Upgrading House Batteries to Lithium - Page 5

**creativepart** · 08-16-2020, 02:38 PM

Wow Don... that helps a LOT.

To clarify, this applies to the 2020 Spinter-based models only. So, as far as we know models based on a Ford Transit chassis don't necessarily have this Charge-Mate - but they may or may not have something similar. It would be good to know about that detail.

Thanks for the help on the Trik-L-Start, too. Important info there as well.

AJMike · 08-16-2020, 02:53 PM

Quote:

Originally Posted by Ontario Don

An additional change for this model year, was the elimination of the emergency start feature and the continuous - duty solenoid that has been in the View for years. Evidently both the Charge Pro 40 and the elimination of the emergency start relay was at the request of Mercedes Benz, for warranty reasons.

Loss of the ability to bridge between the starter and house batteries in an emergency? That does not sound like an upgrade to me.

Ontario Don · 08-16-2020, 03:04 PM

Forgot to mention that the Chargemate Pro 40 does have the capability to perform the old emergency start, but it is not as easy as it used to be... I guess both Winnebago and Mercedes have warranty issues they are trying to control.

DavidM · 08-16-2020, 03:36 PM

It is my understanding that B2B chargers take alternator output at a low voltage high current level and convert it to high voltage medium current input that a lithium battery needs for fast charging. For example most older alternators have a fixed voltage output of 13.5-14.0 volts. The lower end won't charge a lithium battery effectively. The Mercedes Sprinter alternator is a smart one and reduces its output voltage even more- about 12.5V when the chassis battery is fully charged meaning that a lithium battery will get very little charge from it in that mode.

The B2B resolves this by converting the voltage and current to make it work.

Does the Mastervolt Chargemate do the same thing?

David

Ontario Don · 08-16-2020, 06:11 PM

Well, good question. I don't believe so, as my understanding of the Chargemate Pro 40 is that it is a pretty simple current limiter and battery isolator. I don't see any of that type of capability in the literature specs, nor does the web price reflect something that clever. Winnebago did not mention that type of functionality.

I've always looked at the alternator as the bottom of the food chain when it comes to charging coach batteries. After a smart coach battery charger that is optimized for a Lithium battery, (using shore power or a genset), and a solar controller that is optimized for Lithium, I've considered an alternator as more or less brute force charging. Unless you invest in a mid-line smart component as this thread has suggested, my experience has been you take what you get. Is what it gives you good enough for Lithium?

Well, again, I'm not 100% sure, but based on my research I am comfortable having a look. When poking around the web to see what others have done, I note that most of the concerns center on not getting to realize the maximum potential of a Lithium battery due to a coach charger that is not optimized for that chemistry, or a solar controller that is not optimized for that chemistry. (And, using a Trik - L - Start instead of the new version of the Amp - L - Start.) An alternator that drops the charging voltage to less than ideal charge voltage? I have not seen concerns there, yet... but you have given me incentive to keep looking. Sounds like we need some more input from others in the know.

What I have seen on the Sprinter Class B we are about to trade in has not given me concern about the upgrade. On the Roadtrek we have, the solar panel is keeping an eye on the chassis battery, and any time I have checked, the chassis it is sitting around 13 volts depending on what the coach AGM batteries are doing. Even though the chassis battery is fully topped up, anytime I have checked after engine start the alternator output is always sitting in excess of 14 volts. When cruising, and checking the voltage on my old Scan Gauge, the alternator output is always in excess of what would keep a Lithium battery happy. That is on a 2013 Sprinter; so it is likely that the Sprinter alternator specs you describe are related to a new and improved version of the alternator...?

My original post was more directed at the 2020 View / Navion owners who were concerned about damaging their alternators due to excessive charge capabilities of Lithium batteries. The Chargemate Pro 40 that Winnebago has installed in the 2020 View / Navion fleet is intended to take care of that concern.

If I get some data that helps this discussion, I will post asap. We ordered our View last October, so are looking forward to actually being able to work with it instead of just thinking about it.

Cheers,

AJMike · 08-17-2020, 11:52 AM

I need to preface this by commenting that I am not an expert on batteries, Lithium or otherwise, or on auto charging systems, so take that into account when reading this post.

I had assumed that the charging voltage of the standard shore inverter/charger, at about 13.6 volts, was not enough to fully charge Lithium batteries, which are supposed to charge at 14.4 volts or so, but when speaking with the support folks at BB I was told that I was wrong about that. They told me that a standard shore charge of 13.6 volts matched the resting voltage of the Lithium batteries and thus would fully charge their batteries.

Before finding this out I bought the Progressive Dynamics pendant to allow 14.4 volt charging for the Lithium batteries and planned to upgrade the inverter/charger to the Lithium compatible version this Fall, but based on what BB told me I have decided that I do not need to spend the upgrade money.

