Hi all,https://youtu.be/jgoIocPgOugThe video offers solutions.

Are there reports of burnt up Alternators from RV'ers installing Lithium Batteries and the Chassis charging system is not designed for Lithium? Doug

The Balmar alternators and regulators are very popular with the sailing community, but they are $$$$ !!!The video below discusses charging lithium batteries, but everything they talk about applies to lead-acid and AGM house batteries, just change some of the settings on the charge controller.Charge LITHIUM Batteries While Driving - System Setup

Anyone that charges batteries in a cruising sailboat needs to invest in better ventilation. I've been aboard dozens and dozens of sloops schooners and ketches down here that raise temperatures to above 100F in salons, and galleys when charging batteries.MOST sailboat engines feature a 2 to 1 or higher pulley to pulley ratio between the engine and alternator. Few engines run optimally at dead idle. Speed is carefully adjusted to hit the "sweet spot" which eliminates jungle drums roughness, noise and vibration.Floor and rug drying 120vac fans can inject enough air into an engine compartment to lower air temperature as much as fifty degrees. Not theoretically. I used to haul mine as part of my tool load.The main problem with new fashioned alternators is they have internal fans. Adapt a proper external fan and suddenly temperatures drop dramatically.Remote rectifier bridges not only remove junction and heat sink heat but open up the slip ring end of the alternator to cooling air.So the test with the Bosch alternator included playing with a stacked deck. The motor they used was a 1720 RPM with very little pulley advantage. See what happens at 3,000 alternator rotor RPM. The new class of rectified WYE stators allows extremely high amperage at extremely low RPM. FAR FAR FAR slower than what an automotive application can operate at. 3.5 to 1 pulley ratio is very common.But don't get me wrong. Heat is a terrible enemy of any alternator. My Niehoff and my 50SI 24 volt units are fed cooler air. And both have anodized copper fin stacks for external rectification.Also..........A single group 31 battery can accept over 100 amps. A series parallel stack of 4 cheap golf car batteries will eat 120+ amps for longer than I care to state.So the LITHIUM hook in the BALMAR ad is misleading. The entire concept is invalid.As a designer, meaning rotor, stator and rectifier concepts makes me eligible to judge this stuff.If a cruising sailboat alternator has to have its charging potential curtailed to prevent burning up, then it's suffering from a FATAL FLAW. Read garbage, quackery and incompetent system design.

Those tests on the PM of the none Belmar alternator are bogus because in most motorhomes the rpm of the alternator is 3 times the crank speed so at 800rpm crank speed(idle) the alternator would be doing 2400 rpm thus cooling a lot more. and when I drive down the road at 1900 rpm the alternator is doing 5700 rpm and could be putting out 165 amps. It might burn up at that amount of amps,but hasn't yet because it never reaches that.JMHO

The more **** you stuff into an electronic control unit the more there is to go wrong. Tiny 30 and 40 horsepower sailboat motors use cutouts to stop charging if the engine doesn't have enough power to fight a current. They also use a 30 second ramp enabler to prevent cold start alternator drag down. Useless for automotive.New motorhome electrical design is so stupid on some pushers they control voltage regulators with a remote sensing connection instead of minimizing charge cabling voltage drop.Just as a chuckle my 2 remote rectifiers have 6 rectifiers each. They are stud type PLATING rectifiers 1,200 amp 1,675 PIV. They use a 1? wrench and have 2/0 braided leads. A 1?" hole was drilled for the studThey weigh 2 pounds each. The heat sinks are ³/16" anodized copper. Even back then the copper cost me a hundred dollars as did the anodizing.

how to not destroy an alternator when charging LI batteries.

27 Replies

StirCrazy
Moderator
Dec 09, 2021
3 tons wrote:
Kinda makes me wonder, whatever happened to the minority idea (now defunct?? ..R.I.P.) that Lithium batteries (LFP’s) don’t charge any faster than FWC’s??

3 tons

:B
3_tons
Explorer III
Dec 09, 2021
time2roll wrote:
My trailer charges about the same with LA or LFP. No fuse issues, no alternator issues.

I choose not to charge my 200a/h LFP from the alternator because I prefer (say, once fully charged…) not to have it maintained at 100% SOC…I suppose a switch would remedy this, but as a desert camper I’m mostly able to keep within a decent SOC range (based on usage) with just harvest alone…

3 tons
time2roll
Nomad
Dec 08, 2021
My trailer charges about the same with LA or LFP. No fuse issues, no alternator issues.
otrfun
Explorer II
Dec 08, 2021
. .
3_tons
Explorer III
Dec 08, 2021
Kinda makes me wonder, whatever happened to the minority idea (now defunct?? ..R.I.P.) that Lithium batteries (LFP’s) don’t charge any faster than FWC’s??

3 tons
pianotuna
Nomad III
Dec 08, 2021
Because of the low resistance an LiFePo4 may appear to the alternator as a dead battery. So the alternator might tend to run flat out.

However, the charging wire is often rather skimpy. That probably limits the current.

Perhaps one of the folks who has Li could use a clamp on meter and measure what is going on?

I do know that at 875 amp-hours of lead acid, I was blowing a 60 amp fuse on the charging path to the house bank.

I moved to dual 50 amp automatic circuit breakers, adding a 2nd charging path as well as manual control of the isolation solenoids. I have a meter that reads to 70 amps--and then displays dashes. I saw dashes.
MDKMDK
Explorer
Dec 08, 2021
dougrainer wrote:
Are there reports of burnt up Alternators from RV'ers installing Lithium Batteries and the Chassis charging system is not designed for Lithium? Doug

Only on the Victron video.
MDKMDK
Explorer
Oct 21, 2021
Huntindog wrote:
pianotuna wrote:
Hi all,

https://youtu.be/jgoIocPgOug

The video offers solutions.
This guy isn't all that bright,
When an altenator is installed on a automobile, it is driven by the crankshaft pulley which is much larger. Usually a 4 to one ratio. So even at idle, it would be turning over 2000 rpm

Victron sells several "alternator protection devices" and so, have a dog in the fight. If the alternator doesn't start smoking, you won't buy their stuff to protect yours.
They also supply very little specific information about the alternator's specs, even where it came from, had it been used before, and so on. Then they connect it to a lithum battery with the same "shrouded in mystery" BMS specs. Many people choose to believe it because they've had good luck with other Victron hardware, that's understandable, and everyone always raves about it, especially on the sailing/yachting forums. I've never used any of it, and I haven't had any major problems as a result of not spending my money on their stuff.
Honestly, does anyone know anyone that burned up their alternator charging a lithium battery bank? Or burned up their own? I don't, nor can I find any internet posts that support the notion. (cue the deluge of "I know someone..." replies)
Huntindog
Explorer
Oct 21, 2021
pianotuna wrote:
Hi all,

https://youtu.be/jgoIocPgOug

The video offers solutions.
This guy isn't all that bright,
When an altenator is installed on a automobile, it is driven by the crankshaft pulley which is much larger. Usually a 4 to one ratio. So even at idle, it would be turning over 2000 rpm
MDKMDK
Explorer
Oct 21, 2021
dougrainer wrote:
Are there reports of burnt up Alternators from RV'ers installing Lithium Batteries and the Chassis charging system is not designed for Lithium? Doug

Old thread, good question. I have googled this, and asked for anyone with a real world experience burning up their alternator with lithium batteries to describe the event, and to date the response is usually "crickets".