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Old 08-11-2015, 06:18 PM   #61
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Thanks for doing this. Very interesting.

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Shutoff charger and unplugged
Hmm. I was picturing you disconnecting the battery BEFORE shutting off the charger (although i could understand you being squeamish about that). Although I suspect that it won't matter, this IS a loophole in your experiment: Depending on the impedance of the charger, it is conceivable that you lost the surface charge as soon as you shut off the charger. Dunno...
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Old 08-11-2015, 06:23 PM   #62
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I have always been kind of confused by the multiple charger thing. Seems too good to be true that one could connect two or (in this case) three chargers all together and have the right thing happen. I guess the right thing to do is to carefully tweak the thresholds of all the chargers to try to coax the right behavior out of the system.
We have had a lot of discussions about all the interactions and how unpredictable they are, and it can be very confusing and hazardous to your batteries

The part that is the oddest to me is that it should be really easy to not have the conflicts and have the 3 charging sources all work correctly at the same time or individually.

Perhaps I am very naive or missing something obvious (both very possible with me) but as I see it, all you have to do to have everything play well together and take care of your batteries will be to have three things in all the charge sources.

1. The various charge parameter voltages set the same.

2. They all have to do a full charge cycle whenever activated

3. All the sources do the transitions between stages based on a shunt to the batteries (only) so the don't see loads or any influence from the other sources.

For instance if the engine alternator is pounding away at 100 amps at absorption and the solar is on, they both are in absorption. The solar will not shut off because it is looking at amps to the batteries which is still high. It doesn't care that the amps are coming from the engine. If you shut off the engine the solar just carries on. The engine aternator wouldn't care either, as it would stay on until the amps to the battery were correct for full charge. In a perfect world, you could have shore power, solar, and the engine generator all running in absorption and when the batteries got to the return amps, all 3 would go to float, right at the correct time.

As Avanti says, you can tweak all the settings in non-shunt setups, but also as he says, it is unrealistic to think it will work right without interactions. The big thing is to get the loads out of all the equations, IMO.
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Old 08-14-2015, 03:04 PM   #63
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My alternator kit showed up from Nations yesterday.

DualAlternatorKit.jpg

Three day free delivery. Everything looks substantial. It came with the regulator pre-wired and with a tag documenting the default programming. Instructions a bit sketchy, but not too bad.

Installation looks easy except that (a) the OEM serpentine belt has to come off, and (b) an existing hole in the engine needs to be tapped. They did provide the tap, though.

Stay tuned...
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Old 08-19-2015, 07:39 PM   #64
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Working on my alternator installation, and I have a quick question.
Our house battery is way in the back of the Sprinter, so it is a long run from the alternator/regulator to the battery. My plan is to run a 3/0 cable from the 200amp alternator to the battery--roughly 20 feet--and tap it in the center for the feed to the coach distribution panel.

The question has to do with the regulator's "battery sense" input. The regulator will maintain its target voltages as seen at this input. Is it worth running a separate wire all the way back to the battery for this input, or will the voltage drop across the 3/0 cable be negligible? 3/0 should be pretty ample for this situation, but it is the voltage at the battery that we care about. I guess I could just wait and measure, but it would be easiest to pull this wire when I am doing the big one. Thoughts?
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Old 08-19-2015, 07:40 PM   #65
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P.S. -- Hope nobody minds my hijacking this thread. Let me know if I should start a new one.
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Old 08-19-2015, 07:56 PM   #66
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You will be able to calculate the voltage drop over the cable length off of the wire sizing programs and then see if you can stand that much reduction. It will be current dependent and the drop get to be less as the battery fills. I think you will find that using the sense wire at the battery will be by far the best, as then it will keep the voltage constant, and if the smart charge works right, that will be good for charging.

The big question will be how well the regulator does in getting the battery full without overcharging. The battery monitor should tell you if are there based on the amps to the battery.
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Old 08-19-2015, 08:48 PM   #67
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Yeah, well... According to my calculator, @200A and a bulk charge voltage of 14.38V, I would drop .49V (3.41%), yielding a voltage of 13.89.

Of course, my 4 AGMs are not going to accept anything close to 200A--I only got such a big alternator in anticipation of a future Li upgrade.

At a more reasonable 85A, I would lose .21V, or 1.46%, yielding 14.17V. Probably fine. OTOH, after going this far, I guess I should do it right...
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Old 08-19-2015, 08:55 PM   #68
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It will be very interesting to see what the AGMs will accept. 440ah? right?

