How to not blow up MY Alternator when charging Lithium

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How to not blow up MY Alternator when charging Lithium

August 16, 2024, 11:44:40 am

I know this topic has been touched upon on this forum but I am still puzzled about what I should do or not do with my coach.
I just installed a 300 AH lithium house battery and I have not started the coach yet. I have the standard alternator that came with this 1993 U225 which I believe is set up to charge both the starting battery and the house battery.
I found this video which attempts to explain the situation but most of what they are saying goes right over my head.
Obviously I don't want to blow up my alternator or damage the lithium battery.
What are the available solutions?

https://youtu.be/jgoIocPgOug?si=w8r9Bxoo5GpwlwxS

Re: How to not blow up MY Alternator when charging Lithium

Reply #1 – August 16, 2024, 11:55:10 am

You may need some sort of load stabilzer, softener . BTB charger looks like the solution .
I removed my atuo charge/ isolator and only combine my systems when needed for the AC while driving . I also have a cheap 100 amp alternator charging the LI Po4 batts, as well as solar .

Re: How to not blow up MY Alternator when charging Lithium

Reply #2 – August 16, 2024, 12:35:45 pm

This not only happens to lithium, but also when battery bank sizing is drastically increased. Also note for that video that is a vehicle with what I'll call a toy alternator.

So, here are the 3 main questions:
What size is your alternator?
What is controlling the house battery charging from the alternator? Is it Relay or battery isolation diode with sensing on chassis battery?
What size and type of battery before?
What other loads need to be supported while charging, running off the alternator? This is where folks really get in trouble.

You answer those questions, and I can tell you what you need to make this work.
You can p-mail me at dennis-vw-service@outlook.com

Dennis

Re: How to not blow up MY Alternator when charging Lithium

Reply #3 – August 16, 2024, 12:37:39 pm

Thanks Mike. I know you've put a lot of work into your coach's solar setup.
In my case, for the foreseeable future I will be making a few 10 to 15 mile trips per year with a lithium battery that is close to being full.

Re: How to not blow up MY Alternator when charging Lithium

Reply #4 – August 16, 2024, 12:48:43 pm

Hi Dennis. Thank you for your comment. As for your questions:

What size is your alternator?
I do not know.

What is controlling the house battery charging from the alternator? Is it Relay or battery isolation diode with sensing on chassis battery?
All I know is I have an isolator.

What size and type of battery before?
The previous house battery was about 100AH AGM and my MTTP solar controller is set for that.

What other loads need to be supported while charging, running off the alternator? This is where folks really get in trouble.
None that I can think of. I usually run the dash AC.

Re: How to not blow up MY Alternator when charging Lithium

Reply #5 – August 16, 2024, 02:11:20 pm

Quote from: Dakota Slim – August 16, 2024, 12:48:43 pm

Hi Dennis. Thank you for your comment. As for your questions:

What size is your alternator?
I do not know.
Do you have any documentation? Label on the alternator itself. Is it a large body Leece-Neville? Send picture. I'm thinking based on year and engine you have 160 amp. Can be easily upgraded.

What is controlling the house battery charging from the alternator? Is it Relay or battery isolation diode with sensing on chassis battery?
All I know is I have an isolator. If it is the isolator in front of the engine it most likely is the diode type. Send pic. This is actually a good thing for lithium.

What size and type of battery before?
The previous house battery was about 100AH AGM and my MTTP solar controller is set for that.
Going from 100 A/H AGM to 300 A/H even staying AGM is a huge jump. Battery chargers' control and limit current. Alternators do all that they can to deliver current to reach a set voltage. Batteries will absorb that current based on size, type, and state of charge. Looking at fixed voltage of 14 volts, AGM will bulk accept about 25% to 40% of A/H capacity. So going from 100 A/H to 300 A/H brings bulk from 40 to 120 A/H. Lithium can be as much as 1/2 or more of the rated capacity. 300 A/H lithium can put you up to 150 A/H alternator charging. As for other loads, lights, radio, TV, heaters, refrigerator, etc. any house battery load gets added to this. Then there is also the chassis loads and chassis battery charging. These combined loads are why alternators fail. Residential fridges are really bad for these marginal set ups.

The diode block isolator system helps with lithium as the voltage drop across it helps to limit the current during the bulk charging phase. Be sure that the boost switch is "off" as that affectively will connect the alternator voltage sense to the house batteries spiking that current load.

