Will Prowse testing drop in Lifepo4 over current protection. Quite surprising.

[Barking Sands]

Some of these "halfway decent" batteries dont appear to do what they should do. Many complaints on drop ins are that they are too quick to shutdown on a particular amp load. But not shutting down at all is probably worse. Of course that is just confirmation for the need of a proper fuse. But I have seen some rely on BMS parameters alone to constrain amp loads. Looks like some BMS protections on common batts dont even work.

 

[tiltrider1]

I know the Eco-worthy batteries shut down instantly when dead shorted. I don’t know what would happen if you tried to pull 250 amps, they are rated for 200 amps. On the other hand, other than a dead short I can’t imagine more than 100 amps hitting my bank which is 4x200 BMS.

 

[Delta Riverat]

Got it covered. 250A terminal fuses on all batteries, 400A class T on main. Not going to worry about it.

 

[mdstrum]

WE have a bank of six battleborn 100amp and have had NO issues for the last 3 years...we have also have 4 in our sprinter class B RV same no issues, we have run large loads and run them all way down, I think the issue is getting a quality company and talking to there support prior to install so ensure everything in the system is compatible and configured correctly to work with the BMS/Batteries

 

[tiltrider1]

WE have a bank of six battleborn 100amp and have had NO issues for the last 3 years...we have also have 4 in our sprinter class B RV same no issues, we have run large loads and run them all way down, I think the issue is getting a quality company and talking to there support prior to install so ensure everything in the system is compatible and configured correctly to work with the BMS/Batteries

I agree, factory support is going to be one of the most important features to purchasing a battery.

While you can buy really cheap LFP’s off of Amazon I chose a company that answered the phone and could give me technical answers. That company was Eco-worthy. One year in I am satisfied. However, things have changed. You can now bet Bluetooth monitoring and self heating batteries. There are now more things to consider before just buying a name or amp hours.

 

[Delta Riverat]

I went with Li Time because they had consistent good Will Prowse reviews for performance and build quality and a UL approved BMS. The new 280 AH unit also has low temp protection but the 300's don't. Wasn't worried about that though as it doesn't freeze here.

 

[rgano]

Thanks for posting that test. I am not about to switch to lithium-based batteries on my boat for a whole host of reasons, but I enjoyed learning about the belt and suspenders mode (fusing them) he suggests as well as other aspects of these batteries.

 

[SeaGator]

Watching Will Prowse YouTube videos is a must for anyone thinking of changing over to lithium and wondering which battery to invest in.

I went with two LiTime 460Ah batteries in parallel. Best bang for the buck when they were on sale. They also have good DC to DC chargers if you don't want to pay the cost of the popular blue brand.

 

[twistedtree]

I went with Li Time because they had consistent good Will Prowse reviews for performance and build quality and a UL approved BMS. The new 280 AH unit also has low temp protection but the 300's don't. Wasn't worried about that though as it doesn't freeze here.

I’m curious what UL standard the BMS meets? Do they say?

 

[Delta Riverat]

UL 1973

 

[Jeff F]

Got it covered. 250A terminal fuses on all batteries, 400A class T on main. Not going to worry about it.

I thought I had it covered. Then one day I shorted out the + terminal on the alternator with a wrench.

As far as I can tell both batteries disconnected briefly as designed, then came back to life shortly after.

 

[Delta Riverat]

Hehe, must have caused a "tense moment", eh? My batts are rated for 200A continuous and 400A for 5 seconds. I think the fuse would go before the BMS shut down. That's of course after the wrench welded to the case...

Another reminder to lift the batt negatives before working on stuff connected to the batteries -

 

[heysteve]

I put a Blue Sea 5191 terminal fuse block on each battery as extra insurance. Simple and easy to do.

 

[Delta Riverat]

Yup, have one on all 3 batteries. Good to have fuse close to battery eh? Couldn't get any closer than a terminal fuse.

 

[HeadedToTexas]

Between starting our big Cummins QSB, running our electric bow thruster, 1000 watt electric windlass, 3000 watt Xantrex inverter, electric stove, and generator starting, it feels like we have a lot of electrical load demands. Overcurrent protection and alternator protection when the BMS disconnects are both critical. Are you guys running LiFePo batteries supplying the same types of loads, or do you have lead acid batteries to supply those higher current demands?

 

[twistedtree]

Between starting our big Cummins QSB, running our electric bow thruster, 1000 watt electric windlass, 3000 watt Xantrex inverter, electric stove, and generator starting, it feels like we have a lot of electrical load demands. Overcurrent protection and alternator protection when the BMS disconnects are both critical. Are you guys running LiFePo batteries supplying the same types of loads, or do you have lead acid batteries to supply those higher current demands?

