LiTime 12v 230ah LFP $469

[dhays]

Is that thruster rating peak amps or continuous? Large thrusters are tough. It will be fine for my little windlass though.

I have a 500 amp carbon pile load tester along with an inverter. Ill get that carbon pile tester smoking and see how long it can take 500-600 amps.

The only information I was able to see for the Vetus was 650amp. It is a 14 year old thruster. Their current 95kg thrusters much be more efficient as they say that it is 610 amps.

 

[Barking Sands]

The only information I was able to see for the Vetus was 650amp. It is a 14 year old thruster. Their current 95kg thrusters much be more efficient as they say that it is 610 amps.

LOL...5.7KW. That's quite a bit any way you dice it!

 

[mvweebles]

"This function is only tested under the condition of soc>60%@25℃. Even so, frequent high-rated discharge will still have an impact on the life of the battery. If this peak current is output frequently, damage may even occur.".

Wow! Using a battery within the specs is not recommended. Well that certainly changes the use case recommendation!

Will Prowse's most recent review is of the Ecoflow 12v 100AH trolling battery ($220). He tests the hi-discharge claim of 300a for 30-secs which it does indeed deliver. He of course has no way to tell whether repeated high discharge use would damage the battery.

My thruster is protected by a 400a fuse. Under normal usage, it draws under 300a. I know this because last year my anchor was hopelessly fouled on a rock. I tried maneuvering the bow around using the prolonged thruster and it eventually tripped the fuse which I later discovered was a 300a fuse, not the specified 400a fuse.

At any rate, batteries designed for trolling motors seem to have slightly different BMSs.

Peter

 

[Barking Sands]

Wow! Using a battery within the specs is not recommended. Well that certainly changes the use case recommendation!

Will Prowse's most recent review is of the Ecoflow 12v 100AH trolling battery ($220). He tests the hi-discharge claim of 300a for 30-secs which it does indeed deliver. He of course has no way to tell whether repeated high discharge use would damage the battery.

Peter

I think they are just warning that hitting peaks every time will lower life expectancy. I think this is true of all Lifepo4 batts pushing large amps. I have been reading other "crazy" forums were its common to use no BMS on lifepo4 cells for windlass and thrusters. The cells themselves will do it, but at a cost to their longevity. And of course if a BMS is put inline it needs to have that amp load capability. I think this warning is just being honest that hammering these to peak every cycle comes at a cost. Like anything it would be best to leave some wiggle room. But it can do it.

I just did some testing on the little 120ah version. It can give 500 honest amps for 25 seconds. I think I was losing a bit on amps on my poor alligator clips on the terminal too. They got pretty hot. This was measured with a DC clamp amp meter on the wires so the heat loss at the alligator clips was not accounted for and I did not have a chance to read the app, which would have accounted for the heat loss too. Ill be doing a few more timed tests at various amp loads to plot it out. But a pair of these looks like 1000 amps for 25 seconds or less will work.

 

[dhays]

I think they are just warning that hitting peaks every time will lower life expectancy. I think this is true of all Lifepo4 batts pushing large amps. I have been reading other "crazy" forums were its common to use no BMS on lifepo4 cells for windlass and thrusters. The cells themselves will do it, but at a cost to their longevity. And of course if a BMS is put inline it needs to have that amp load capability. I think this warning is just being honest that hammering these to peak every cycle comes at a cost. Like anything it would be best to leave some wiggle room. But it can do it.

I just did some testing on the little 120ah version. It can give 500 honest amps for 25 seconds. I think I was losing a bit on amps on my poor alligator clips on the terminal too. They got pretty hot. This was measured with a DC clamp amp meter on the wires so the heat loss at the alligator clips was not accounted for and I did not have a chance to read the app, which would have accounted for the heat loss too. Ill be doing a few more timed tests at various amp loads to plot it out. But a pair of these looks like 1000 amps for 25 seconds or less will work.

Yeah, if one battery can do 500amps for 25 seconds, two of those could likely handle my thrusters without a problem. If I recall these are a Group 27 size so two of them would have the same footprint as an 8D.

 

[Barking Sands]

Yeah, if one battery can do 500amps for 25 seconds, two of those could likely handle my thrusters without a problem. If I recall these are a Group 27 size so two of them would have the same footprint as an 8D.

Maybe..its still cutting it close on a timeline. I guess 25 seconds is quite a bit. But each subsequent bump may reduce the next bumps time. Ill check that too. Like, how many 500 amp 20 second bumps can it do in a row separated by 20 seconds?

And then there is cost. The ones Peter linked to did an honest 300 amps for 30 seconds. You could get 3 of those. However it looks like those dont have bluetooth or any way to determine SOC..as I would assume that Epochs detailed discharge rating based on SOC would probably apply to any Lifepo4 batts. SO not knowing SOC may be a problem on occasion. You could add a shunt for SOC tracking.

