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Old 06-10-2016, 09:17 AM   #41
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Thanks for the story Interblog. Sadly, that is the reality of high current devices. I always, always remain concerned of these how powered inverters. So much current is going through them that the slightest failure can be catastrophic. Best designs have multiple redundancies but even then, normal operation allows very high currents to travel through the devices so there can't be a protection against that.

To some extent, that is one of my concerns with the BMS that LB_3 is planning to use. One lock up of the microprocessor due to a bug could cause serious problems especially with Lithium batteries that can output incredible amount of current. In the normal application where that was designed for, i.e. off-grid cabin, that is less of a concern. The equipment can be on concrete floors, away from main home, sleeping area, etc. But in our case, we are living with and on top of such things!

For this reason, I am purusing multiple paths to get Lithium on board with this BMS being one.
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Old 06-10-2016, 11:08 AM   #42
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It's starting to sound like the US Navy has a good reason not to allow lithium, batteries or otherwise, on-board their subs.
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Old 06-10-2016, 01:17 PM   #43
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It's starting to sound like the US Navy has a good reason not to allow lithium, batteries or otherwise, on-board their subs.
Right on! Looks like US Navy when valve regulated lead acid (VRLA) batteries using its thin plate pure lead (TPPL) technology batteries about ten years ago...
http://www.prnewswire.com/news-relea...-74152832.html

GO NAVY!!
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Old 06-10-2016, 01:25 PM   #44
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I didn't expect this thread to advance so quickly so I'll post some more of my recent adventures.....


AM SOLAR has been selling a complete system from Victron Energy that would be much more plug an play but they're currently sold out. Besides, if all I ever do is work on the RV installing other people's stuff, I'm going to start viewing the RV as more of a job and I've already got one of those. This is fun for me since I'm not very good with electronics and its proving to be a fun learning curve to climb. :-P.
Since you are having so much fun I assume you are following some of the Lithium battery threads on the Cruisers Forum. They recently started a new thread on LiFePO4 battery systems to augment their epic LiFePO4 for House bank thread that has 5200 posts and almost 648k views.

http://www.cruisersforum.com/forums/...ns-166798.html
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Old 06-10-2016, 01:34 PM   #45
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It's starting to sound like the US Navy has a good reason not to allow lithium, batteries or otherwise, on-board their subs.
Just discovered the Japanese are now trying to build a lithium battery system for submarines....

http://gentleseas.blogspot.com/2015/...ith-soryu.html

Diesel powered submarines do need more battery power for extended missions. Some good background reading on the complexity of using lithium batteries....
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Old 06-10-2016, 03:07 PM   #46
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Right on! Looks like US Navy when valve regulated lead acid (VRLA) batteries using its thin plate pure lead (TPPL) technology batteries about ten years ago...
http://www.prnewswire.com/news-relea...-74152832.html

GO NAVY!!
After reading about this type of battery, I see why there's still a vent for the house batteries. I recall someone posting some time ago that AS just left it even tho it wasn't needed for AGMs. Oops. Apparently an AGM can vent H & O under certain conditions.

Thanks for the link. And yes, GO NAVY!
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Old 06-10-2016, 07:48 PM   #47
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We had a battery charge controller at work several years ago that I continue to curse to this day. After about 6 years of operating this device without failure, someone decided there was a failure mode where the device could lockup after switching into a bulk charge mode but before the telemetry would be updated telling us the charger was cooking the batteries. Engineers estimated it would take 40 hours before the battery would build up enough pressure to burp any hydrogen gas so my team had to come in every day including weekends and holidays to ping this damn device to confirm it wasn't locked up.

Moral of the story? Always reserve one of your telemetry digits for a cyclic counter.
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Old 06-11-2016, 04:33 PM   #48
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LB_3, may I ask why you are going the route of the separate charger/inverter? Yes, I realize the charge profiles can be problematic somewhat with 3-stage chargers. But getting a separate charger would cost a big hit to the space budget. A charger that puts out 50 amps as the current inverter does is a box almost as big as it! It is a non-starter in my case as I just don't have the space for that and new batteries.

With the current inverter/charger, I can use the new solid state relay to kill its output when charging completes. And likewise, kill its input in reverse when the batteries hit bottom. I can't think of a scenario where I would want to shut down the charger, but use the inverter. If charger working it means I am on AC power so don't need the inverter anyway.

Am I missing a use case you have thought about here?
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Old 06-11-2016, 07:58 PM   #49
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I was wondering the same thing. We use Magnum and now Victron inverter/chargers in almost every solar/lithium installation that we do.

There are no issues with setting a custom charging program specifically tailored for lithium requirements, just like the Blue Sky and Victron solar charge controllers.

I am very interested in your reasoning.


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Old 06-12-2016, 01:04 AM   #50
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We have a 2007 Interstate so if we want 120v AC power our only option is the generator or shore power because we don't have an inverter. So for us I'm already having to eat into storage space regardless of whether I add one device or two.

