Alternator and Lipo

[Xlion]

On my sailboat I have a yanmar 3ym20 with a 60A alternator located in a small engine room. I’ve also installed a victron Orion dcdc 12/30 wishing to switch my gel 140A battery to a lifepo4 100A, but when I was close to do it the doubt about the possibility that I could bring my alternator in overheating stopped me. Does anyone just done something similar on his system?
Ty

[Flod]

It can be done but there is some things to consider. It’s not a direct replacement with your gels. You need to think about:
1. Protect your alt from overheating (you already figured this out)
2. Protect your alt from a sudden disconnect from the load caused by the bms cutting the charge bus
3. Protect your new lifepo4 batteries from overcharging and to deep discharging

The above can be done in many ways depending on what stuff you already have (like your dcdc charger) and how you want things. With your setup I would consider to have the alt charging your starter battery, let the dcdc charger charge your lifepo4 from the starter and add a bms that either control the dcdc charger directly if possible or a relay that can cut the power. Then another relay to cut at low voltage. Tips of reading are marinehowto and you could look at the gwl power site to get some ideas and prices of stuff.

[smac999]

Assuming the alternator is connected to the engine battery. And the 30a dc to dc goes to the lithuim then you are fine. It will limit the alternator to just over 30a. (30a to house and a bit to the engine battery).

Assuming you have the Orion smart. Which you want for programming the voltages. You can also limit the max current To less then 30a if want. 30a from a 60a alt is Likly fine.

[Pete7]

Originally Posted by Xlion

doubt about the possibility that I could bring my alternator in overheating stopped me. Does anyone just done something similar on his system? Ty

Just doing this now. I have bought but not yet fitted a replacement 100A alternator in place of my Volvo 60A. Also plan to fit a alternator regulator which has temperature control if the alternator overheats.

You could fit something similar for your Yanmar without breaking the bank. A 90A alternator is available for £160. https://www.startermotor-alternator-...32-11188-p.asp

The Advanced regulator is £140 https://sterling-power.com/collectio...tor-regulators

This would allow you to add additional DC>DC chargers in the future or give a wider margin for anchor windlass or bow thruster.

The final thing to do is ensure any alternator has some cooling air.

Pete

[Xlion]

Thank you all for the answers. After reading your suggestions i've installed a temp sensor on my alternator discovering that it work around 72 celsius degrees working at 15 Amps yet, but at full working with a Lifepo4 battery and the other stuffs on i will need around 50Amps continuous (the Orion input/output current can't be trimmed), i discovered also that my basic alternator can't work over the 80 degrees, over this line on long term use it could be damaged cause the bearing's grease will flow out with all the connected issues. So now i am sure to need an high power alternator with a smart regulator that use a temp sensor. I took a look at the sterling systems, but seems they have just a dumb overheat protection that stop the alternator at 120 celsius degrees leaving it start again when temp go down and giving sometimes some pingpong issues. The best solution look like to install a balmar with a smart regulator improoved with temp sensor on the alternator, it will module the amps production calibrated on the fixed temperature. Seems just Ballmar made this kind of items and they are really expensive here in italy (alt plus regulator over 1800 euro), so at the moment i will use for one more year the AGM batteries slowly building the new system and waiting the Lifepo4 prices will go down a bit more. Ty again at all.

[SOLAR SUPPORT]

Does Lifepo4 replacement with lead acids really requires alternator replacement? Does adding a Dc-dc charger realy necessary to limit the charge current that Alternator can hande with?

I am still using AGM batteries but planing to replace them with Lifepo4 ones next year. That is why I try to understand the system requirements and trying to calculate the total cost of this transition.

Constant high loads on the alternator generate high heat energy within the alternator itself leading to malfunctioning. Because alternator can't cool enough itself and it has gone. That is it.

Isn't it possible to add a bimetal thermostat which normaly close and open over 80 degrees celcius connected to exciter of the alternator. The total cost is 5$! What do you think?

[Xlion]

Originally Posted by SOLAR SUPPORT

Does Lifepo4 replacement with lead acids really requires alternator replacement? Does adding a Dc-dc charger realy necessary to limit the charge current that Alternator can hande with?

I am still using AGM batteries but planing to replace them with Lifepo4 ones next year. That is why I try to understand the system requirements and trying to calculate the total cost of this transition.

Constant high loads on the alternator generate high heat energy within the alternator itself leading to malfunctioning. Because alternator can't cool enough itself and it has gone. That is it.

Isn't it possible to add a bimetal thermostat which normaly close and open over 80 degrees celcius connected to exciter of the alternator. The total cost is 5$! What do you think?

I thought about it too, but i am sure it would work just as the protection thath the Sterlin have on the external regulator, pushing the alternator to the limit, stopping it and leaving it restart till the limit is back again, making an useless fight between the alternator and the batteries which want more current. It could work or not, but appear as a cheap solution that could create other issues and not for a good professional use. And it could be useless too because i didn't say that the stock alternator usually has an overheat protection too (surely it is on the 80A stock mounted on the Yanmar YM series), i know it because talking with some people from northern europe in another european forum, they told me to have mounted on their boats (around 35ft) a 100A Lifepo4 batteries simply connecting it on the charging relais not using a dcdc charger or other things, they simply swithced from agm to lifepo4; seems that the alternator work hard for a while giving around 60A (with the stock 80A i told about before), going down (probably when the overheat protection start to work) after some minutes and doing this till the batteries are fully charged (and it happen fast). But i don't like to have a security protection that work as a normal system, i think it isn't the way it has builded for. Anyway they have a relative small Lifepo4 used mostly for daily sailing, my target instead is to have a new system with enough capacity to switch in a significant way my life on board using electricity for the stove (instead the gascylinder), nespresso machine, watermaker always on etc, otherwise all this expensive work will be just another way to burn money (and probably the alternator too.. lol). On this point of view i still can't find a better cheaper way that the Balmar offer.. but i will continue to search it for a while!

[Flod]

I have a sterling alt to bat charger to Protect my lifepo4 and my alt. I have never seen what you described. I understand that it could happen but it don’t. For me the stock alt outputs maybe 60-65A for like the first hour and if the batteries aren’t fully charged by then the Sterling (or the internal temp sensor) takes it down to 20ish A. Then it stays there and after x number of time the bank is full and the bms disconnect it. The on-off thing that you in theory can predict is not occurring in the real use case

[Xlion]

Originally Posted by Flod

I have a sterling alt to bat charger to Protect my lifepo4 and my alt. I have never seen what you described. I understand that it could happen but it don’t. For me the stock alt outputs maybe 60-65A for like the first hour and if the batteries aren’t fully charged by then the Sterling (or the internal temp sensor) takes it down to 20ish A. Then it stays there and after x number of time the bank is full and the bms disconnect it. The on-off thing that you in theory can predict is not occurring in the real use case

This is a great news, how big is your Lifepo4?

[Flod]

200ah winston so not very large. My friend have the same setup with 400ah with the same experience

[Xlion]

So I’ve been misled by some bad news as the YouTube video about the burned alternator directly connected to the lipo battery, if i had this information before surely i bought the lipo instead new agm... ty very much for the information sharing

[Flod]

I’m not saying that it’s impossible to burn your alt with a lifepo4 setup but in my setup and the use cases we have it haven’t happened during the 2 entire seasons I have had this installation

[Xlion]

Yes, and worked in the same way for my two norvegian friends... so at this point I have to say that your set work fine