset the 3 minute timer which suspends manual connection of the batteries at the DBC which would explain why KellyM and I were not able to manually reconnect them. Certainly worth looking into, I may setup a separate voltage meter wired direct to the battery as an experiment.

 

[remote camper]

Guys-

I don't want to be a pain. I think one point that is going missing here is that 14.7 volts is needed to fully charge the battery before charge voltage can be lowered to 13.6 volts. Conventional thinking is that as long as there is a charge of 13.4-14.4 volts going to the Platinum it is fully charging. It's not, not with the Platinum and other AGMs that require similar profiles. As a battery charges, its resistance to charge (taking on amps) increases. For conventional flooded batteries that reistance is overcome and full charge is reached at ~14.4 volts. That's within the range of many if not most alternators as long as their output is not sucked up by other high amp accessories. Actually, you have to put MORE amps back in than you take out...on the order of 10% to as much as 20% more to overcome charging inefficiencies.

Odyssey has found the Platinum needs 14.7 volts to overcome that resistance to complete charging until its charging needs drops to ~ <100 milliamps. At that point the voltage can and should be dropped to 13.6 volts. Since the typical automotive system doesn't do that, the battery is slowly starved (and actually sulfates). If the Platinum never recharges completely, it starts to deteriorate, if ever so slowly. Coupled with the disconnect cutoff drawing the battery down to 12.7 adds to the issue. That's why something like the Ultimizer is needed. Even if there are other issues, these two are going to persist long after the others are corrected. To be sure, don't take my word for it. Run this by the right people...the Odyssey engineering dept. It's free. I don't care if I'm wrong. For you guys it just needs to be right, whatever the answer turns out to be.

I've said enough now and am going to observe for a while.

 

[dstock]

Guys-

I don't want to be a pain. I think one point that is going missing here is that 14.7 volts is needed to fully charge the battery before charge voltage can be lowered to 13.6 volts. Conventional thinking is that as long as there is a charge of 13.4-14.4 volts going to the Platinum it is fully charging. It's not, not with the Platinum and other AGMs that require similar profiles. As a battery charges, its resistance to charge (taking on amps) increases. For conventional flooded batteries that reistance is overcome and full charge is reached at ~14.4 volts. That's within the range of many if not most alternators as long as their output is not sucked up by other high amp accessories. Actually, you have to put MORE amps back in than you take out...on the order of 10% to as much as 20% more to overcome charging inefficiencies.

Odyssey has found the Platinum needs 14.7 volts to overcome that resistance to complete charging until its charging needs drops to ~ <100 milliamps. At that point the voltage can and should be dropped to 13.6 volts. Since the typical automotive system doesn't do that, the battery is slowly starved (and actually sulfates). If the Platinum never recharges completely, it starts to deteriorate, if ever so slowly. Coupled with the disconnect cutoff drawing the battery down to 12.7 adds to the issue. That's why something like the Ultimizer is needed. Even if there are other issues, these two are going to persist long after the others are corrected. To be sure, don't take my word for it. Run this by the right people...the Odyssey engineering dept. It's free. I don't care if I'm wrong. For you guys it just needs to be right, whatever the answer turns out to be.

I've said enough now and am going to observe for a while.

Agreed, there is a long term component to maintaining these Odyssey/Diehard Platinum batteries and if I continue to run them, I will invest in an Ultimizer to try to avoid this in the future.

 

[remote camper]

Agreed, there is a long term component to maintaining these Odyssey/Diehard Platinum batteries and if I continue to run them, I will invest in an Ultimizer to try to avoid this in the future.

If a (single bank) Ultimizer is connected to the main battery at 12.7 volts, it will likely start in the absorption stage at 14.7 v. It might start in the bulk stage, but I just don't know. If it does, it will eventually proceed to absorption and voltage will exceed the 13.1v to reconnect both batteries and start charging both. A single bank Ultimizer wasn't really designed to charge 2 batteries at once that are deeply discharged, but it might be ok from 12.7 volts up. I recommend you take that up with Odyssey before you buy it.

The Ultimizer will sense an addtional load (a higher current demand caused by the solenoid), but I don't know how it will handle that condition. That should be taken up with Odyssey, too.

My guess is that once the Ulitmizer is connected to the main battery, the voltage increase will reconnect the batteries and try to float both at 13.6 volts and keep them there (with the solenoid energized). But since the solenoid draws a current (780ma?) that is above the charger's ~100 ma cutoff for float and with both batteries in the circuit, it will want to keep voltage at 14.7, which you really don't want, either. At this point, I think Odyssey has the answers you need.

