Opinions needed on charging upgrades

[booster]

Marko had a great topic on the his electrical upgrade a while back, so some of this may be similar, but somewhat different.

I have been messing around with our system (07 C190P Roadtrek) for while, comparing what the Trimetric says for state of charge vs the load on voltage method that has been put out by Handybob, and relayed here. It is interesting info, and incomplete at this time, but another issue came up as I was doing it.

We have 4 batteries total in our van. Two 6volt Trojan T145 (260AH), one 12volt Trojan SCS200 (115AH), and a marine starting battery, GP27 from Costco (85AH) for a starting battery. All are run off of the OEM Tripp-lite RV750 inverter/charger (45 amps). The starter is isolated during discharge, and may or may not be (selectable) during charging. What I found was that the specific gravity on the 6 volts came back less on each recharge cycle, while the 12 volt battery came all the way back each time. Odd part was that the 6 volt batteries were showing full voltage of 13.3 when right off the charger and 12.7 volts after the surface charge was removed, but the specific gravity was only at 1125. This was after only 5 cycles of testing. This is classic sulfation, stratification symptoms, so I equalized the 6 volts (3 times as it is a fairly short, timed, equalize on my charger), and they came back to 1265. After overnight on float were at 1275, and back to normal.

I don't know what is going on, because what I have always heard about mismatched batteries, is that the one that is getting charged sooner (in this case the 12v) would be the one with problems, not that the others would be low on charge, but up to voltage, so they kick out the charger to float.

Since separating the 6v from the 12v batteries would be pretty easy, I started to look at different chargers with multibank capabilities, but ones with totally isolated banks and charging are very rare, huge, and very spendy. The normal multibanks keep the batteries from feeding one another, but seem to charge as if they were connected, which is what I have now. Blue Sea does make a 3 bank charger that will monitor each bank separately (P12), and take each bank to "prefloat, reduced voltage" separately to not cook the first done batteries. That might do it, I have an e-mail off to them to ask about it. The charger also has a "user" programmable setting for the profile, so I also asked if that could be set at the 14.7/13.2 volt settings that Trojan is asking for. I think the conditions I used in my testing are exactly whey Trojan wants the batteries hit hard and charged quickly to reduce sulfation and stratification. The Blue Sea also has an equalization setting, so as long as I put in battery disconnects, we could equalize on the road, whenever we had shore power or generator, without having to disconnect any of the van wiring to prevent overvoltage damage. That combined with the 14.7 absorption voltage should help the situation.

I don't have good diagram drawn yet, but it would wire up something like this.

Bank 1 would be 6 volts and also to the 12v power relay for the van

Bank 2 would be for the 12v shore power battery and the starter battery 12v

There would be a new 12v power relay, like the existing one, between the two battery banks. It would be controlled by a SPST relay, 110 volt coil. The coil would be activated whenever AC power was going to the charger. The contacts would be 12v off of either battery and would open the connection between the banks when the charger had power, and close them when not charging. This would allow us to use all the batteries when discharging, if we want to.

Each bank would also have a manual disconnect switch that would let us disconnect the banks for equalizing, or to use the banks one at a time, so the mismatched batteries don't interact with each other. It might also need a manual switch on the new power relay control to make sure they are separate if we want to use just one bank.

That leave us to the point of not having an inverter, as it would go away with the Tripp-lite. I think we will do a 1000 watt Samlex pure sine wave inverter. The Tripp-lite has a transfer switch to run two outlets in the van on shore or inverter power automatically, so it will need a Xantrex inline transfer switch to make that part work. The space will be very tight, but I think it will all fit in the same area behind the right rear wheel well with a bit of modification to the bed supports.

