In this video, I refer to a thermal switch I bought. It was a 10amp, normallyclosed thermal switch. I chose one rated for shutdown at 110degrees C. That temperature is something you should choose yourself, but I think that is a good number for a thermoswitch mounted inside the alternator case.

In preparing for this video I searched eBay again and found a better choice. This is the same basic thing, but this one is rated for 16a. That would be more then plenty for any alternator I've seen. Also, it's CHEAPER!

https://www.ebay.com/itm/144996884088...

Another thing that I wish I had talked about in this video was engine room ventilation. It seems basic but keep it cooler around your alternator and your alternator will run cooler!

Well as I say the description section is how I reserve the right to get smarter.


If you'd like to learn more about my BankManager:
https://marinedcac.com/pages/bankmanager

Here is a link to the video where I talk about engine belt upgrade    • Boat DIESEL ENGINE Hacks & Oil Change...  

Have questions or comments? Leave them below! We do our best to read and answer all comments on our channel.

Thanks to @chazgeisler6213 for the chapters

(00:00) Introduction

Clark introduces the topic: LithiumIon phosphate batteries vs. alternators.
Common question from viewers: How to deal with alternators when using lithiumion phosphate batteries.
(00:43) Lithium vs. Lead Batteries

Lithiumion phosphate has a Battery Management System (BMS) that protects the cells by shutting off the battery when it goes outside the safe zone.
Lithium batteries can absorb power faster compared to lead batteries, which need slower charging above 80%.
(01:56) Alternator Function

Alternators produce power (voltage × amps).
If the battery disconnects, the alternator's voltage spikes, potentially damaging the diodes.
(03:13) Problem Explanation

Sudden loss of power when lithium battery shuts off, causing alternator damage.
Voltage spikes can affect other electrical components on the boat.
(04:21) Example of a RealLife Issue

A boat with lithium batteries loses power after the BMS shuts down the battery, and the alternator's diodes are burned out.
The owner didn't realize the issue until months later.
(05:29) Solutions

Classic solution: Keep the battery connected to the alternator at all times, but not ideal with lithium as the BMS needs to disconnect for protection.
DC to DC charger: Possible but inefficient due to power loss.
Hybrid system: Combine lead and lithium batteries with a "bank manager" to prevent damage.
ABYC solution: Expensive modification with a special BMS that sends a signal to shut down the alternator before the battery disconnects.
(08:15) Power Absorption Differences

Lithium batteries can absorb power without tapering off, unlike lead batteries.
This creates more strain on alternators, especially highoutput ones.
(09:18) Heat and Alternators

Alternators generate heat when producing power.
Fans help cool the alternator, but more powerful alternators create more heat.
(11:03) Upgrading Alternators

Upgrading to a higheramp alternator can cause more heat.
Highoutput alternators may overheat if not used properly.
(12:28) Proper Alternator Use

Start engine, raise anchor, and avoid letting the engine idle too long.
Alternators work best at higher RPMs with good airflow.
Avoid revving the engine while in neutral as this generates heat without cooling.
(13:32) Overheating Alternator Risks

Operating alternators at maximum output without proper airflow can damage them.
Hightemperature alternators may require thermal management systems.
(15:54) Solutions for Heat Management

Use an external regulated alternator with thermal protection to avoid overheating.
Install a thermometer on the alternator for monitoring.
(17:08) Thermal Switch Option

Use a thermal switch to cut power when the alternator reaches a set temperature (e.g., 110°C).
This switch can protect alternators from overheating.
(18:20) Modifying Alternators

Internal regulator alternators may need to be modified to include thermal switches.
Modification allows for better heat management and protection.
(19:28) Upcoming Video and Closing

Clark will explain how alternators work internally and how to modify them for better heat management.
Final thoughts on protecting alternators when using lithiumion phosphate batteries.
(20:02) Conclusion

Clark hopes this video answers common questions about alternators and lithium batteries.
Viewers can ask more questions on Patreon for further videos.


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