What other loads need to be supported while charging, running off the alternator? This is where folks really get in trouble.
None that I can think of. I usually run the dash AC.
Radio, TV, heaters, refrigerator, lights, etc. any house battery load gets added to this.

Re: How to not blow up MY Alternator when charging Lithium

Reply #6 – August 16, 2024, 03:04:55 pm

A Victron non isolated 30 amp Orion B2B is my solution to protect my 160 amp alternator from overworking to charge my 600 amph lithium batteries. It replaces the diode based isolator, keeps the battery combiner solenoid (boost switch) and utilizes a single stud insulated attachment point for the alternator lead that normally comes into the center lug of the isolator. The isolator gets removed.

Roger drew me a diagram for wiring it up based on a first hand inspection of my coach. We used the same setup on Propman's coach when he converted to lithium house batteries. You do need to read the Orion info sheet carefully and a magnifying glass will help!

A coach often gets modified over 30 years so nobody can make a blanket statement how to set up your coach without inspecting it or reviewing a set of good photos provided by you of your alternator, isolator, boost switch, and battery connections.

Victron has a robust ecosystem of parts that play nice with one another and can be monitored from your phone via Bluetooth and their phone app. The components seem to hold up well in my experience. There are other solutions out there. If you go Victron, take a picture of the puk code and serial number for your files before you install it.

Lots of DC amps in the house and start batteries so you need to be careful to avoid accidental shorts.

Re: How to not blow up MY Alternator when charging Lithium

Reply #7 – August 16, 2024, 03:22:28 pm

This topic is has gotten way above my pay grade.
This is the original spec sheet and a photo of my isolator. I have to believe the alternator is the original 160 amp. Until now, the only changes were the addition of solar and an MTTP controller in 2016 and a change from the original gel cell batteries to lead acid and/or AGM. At one point I had 300AH of Trogans for the house.
Oh, and the boost switch works.

Re: How to not blow up MY Alternator when charging Lithium

Reply #8 – August 16, 2024, 03:44:12 pm

Realmccoy, is there a reason for going with a non isolated rather than with isolated?

https://youtu.be/naSy08ZhGZE?si=1MXI4pPc3nHPocp5

Re: How to not blow up MY Alternator when charging Lithium

Reply #9 – August 16, 2024, 03:47:56 pm

This is how I did mine

Re: How to not blow up MY Alternator when charging Lithium

Reply #10 – August 16, 2024, 03:55:13 pm

Quote from: Dakota Slim – August 16, 2024, 03:22:28 pm

...a photo of my isolator.

Isolator looks like a Hehr Powerline, same as originally came on our coach. Photos below show how ours was connected. Note that the two AUX BAT (coach) battery posts are jumped together, supposedly to double the number of diodes handling the charging current going to the larger battery bank.

Re: How to not blow up MY Alternator when charging Lithium

Reply #11 – August 16, 2024, 04:51:39 pm

Quote from: Tommy D – August 16, 2024, 03:47:56 pm

This is how I did mine

Thanks Tommy. I have that same trickle charger.

Re: How to not blow up MY Alternator when charging Lithium

Reply #12 – August 16, 2024, 07:11:02 pm

OK! So what kind of loads are you supporting that you need 300 A/H of battery? Are you using an inverter? What size? What is on it? How long/often do you need it?

So yes, you have a 160 A/H alternator and what is known as the DUVAC setup with the diode isolate. This set up along with the robustness of the large body Leece Neville alternator is the main reason things survived the past 300 A/H battery bank. I would suggest with this setup that 200 A/H lithium will drop in, 300 A/H will be pushing it. With power/current monitoring you may be able to manage it.

As for the suggestion to use a B2B charger that could be a good option. You will want something around 40 to 60 amp. 60 amp into a 300 A/H battery is a 5 hour rate. Any loads on that battery while driving/charging will add to that time. As you have a propane generator yo may also want to look at what you have for charging while on generator. For my 600 A/H lithium bank I have a 3,000-watt inverter with a 150 A/H charge section. Worst case 4 hours for full charge. I have a lot of stuff that needs power including the Oasis heat. For the 3 zones and the burner I need 25 A/H for it run. Running my generator 1 to 2 hours a day now supports my needs. If I go full time will look to add solar.

