Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > MH-General Discussions & Problems
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 09-04-2022, 07:45 PM   #29
Senior Member
 
Isaac-1's Avatar
 
Join Date: Jun 2016
Location: SW Louisiana
Posts: 7,612
Quote:
Originally Posted by twinboat View Post
...
Second issue is that your not getting a 100% charge on the Lithium batteries. They require 14.5 volts to get to 100% and alternators don't charge that high.

Battery to battery chargers boost the chassis battery voltage up to 14.5 volts.

This is making the assumption that the alternator is the sole charging source, many / most people with LiFePo4 batteries also have solar and likely a converter or inverter charger as other charging sources. Also it is important to understand that even at 14.0VDC charging source you will reach over 99% SOC with LiFePo4 batteries.
__________________
2002 Safari Trek 2830 on P32 Chassis with 8.1L w/ 400 watts solar 420Ah LiFePo4
2017 Jeep Cherokee Overland & 2007 Toyota Yaris TOADs with Even Brake,
Demco Commander tow bar and Blue Ox / Roadmaster base plates
Isaac-1 is online now   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 09-04-2022, 08:51 PM   #30
Junior Member
 
Clark clan's Avatar
 
Join Date: Sep 2018
Posts: 21
If you are fully charged before you pull out, you should be fine. I have the BIM recommended by BattleBorn that cuts power off and on to the batteries to protect the alternator.
https://battlebornbatteries.com/prod...ation-manager/
Clark clan is offline   Reply With Quote
Old 09-04-2022, 08:57 PM   #31
Junior Member
 
Join Date: Jul 2022
Posts: 14
There is a fairly simple solution.

The problem is created by the low impedance of lithium batteries in comparison to lead-acid batteries.

On a lead acid battery the charging current flowing through the internal battery impedance (resistance) causes the battery voltage to appear higher by the amps x resistance. The higher voltage protects the alternator because alternator regulators are designed to taper current off as the voltage rises so higher current = higher voltage and the alternator cuts back to a safe current.

But the voltage on lithium batteries doesn't rise like lead-acid batteries so the alternator gets overloaded.

There is a very simple solution. We have used this technique on over 100,000 installations on boats over the last 30 years. (We sell devices that use this method.)

You add artificial resistance to replicate the impedance of a lead acid battery. The resistor is a length of copper wire. With the added resistance the voltage is higher at the alternator and current reduced to a safe level like it would on a lead-acid battery.

The gauge and length of wire can be determined experimentally with a clamp on DC ammeter. For a 100 amp circuit we typically use about 6 feet of 6 gauge wire - use this as a starting guide. For a 50 amp we typically use 4 feet of 10 gauge wire. Test under maximum rpm on a low battery and adjust the length so the current is well below alternator rating. (Don't adjust to "rated" current, alternators cannot put out rated current continuously, if at all!)

The added resistance to replicate a lead-acid battery can be anywhere in the charging circuit between the alternator and the battery, outgoing current to loads does not need to go through the resistor.

The voltage drop does not reduce the final charged voltage because as the battery voltage rises during charge up to over 14 volts, the charging current tapers off to zero. So the drop in the extra resistance also tapers off to zero and the battery still gets a full charge.

Don't coil the excess cable, it can heat up at max current and soften the insulation.
Ann-Marie is offline   Reply With Quote
Old 09-04-2022, 09:31 PM   #32
Member
 
Country Coach Owners Club
Join Date: Jul 2014
Posts: 32
I think there may be a different problem.

No matter the Li battery’s capacity, it’s the voltage that controls your alternator. At just 10% charge, your li battery has as much voltage as a Lead battery at 90% charge. So, since your ‘voltage regulator’ thinks that you have a lead battery, and it thinks that lead battery is nearly full, it reduces the charge amps. Batteries do not draw anything from the alternator; the power from the alternator has to be forced into the battery with higher voltage than the battery. The voltage regulator, again, controls that.
ereck.po is offline   Reply With Quote
Old 09-05-2022, 01:18 AM   #33
Senior Member
 
Join Date: Jul 2007
Posts: 236
Quote:
Originally Posted by bpu699 View Post
Lots of videos on you-tube of alternators burning up with just ONE lithium battery.

From what ive found, you cant goto lithium without limiting current output...