Along the same lines of thought, I think I will put the old regulator back in the van alternator. I had changed it out to a lower voltage version shortly after we got the van, as it was running at 14.4/14.6 volts all the time and boiling out the coach battery water on long drives. The one in there now runs at about 13.8/13.9 volts. When I did the solar install, I rewired a disconnect switch on the separator, so it can be disconnected at any time, so now it is easy to shut off the alternator voltage to the coach, except when we need to charge the batteries. That way we can hit the batteries hard at 14.6 volts for short trips to get them fuller, faster, and also get a mini-equalize at the same time. Our daily drives are going to be much shorter now that we are retired, so it should work better for us, as long as we remember to shut them off if we are going to drive for many hours.

I think with the less than full charges we will get off solar, and the mismatched batteries, this is probably something we need to do if we want to keep decent battery capacity and life.

If anybody has any experience or thoughts on this, I would appreciate any input, as this all pretty new ground to me.

[markopolo]

Do you know what the charge profile looks like on your Tripp Lite - Bulk / Absorption / Float voltages? I'm just curious as I can't find any info.

Looks like you've confirmed that the Tripp-Lite is under charging your Trojan batteries. I saw a post where someone reported seeing their Tripp Lite only get to 14.3v. That is low for Trojans from the info you've previously posted.

I know I'm not helping much with your questions but your plan looks good to me.

A few comments:
A larger capacity inverter would allow you to run the microwave oven or maybe a coffee maker.
You might be able to power an additional circuit with the inverter transfer switch depending on how the coach is wired.
Is your Tripp Lite the 750 model? If so DIP switch A2 will disable the built-in charger allowing you to keep the Tripp Lite and just get a new multi-bank charger.

I have a manual, make-before-break, Bank 1, Bank 2, Both, Off, battery selector switch that gives me a lot of options. Maybe something like that would be useful.

I briefly looked at a few multi-bank chargers but got scared off by the high price / relatively low output specs I saw. It was a couple of years ago though.

Finding a charger that will do the 14.7v or (14.8v when I looked at Trojans site tonight) might not be easy.

[booster]

Originally Posted by markopolo

Do you know what the charge profile looks like on your Tripp Lite - Bulk / Absorption / Float voltages? I'm just curious as I can't find any info.

Looks like you've confirmed that the Tripp-Lite is under charging your Trojan batteries. I saw a post where someone reported seeing their Tripp Lite only get to 14.3v. That is low for Trojans from the info you've previously posted.

Our Tripp-lite runs at about 14.3/14.4v most of the time, 13.5v at float. When I looked up what the listed for equalization voltage, it said 14.2v (edit new source), which made absolutely no sense to me.

I know I'm not helping much with your questions but your plan looks good to me.

A few comments:
A larger capacity inverter would allow you to run the microwave oven or maybe a coffee maker.
We have discussed that one a lot. It appears we would need to go to the 1500 watt inverter to do it. Between the batteries and the van running the power would be easy, less so on just batteries, unless it was a very short time. It would make life a bit easier, compared to starting the genny for a quick warmup of something. We may still go a bit bigger, but it would also entail changing the wiring for the microwave to get it on the inverter circuit, which may or may not be easy. The microwave and the inverter outlets are close together in the kitchen, but I don't know how it would work out to tie them together, access wise.

You might be able to power an additional circuit with the inverter transfer switch depending on how the coach is wired.
Is your Tripp Lite the 750 model? If so DIP switch A2 will disable the built-in charger allowing you to keep the Tripp Lite and just get a new multi-bank charger.
It is a 750 model. I did consider keeping it in the original plan. I was going to use it to charge the 12v batteries, and buy a single output charger for the bigger 6 volt ones. Then I figured even the 12v batteries (per Trojan) would like the higher voltage, the equalization of the Tripp-lite is weird, and having a pure sine wave inverter would be nice, as most of what we use it for (rarely though as we have most stuff as 12v now) is electronics. It is amazing how all these projects grow in complexity the more you look at them

I have a manual, make-before-break, Bank 1, Bank 2, Both, Off, battery selector switch that gives me a lot of options. Maybe something like that would be useful.
I have been looking at all the various models of them. It is pretty cool that they have so many versions of them. I still haven't come up with a good way to isolate the van electronics, van separator, and the batteries one at a time, for equalizing, without removing a bunch of wires. I really don't like having removed, hot wires, hanging loose while equalizing, especially if we are traveling. I need to contact the manufacturers of the separator and the 12 van power relay, to see if they could handle the higher voltage of equalization. If so, my life gets much easier, and with many less switches to deal with.