Epoch is coming out with a comm box for the 120 and 300 dual purpose that may have an NMEA output. That would be REALLY nice to plumb these into a plotter so you could easily check SOC prior to deploying the thruster or Windlass.

Any way you cut...there are so many options and possible configurations its hard to make a choice...lol. And the options grow every day and a costs keep dropping.

 

[Marco Flamingo]

So all precautions needed for direct alternator charging still apply.

And if I understand the precaution, one method is to somehow have a lead acid battery in the mix and use a DC/DC gadget or other form of "protection" to avoid the possibility of an LFP BMS shutting down. I've looked around and haven't seen any actual claims of a BMS shutting down and blowing the alternator diodes, so if it happens, it is apparently rare. But what if there are two LFP batteries (#1 and #2) and the switch is set to Both? Then if Batt #1 BMS trips because of some rare anomaly, does battery #2 save the diodes? Question then is, if a BMS failure on #1 is rare as hen's teeth, is #2 failing at the same instant (i.e., Both) rare as rocking-horse apples?

Which leads me to another question. If diode failure is a likely problem, why aren't the diodes configured in a plug-and-play module serviced from the exterior of the alternator? Ooops, I fried my diodes. It will take me a minute to slip in one of my $6 diode chips that I keep as a spare. No need to pull the alternator and look for a rebuild shop.

 

[Barking Sands]

And if I understand the precaution, one method is to somehow have a lead acid battery in the mix and use a DC/DC gadget or other form of "protection" to avoid the possibility of an LFP BMS shutting down. I've looked around and haven't seen any actual claims of a BMS shutting down and blowing the alternator diodes, so if it happens, it is apparently rare. But what if there are two LFP batteries (#1 and #2) and the switch is set to Both? Then if Batt #1 BMS trips because of some rare anomaly, does battery #2 save the diodes? Question then is, if a BMS failure on #1 is rare as hen's teeth, is #2 failing at the same instant (i.e., Both) rare as rocking-horse apples?

Which leads me to another question. If diode failure is a likely problem, why aren't the diodes configured in a plug-and-play module serviced from the exterior of the alternator? Ooops, I fried my diodes. It will take me a minute to slip in one of my $6 diode chips that I keep as a spare. No need to pull the alternator and look for a rebuild shop.

More than one way to do it. The main precaution I was thinking was to have an external regulator programmed with the proper absorption voltage so it does not exceed the BMS overvolt limits such as 14.6 or 3.65 per cell which would gaurentee a bms disconnect. Most other bms disconnects other than thosevtwo are very rare. And probably add an alternator protective device like the Balmar or Sterling unit. Or use an internal regulated unit with dc2dc. But there are many other steps and tests and monitoring and temp checks you can do to ensure success.

I just added the Orion 50 amp dc2dc on my generator alternator/gen batt to do some tests this week.

I wanted to maximize charging from the little 4.4kw Westerbeke and Multiplus2.
the multiplus2 is a 120 amp charger but will heavily derate with heat. In summer here your lucky to get about 100 amps dc charging. But the gen has more to give than what the MP2 can. So I added a victron IP22 30 amp plug in charger. Then added the victron 50 amp dc2dc to take off additional power from the little Hitachi 55 amp gen alternator and set the Victron dc2dc down to 30 amps to test. The results were good and was able to squeeze out 30 amps maintaining an alternator temp of 195 f. I think the gen running at continous 1800 rpm helps with cooling. So that gave me 160 to 165 amps charging off an 8hp (rated at 1800) baby generator. Gen hz no load 62.5 and loaded about 59.5. I think thats all she's got..lol.

I will get one more 50 amp dc2dc for the Perkins driven 100 amp Balmar and set at 50 amps. That should get me up to 200 to 210 charge amps for the 920ah lithium batt pack. I'll see if I can squeeze in around 600 to 800 watts solar soon. Big batt banks are great but getting the capacity back in seems to be the main challenge.

 

[Marco Flamingo]

Which leads me to another question. If diode failure is a likely problem, why aren't the diodes configured in a plug-and-play module serviced from the exterior of the alternator? Ooops, I fried my diodes. It will take me a minute to slip in one of my $6 diode chips that I keep as a spare. No need to pull the alternator and look for a rebuild shop.

To quote myself and maybe answer my own question, it looks like Balmer may have the solution if I understand what this gadget does. An external "alternator protection module" that attaches to the back of the alternator. I'll have to look into it to see if it can handle the voltage surge from a LFP BMS shutting off. Seems too simple a solution, although literature says it handles the voltage surge from a lithium battery BMS shutting off. $80 solution?