If BB Lithium batteries will fully charge at 13.6 volts from shore power then perhaps there is not any need to charge at that rate from the alternator either. Of course there needs to be some protection for the alternator itself, be that a DC-DC charger or a BIM, but perhaps using a charging voltage of 13.6 volts from the alternator is sufficient if it is sufficient voltage from shore power through the inverter/charger.

Ontario Don · 08-17-2020, 12:25 PM

Hello - well, that makes two of us, for sure. But, I do know that 13.6 volts will only get your Lithium batteries a little over 90% SOC.

My understanding is that Lithium battery manufacturers advertise their batteries as drop-in replacements being able to use the legacy coach's charging system and solar controller, knowing that a legacy coach will charge their Lithium batteries just fine - but only to a little over 90% SOC. For most folks, this loss of the full charging potential of their new Lithium batteries is not going to be a big deal. Don't forget that by dropping in Lithium batteries you are going to get almost twice the usable capacity compared to the old LA batteries, so for some that last five or six percent of usable SOC is not a big deal. I think I would subscribe to that philosophy, if I was upgrading to Lithium without the desire to change out the charger and solar controller, and potentially not get worried about the last little bit of charging capability from an alternator if it did not continually provide 14 plus volts.

Not sure where BB was going with their info, as their voltage charts clearly show that you will only get 90 to 95% SOC at 13.6 volts.

Here is a great article that helped me out quite a bit when doing my research. (I'm new to this forum, but I think I read that it is legit to post a link)

https://www.solacity.com/how-to-keep...tteries-happy/

Cheers,

AJMike · 08-17-2020, 03:16 PM

Quote:

Originally Posted by Ontario Don

Not sure where BB was going with their info, as their voltage charts clearly show that you will only get 90 to 95% SOC at 13.6 volts.

As I said, I am not an expert at any of this, and have plenty of questions myself about how the Lithium batteries operate. However, ...

We just returned from an 8 day trip, the only trip of the year where we stop every night with hookups, and I can say that our Lithium batteries were at 100% every morning after disconnecting from shore power, even if they were not at 100% when we connected them. I did not use the pendant so the charging voltage was 13.6 volts or so, but the batteries were always at 100%.

Take that for what it is worth, but I believe that the BB techs were correct when they told me that even at 13.6 volts the batteries would charge to 100%. That is what I saw when on the trip, based on the Victron battery monitor display. In fact shore power did such a great job in keeping the batteries at 100% that I turned off the DC-DC charger after the first morning of the trip and did not turn it back on for the rest of the trip. Shore power was more than enough.

Ontario Don · 08-17-2020, 03:28 PM

Great news, thanks kindly for the info.

8 day trip... very envious.

Cheers,

Ontario Don · 08-17-2020, 03:45 PM

Last one from me, I promise - Turns out I was looking at the generic Lithium battery SOC chart when I made the "not sure where BB was going with their info" statement. The BB SOC chart clearly shows 100% for 13.6 volts and above.

Likely why they are such a popular choice in RVs these days.

Sorry to all for the lack of accuracy.

Cheers,

AJMike · 08-17-2020, 04:34 PM

Quote:

Originally Posted by Ontario Don

8 day trip... very envious.

Ha! It was supposed to be a 12 day trip but one of our destinations, Islan Blanca RV Park at South Padre Island in Texas, was closed to those who did not already have a reservation so we had to cut the trip short.

AJMike · 08-17-2020, 04:38 PM

Quote:

Originally Posted by Ontario Don

Last one from me, I promise

Please, don't make this your last post. I am always interested in hearing from new people on this forum.

Quote:

Originally Posted by Ontario Don

Sorry to all for the lack of accuracy.

I learn something new from almost every thread I read, and this was no exception. I did not know that there was a difference between SOC charts for generic and BB Lithium batteries, so I learned something today. Thanks for your posts.

mgreenwa · 10-06-2020, 10:38 AM

Great info here. Quick deep-detail technical question:

Does anyone know the specific connection logic between the alternator and the house batteries? That is, is there a findable wire going from the alternator to the coach batteries? I've only ever seen one big positive wire leaving the alternator, one that connects it to the chassis battery positive (on an auto). I'm trying to get a sense of the wiring layout logic before I start crawling around under the rig looking for things.

Mike - BagoNoob

**creativepart** · 10-06-2020, 10:47 AM

Mike, it pretty much is determined by how your coach is wired and not all of them are the same. You can look at the wiring diagrams for your chassis - we have no idea what RV you have - and see how that connection is made.

On my motorhome its through a couple of solenoids with a disconnect, an isolation manager and a bridge to use for Aux starting if necessary. At least, I think that is an accurate description of how it's set up.