I briefly looked at a few multi-bank chargers but got scared off by the high price / relatively low output specs I saw. It was a couple of years ago though.
I totally I found the same thing, and almost all of them are shared output, not totally independent, so you lose a lot of the benefit. The Blue Sea appears to be the first one to try to address the battery mismatch problems with the shared output power

Finding a charger that will do the 14.7v or (14.8v when I looked at Trojans site tonight) might not be easy.

The only ones that I have found that have the higher voltage and multiple outlets are from Sterling. They have many more voltage settings than the others do. At this point, I still don't know if the Blue Sea will allow the higher voltage for absorption and lower for float the Trojan recommends. They have a user programmable profile, but don't list the ranges. I have an e-mail into them asking about it, as I like their multi-bank setup

One interesting(?) thought I had about all this is that a lot of RVs use 6 volt GC2 batteries for coach batteries, many of them Trojans, and all would also have plain old 12 starting batteries. If they are on a separator, they would have similar mismatch issues, and could be boiling a lot of fumes into the engine compartment, if they have a normal wet cell, not the low gassing type the come in a lot of vehicles now. Roadtrek apparently had some issues in the Sprinters where they put coach batteries under the hood. They got some pretty severe corrosion issues (Yahoo board) when they used wet cells.

[booster]

I think I may have a workable method for this. The hardest part is keeping the batteries separated when needed, and combined when needed that way. Also need to isolate all the electronics from the equalizing voltage. Using manual disconnects at the batteries helps with isolating without a bunch of big panel mount switches to do it. The Blue Sea ACR is really nice, as it works like a separator when the engine is running to combine the batteries, but separates them when the charger is running, or they are discharging. I still need info from Blue Sea on the charge profile I could get (14.7/13.2).



If I have room, I think the 1500 watt inverter might as well be used, as I can worry about the other wiring to the microwave anytime. If I wanted to use the engine alternator to help, I would also need to add another wire to the Roadtrek one, and another parallel set of 80 amp breakers in line.

After reading the instruction sheet for the Blue Sea charger, I think that a lot of the trouble with the Tripp-lite may be with the absorption hold time. With the Blue Sea, you program in a minimum time, maximum time, and amp maximum to go to float, for each bank. The stress very heavily that the hold time needs to be right. The Tripp-lite moves very quickly to float, it appears.

[markopolo]

I'd put the inverter on the other side of the existing 200A relay. I'd want the inverter to run off the house batteries but get an "assist" from the alternator when/if you decide to run the van engine.

I'd leave the existing shore power / generator transfer switch as it is but add one of those Xantrex inline inverter automatic transfer switches. You could even add two of them if needed depending on how your van AC panel is wired and what outlets you want to be able to run off the inverter.

[booster]

Originally Posted by markopolo

I'd put the inverter on the other side of the existing 200A relay. I'd want the inverter to run off the house batteries but get an "assist" from the alternator when/if you decide to run the van engine.

I'd leave the existing shore power / generator transfer switch as it is but add one of those Xantrex inline inverter automatic transfer switches. You could even add two of them if needed depending on how your van AC panel is wired and what outlets you want to be able to run off the inverter.

Yeah, the inverter place is questionable. I went back and forth on that one, and it just kind of stayed there, even after I added the selector in the place it is. The inverter was originally after the relay to isolate it from the equalize voltage, but if the selector is OFF, it is OK anyway. Thought it might be nice to be able to kill all power to it easily, but I guess that isn't all that important, and it would be easier on the relay with it on the other side for sure.

On the transfer switch, I should have been a bit clearer, I think. The one shown in the drawing is a new Xantrex one put inline. The OEM one stays put to handle the generator/shore power connections and feeds the charger and new transfer switch.

