insufficient battery alternator charging for lithium battery

[ers61]

I connected lithium batteries to alternator. I've 2 alternators (catamaran) they are rated @125 amps however charging is 40-50 amps max. 2 at the same time maybe 70-80 max. what is limiting the current ? they are smart alternators with voltage input. is it alternator sensing the engine battery to limit current or anything else to test ?
according to many people on internet alternator would have burn't from overheating or overdelivering their rated current at lower rpms. what is different ?

[SOLAR SUPPORT]

The permanent capacity of the alternator is not the same as the capacity written on the label. When charging lithium batteries, a dc-dc charger or an external regulator that controls the operation of the alternator is used, which reduces the alternator current label capacity by approximately 50-60%. Your setup looks safe.

[Pete7]

That 125A rating is likely at much higher alternator revs than your engine/alternator pulleys are geared for. Looking at the Victron YT videos of the alternator burning up, they are running the alternator quite slowly so not enough cooling for the power generated.

We see 50A from our 100A alternator, again pulley ratios are the likely problem, but I don't want to spend $500 to change that. Also since we have an old VP 2003 the belt is only 3/8" or so. Nor do we need to. The DC>DC Orion will produce 30A for charging our LifePO4 and that is sufficient for the occasional need if solar isn't keeping up.

If your alternators are only warm and not hot, then as SS suggests leave well alone and the alternators should last a long time.

Pete

[carraiguna]

I have a similar setup with 2 x Valeo alternators = 125 amps rating.
Lithium bank 400 Ah.
Alternator output would drop after 10 minutes running to 30-40 amps.
I fitted 2 x Balmar 618 external regulators and now I get a steady 80 amps from the alternators with alternator temp ~ 95 degrees.
The Balmar belt manager setting is 75% and temperature limit is 99 degrees.

[ers61]

Originally Posted by SOLAR SUPPORT

The permanent capacity of the alternator is not the same as the capacity written on the label. When charging lithium batteries, a dc-dc charger or an external regulator that controls the operation of the alternator is used, which reduces the alternator current label capacity by approximately 50-60%. Your setup looks safe.

yes i know but the interesting bit is i didn't use these. technically i would expect my alternators to run hot and burn but that didn't happen.

[ers61]

Originally Posted by Pete7

.

We see 50A from our 100A alternator, again pulley ratios are the likely problem,

why would they do that ? it's the stock alternator on yanmar engine.what's the point of putting a pulley which won't run the alternator at full power ? and if this is the case then why people buying dc-dc chargers or balmar regulators for the existing alternator ?

what i can see is connecting lithium direct to alternator is no problem soo far

[ers61]

Originally Posted by carraiguna

I have a similar setup with 2 x Valeo alternators = 125 amps rating.
Lithium bank 400 Ah.
Alternator output would drop after 10 minutes running to 30-40 amps.

what i understand from your reply is the valeos regulate itself and drop the current when get hot ? like after 10 minutes ? this could be the reason than. its a shame they get hot after 10 mins though

[Pete7]

Originally Posted by ers61

why would they do that ? it's the stock alternator on yanmar engine.what's the point of putting a pulley which won't run the alternator at full power ? what i can see is connecting lithium direct to alternator is no problem soo far

My 100A alternator is an OEM replacement for the original 50A Valeo. I just used the same pulleys. New pulleys could change the ratio and spin the alternator much faster increasing the output.

Why don't manufacturers do it? probably because they want the alternator to last and as standard it meets most customers needs. What is 125A, 3hp perhaps, customers want that rather than 125A on a charter boat, the big market at the moment.

[carraiguna]

Yes, I originally expected to have issues with the Valeo's running very hot like in the Victron YT video. I had planned to purchase the Balmar 618 but I was in the Caribbean and operated for a couple of months before I got them.
If you measure the output of the alternator (clamp meter right at the alternator) you will see that it starts out delivering 90+ amps and then drops after some time 10 - 20 minutes. There must be some form of internal regulation.
Now I feel much better being able to regulate the output to a steady 80 amps using the "belt load feature" and also have the backup casing temperature limitation provided with the Balmar programmable temperature limitation.