Let me know what you have now and want for the future and what type of investment you are willing to make. and I can be more helpful.

Re: How to not blow up MY Alternator when charging Lithium

Reply #13 – August 16, 2024, 08:44:00 pm

The non isolated is cheaper and our coaches ground to the frame in many places. No need to isolate is my understanding. Tommy D's photo is very helpful.

Re: How to not blow up MY Alternator when charging Lithium

Reply #14 – August 16, 2024, 09:38:15 pm

Quote from: Dakota Slim – August 16, 2024, 03:44:12 pm

Realmccoy, is there a reason for going with a non isolated rather than with isolated?

The isolated B2B would be used in a marine application where the fiberglass hull does not provide a common ground. Isolation also is useful when you are running 2 or more B2Bs and want total separation of the battery banks. The non-isolated is fine for typical RV use.

Re: How to not blow up MY Alternator when charging Lithium

Reply #15 – August 16, 2024, 09:51:56 pm

Dennis, my coach is real simple compared to yours. When I was an off grid snowbird with this coach I had 300 AH (150 usable) of lead acid for the house, powered by 500 watts of solar. I had (and still have) a 750 watt inverter that powers one house circuit where I have a laptop computer, a low voltage desk lamp and various other low voltage devices.
Other than the control board and a couple sets of computer fans for the Norcold refrigerator and some LED lighting, nothing else used my house batteries. Right now I'm probably using less than 50 AH.
I never let those house batteries go below 12.3 volts but in the short sunlight days of winter they would reach 12.3 volts within a few hours after sundown -- or sooner if it was cloudy. The batteries were usually back to 100% with a few hours of sunlight.
When covid came in March of 2020, I plugged in at a friend's house in AZ. I eventually replaced those lead acid house batteries with an AGM battery (100+- AH) about a year and a half ago, thinking that when the price of lithium came down and I had some spare cash I would switch.
That time is now, and I purchased a 300AH lithium battery because I want to be ready if I do go back off grid.
I chose 300 AH because it is twice as many AH's as I had before and I believe I can keep it at (or close) to 100% on solar if I do go off grid.
I think Realmccoy, Tommy D and Chuck have given me the answers I need. It's hot as can be down here right now with no relief in sight but I'll compare their photos with what I have to work with. I don't plan on starting or moving my coach for another 6 or 8 weeks.

Re: How to not blow up MY Alternator when charging Lithium

Reply #16 – August 17, 2024, 01:05:13 am

This is one of those "do as i say not do as i do" moments but i ran over a year with the stock configuration on our 800 AH lithiums without issues. I was expecting something but nothing.
I eventually went to Off The Grid RV in Quartzsite and he put on a Lithonics device. Same thing that they use on telephone trucks and the like with 2 battery banks.

Re: How to not blow up MY Alternator when charging Lithium

Reply #17 – August 17, 2024, 10:51:41 am

Quote from: Bob & Sue – August 17, 2024, 01:05:13 am

This is one of those "do as i say not do as i do" moments but i ran over a year with the stock configuration on our 800 AH lithiums without issues. I was expecting something but nothing.
I eventually went to Off The Grid RV in Quartzsite and he put on a Lithonics device. Same thing that they use on telephone trucks and the like with 2 battery banks.

Thanks Bob & Sue. I know that someone on this forum had previously mentioned using lithium with a stock configuration without a problem.

Re: How to not blow up MY Alternator when charging Lithium

Reply #18 – August 17, 2024, 05:38:26 pm

As I mentioned earlier, sized correctly and with your charging and alternator set up drop in will work. My recommendation form scratch would be 200 A/H. 300 A/H is a bit marginal. I would do some current monitoring to see what your actual charging load is. If you do not have any on board current, power monitoring you can get a reasonably priced clamp on ammeter.

As a bench mark, I now have 2, 300 A/H lithiums for a 600 A/H bank. I have a 270 A/H alternator and the diode isolator setup similar to yours. Initial charging is about 140 A/H with at about 13.6 volts while the chassis battery is at 14-14.2. That drop across the diode block at that high current level is a desirable feature of that set up. The bank pulls that current until about 90% which at that point the battery BMS limits the current and the voltage then raises. As the battery get close to 100% The BMS further limits the current to about .3, .4 amps.

