New Aire Alternator upgrade

[Motoaxe]

Hi all!

We have a new 2022 new aire and want to feel confident about our alternator not burning out while bridge charging the new Victron lithium house bank. Anyone with experience in using the stock alternator or is there an aftermarket one with an external regulator that someone might suggest?

[redbaron73]

With a DC to DC charger, there is no risk.

Without one, there is no alternator that will survive.

[Motoaxe]

We have alternator charging a large lithium bank (2400 amp hours) our boat and has been working well for over 600 hours underway so far. Why will they not last on the Newmar?

[tabrewer]

I have a 900 amp lithium battery bank with the stock alternator, no DC to Dc charger...4 years no problems.

[2cyber71]

My Horizon came with a 240 amp alternator it has a 450 ISL and a magnum inverter. They put them on the 42Q.
The 40A has the 160 amp alternator

[redbaron73]

Originally Posted by Motoaxe

We have alternator charging a large lithium bank (2400 amp hours) our boat and has been working well for over 600 hours underway so far. Why will they not last on the Newmar?

In short...because the litithum will keep the alternator running at full load, and shorten the life of the alternator.

A dc to DC charger will ensure the alternator gets a rest, while still using the energy from the alternator to charge the lithium.

Smaller banks can use an isolator, but will eventually cause the alternator to fail earlier.

Dc to DC chargers are cheap insurance.

Here is what victron has to say:


https://youtu.be/jgoIocPgOug

[Rd1]

From a few years back, I recall Spartan had different amp alternators for the different newmar models. Even in some cases if the engine and chassis were the same, they had higher amp alt for the higher model. If I recall KA had 350a(?) alt. then 270a for EX, 210 for LADP etc..

don't know if freightliner offered that

[twinboat]

It's not just the size of the Lithium bank that can overheat the alternator. It's how deeply you discharge.

If you went with lithium because it's the thing to do and you don't dry camp much, the alternator will only work for a short time at full output and last a long time .

You are also only charging your lithiums to about 80% if your using a stock 14.2 volt alternator.
A Batt to Batt charger raises the output voltage to get the lithiums up to 100% state of charge.

Last is if your using the stock wiring, the alternator isn't reaching full output. Replace the 8 gauge wire from the alternator to the battery terminal on the starter motor with a 2 gauge wire and watch it work hard.

Sent from my SM-A025V using iRV2 - RV Forum mobile app

[10 fan]

I have heard many say it will burn up the alternator but only one said his burnt up. I bought the LI BIM for mine which connects for 20 min and off for 15 ( or vise versa). I bought a blue tooth clamp on ammeter with temperature probe to do my own test. After about 15 different tests all in summer I saw almost no difference in temperature with the probe duct taped to the alternator case. My average amp draw was 36a with no battery charging and a max draw of 115a. I tested with the batteries 20% soc to 80% soc running and not running one AC unit. I do have 2400w of solar and 1400ah LPO4 batteries. I don't record my solar output but have seen 121a feeding the batteries. Per Cummins my 240a alternator is 100% duty rated. Because I am running at less than 50% max I am very confident with set up and installed a latching relay to my boost switch so I can charge for as long as I want. The meter was about 60$ on Amazon. Do your own test before burning up or wasting money. I had fun using the meter checking between batteries and many other things. Clamp it on and hit start on your phone to record for hours. Different coach wiring size, connections, connectors, lenght, ? experenced tech, alternator, batteries will make a big difference. One will last forever and another will last a week. It also helps you get to know your system.

[Motoaxe]

Interesting! I love hands on actual r&d! Is this on a Cummins isl9? Tell me more about the latching relay and installation…..

[10 fan]

Yes Cummins 450 ISL9. I checked on Amazon and mine is not available. Here's a picture. It has 2 Latching relays, Only needed 1 so I have a spare. Cheap and easy project. Think I paid $16. My system has worked perfect for almost 4 years and 49.000 miles. Solar, batteries, 2 inverters running the entire panel.

[Motoaxe]

Thanks! I’m formulating my solution and that latching relay idea is golden!

[paul65k]

So the right answer is it all depends

The OP has not told us how many Lithium batteries they have...... this will truly make the biggest difference.

I hear lots of people say..... I don't have a DC-DC and NEVER had a problem...... the only thing they forget to add is YET.

The fact is that more than 4 100Ah Victron or other LiFePO4 batteries can and will draw more amps than your alternator was made to produce.... it's just a fact, not an opinion

A DC-DC converter/smart charger like the Victron unit(s) can and does provide charging to your lithium batteries in a way that will not overburden your alternator that was designed to charge Lead-Acid batteries and their unique charging profile.

The "I've never had a problem" crowd is absolutely correct right up until the time THAT THEY DO!!!

At a minimum, a Li-BIM unit should be installed. While this is the most rudimentary solution, not as elegant or even as safe in the long run, adding neither of these devices is very much like playing "Russian Roulette" with your alternator, and likely if you do have a problem and it fails..... it will almost always happen at the most inopportune time.

I speak from personal experience as well as from the perspective of a commercial RV Solar/electrical installer.

Good luck!