[kmacdonald]

Originally Posted by Pete7

That 125A rating is likely at much higher alternator revs than your engine/alternator pulleys are geared for. Looking at the Victron YT videos of the alternator burning up, they are running the alternator quite slowly so not enough cooling for the power generated.

We see 50A from our 100A alternator, again pulley ratios are the likely problem, but I don't want to spend $500 to change that. Also since we have an old VP 2003 the belt is only 3/8" or so. Nor do we need to. The DC>DC Orion will produce 30A for charging our LifePO4 and that is sufficient for the occasional need if solar isn't keeping up.

If your alternators are only warm and not hot, then as SS suggests leave well alone and the alternators should last a long time.

Pete

Yes. I have a 40 amp alternator and a 30 amp victron DC to DC charger. LA start battery wired to alternator. When I run the motor its for propulsion, not for charging. I use a honda generator (EI2200) to run a 75 amp Iota charger when solar wont keep up. Thats usually only in the winter months with less solar charging time. Charging with propulsion engines is expensive. By the way, an alternator takes 1 HP per 25 amp output at 12V. My alternator never outputs more than 30 amps at any reasonable cruise rpm and it doesnt get very hot. 326 AH LiFePO4 and 320 W solar.

[hlev00]

Use your IR thermometer to check the alternator temperature when it is not charging as expected. That will help inform you if it is likely throttling due to temperature. If you don't have one, you should. They are very helpful. If nothing else they help settle the debate over how cold the water is before swimming.

How is the ventilation in your engine room? I bought my boat used and the blower was not working at the time of purchase so I never realized I needed one until my four month old Balmar died, likely from over heating despite its derating under over heating conditions. At least that was Balmar's best guess at the time.

Harry

[ers61]

Originally Posted by hlev00

Use your IR thermometer to check the alternator temperature when it is not charging as expected. That will help inform you if it is likely throttling due to temperature. If you don't have one, you should. They are very helpful. If nothing else they help settle the debate over how cold the water is before swimming.

How is the ventilation in your engine room? I bought my boat used and the blower was not working at the time of purchase so I never realized I needed one until my four month old Balmar died, likely from over heating despite its derating under over heating conditions. At least that was Balmar's best guess at the time.

Harry

what is a good temperature reading for an alternator?

[ers61]

Originally Posted by kmacdonald

Yes. I have a 40 amp alternator and a 30 amp victron DC to DC charger. LA start battery wired to alternator. When I run the motor its for propulsion, not for charging. I use a honda generator (EI2200) to run a 75 amp Iota charger when solar wont keep up. Thats usually only in the winter months with less solar charging time. Charging with propulsion engines is expensive. By the way, an alternator takes 1 HP per 25 amp output at 12V. My alternator never outputs more than 30 amps at any reasonable cruise rpm and it doesnt get very hot. 326 AH LiFePO4 and 320 W solar.

so you can take full 40 amp from your alternator. istill wonder why i can't take 125amps. whats the point it it drops after 10minutes why they label it as 125 amps?

[ers61]

Originally Posted by Pete7

That 125A rating is likely at much higher alternator revs than your engine/alternator pulleys are geared for. Looking at the Victron YT videos of the alternator burning up, they are running the alternator quite slowly so not enough cooling for the power generated.

We see 50A from our 100A alternator, again pulley ratios are the likely problem, but I don't want to spend $500 to change that. Also since we have an old VP 2003 the belt is only 3/8" or so. Nor do we need to. The DC>DC Orion will produce 30A for charging our LifePO4 and that is sufficient for the occasional need if solar isn't keeping up.

If your alternators are only warm and not hot, then as SS suggests leave well alone and the alternators should last a long time.

Pete

where can i find for valeo/yanmar 125 amp altenator rating ? maybe this is the case

[sailorboy1]

It is something in the regulation of the alternator. So how is it regulated?