Mitsubishi 115a alternator

[ben373]

I have a Volvo with the 115a alternator approx 2015 charging 309ah of LifePo4

I also have a Renogy 40A dc to dc charger. I have rigged up a system to give me fast charge by bypassing the dc to dc. I am further looking at automating this based on temperature.

I am finding that the Alternator will start charging at 83A but then gradually gets to 63A after 20 mins or so. Temperature is around 100c at the top of the alternator windings.

It would seem that the Alternator has temperature compensation built in? Does anyone have definitive information on this??

With the 40A dc to dc running total draw 50A the alternator gets to 80c

Thanks in advance.

[PaulCrawhorn]

The C-rate ratio is fine there so the LFP bank does not need any protection from overcurrent until ambient starts getting colder than "sweater weather".

So you only need to worry about current limiting to protect the alternator.

A good VR will do that, Wakespeed / APS

or the OG Balmar MC-612

Then the DCDC can be repurposed, higher current rates and help KISS

[PippaB]

The Nordkyn Design VRC was designed largely around the 115A Mitsubishi alternators found on Volvo engines. When running with an alternator temperature sensor it doesn’t start limiting until 120C. That makes me guess that the alternator doesn’t have a temperature sensor, which in turns makes me think the voltage sensing wire is leading to the down ramp in amperage? Where is the sensing wire connected and what is the voltage referenced to the alternator case?

[more]

Originally Posted by ben373

I have a Volvo with the 115a alternator approx 2015 charging 309ah of LifePo4

I also have a Renogy 40A dc to dc charger. I have rigged up a system to give me fast charge by bypassing the dc to dc. I am further looking at automating this based on temperature.

I am finding that the Alternator will start charging at 83A but then gradually gets to 63A after 20 mins or so. Temperature is around 100c at the top of the alternator windings.

It would seem that the Alternator has temperature compensation built in? Does anyone have definitive information on this??

With the 40A dc to dc running total draw 50A the alternator gets to 80c

Thanks in advance.

yes alternator have temperature protection and also have relatively low voltage 14.00-14.2 14.5 +-3% depend also i see one 12v
on my 2 boats upgrade, i have 14.05V for a lithium battery. i buy original Volvo penta use perkins series 402 engine ,alternator is original box perkins 100A regulator 14.05V
But 100 A charge in beginning afternoon drop to 80-60A on end charge because voltage is low drop to 10-20A price of this alternator is very low from 50$ to 500$ some alternator different price.
https://chinarunrun.en.made-in-china...003tr0091.html

we don't repair in workshop alternator because is more cost 1-2 hour for work vs buying new alternator for 100€
but if you curios you can open and check brush holder/regulator number
with this
http://www.metroautoinc.com/Download...%20Catalog.pdf

[hjohnson]

Originally Posted by ben373

I have a Volvo with the 115a alternator approx 2015 charging 309ah of LifePo4

I also have a Renogy 40A dc to dc charger. I have rigged up a system to give me fast charge by bypassing the dc to dc. I am further looking at automating this based on temperature.

I am finding that the Alternator will start charging at 83A but then gradually gets to 63A after 20 mins or so. Temperature is around 100c at the top of the alternator windings.

It would seem that the Alternator has temperature compensation built in? Does anyone have definitive information on this??

With the 40A dc to dc running total draw 50A the alternator gets to 80c

Thanks in advance.

Mitsubishi Alternators, and their internal regulators are pretty notorious for being very conservative in how they backoff as they heat up. Due to our small engine (Yanmar 1GM10) we're planning to use just an 80A unit. However, we've had it modified for an external regulator, and will use that regulator to drive the alternator as hard as is safe to do so.

In our case, we've picked up a Wakespeed WS500 which will integrate with the rest of our power system, and will have the alternator directly charge our LiFePO4 bank.

When we finally upgrade our engine (probably to a Beta 14 or Beta 16), we'll upgrade to a 120A alternator with better cooling, and use the same regulator.

We do have an 18A DC-DC charger in our setup, but it's only in use to keep our starter battery topped up.

[ben373]

Thanks for the replies, the sensing wire is connected to the LifeP04 and. Charging is between 13.2 and 13.4 volTS

[SOLAR SUPPORT]

I have shared the link below about the alternator modification I made for the Mitsubishi 115A on my own boat.

https://www.cruisersforum.com/forums...es-259773.html

This solution requires the existing Mitsubishi 115A alternator to be taken off the engine and disassembled by an experienced electrician. By opening and closing the connection of one of the rotor warning brushes from the outside, the alternator charge is turned off when the internal temperature or system voltage values ​​reach the limit values. When these limits are lowered, the alternator automatically resumes charging. In this way, the overheating of the alternator and the activation of the high voltage protection of the Lithium batteries during the charging of the alternator are prevented.