Ontario Don · 10-06-2020, 10:51 AM

Mike - What type of RV do you have? If it is a View, I can tell you where you might want to look...

Cheers,

mgreenwa · 10-06-2020, 11:25 AM

Thanks.
I've got a 2007 Itasca Sunrise.
It has the Battery Boost switch, so I'm guessing that any direct house-to-chassis battery connection is managed with a solenoid. I've read and understood the info about needing to regulate the alternator's charging of LifePo house batteries but have yet to nail down the specifics of how my rig is physically wired to decide how/which solution to pursue (BIM or DC-to-DC).

Ontario Don · 10-06-2020, 12:13 PM

Mike - While waiting for an answer from someone who knows the specifics of your Sunrise, and if you've got a minute to goof around, maybe check under the First Officer's seat...

Winnebago has put the solenoid there on the View.

Cheers, and good luck!

**creativepart** · 10-06-2020, 01:47 PM

Quote:

Originally Posted by Ontario Don

Mike - While waiting for an answer from someone who knows the specifics of your Sunrise, and if you've got a minute to goof around, maybe check under the First Officer's seat...

Winnebago has put the solenoid there on the View.

Cheers, and good luck!

Not likely Don. A Sprinter based RV, sure. But this is a standard motorhome. I'm not sure if it's a Ford or Workhorse chassis, but it's no Sprinter.

I got some time and found the Chassis Wiring Diagram.

http://www.winnebagoind.com/diagram/...ire_157461.pdf

There will be a compartment, many times right next to your steps, but not always and it has a removable panel that is labeled that has your power solenoids behind the panel.

Here is a screen shot of that panel and another of the wiring for your charging solenoids.

caoqiang1 · 11-19-2021, 01:31 PM

Quote:

Originally Posted by creativepart

There is one thing you did not mention in your original post.

The LiPo battery companies like to refer to their batteries as "drop in replacements" for your current LA/AGM house batteries. But it's not exactly true.

The issue is that your alternator on your RV can be an issue. Most of the battery sellers will advise you do something to protect your alternator. Some take that advice and some don't but you should be aware of it.

The main workarounds I've seen for this are:

1. Put the charge line from the alternator on a switch so you can turn off charging the house batteries when driving - the chassis battery would still charge though. Of course, that means you won't be charging your house batteries as you drive your RV.

2. Put an BIM device between your house batteries and your alternator. This connects the alternator for a while, then disconnects it for a while, then turns it back on again.

3. Put a DC to DC charger between the alternator and your batteries. This takes the DC voltage from your alternator and applies smart charging rules to the process of charging the house batteries. You can control the charge rate and protect the alternator.

There is a 4th way and a number of people follow this way - and that's to do nothing. Just let the alternator charge as it wants to and worry about any problems latter. I guess there is a 5th alternative that even less people use and that's to add a special dedicated alternator made just for charging LiPo.

By the way, the problem is that your alternator is made to charge LA batteries and LA batteries naturally increase resistance to charging as they get closer to fully charged. But LiPo batteries don't do that so they can take more and more amps from your alternator and the end result is your alternator can over heat and be destroyed.

I think at present the DC to DC charger is the preferred way to protect the alternator and those expensive LiPo batteries. Though you'll find folks on all sides of this debate.

The battery I just bought has a 100A BMS, would that avoid alternator issue?

Wyatt · 11-19-2021, 02:03 PM

Quote:

Originally Posted by AJMike

As I said, I am not an expert at any of this, and have plenty of questions myself about how the Lithium batteries operate. However, ...

We just returned from an 8 day trip, the only trip of the year where we stop every night with hookups, and I can say that our Lithium batteries were at 100% every morning after disconnecting from shore power, even if they were not at 100% when we connected them. I did not use the pendant so the charging voltage was 13.6 volts or so, but the batteries were always at 100%.

Take that for what it is worth, but I believe that the BB techs were correct when they told me that even at 13.6 volts the batteries would charge to 100%. That is what I saw when on the trip, based on the Victron battery monitor display. In fact shore power did such a great job in keeping the batteries at 100% that I turned off the DC-DC charger after the first morning of the trip and did not turn it back on for the rest of the trip. Shore power was more than enough.

I think the thing that can trick people into thinking that their Lithium batteries being fully charged, is that the Victron will show 100% when connected for the first time. It syncs itself and uses that as the baseline, when in all actuality, it's probably something less than that.
WFCO, the manufacturer or our charger/converter, said that their system WILL NOT charge Lithium batteries to 100%, but rather only ~90%.
They now sell a more-or-less drop in swap out for the charging unit that corrects this. When I added that, my batteries "said" 100% but began charging more. Once I was sure they had fully charged, I re-synced the Victron to 100%, to create a new, more accurate baseline for the Lithium batteries.