I think, could be wrong of course, that I would get engine assist to run the inverter/microwave with the setup shown, plus both battery banks. The side of the 12v relay shouldn't change that either, I think. The microwave says 700 watts of microwave power, 1000 watts of input power. I know that I have read of lots of folks that have had trouble running them on inverters, especially the modified sine wave versions. I would hope 1500 watts continuous, 3000 surge would be enough to get it running and keep it running. Once running, the alternator should be able to keep it going at about 80 amps of 12.5 volts.

When on engine power:

OEM separator would be closed
ACR would be closed
Selector on BOTH banks (actually could be on anything but OFF since the ACR would have the banks connected together and to the alternator connection

I just went out and tested the Tripp-lite again, this time looking for a minimum absorption time. Apparently there isn't one if the batteries are full, as it would kick right into float. There may be a threshold voltage it needs to be under to start charging, but the 13.0v that the batteries are at right now (just off charge a while) made it go right to float. This kind of contradicts the video on the Trojan site, where the QC lady said you can do a "seudo equalize" with a smart charger by doing a full charge, and then unplugging and replugging it in to get it to go back to the higher voltage for a while. From the instructions, I think that would happen on the Blue Sea, but it doesn't specifically say it. The little Ctek smart charger I have does do a fairly long absorption time, even when restarted on a full battery showing 13.3v of surface charge.

[markopolo]

I made a mistake. I confused the 200A relay with the Separator which I now clearly see. What you've planned looks good to me. And yes, it would be great to kill all power to the inverter easily. Only thing is that the relay is point of failure which gets mentioned occasionally on forums and groups.

That's a lot of work planned. Is it 6 gauge inverter wiring now? Also 6 gauge at the relay?

Would you consider getting rid of the Trojan batteries instead or would you lose too much capacity swapping them out? It appears that the Tripp Lite is taking care of your 12v battery ok. I wonder why that is? Is it not used as much or just happy with the lower charging voltage?

[booster]

Originally Posted by markopolo

I made a mistake. I confused the 200A relay with the Separator which I now clearly see. What you've planned looks good to me. And yes, it would be great to kill all power to the inverter easily. Only thing is that the relay is point of failure which gets mentioned occasionally on forums and groups.

That's a lot of work planned. Is it 6 gauge inverter wiring now? Also 6 gauge at the relay?

According to the Roadtrek wiring diagram (chuckle, chuckle), it has a short 6 gauge from the last 80 amp breaker to the relay (like 6 inches long). It shows 4 gauge from the breaker to battery binding point under the van, and to the separator in the front. It shows 2 gauge to batteries themselves, which is weird because it carries less than amps than the 4 or 6 gauge wires. Charger also on 6 gauge with inverter internal. I will need to look at the voltage loss charts to see how big all will have to be, and what breakers to get. You happen to know what brand the inline breakers they use are?

Would you consider getting rid of the Trojan batteries instead or would you lose too much capacity swapping them out?
The thought of going AGM is always tempting, but I would lose about 75AH of capacity, I think. It was always a tough point because of the mix of batteries with wet starter and high alternator voltage, but still tempting. One thing this adventure has pointed out, is that you batteries can be in very rough shape capacity wise, based on specific gravity, and the voltages look just fine, even with light loads. I was very surprised at that. I have read similar things happen with AGMs, but you would never know it because you can't check state of charge with specific gravity. You wouldn't know until you noticed the reduced run time

It appears that the Tripp Lite is taking care of your 12v battery ok. I wonder why that is? Is it not used as much or just happy with the lower charging voltage?

I think it must be getting the voltage up to absorption levels on both battery sets, but the 260AH of 6 volts are still basically in bulk charge, while the 12v is ready for absorption. The absorption time/current level trip out based on the starting point of the 12v while the 6 volts may not even really be in absorption

Odd to be sure, I wish I understood all this stuff a bit better.