Lifeline says theirs will take up to 5C if down and at full charge voltage, so that would be over 2000amps. You are looking at under .5C so I think you will get to 200 if the voltage is up. It won't stay there though as the alternator will heat up. I am looking at the same issue, so what happens with yours will be of extreme interest to me. You have much larger wire, however.

For reference, our 375ah of wet cells will accept about 100 amps when at 50%, and AGM are supposed to be much more accepting.
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Old 08-19-2015, 09:05 PM   #69
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440 is correct.

Yes, this is going to be interesting. It took me awhile to convince myself that a second alternator was worth it, but I have to say that I am looking forward to getting rid of all of the mysterious interactions with the Sprinter's opinions on things. This is especially true with my I4 engine which supposedly has new and even more intelligent energy management systems. Things should be a lot more transparent once I get this up and running.

So, you've actually seen your battery take 100A in real life? I'm surprised. That would be nice.
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Old 08-19-2015, 10:19 PM   #70
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The 100 amps was on 375ah of Trojan deep cycle wet cells at 50 SOC, and they were only seeing about 13.8 volts, so at full voltage of 14.6 and lower SOC it would be even more. AGMs are said to charge over twice as fast, so that is a lot of amps.

The 440ah of Lifeline AGM I have on the bench test will pin the 100 amp Magnum charger at about 110 amps when first connected and at 70% SOC. It goes down to about 98 amps as the charger heats up and stays there for enough time to get to about 80% full. When first plugged in, the voltage will drop to 13.7-13.8v when the charger capacity is maxed out, so the batteries will accept a whole lot more, it appears. Lifeline said that the 440ah GC2 batteries setup at 12v would easily accept 500amps if it was available at full voltage.

My bet is that you will easily pin the alternator capacity with your setup, if you are more than about 20% discharged. Be sure you have the temp compensation on.
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Old 08-19-2015, 11:05 PM   #71
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Wow. Looks like I was poorly calibrated with my expectations. This upgrade is going to be better than I though. Thanks for the feedback. I actually didn't buy the battery temperature sensor for the Balmar (I have the alternator one though). I made that decision before I decided to upgrade the wire to 3/0. Guess I'd better order one, huh?
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Old 08-19-2015, 11:20 PM   #72
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Wow. Looks like I was poorly calibrated with my expectations. This upgrade is going to be better than I though. Thanks for the feedback. I actually didn't buy the battery temperature sensor for the Balmar (I have the alternator one though). I made that decision before I decided to upgrade the wire to 3/0. Guess I'd better order one, huh?
I just looked at the Blue Sea circuit wizard, and your 3/0 should be good for over 200 amps even in conduit (heat limiting), so you are way safe. I don't know how hot the area your batteries will be is, but even if relatively cool, the high charge rate will warm them a bunch. In the nice cool garage ours went from 72 degrees to just over 80 degrees charging from 50% SOC. I think temp compensation is a necessity, especially since you could see long periods of float. Do you have temp comp on the solar and shore chargers?

Lifeline lists the GPL4CT (GC2) at recommended charge rate of 550 amps, so 4 of them would be at 1100amps. For discharges of 50% or more, they want a recharge rate of AT LEAST .2C or in the 440ah it would be 88 amps minimum. At lesser discharges the rate can be less, they claim.
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Old 08-20-2015, 03:42 AM   #73
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I'm also working an upgrade to four Lifeline GPL-4CT batteries. Those numbers of 1100 amps charging and minimum of 88 amps need to be but in context from the Lifeline web site and Technical Manual.

For max charging is says:
"The GPL-4CT is designed for charging amperages up to 550 amps or 250% of the rated Amp Hour Capacity due to low battery internal resistance."

That's not the recommended charge rate -- it is the maximum designed charge rate.

For minimum charging it says:
"For repetitive deep cycling applications (deeper than 50% DOD), chargers should have an output current of at least 0.2C (20 Amps for a 100Ah battery)."

Thus a charge rate of a least 0.2C is recommended for deeply discharged batteries.

After my research I've concluded that a second alternator is a must if you have lithium house batteries. Since I don't plan to ever upgrade my current van to lithium I'm not going to install a second alternator and will rely on my Sprinter's 220 Amp alternator.
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Old 08-20-2015, 01:14 PM   #74
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Yep, I should have said up to 550 amp, which is what I had mentioned when Lifeline when saying Lifeline allows up 5C on all the batteries. My point is that maximum charge rates are mute in our vans because they are all way above anything we can deliver, except for some single and wet cell stuff. All these big bank setups will pull pretty much whatever you can put out.

