DC-DC Charger

[heysteve]

Or I can add 2-6v GC for under $500 and get an extra 200 Ah and also save $ by not needing a DC2DC charger for the lithium.
10-6v GC 1000 Ah for same price as one Kilovault 200Ah, hmmm. Did I mention I have a generator?

I haven't checked prices lately, but I was under the impression that LFP batteries were generally price competitive with LA when comparing useable AHs. It's all the other changes to the charging/electrical system that makes it expensive.

Also, charging by generator is WAY better with LFP as you can charge at max rate up to 98% SOC or so. Of course, if you have a great solar setup then that helps mitigate the LA charging issue but that's often a challenge on smaller trawlers.

 

[CMS]

PB
"Marine how to", Rod Collin's website, has many good tips and articles on this multi layered subject. Nigel Calder is on top of this area as well. He has a great ongoing blog worth pulling up on UTube.

BTW, not all are fans of Renogy LFPs so double check pros and cons of others with Rod's website as a guide.

For Drop-ins this may help:
https://marinehowto.com/drop-in-lifepo4-be-an-educated-consumer/


FWIW MHT is now supported by reader donations and affiliate programs. Renogy is so bad, customer service is offensively bad, ask me how I know... that you won't find it under any of our recommended products links. We won't do that to our readers..Buy Renogy but plan on zero support...

 

[SteveK]

I haven't checked prices lately, but I was under the impression that LFP batteries were generally price competitive with LA when comparing useable AHs. It's all the other changes to the charging/electrical system that makes it expensive.

Also, charging by generator is WAY better with LFP as you can charge at max rate up to 98% SOC or so. Of course, if you have a great solar setup then that helps mitigate the LA charging issue but that's often a challenge on smaller trawlers.

Say I have $1200 burning a hole in the pocket. I can buy 4-6v GC batteries and get 400 Ah of which 200Ah is suggested usage OR
I can buy a single 200Ah lithium where it is 100% usable.
The conversion costs to Li don't seem to have an end.

 

[SteveK]

For Drop-ins this may help:
https://marinehowto.com/drop-in-lifepo4-be-an-educated-consumer/


FWIW MHT is now supported by reader donations and affiliate programs. Renogy is so bad, customer service is offensively bad, ask me how I know... that you won't find it under any of our recommended products links. We won't do that to our readers..Buy Renogy but plan on zero support...

I have read that article a few times now. Any idea when it was written? Things continue to change rapidly and what was correct last year may be incorrect this year.

 

[Iggy]

The Kilovault looks impressive, but pricey outside of the US, $2500 Can$ Over twice the Ampere Time and renogy for example. I would rather buy two than put all the eggs in one basket. Or I can add 2-6v GC for under $500 and get an extra 200 Ah and also save $ by not needing a DC2DC charger for the lithium.
10-6v GC 1000 Ah for same price as one Kilovault 200Ah, hmmm. Did I mention I have a generator?

I don't now where in Canada you are but they have a warehouse just 15milies south of Boston. ROAD TRIP!!!!

 

[SteveK]

I don't now where in Canada you are but they have a warehouse just 15milies south of Boston. ROAD TRIP!!!!

Has Winthrop moved to Boston.

 

[Iggy]

Has Winthrop moved to Boston.

Not yet! But it is the next town north of Boston.

 

[SteveK]

Not yet! But it is the next town north of Boston.

well you got me, I am used to Winthrop WA, which is just south about 20 miles, nice little town.

 

[CMS]

I have read that article a few times now. Any idea when it was written? Things continue to change rapidly and what was correct last year may be incorrect this year.

It is continually updated last edits were this morning...

 

[CarlF]

I have five 300AH Kilovaults (1500AH). The start battery is charged by a Victron DC-DC charger. I upgraded the alternator to a Balmar XT170 and use a Wakespeed regulator. Been using this combination for a year and it has worked out great. Some observations:

Go for at least 800AH of battery. The whole reason for these batteries is to be able to go a long time at anchor without starting a genset. 1500AH lets me go for two days or more (with solar helping)

The Kilovaults must be installed with “equal length cables” to a bus bar. Wiring them like AGMS’s in a string with a plus cable at one end and a negative cable at the other end will void the warranty. Lithium batteries have extremely low internal resistance so they tend to charge and discharge unequally unless the cables are equal length.