That video is B.S. Everyone should watch the little window in the video that pops open showing the alternator is turning 500 RPM. No alternator turns that slow from the gear-up ratio. And no one wants a lithium set charging at 25-40A which is what most B2B/DC2DC converters that are popular deliver. They also won't be able to charge 4 in parallel either. You've got to find a happy medium which may involve installing cutoff switches.



O.P. needs to check load and manage your batteries per what the alternator can handle. If the BMS aren't blue tooth (Battleborn should not only include bluetooth controls but gold plate the things for what they charge) and you can't switch the battery out with bluetooth and a smart phone, then adding individual battery switches may be the only alternative unless you want to what turns out to be a trickle charge using any of the popular B2B units. It's best to only engage the lithium charge relay about 1 hr after start if the coach battery was down a week or more, 15 minutes after start if you've been driving it before killing to gas up, eat or whatever. I imagine it would take at least a 200A alternator to handle a couple of BB in parallel and you have 4. Measuring alternator amps is the only way you can tell what is going on with your system, however..
Don Juane is offline   Reply With Quote
Old 09-05-2022, 10:08 AM   #34
Senior Member
 
Join Date: Apr 2018
Posts: 2,570
Most important to your alt is not only limited output but also cutting the field voltage before dropping a huge load. Charge by time, not by current flow , which you just need to develop a feel for, and have a device or switch that cuts the field winding voltage first when disconnecting. 3.5 volts per cell is a usable full charge on a lifepo4. Anything higher takes forever to put in and won't get you out of the driveway before it's used up. As far as actual charge voltage they are very tolerant on the high side. I've watched videos of 135 volts charge voltage being put into a 72 volt pack. The key is cutting off the charger before they start to go over the 3.5. your inverter has timed settings. Your alternator does not, so you really need a switch at the very least, that first cuts the field voltage, then disconnects the lifepo4s.
shootist is offline   Reply With Quote
Old 09-05-2022, 10:25 AM   #35
Senior Member
 
Join Date: Jul 2007
Posts: 236
The conventional wiring of most RVs provides enough resistance that these resistor cables don't have to be added but the problem is the 4 12V BB in parallel is too much for an alternator, especially with a semi-discharged chassis battery thrown in the mix and especially when the vehicle is started. The chassis lead/acid is a great capacitor-like device that prevents most from fearing unloading issues. A few days or weeks monitoring alternator output will eventually "train" you what the chassis battery charging needs are (usually around 100A at the onset and tapering off to near zero during the first 0.25- 2 hrs of fresh charging.) From there you measure what each of your 12V BB are drawing (likely higher in summer than winter) at the typical low SOC that you reach and you simply add all that up compared to your constant load of the vehicle including computer, running lights, etc and see if your alternator can manage it or not and if not, calculate if you can employ a switching recharging regiment or not to manage the load. You may need an additional alternator and regulator and that can run 3-5 grand. Then you won't have to worry with the large alternator and special regulator - that is - until the belt starts jumping track, vibrations show up, heavier loads on pulleys create unexpected issues, etc. "It's always something".
Don Juane is offline   Reply With Quote
Old 09-05-2022, 10:34 AM   #36
Senior Member
 
richpatty's Avatar
 
Newmar Owners Club
Freightliner Owners Club
iRV2 No Limits Club
Join Date: Aug 2013
Posts: 757
Quote:
Originally Posted by Budreau View Post
I have a 2004 Itasca Horizon 40KD. I have 4 battleborn lithium 12 volt coach batteries. I do not have a Battery Isolation Manager or DC to DC charger. My alternator quit on me and had it replaced to the tune of $1,000. The new one is now also toast a month later, I am quickly figuring out the alternator is overheating on long drives.

I need to get a BIM or DC to DC charger obviously. But in the meantime, can I disconnect all but one coach lithium battery to avoid overheating the alternator? Any suggestions on what I can do in the meantime? I have some long trips scheduled and deadlines to meet.