[booster]

I went back to the Tripp-lite site today to try to dig out some more info on the model 750. They aren't real forthcoming, though. What I did find was another equalizing voltage. It was give in the same Q&A section as the 14.2 volts was given, but it listed 15.8 volts, which is more like you would expect. I dug through my manual to find out how to initiate the equalize, as I wanted to try it out, to see what voltage I would get. Time is too short to do the upgrade before we go on an extended trip this winter, so if we could equalize, it would save the batteries some, I would think.

I repeated the shore power connection test with a full 12v battery (6 volts disconnected), and just like before, it went to absorption voltage of 14.4 for about 30 seconds and then went to float.

I left the 6 volts disconnected, and disconnected all the things that could get hurt by the high voltage of equalizing. Coach cable at separator, solar fuse, Trimetric fuse, 12v power relay off (doesn't look to have any electronics in it an doesn't pass anything when off, except power to the switch). I found the tiny dip switch that they say to move for 3 seconds to initiate the equalize, but it was already in the activated position, which they say it shouldn't be except for the 3 seconds. Moved it to the correct position, and then unplugged and replugged the AC power. Did the 3 second switch move and then went and checked the battery voltage. 15.7v!!. Let it run a few minutes and shut if off by disconnecting the shore power.

I then hooked up the 6 volts to see if the equalize had enough current to do all 3 batteries at once (basically needed to hold voltage). Plugged it back into AC power, and it went to absorption, but now it stayed there. The 6 volts were full, as was the 12v, so the batteries had to be over 13.0 volts, but it stayed in absorption. It has been about 40 minutes so far. Perhaps that switch being in the wrong place was what was causing the early drop out of absorption? It is easy to see how the wrong switch could have been set at the Roadtrek factory, as they are tiny, group B is to the left of group A, and they number right to left. Probably time to check the rest of them to see if they are correct.

Once it gets done, I will try the equalize on all the batteries at once (except the starter) and see how that goes. If this works, all I will need to do is add switches to the solar and Trimetric power, add a disconnect at the separator, and change the alternator regulator. Maybe it will work well enough that we won't need the upgrade?

Update-Well it ran two hours, which the listed as absorption time, at the 14.4 volts and then went to float. It never would have even started that phase before, so the switch must have something. Put it into equalize and it got to 15.35 volts, so is a little short of capacity to do all the coach batteries at the same time, which probably better anyway because the don't match.

We never really ran into a problem with battery life, but we never took them down as far as I was doing in my state of charge tests, so that may be why we didn't notice. Also don't know, because we weren't watching how long it stayed at charging voltage before going to float. It does look like I need to repeat the testing to see if the 6 volts go down on specific gravity, with similar cycles, now that the switch is in the right position.

[markopolo]

The equalization DIP switch could very well have some effect.

CAUTION: Do not leave DIP switch #B3 in the down position after beginning process.

Tripp Lite warns against leaving it in the down position. I doubt they'd need the caution note if it had no effect at all.

It would be great if it turns out the equipment you have will do the job.

[booster]

I think I may finally be getting some useful information. I just ran the batteries down about 30% at a relatively high (higher than our normal use rate). The specific gravity difference in the 12v vs the 2X6v was negligible.

Put it on the Tripp-lite charger and it charged at near 40 amps, tapering to 25amps for about an 1.5 hours and then hit the 14.4 absorption voltage, which had been at 13.2v at the charging start. So far, so good. It ran the stated 2 hours at absorption and and went to float, but at that point is was still putting out over 15 amps. It went to 1.6 amps at the 13.5v at float.

I checked the specific gravity and got 1265 (93%) on the 12v and 1250 (83%) on the 2X6v. Earlier, about 1/2 the way through the absorption, the specific gravities were even, at 1245 on all of them.

So, I guess the bottom line is that the Tripp-lite goes into float early, even on the 12v battery, and very early for the 2X6v. That backs up what I saw earlier, and would probably get worse on each repeating, non-full charge cycle.