If you are putting in an alternator over 100amps it makes no sense to use just 30-60 amps of the 100 amps to charge the house bank through a DC-DC charger. Some installers are putting in multiple DC-DC chargers but this is kind of silly.

An alternator charging a house bank must use an external regulator with a temperature sensor on the alternator to reduce the charging rate if it overheats. The Balmar XT170 is a great alternator for Lithium’s as it has special windings and cooling to stand up to the huge draw of a lithium bank. It will keep pumping out 150amps even when hot. A typical OEM alternator will be lucky to put out 50amps after it’s hot (if it doesn’t self destruct). If you want to stick with a typical alternator then have it charge the start batteries and send 30amps to the house with a DC-DC charger (not that 30 amps will do much). I prefer the Wakespeed over the Balmar regulator. You can program it with a cell phone connection and it also communicates with Victron displays so you know what’s going on. It also can be set up to control charge based on amps in and out rather than just voltage.

A well designed lithium system should never have a BMS shutdown. Mine has never come close. But you do need to protect your alternator just in case. The Victron DC-DC charger will absorb the surge of a BMS shutdown by sending it to the start battery. For belts and suspenders also install a Balmar Alternator Protector on the alternator.

Be sure the installer uses big cables (I have 2/0 between batteries and 4/0 to the main bus). Also a T-Class fuse. I also put a Blue Sea MBRF fuse on each Kilovault battery to meet the ABYC standard that a fuse should be within 7” of the battery.

 

[Bduffey]

Morning

You could also consider the ProIsocharge from Promariner. You put the alternator output to the unit and it will first charge up the start batteries and then it will direct the alternator output to the second, etc. You can have from 2 to 4 banks, with 1st being the priority bank that will get charged up first. The unit will not allow any power being shared between banks. It’s just charging input only, not power distribution. They function fully automatic and can work with the advanced external alternator regulators.

You will need to isolate the start batteries from the house. You can use 3way heavy duty switches so you can connect them back for emergency start, etc.

All my batteries are the same chemistry which makes life much easier.

I have one for each alternator and they works quite well.

Available is several combinations of output capacity and number of banks required.

Safe Travels

 

[Iggy]

The ProIsocharge sounds very interesting! But In the overview on there site it sounds more like a normal isolator with no voltage drops like the olds ones, but giving the starting bank priority. As you mentioned, you can not mix chemistry. I am sorry to say that the ProIsocharger charger can not do what a DC to DC charger can do. Mix chemistry.

But the point behind all this, is how to charge you starting bank and your Li bank. That's were the DC to DC charger fits into this thread.

" ProIsoCharge delivers digitally controlled alternator output distribution while protecting the health of engine start batteries, isolating and charging up to 3 other independent battery banks off of a single alternator (model specific). For dual engine applications, ProIsoCharge offers an exclusive 2 alternator input model with up to 4 battery banks. Save space and time by eliminating traditional diode based isolators and ancillary voltage sensitive relays or solenoids, isolating and charging multiple battery banks simultaneously."

 

[SteveK]

Fet isolator for FLA start and lithium house. Will that work to protect the alternator from a lithium shutdown and yet continue to charge full tilt the lithium?

 

[C lectric]

If the BMS shuts down the Li batteries then they are isolated from the alternator so no more charge will go to the Li batts.

Charge will continue to the eng. start batts. through the FET isolator. There could still be a catch though with the alternator. If the eng. start batts are full and the Li through the BMS is disconnected you could still damage the alternator.

If the disconnect is abrupt enough, with no where for the charge current to go, there will be a voltage spike at the alternator from the abrupt cut off which will likely blow the diodes.

One thing I can think of doing is to tie the BMS to a small relay that is installed in the alternator armature control line from the external regulator.

That way as the BMS disconnects the Li batteries it also disconnects the armature/regulator line so there is no more current telling the alter. to produce current.

There ae some details to work out such as a bypass switch for the armature/regulator feed line so once the event is done the regulator/alternator could still be armed to continue producing current for the eng. start batts. and the other loads.

However, this is a suggestion and some poking about will be needed to ensure it will work. There may be some cautions to be observed. Talk to the regulator and battery mfgr. representatives.

 

[SteveK]

I have lost interest in Lithium conversion.
It will be easier to add or replace FLA as everything is geared to it. Too many things need to be added to convert totally and too many dead ends to convert partially.