Thanks in advance!
I was wondering what was the capacity of the fried alternator?
__________________
2017 Newmar Ventana 4310
1,440W solar / 800 AH Lithium
2007 CR-V
richpatty is online now   Reply With Quote
Old 09-05-2022, 11:48 AM   #37
Senior Member
 
Rexhall Owners Group
Join Date: Dec 2010
Location: L.A.
Posts: 408
Replaced the lead acid with 2 Lion Energy 105 Ah Lifepo4 batteries 2 years ago. Did nothing to protect the Alternator. Since I put them in, we've traveled more than 11,000 miles and have not had any issues. Not sure if it's just luck, that we only have two batteries, or what I do to minimize potential alternator damage.

We only run the engine for a few minutes in the morning when getting ready to leave a site. That's to bring in the slides and raise the jacks. The engine RPMs are generally pretty high first thing so alternator unlikely overheating. Then the engine is off until we leave our site.

Even though the Lithium batteries have a maximum charging current of 100A, I've never seen our battery monitor over 50 amps.
__________________
GaryB1st
2005 Pace Arrow 35G
2016 Jeep Wrangler JKU Willys trim
garyb1st is offline   Reply With Quote
Old 09-05-2022, 01:10 PM   #38
Senior Member
 
Join Date: Jul 2007
Posts: 236
Just a side note that the debate really needs to be subject-ified with numbers when it comes to what kind of equipment you have, what your loads are and battery types, etc. Otherwise it all turns into "We had a great time on the way to California" vs. "we had a major accident on the way to California." (Which does either mean?) Assuming you're talking alternator charging, you have to know the voltage your alternator attempts to seek with no load (generally 14.2, at least in pre 2020 vehicles), what the lead/acid chassis battery demands say at 50% SOC, what your auto electronics draws constantly with both figures for no dash vent fan on high and with dash vent fan on high plus running lights, car computer, load etc. Of course one thing no one included here and quite surprisingly is their alternator capacity. For example I have 150A alternator that I can keep a 560 LiFePo4 bank charged with a varying flow of 50-120A but it has to be controlled by knowing what the chassis is demanding of the alternator at every moment and when the chassis "throttles back" to allow me to use what I need, I have to be watching and go in there and take it. It has to occur with management and you can either "do it by hand and on the fly" or you can spend several grand to have it done automatically and hope that you can get even half of what you were able to do "by hand". It's not always an exact science. The exact part, however, is exactly how many days is it going to take someone to charge a 500+aH lithium set with a $300 B2B cranking out 25A-40A constantly and the answer is "likely a few more than you had planned" ;-)
Don Juane is offline   Reply With Quote
Old 09-06-2022, 01:39 AM   #39
Senior Member
 
Join Date: Nov 2016
Location: Oregon occasionally, Baja often
Posts: 618
Quote:
Originally Posted by bpu699 View Post
.
The linked video is grossly misleading.
.
a)
* engine RPM is transmitted through a pulley to a pulley on the alternator.
Those two pulleys operate on a ratio, 1:3 is common.
With a 1:3 pulley ratio, at a normal traveling cruise speed with the engine at 1,500RPM, the pulley ration turns the alternator at around 4,500RPM.
.
Our ExpeditionVehicle Cummins likes to cruise at 1,800RPM.
With our 1:3 pulleys, our alternator is spinning at around 5,500RPM... its sweet-spot according to the spec sheet.
.
b)
The video shows a midget small-house alternator suitable for intermittent-duty in a compact economy sedan.
For comparison, the 60-amp alternator on my ancient BMW motorcycle is about that size.
.
The alternator on our ExpeditionVehicle Cummins 505ci/8.3-liter engine is a 220-amp big-house rated for continuous-duty.
For our big-house, we invested us$188 new at a semi-truck dealer.
Removing the old, installing the new took me about six minutes.
.
.
Somebody in this thread says they paid us$1,000 for a new alternator installed.
That seems high...
.
c)
Our Lifeline Concorde AGM bank is going strong -- for our use -- at nearly two decades full-time live-aboard.
No gadgets to charge our bank other than the standard voltage regulator, split to the starts first, then the bank.
Based on second-hand information from users, we think LiFePo4 are too fussy for us.
LargeMarge is offline   Reply With Quote
Old 09-06-2022, 10:23 AM   #40
Senior Member
 