I did the unplug/replug routine on the shore power, and the Tripp-lite did go back into absorption without immediately going to float, so the messed up switch position probably was causing that issue, making everything worse for getting to full on the batteries. It should run another 2 hours at 14.4 volts, so it will be interesting to see how full the batteries are then. I guess the good part is that the unplug/plug thing could easily be done at a campground when you get there to charge back up after a while of boondocking. Add in the equalize function and you should be able to get back to full capacity. It would take probably 8 hours to do all that for our 375AH bank, though.

I took another look at the Trojan recommended charging profile, and they show absorption (or even higher) right up to the 100% charged point. I think this points out that the Blue Sea charger probably would be a good choice for solving these issues. By being able to set a minimum absorption time, and a maximum amount of amps allowable before going to float, for each bank, you should be able to take everything to full, every time. The charge times should also be a bit shorter at 14.7/14.8 than at 14.4 also.

I have been e-mailing back and forth with a guy at Blue Sea (very helpful) about some of the oddities I would like to try. I hope he can come up with information of what will, or will not, work, so I don't blow up some very expensive parts. The ideal would make it so the charger would run off the inverter, off the engine, while driving to give a better charge than the alternator does, and also to be able to run the inverter off the engine and batteries for the microwave, or just off the batteries when not using the microwave. The wants are kind of mutually exclusive unless you use a lot of relays, or if the charger is made to handle the oddities it would see (it may be).

I also think I will move the solar output to the batteries to only charge the selected bank (when I can select banks in the future), as we have a lot of battery compared to solar, and if we want to get a given battery closer to full, and at higher charge voltage, we will need to limit the capacity the solar is working on.

All this is very interesting and does kind of explain why there seems to be a very wide range of success in living off of batteries. How you live would make a huge difference in results. In many ways, the old high voltage single stage charger, and high alternator voltages would work better for live on batteries, drive some, plug in once in a while, folks, while the newer equipment would not do as well for them.

Edit--Well, it went out of absorption in about 5 minutes, as soon as it showed about 10 amps to the batteries, with no coach load. Repeated the test, same result. Repeated it again, but turned on 9 amps of coach load, and it kept running in absorption. Obviously, the Tripp-lite uses 10 amps as max before float, and it even overrides the 2 hour absorption setting. Not good at all. The must do it to compensate for coach power use while charging, as they don't want to stay in absorption too long. Bummer.

Looks like the only way to get it to do a full charge would be to have 10 amps of coach load when you try to do the unplug/plug to get more absorption time.

[peteco]

Over 3 years since this discussion, so it may tax your memories here. I just tried the Tripplite equalization function for the first time on the two 6-volt Deka batteries in my Roadtrek. These batteries are over 6 years old and have performed well. The batteries are presently at a specific gravity of 1.262-1.265. Temp is about 68-deg. When I apply 120v to the vehicle the Tripplight goes to 14.3v briefly and then drops to 13.5v. When I select the Equalize Battery Charge DIP switch for 3 seconds, the charge voltage stays at 13.5v. Does it not go to equalize voltage because of the high state of charge of the batteries?

[booster]

I just went back and read the earlier posts, boy there has been a lot of water over the dam since then

It sounds like yours is doing what ours did when the dip switch was in the wrong position from the factory. It would bounce out of absorption or equalize right away. The description is in an earlier post in this thread. The equalize normally would want the batteries to be full, and many chargers will run a full charge cycle first whenever you select equalize, so I don't think the near full batteries should be causing it.

Ours did equalize once I got the switch into the correct position, then unplugged and plugged back in shore power. Then the 3 seconds worked, also in the earlier post. It ran at 15.7v at that point. I think it was set to run about an hour IIRC.

Roadtrek may have been intentionally putting the switch in the wrong place to help prevent overcharging near full batteries, hard to tell with them.

[peteco]

The Equalize switch was in the correct position (Reset) to begin with. Then I flipped it to the Equalize position. The manual says to return the switch to Reset after 3 seconds. I probably took 4-6 seconds to get it back at it is tricky to reach with a mini-screwdriver. Perhaps it is very sensitive to the time in Equalize. I will check again in the morning.