Lithium conversion needs to be part of a complete rebuild plan $$$$ to replace what already works.

 

[Iggy]

I have lost interest in Lithium conversion.
It will be easier to add or replace FLA as everything is geared to it. Too many things need to be added to convert totally and too many dead ends to convert partially.

Lithium conversion needs to be part of a complete rebuild plan $$$$ to replace what already works.

I disagree with you, but to each there own.

I added lithium to my house bank. My house bank was connected directly to the ALT and a VSR was used to charge the starting bank. I remove the VSR, add two DC to DC chargers using the wires from the VSR. Moved the Alt sense wire to the starting bank and I was done. I already had two battery switches connected, one for the house and a parallel switch. Other than cabling and adding some fuses, I was done.

I have three house batteries, if all three BMSs where to shut down the ALT is protected. Than turn the house bank off and turn the parallel switch on. Up and running again!

The problem using a isolator is that your using the Alt's regulator to charge and that can only be setup for flooded/AGM or Li. Not both.

This worked all last year with no problems and a little fine tuning to the setting in the DC to DC chargers. The Bluetooth app was great to see into each battery and see what was going on and the chargers had there app too.

 

[catalinajack]

Thanks, at twice the renogy.

This is where I find shopping for this product interesting.

We only know what product we have used, is one twice the cost twice as good.

Sometimes, price equates to quality.

 

[catalinajack]

sunchaser;



All LFP cells are made in China.



Bruce

Are they all made by the same manufacturer? Don't you think there may be different quality control among the different producers?

 

[catalinajack]

mvweebles;



That seems to be the way with Chinese companies. They will stonewall you until you give up.



If I do buy Renogy, I will pay with the credit card and not my debit card.



Bruce

Debit cards have long had the same purchase protections as do credit cards. My wife just had this experience with a Chinese "leather" pocketbook purchased with a debit card. Emails for a return went unanswered until a dispute was initiated. Then, they asked us to suspend the dispute. No way. Got credit to our account within a week. Then, they wanted us to return the product at our expense even though their website said otherwise. When we get a prepaid shipping label, they will get the pocketbook back. I suspect we will not hear from them again. Nope, we will never purchase ANY product directly from China. Far too much risk.

 

[catalinajack]

Say I have $1200 burning a hole in the pocket. I can buy 4-6v GC batteries and get 400 Ah of which 200Ah is suggested usage OR

I can buy a single 200Ah lithium where it is 100% usable.

The conversion costs to Li don't seem to have an end.

LFP batteries are not 100% useable. They are 80% useable in the same sense that FLA batteries are 50% useable.

 

[Jeff F]

This worked all last year with no problems and a little fine tuning to the setting in the DC to DC chargers. The Bluetooth app was great to see into each battery and see what was going on and the chargers had there app too.

Sounds very well thought out.

I had a flash of inspiration reading your post. Do you have separate chargers for each bank?

I have two batteries in parallel. Maybe assigning a charger to each would solve a minor nagging concern. I suppose I'd have to add another shunt as well, but that's NBD.

 

[Jeff F]

LFP batteries are not 100% useable. They are 80% useable in the same sense that FLA batteries are 50% useable.

Mmm. That's not quite true.

 

[catalinajack]

I disagree with you, but to each there own.

I added lithium to my house bank. My house bank was connected directly to the ALT and a VSR was used to charge the starting bank. I remove the VSR, add two DC to DC chargers using the wires from the VSR. Moved the Alt sense wire to the starting bank and I was done. I already had two battery switches connected, one for the house and a parallel switch. Other than cabling and adding some fuses, I was done.

I have three house batteries, if all three BMSs where to shut down the ALT is protected. Than turn the house bank off and turn the parallel switch on. Up and running again!

The problem using a isolator is that your using the Alt's regulator to charge and that can only be setup for flooded/AGM or Li. Not both.

This worked all last year with no problems and a little fine tuning to the setting in the DC to DC chargers. The Bluetooth app was great to see into each battery and see what was going on and the chargers had there app too.

I agree with Steve K. Unless you are that boater who anchors for more than three days on a very regular basis, LFP (IMHO) is just not worth the bother and never mind the expense. My luddite FLA eight golf car house bank, which doubles as my starting battery, is 6 years old and tests to 97% of original capacity (150 documented 50% or sometimes more cycles). In 4 or 5 years, I can replace it for $1,500. I am 72 years old. I would never come close to breaking even on a quality LFP installation.