Join Date: Nov 2018
Location: Beaver Dam, Wisconsin
Posts: 3,876
Quote:
Originally Posted by LargeMarge View Post
.
The linked video is grossly misleading.
.
a)
* engine RPM is transmitted through a pulley to a pulley on the alternator.
Those two pulleys operate on a ratio, 1:3 is common.
With a 1:3 pulley ratio, at a normal traveling cruise speed with the engine at 1,500RPM, the pulley ration turns the alternator at around 4,500RPM.
.
Our ExpeditionVehicle Cummins likes to cruise at 1,800RPM.
With our 1:3 pulleys, our alternator is spinning at around 5,500RPM... its sweet-spot according to the spec sheet.
.
b)
The video shows a midget small-house alternator suitable for intermittent-duty in a compact economy sedan.
For comparison, the 60-amp alternator on my ancient BMW motorcycle is about that size.
.
The alternator on our ExpeditionVehicle Cummins 505ci/8.3-liter engine is a 220-amp big-house rated for continuous-duty.
For our big-house, we invested us$188 new at a semi-truck dealer.
Removing the old, installing the new took me about six minutes.
.
.
Somebody in this thread says they paid us$1,000 for a new alternator installed.
That seems high...
.
c)
Our Lifeline Concorde AGM bank is going strong -- for our use -- at nearly two decades full-time live-aboard.
No gadgets to charge our bank other than the standard voltage regulator, split to the starts first, then the bank.
Based on second-hand information from users, we think LiFePo4 are too fussy for us.
The video is accurate as far as I can tell. All parameters cited in the test are accurate. Performance measures are accurate. Conclusions are correct for the parameters used. Other systems may produce different results.

The OP has already tested his. It performs just as the video suggests. He toasted two alternators just like in the video. This does not mean yours will toast. It all depends on the whole system and how you use it.

Victron makes some of the best RV systems available. Much more information is available from Victron and from the best Li battery manufacturers. If you do not have the knowledge to understand, feel free to use the support and system review provided by the best Li battery manufactures. There is one Li battery manufacture who will not sell you their batteries unless you participate in a planned system review.
__________________
Paul Bristol
Kodiak Cub 176RD
Nissan Pathfinder 2015
Persistent is offline   Reply With Quote
Old 09-06-2022, 04:14 PM   #41
Member
 
MechEngrSGH's Avatar
 
Join Date: Dec 2021
Location: Home @ Riverside, CA
Posts: 93
Quote:
Originally Posted by shootist View Post
You still have the problem of the bmi's disconnecting under a high charge current. There has to be protection for your inverter and generator. Onans hate being disconnected under load.
The BIM only disconnects the charging cable between the house batteries and starting batteries/alternator. It has no effect when charging from any source other than the alternator.
MechEngrSGH is offline   Reply With Quote
Old 09-06-2022, 04:24 PM   #42
Member
 
MechEngrSGH's Avatar
 
Join Date: Dec 2021
Location: Home @ Riverside, CA
Posts: 93
The limit of the BIM to 'protect the alternator is that it is a duty cycler that presents the alternator with half the load it would otherwise experience. There is still nothing monitoring alternator temperature (the only measurement that really matters) and shedding load when the temperature is too high (120C/248F).

The ONLY WAY the alternator can be protected under any/all circumstances is to monitor its temperature and reduce the load when it gets too hot. The only way to do that is to use selective load shedding (disconnecting) of optional loads (like battery charging). I have built a thermal switch to do just that and it will work with either a B-B charger or a split charge relay.


The BIM came about because there is nothing else that can be done if trying to operate the vehicle and charge the house batteries directly, simultaneously (other than a B-B charger). The high current that could be 'dumped' by the BIM shutting off can typically be handled by the LA starting battery and the avalanch diodes in the alternator.
MechEngrSGH is offline   Reply With Quote
Reply

Tags
alternator, charging, lithium



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Will Lithiums cause starting battery to drain? SavnTheWales Class A Motorhome Discussions 8 06-27-2022 12:21 PM
Microwaves and Lithiums BitReaver Technology: Internet, TV, Satellite, Cell Phones, etc. 36 04-27-2022 04:06 PM
I ruined my tow-bar (arg!) ARNE-T Winnebago Industries Owner's Forum 74 08-02-2008 06:21 PM
A vacation ruined RV Wizard MH-General Discussions & Problems 17 06-26-2008 06:32 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 07:38 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.