I’m using LFP in two different instances to power 16kva of inverters with no issues. I have run hvac, electric dryer, electric over, two 240v Watermakers, and even a 250a miller
Welder. I have dual BMSes rated at 1000a each. Recharge is at 575a from generator, or 350a from alternators. What a system can do all depends on how you build it

 

[SteveK]

Are you guys running LiFePo batteries supplying the same types of loads, or do you have lead acid batteries to supply those higher current demands?

I am using start battery to operate engine starter & windlass. While house bank could do it, my thought is the start battery will be fully charged in short order, whereas the depleted house bank takes longer time, so why add to house charge time.

 

[Delta Riverat]

I have dedicated lead acid engine starting batts and 880 AH LiFePO4 (280 on House 1 and 600 on House 2) to run everything else on the boat.

The LiFePO4 bank is capable of 600A continuous in parallel.

 

[rslifkin]

I’m using LFP in two different instances to power 16kva of inverters with no issues. I have run hvac, electric dryer, electric over, two 240v Watermakers, and even a 250a miller
Welder. I have dual BMSes rated at 1000a each. Recharge is at 575a from generator, or 350a from alternators. What a system can do all depends on how you build it

Out of curiosity, is that 16 kva of inverters running on 24v or 48v? That's quite a bit of power.

 

[twistedtree]

Out of curiosity, is that 16 kva of inverters running on 24v or 48v? That's quite a bit of power.

24v. I would have preferred 48, but there were/are no mainstream high output, continuous duty alternators available.

 

[rslifkin]

24v. I would have preferred 48, but there were/are no mainstream high output, continuous duty alternators available.

Any issues dealing with the huge currents involved? I'm debating whether to stick with 12v for 6kva worth of inverters or to go through the pain and expense of converting an existing 12v boat to 24v (and still needing a 12v bus for certain things).

 

[twistedtree]

Any issues dealing with the huge currents involved? I'm debating whether to stick with 12v for 6kva worth of inverters or to go through the pain and expense of converting an existing 12v boat to 24v (and still needing a 12v bus for certain things).

It’s fine, but it’s a lot of copper in cables and bus bars. I think it’s telling that it’s hard to fine an inverter over about 5kw that is 12v, and that some of Victron’s larger inverters are now available in 48V.

Id do everything I could to avoid building a 6kw system in 12v, especially with LFP. The voltage drops become significant very quickly such that everything needs remote voltage sensing, and there is still a lot of equipment that doesn’t have it. But I appreciate the difficulty in switching. But I’d try real hard to find a way.

 

[psneeld]

build a 24-48 volt battery bank out of 12V batteries that can be separately tapped for 12V needs?

 

[rslifkin]

It’s fine, but it’s a lot of copper in cables and bus bars. I think it’s telling that it’s hard to fine an inverter over about 5kw that is 12v, and that some of Victron’s larger inverters are now available in 48V.

Id do everything I could to avoid building a 6kw system in 12v, especially with LFP. The voltage drops become significant very quickly such that everything needs remote voltage sensing, and there is still a lot of equipment that doesn’t have it. But I appreciate the difficulty in switching. But I’d try real hard to find a way.

That's the dilemma I've been facing. It would be 2x 3kva inverters, so the biggest single amp draw device would be in the 300 - 400A range, and the inverter to battery distance is only a few feet. But it's a lot of current to deal with. Charging sources would be all Victron (inverters, MPPTs and DC-DC converters) so DVCC takes care of the remote voltage sense issue at least. In that sense it's less current than 16kva at 24V, but it's still in the realm of 24V being preferable.

I'll have to do a thorough audit of systems on board to figure out what can take 24V as-is, what can be replaced (and at what cost) and what has to stay 12V no matter what.

Realistically, I don't actually need to be able to pull 6kva from the inverters, but a single 3kva isn't quite enough I think (too much power management when cooking unless I fire up the gen). 4 - 5 kva would be plenty, but I'm looking at the Victron 2x120 units (which only come in 3kva).

 

[twistedtree]

build a 24-48 volt battery bank out of 12V batteries that can be separately tapped for 12V needs?

That doesn’t work with LFP, creating a very difficult balancing problem. With lead the batteries balance out during absorb and float. Basically the high cells get overcharged while the lower cells catch up. Lead is fine with such an overcharge, but LFP isn’t.