We are not marina-to-marina boaters. We are in one place more often just one night, sometimes two nights, and occasionally three nights. It takes us 16 hours of profligate juice use to get to 50% SOC. If we chose to be juice misers, we could likely last two days without the generator, but we don't bother. One night stays? The next days run, the batteries are fully recharged in less than six hours. Two night stays require about two hours of generator time. So, LFP (and solar) would not add anything to my boating experience. For some, it does, but at a significant cost and tons of installation headaches; to wit, this lengthy discussion.

My sense is that, for many use profiles, LFP is that new and shiny thing that some just must have.

 

[Jeff F]

My sense is that, for many use profiles, LFP is that new and shiny thing that some just must have.

That I can agree with!

 

[catalinajack]

Mmm. That's not quite true.

So, educate me. What is the useful range of LFP batteries, and how long will they last at various states of discharge? Surely, you are not suggesting it is 100%. According to Victron's datasheet, their LFP batteries are good for 2,500 cycles at 80% discharge, 3,000 cycles at 70%, and 5,000 cycles at 50%. Obviously, discharging them more than 80% will reduce the number of cycles beyond 2,500. How many cannot be known, but it is likely a significant reduction, which is a huge factor in lifetime ownership costs.View attachment Datasheet_12_8_&_25_6-Volt-LiFePO-batteries-Smart-EN (1).pdf

 

[Jeff F]

Yeah, but LFP will happily live at 10% SoC for months on end with little if any harm.

I dunno. As I've pointed out elsewhere, I drove an electric car for four years. Three of my kids learned to drive in it. Plugged it in every night and occasionally pushed it in the driveway.

After 4 years the battery was at 96% original capacity. On my boat I'll use 100% of capacity whenever it suits me.

ETA: I'm currently living aboard tied up. I've got my LPO bank on small house loads plus the inverter. The inverter shares AC power with 9 kw heat + bubblers. Inverter is throttled to about 600w AC input.

So net effect is that I have a steady load of ~15a, spiking at times to ~150a for an hour max, supported by a ~40a charger. It's an interesting and useful real-world experiment that's been very successful.

Lithium makes this possible. Not that it would be impossible with LA, but you probably wouldn't go there. My SoC varies between 20-100%. I don't really care where it is in that range.

Eta2: I was always last in line to drive that car in my household. I'll own another some day.

 

[twistedtree]

Sounds very well thought out.

I had a flash of inspiration reading your post. Do you have separate chargers for each bank?

I have two batteries in parallel. Maybe assigning a charger to each would solve a minor nagging concern. I suppose I'd have to add another shunt as well, but that's NBD.

As long as the batteries are paralleled, it won't make any difference. I guess I'm not seeing any advantage. If one battery disconnects, you would still want both chargers operational on the remaining batteries. And if a charger dies, you would still want the surviving charger to charge all batteries. In fact, with internal BMS disconnects, I don't see how you can direct the charge output in any way. Or maybe I'm not understanding the configuration?

 

[twistedtree]

Yeah, but LFP will happily live at 10% SoC for months on end with little if any harm.
.
.
.

ETA: I'm currently living aboard tied up. I've got my LPO bank on small house loads plus the inverter.

Do you really mean LPO (lithium-ion polymer), or do you mean LFP (LiFePO4)?

 

[Jeff F]

Do you really mean LPO (lithium-ion polymer), or do you mean LFP (LiFePO4)?

Sorry. I'm working on accurate terminology. Sometimes I slip. I meant LFP.

 

[Jeff F]

As long as the batteries are paralleled, it won't make any difference. I guess I'm not seeing any advantage. If one battery disconnects, you would still want both chargers operational on the remaining batteries. And if a charger dies, you would still want the surviving charger to charge all batteries. In fact, with internal BMS disconnects, I don't see how you can direct the charge output in any way. Or maybe I'm not understanding the configuration?

This is related to my earlier thread. Right now I have two batteries hard-wired in parallel. I'm brainstorming ways to monitor each, or at least recognize a disconnect.

But now that I think about it, charging them independently has no value for me as I want to keep the batteries combined in a single bank.

Never mind.