And purchasing a separate inverter when we never had one isn't like throwing out a perfectly good $1200 inverter/charger just to replace it. I'm also not sure I will need to use shore power to charge the battery if the solar and alternator charging become much more efficient. If I need a charger I can get a 70A charger for $235. Add the $636 for the inverter I just purchased and I still come out ahead except for the additional space.

One issue you might have is if losing DC power to the Magnum inverter/charger causes the integrated transfer switch to stop functioning. I don't know much about the Magnum inverters.

But I think your logic is sound. First generation battery management systems just killed everything when cell voltages were out of spec, but that is the dark ages compared to what we're discussing.
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Old 06-12-2016, 06:44 AM   #51
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.....It is a non-starter in my case as I just don't have the space for that and new batteries.
.....
The issue of space calls for thinking outside the box. I think Airstream was thinking outside the box when they put our existing coach AGM battery under the cab's passenger seat. In that case, not necessarily optimal thinking outside the box.

I don't believe we have made a final decision yet (LB_3 will make the call), but at this point, my front-running idea for accommodating these components is to raise the floor of the wardrobe and reconfig the space beneath (our existing converter currently lives in that space). The wardrobe floor could easily be adapted to sit on some rails or edge strips such that the bottom piece just pops up and removes like taking the lid off a stove pot, for easy access to the area below. And there's nothing that I want to store in the wardrobe that is going to be imperiled by the loss of X number of vertical inches. Soon after acquiring our Interstate, I created this hyper-efficient overhead clothing storage system and much of the time, I don't even use the wardrobe.

I came upon this idea after observing too many scenes like these below. These are just impossible working conditions - LB_3 sideways on the narrow floor often with his body half-inserted under the cabinetry trying to grapple with components (in the right photo, his raised knee is basically pointing at the aforesaid wardrobe). Ergonomic improvements are desperately needed. But the final config will be dictated by the components.
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Old 06-12-2016, 08:50 AM   #52
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The battery under the passenger seat is Mercedes' standard placement for an auxiliary battery.
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Old 06-12-2016, 10:13 AM   #53
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Thanks for the explanation LB_3. Loss of inverter transfer switch capability is something I had not considered. In our case, it will mean the TV will not function as that is on the Inverter driven outlet when the charge is complete.

Wonder if that ever happens with the 3-stage charger. By setting the float voltage lower than bulk/absorb, high voltage mark won't be reached.

Lew, is this what you are relying on to keep the transfer switch going?
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If I need a charger I can get a 70A charger for $235.
So you made me go and research some more , I and I found this new DC charger: http://www.progressivedyn.com/lithiu...y_charger.html

It is still large but reasonably priced and has a simple fixed output voltage so should allow for rapid charging of Lithium cells. It comes in different current ratings. It is too new to find it on sale but this place has the 60 amp one for just $300: https://advancedsportvehicles.com/pr...-pd9160al.html

I am putting my batteries inside the coach so I really have to search hard to find a way to fit this in there.

Shame it doesn't have an enable wire. It would be trivial to add it given all the protection circuits it has. If I go this route, I may open it up and figure out a way to do that. Else it requires an AC relay to switch it off on full charge condition. It does say it internally monitors charging so maybe it works as is? http://www.progressivedyn.com/pdfs/1...%20English.pdf

"The system was
designed to sense voltage on the battery and will taper the
charging current as the battery becomes charged. "
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Old 06-12-2016, 11:36 AM   #54
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Bestconverter.com has that line of chargers for sale:

http://www.bestconverter.com/Lithium...ers_c_221.html
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Old 06-13-2016, 09:50 AM   #55
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Bestconverter.com has that line of chargers for sale:

http://www.bestconverter.com/Lithium...ers_c_221.html
Thanks. I will return the favor by giving a link to these dc-to-dc chargers that don't require control of the engine alternator: http://www.sterling-power-usa.com/St...rycharger.aspx

It also has a Lithium charge profile but like others, it has its own mind of when to go into trickle charging. More and more what they consider Lithium is a smart battery with internal BMS, not what we are building. Same was true of the other charger.

If all works out, the trickle charge mode will replenish the energy taken by always on systems. If not, Solar BMS and the logic in these batteries may fight each other.

What we really need are "dumb" chargers with no logic at all, much like raw PV panels for which the Solar BMS is designed.

Engine charging has been the best source of charge for me so far. So one way or the other, I will find a way to shoehorn one in there.
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Old 06-13-2016, 12:39 PM   #56
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Another data point. Let the fridge/freezer run overnight on not so full batteries. This morning the voltage was down to 11.3 or so.

Turned on the engine and to my pleasure, noticed it was pumping over 100 amps into the batteries running at idle! It overflowed my 100 amp dc current clamp. Surprisingly and credit to Mercedes, there was almost no smell or smoke out of the exhaust pipe. And of course it is nearly silent compared to the generator.

Aftermarket 280 amp alternators put out 200 amps and are plug compatible with the OEM unit. Using that, one should be able to charge the Lithium batteries in an hour. The only hitch is being able to shut it off.