If this works out the same on your coach, then the single 300 A/H battery will pull about 70 A/H from the alternator. Again, the Leech Neville should handle it.

Re: How to not blow up MY Alternator when charging Lithium

Reply #19 – August 18, 2024, 07:18:31 pm

No need for isolated.

I wanted 60 amp charge, so paralleled 2 Victron B2B's. Also wanted to keep the Trick-L-Start for chassis batteries, so ran a wire to dash to switch off/on the B2B's.

Circuit breaker is for the charge circuit for the toad.

Re: How to not blow up MY Alternator when charging Lithium

Reply #20 – August 18, 2024, 09:26:25 pm

I think I will have a non-isolated Orion with about 10 hours on it that'll I'll be looking to sell soon. I installed it a week ago and have since decided to change over to an isolated one that'll allow me to connect to my smart shunt. Still solidifying the details of the install for the isolated one.

Re: How to not blow up MY Alternator when charging Lithium

Reply #21 – August 18, 2024, 11:09:04 pm

Quote from: Elliott – August 18, 2024, 09:26:25 pm

I think I will have a non-isolated Orion with about 10 hours on it that'll I'll be looking to sell soon. I installed it a week ago and have since decided to change over to an isolated one that'll allow me to connect to my smart shunt. Still solidifying the details of the install for the isolated one.

Decisions, decisions.
I could actually go with 3 battery banks and forget about the Orion. As long as I'm plugged in to shore power, I could just use solar to charge the lithium battery and use the converter and alternator to charge my AGM house battery and lead acid start battery as they were designed to do. I was using the trik l start to use the house battery to top off the 8D starting battery.
I could use my trik l start (or maybe a 2nd) to use the lithium battery to keep both the house and start batteries topped off.
I'm really not running anything except the 12v lights, the Norcold control board and computer fans to help the Norcold cool in the summer off the house battery at this point. I just want additional house battery AH if I ever go off grid for for any length of time again or if there is a power outage, Right now, my 750 watt inverter isn't connected to anything.
If I was paying for metered 120 volts I would use the solar and battery power as much as possible but I'm paying a flat rate for the RV space I'm in.

Re: How to not blow up MY Alternator when charging Lithium Do it right!

Reply #22 – August 19, 2024, 06:54:22 am

There is a lot of value to doing this right and having a fully integrated, mostly automated set up. Having a proper inverter install with bypass relay feeding dedicated house loads and receptacles is nice. A 2K to 3K could even run 1 AC based on battery capacity. You also want to consider that as an inverter is a power source, there are code and other requirements for its use and installation. In particular grounding and bonding of the neutral when it is the power source and isolation when the generator or shore power is the power source. You want one with a feed through and bypass transfer relay. GFCI for kitchen, bath, and anything outside. As you have a propane generator running it is a bit costly and getting fuel inconvenient so consider that when you do need it being able to charge the battery bank in a timely manner. You want a higher capacity charging system. I went with the Xantrex 3000 pro-marine in part for the 150 A/H charger. Using the boost switch I canals charge the chassis batteries, (I have3 to get the ISM going).

I would consider keeping the engine charging simple and when needed upgrade the alternator. At that point you may need to upgrade the diode isolator or maybe go to a voltage sensing bidirectional relay. I am considering that upgrade route although the diode block is working well for me.

Yes, so many choices. A properly engineered system will give the safest and most satisfactory performance.

Re: How to not blow up MY Alternator when charging Lithium Do it right!

Reply #23 – August 19, 2024, 09:29:12 am

Quote from: Dennis H – August 19, 2024, 06:54:22 am

I would consider keeping the engine charging simple and when needed upgrade the alternator. At that point you may need to upgrade the diode isolator or maybe go to a voltage sensing bidirectional relay.

In the most basic and trouble-free engine charging system, the alternator is connected directly to the start battery. No isolator is required. The alternator can also charge the other batteries on the coach, if desired, by closing a manual interconnect (solenoid switch). I set our coach up this way and it works great. My report is linked below if anyone is curious:

Delco Remy 28SI Alternator Installation

Re: How to not blow up MY Alternator when charging Lithium

Reply #24 – August 19, 2024, 09:33:39 am

I would NOT upgrade the alternator to a higher-amp unit.

The U225 has the Cummins B engine with 230 HP. Taking a higher HP drain for a larger alternator would not be something I would recommend.

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