I think the second part is exactly what I said, and I mention it because it is probably much more important than being concerned with giving the batteries too much charge rate, which usually is impossible. Most folks count on getting to the 50% discharge, or more, so it will probably be a likely occurrence. The problem is that if you don't have the .2C charge capacity, the other option they list is a constant current charge at the end of the normal charge cycle, which no chargers I know of will do in their programming. Mainly I mentioned it because it points out that even 88 amps is considered a pretty low charge rate on 4 GPL-4CT batteries by Lifeline.

But, and this is the big one, IMO the .2C charge rate is not as big a deal as the daily charging control, and if you don't have the charging control right, the effects of the .2C will probably not be large, as the batteries will have shorter life anyway.

Unless your charging sources are taking the batteries to .5%C at absorption voltage and then stopping charging (to float), on a regular basis (doesn't need to be every cycle) you likely are shortening the life by some amount. There are a very limited number of charging source components that are capable of doing the return amp charging to a programmable amperage, so very, very, few B's are able to get the accurate fill on a regular basis.

We are also going to run off the engine alternator, which in our case is 250 amps, so it will be similar to Boxster. I really don't see any need for a separate setup, either, except for the issues of early belt failures (possible) and shorter alternator life. We both will probably see in the range of 200+ amps when the batteries get to 50% down, if the wiring is big enough, which is a big load on the alternator and belt.
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Old 08-20-2015, 03:24 PM   #75
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We are also going to run off the engine alternator, which in our case is 250 amps, so it will be similar to Boxster. I really don't see any need for a separate setup, either, except for the issues of early belt failures (possible) and shorter alternator life. We both will probably see in the range of 200+ amps when the batteries get to 50% down, if the wiring is big enough, which is a big load on the alternator and belt.
I was in the "what's the point?" camp concerning second alternators until I got some experience with my new Sprinter I4 engine. It is much slower at charging my coach batteries than my old T1N was, even though the alternator is bigger. The chassis battery has all kinds of strange-looking devices mounted directly to both terminals. I have no idea exactly what the are, but I am convinced that some pretty exotic energy management is going on within the Mercedes system. While I don't think that adding a big external load actually breaks anything, I think it exceeds the design assumptions to an extent that the system is unwilling to provide high currents even if the capacity is there. This is no doubt the future. I emphasize that this is mostly speculation on my part, but it fits my observations.

As I said, I am looking forward to no longer thinking about it.
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Old 08-20-2015, 03:30 PM   #76
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Great details booster - thanks! With my upgrade to 440 Ah of Lifeline AGMs I'm also upgrading the inverter/charger to a Magnum MS2000 which has just enough power to get the 0.2C charge needed for recovering routine deep discharges.
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Old 08-20-2015, 03:32 PM   #77
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I should have mentioned that our Chevy has internal regulator and the only connection to the PCM is a field voltage signal to modify idle, AFAIK.

I have read several places that the Sprinters have issues with any messing with the charging systems. Davydd may have even said ARV said the same thing. MB really does put the clamps on changes in the field with their systems.
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Old 08-20-2015, 03:43 PM   #78
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I should have mentioned that our Chevy has internal regulator and the only connection to the PCM is a field voltage signal to modify idle, AFAIK.

I have read several places that the Sprinters have issues with any messing with the charging systems. Davydd may have even said ARV said the same thing. MB really does put the clamps on changes in the field with their systems.
Agree - all the vehicle manufactures are tighning their alternator controls in the effort to seek better emissions and fuel economy. That's likely why the growth in dual alternators, along with the unique requirements of lithium batteries.

Hopefully my 2012 Sprinter V-6 alternator will handle the load. I also have 400 watts of solar on the roof which starts charging as soon as the sun rises.
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Old 08-20-2015, 03:50 PM   #79
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I have read several places that the Sprinters have issues with any messing with the charging systems. Davydd may have even said ARV said the same thing. MB really does put the clamps on changes in the field with their systems.
Many of those comments imply that it is actually DANGEROUS to connect to the Sprinter system. I have never seen evidence that this is true. (I don't think that is what ARV has said, btw). I think that those claims are overblown. What I AM saying is that on the latest models it is increasingly ineffectual. I suspect that this will not be limited to Sprinters going forward.
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Old 08-20-2015, 03:54 PM   #80
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Great details booster - thanks! With my upgrade to 440 Ah of Lifeline AGMs I'm also upgrading the inverter/charger to a Magnum MS2000 which has just enough power to get the 0.2C charge needed for recovering routine deep discharges.
We are using the same charger, with ARC50, and BMK. Have you read the threads on some of the weirdnesses that we have found in the charger programming and controls during our bench testing?
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