 

[dwh]

I don't want to be a pain. I think one point that is going missing here is that 14.7 volts is needed to fully charge the battery before charge voltage can be lowered to 13.6 volts. Conventional thinking is that as long as there is a charge of 13.4-14.4 volts going to the Platinum it is fully charging. It's not, not with the Platinum and other AGMs that require similar profiles.

If that's what the Odyssey engineers told you, then you should call them back and tell them they need to fix their Owner's Manual.

The manual states on Page 6:

"The deep cycle charging voltage must be within 14.1V minimum to 14.7V maximum.

http://www.odysseybattery.com/documents/US-ODY-OM-010_0412.pdf


So according to that manual, 14.7 is not the *required* voltatge - it's the *maximum* voltage.


At least on Odyssey branded batteries... I'm willing to entertain the idea that Diehard branded Odyssey batteries are somehow magically different. Expect me to resist that idea vigorously.

As a battery charges, its resistance to charge (taking on amps) increases. For conventional flooded batteries that reistance is overcome and full charge is reached at ~14.4 volts.

[snip]

Odyssey has found the Platinum needs 14.7 volts to overcome that resistance to complete charging until its charging needs drops to ~ <100 milliamps.

There a couple of problems with this...

For one, there really is no different between flooded and AGM in terms of charging voltages (there IS a difference for Gel type, which are more sensitive to over-voltage and have lower *maximum* limits).

For example, for that ol' reliable flooded battery - the Trojan T-105, the Trojan manual recommends bulk to 14.8v, and absorb at anywhere n the range between 14.1v and 14.7v.

Table 4, Page 13:

http://www.trojanbattery.com/pdf/TRJN0109_UsersGuide.pdf


The second problem I see, is that while it is true that resistance increases as voltage rises toward 100% charged - AGM type batteries are generally known for having a *lower* internal resistance than flooded type. Thus logically, it would take *less* maximum voltage to get an AGM to 100% than it would for flooded.








[NOTE: For the record - I am *not* "picking pepper out of fly crap". I don't actually do that. At this moment, looking at the home page of the forum, I see this:

"There are currently 992 users online. 262 members and 730 guests"

How many of those people do we normally see posting? 100? The rest are lurkers. That's not a problem, but it's good to be aware that they are there. Most of them are still trying to figure out the basics of how all this electo-stuff works. I keep that in mind, and so when posting on electrical threads I tend to A) generalize, B) simplify and C) clarify.

I only jump in and correct people, when I see something that can give a novice "the wrong idea", or when there is some technical data presented which is factually wrong. But even then I usually won't say anything unless it's an important point. For instance, the other day I saw a post where a guy (who should have known better and probably does) stated that solar panels are tested in the lab at 45 degrees temperature. That's dead wrong, but I didn't say anything. Why? Because even though the number was technically wrong - the *idea* was right. It's good for the novices to realize that solar panels' output is temperature dependent. Later, when they learn more, they can get the details right.


Judging by the PMs I get asking electrical questions (which for those watching, does not bother me at all - glad to help), which run the gamut from ************** beginner questions to highly technical questions from power users who need just a bit of advice - my method works, so I'll keep doing it the way I do.


But please, don't feel that I'm picking on you personally - I'm not. I almost never do that except in self-defense. But when under attack, expect me to bite. ]

 

[dstock]

If a (single bank) Ultimizer is connected to the main battery at 12.7 volts, it will likely start in the absorption stage at 14.7 v. It might start in the bulk stage, but I just don't know. If it does, it will eventually proceed to absorption and voltage will exceed the 13.1v to reconnect both batteries and start charging both. A single bank Ultimizer wasn't really designed to charge 2 batteries at once that are deeply discharged, but it might be ok from 12.7 volts up. I recommend you take that up with Odyssey before you buy it.

The Ultimizer will sense an addtional load (a higher current demand caused by the solenoid), but I don't know how it will handle that condition. That should be taken up with Odyssey, too.

My guess is that once the Ulitmizer is connected to the main battery, the voltage increase will reconnect the batteries and try to float both at 13.6 volts and keep them there (with the solenoid energized). But since the solenoid draws a current (780ma?) that is above the charger's ~100 ma cutoff for float and with both batteries in the circuit, it will want to keep voltage at 14.7, which you really don't want, either. At this point, I think Odyssey has the answers you need.

I will speak with Odyssey before I purchase, my plan was to charge the batteries separately at some regular interval to help maintain their health. Again this is my daily driver, it's not going to get plugged in every night, nor does it ever sit for more than a day.