Speaking of shutting off, I let the Magnum charger take over at 50 amps output, going through my solid state relay. I was happy to see the relay passed through this much current and still is cold as a cucumber! So it is a really efficient switch that can be used to shut off the alternator charge output.

As an aside, I did not realize that the PV controller and Mangum output are "wired-or" (parallel) connections. So it seems neither minds having the other back pump charge into them. This is a bit of good news.

Given where I am, I think I going to pass on using the Solar BMS and using a traditional BMS such as Orion BMS Jr. Solar BMS wants to be in charge of all charge current which is good. But it is limited to 100 amps total. This means we can't even use the OEM alternator with it as that would max out its input capacity.

This is a rather messy puzzle to solve and to some extent relies on one's priorities. In our area where sunny weather is not frequent and when it is, we seek out shelter, Solar is not a very viable choice to recharge the batteries after discharging overnight.

Using the engine to charge becomes a very viable tool then as we tend to drive around ours anyway. Indeed that is one of the reasons to get a class B RV.

Anyway, rambling a bit. Appreciate any comments on these thoughts.
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Old 06-13-2016, 01:05 PM   #57
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Turned on the engine and to my pleasure, noticed it was pumping over 100 amps into the batteries running at idle!

The Sprinter 220 Amp alternator has been my default charging choice over the gen set. With 300 Watts of Solar and the Frig running I've rarely needed to resort to running the engine. I'll be on a 2 week trip week after next with both frig and freezer at work so it will be a good test.
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Old 06-13-2016, 09:31 PM   #58
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Amirim, thanks for the alternator charger link. More food for thought.

Thinking out loud. As you noted, I really shouldn't need a fancy charger if all I'm doing is feeding a straight 14.6 volts into the SBMS. I don't mind adding a larger alternator, or even a second alternator if I can use the power. But more than anything, I want to make sure I'm not pulling more amps out of the alternator than it is rated for or than I have wires to transport it. The SBMS will turn it on and off for me so the controlling logic is not necessary in the battery charger. The Lithium batteries just need a current limited 14.6 volts.

On to the new toys from the UPS driver:

The inverter came very poorly packaged:


So I figured I needed to bench test it incase it was damaged:


Ok, my cheap chinese power supply couldn't handle the start up surge without the voltage sagging so I had to go to plan B:

Everything checked out so its back in the box for a couple months until this project is a bit more mature. The inverter is 19" long but only about 9 inches wide. I'm not sure how much clearance I really need for air flow. The manual stated 5 inches but that seems like overkill. More importantly, will I find a place to put it where it won't be ingesting its own exhaust?

This is cool. There is no need to purchase a separate remote power switch because the inverter comes with a kit to relocate the power panel from the front of the unit anywhere within 5 meters:


Ok. Later this week I'll show off some of the other toys I promised last weekend.
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Old 06-14-2016, 09:10 AM   #59
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Good news. After hours of searching yesterday, found the solution to current limiting the alternator. It is from UK company, Sterling Power. They make two different series. This is the first one I found: http://sterling-power.com/collection...ttery-chargers

What's neat is that they not only current limit (to the capacity of the device you buy), but also boost the voltage. They load up the alternator which causes its voltage to droop. But by selecting LiPo profile, it will then boost the voltage up to 14.x volts. Pricing is not too bad either at $350 for the one I am looking at (AB12130): http://www.defender.com/category.jsp...948&id=2289953



Note that some of the others don't have LiPo profiles.

Installation should be dead easy by replacing the current battery isolator with it. Not changes for special wiring required for the alternator!

There is an odd comment in their manual though that I am asking them about. Namely they say the unit must be matched to the Alternator capacity which in our case is 220 amps. I don't need that much current and rather save the space for the smaller one above.

Strangely, they make almost identical set of devices they call "Battery to Battery" charger. They work almost the same as above but have a different profile for LiPo charging from what I recall at lower voltage which I don't like. And even more strange, they charge more for them. Here they are: http://sterling-power.com/collection...ttery-chargers



These other ones have ignition enable pin that makes them easier to control from SBMS.

Speaking of SBMS, I am right now on the path of using a traditional unit. It is the same one that is going into my Lithium electric quad. It is the Orion Jr. The difference is that it doesn't attempt to control the charge so you can pump as much as you want into the batteries. It is like SBMS and external load except that it also does that for external charger. It is more expensive and doesn't do solar.
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Old 06-14-2016, 01:43 PM   #60
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It looks like there is a remote interface for that charger.

http://sterling-power.com/collection...emote-controls

That may mean it's possible to use one of the SBMS output pins to turn the charger on and off so the 100A charging limit of the SBMS would not be a constraint.

Another random thought: Could an aftermarket remote start device be triggered by the low voltage output pin on the SBMS? I don't think I would be interested in this capability but for individuals interested in keeping the air conditioner running for their pets, it might be nice to start the vehicle when the battery can no longer run the A/C.
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