DC to DC charger size

[ice breaker]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

 

[MFD]

I have the original Hitachi 80 amp on my yanmar.
Start battery is still AGM, house bank is new 2x460AH LifePO4.
I bought a Victron OrionXS 50 amp DC=>DC charger.
I currently have it set to limit itself to 40 amps on the input side thinking this would be a reasonable starting point for some testing.
I only have a few hours on the engine so far and it has seemed okay.

When I do some sustained motoring distance later this year and its warmer outside, I plan to watch data on the Orion and check the alternator temperature, etc. and see if I can adjust it up to the full 50 - or (hopefully not) need to lower it.

These Hitachi's are notoriously horrible alternators for sailboats, and getting even 50% (40a) out of them is probably asking too much once they warm up. Maine Sail has a pretty good article on them. One day I might replace it, like when it finally fails.

 

[Johann]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

I have been using the old Victron Orion Smart Tr 30A DC charger from an 80A Hitachi for about 5 years and no problems. The old Orions are pretty inefficient so the alternator was outputting about 40A with no overheating. But my engine room is fairly well ventilated. You could use the new efficient Orion XS 50A. You can adjust the output and input current setting in the Bluetooth app. There shouldn’t be any worries about the starter battery, as there is an ignition activation for the Orion, as well as input voltage lockout/engine running detection.

 

[Stu Jackson]

Maine Sail has a pretty good article on them. One day I might replace it, like when it finally fails.

Here is the article, in full:

Hitachi/Yanmar Alternators: (by Maine Sail)

Some alternators though, such as those made by Hitachi and found on Yanmar diesels, are dumber than a pound of beetle poop. Actually, to the alternator, they are pretty smart but to your batteries and the speed of charging they are flat out stupid. Why?

Hitachi alts with dumb regulators, and some others, limit voltage but also reduce voltage based on alternator temperature. This is a self protective feature installed in the internal dumb regulator to prevent the alternator from cooking itself. Remember voltage is the pressure that allows more current to flow. So, if we reduce the absorption voltage, then we also reduce the current the alternator is supplying.. Any battery at any state of charge simply will not accept the same current at 13.4V that it did at 14.4V and as a result the alternator will run cooler. What do you suppose this does to your batteries over time.......?

The problem is that when cold you will get 14.3V to 14.4V out of the Hitachi but as the alternator heats up the dumb regulator begins to reduce the CV/voltage limit based on the alternators internal temperature. It is not uncommon to find a Hitachi alternator at 13.4V when hot. This is REALLY, REALLY DUMB....

If you have a dumb regulator, and notice the voltage dropping, it is likely a temp compensated dumb regulator. Get rid of it or plan to buy new batteries more often.

If you have a temp compensated alternator or a Hitachi alternator on a Yanmar you really are in dire need of external regulation if deep cycling a larger battery bank.

This is from:
http://forums.sbo.sailboatowners.com/showthread.php?t=125392
and these, too:
Hitachi Alternator and Smart Regulator Instal Question - Cruisers & Sailing Forums
Most practical way to upgrade Yanmar alternator? - Cruisers & Sailing Forums

 

[Johann]

I have the original Hitachi 80 amp on my yanmar.
Start battery is still AGM, house bank is new 2x460AH LifePO4.
I bought a Victron OrionXS 50 amp DC=>DC charger.
I currently have it set to limit itself to 40 amps on the input side thinking this would be a reasonable starting point for some testing.
I only have a few hours on the engine so far and it has seemed okay.

When I do some sustained motoring distance later this year and its warmer outside, I plan to watch data on the Orion and check the alternator temperature, etc. and see if I can adjust it up to the full 50 - or (hopefully not) need to lower it.

These Hitachi's are notoriously horrible alternators for sailboats, and getting even 50% (40a) out of them is probably asking too much once they warm up. Maine Sail has a pretty good article on them. One day I might replace it, like when it finally fails.

A couple of summers ago we motored about 20 hours (two 10 hour days) with the 80A Hitachis at 38-40A output the whole time. It was Florida hot and we ran the AC the whole trip so the Orions stayed in bulk at 30-32A. I had just added cooling fans to the Orions so I was keeping track of their output and efficiency. As long as you have some ventilation I think you will be fine at 40A from the XS.

 

[Stu Jackson]

ANY and ALL alternators WILL WORK more cooly when they are current limited.

 

[Maine Sail]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

Use a Victron Orion XS50 and set it at 40A…

 

[marcham]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

Do you have an external regulator with a temperature sensor? (ie: WakeSpeed, Electromaax)

With a regulator that monitors temp, you can get the max output till max temp is reached. I've set mine to 80 deg C, which is pretty conservative and I rarely see it go over 75 deg C.

Are you planning to connect the alternator to the house battery? You're not getting the full benefit of lithium without making this important change.... then all you need is a small dc-dc converter (10-15 A) to charge the start battery from the house (wired to only be enabled when the ignition is ON).

The hitachi 80A are well built.... but you will only be getting a small amount of amps out of it while it's connected to the starter battery, especially if you don't have an external regulator.

With a 100 Amp alternator, my 630 Ah bank is usually fully recharged daily with 1-2 hrs of motoring (enough time to start, raise anchor, motor out of the bay raise sails, drop sails, motor in, drop anchor...).

 

[MFD]

@ice breaker said they have the original 80-amp alternator that came with their Yanmar.
One reason people do this is to avoid the costs and work of updating the engine based charging system when installing a LifePO4 house bank. At least that was my reason and I am setup the same way.
Basically I just left the alternator and start battery alone, took out the old combiner charging system and put in the DC=>DC start=>house.
One day I may go back and upgrade the alternator and do an external regulator and reverse the DC=>DC charger, but that is not on the roadmap anytime soon. Very little of my charging throughout the year comes from the engine anyway so it is just not a high priority for me.

I only have a few hours on the engine since the change, but notes show that on both runs, the alternator (plus start battery) settled in around 13.7 volts and 40 amps (I have input set to limit at 40) to the DC=>DC charger and stayed that way. I purposefully had the LifePO4 house bank somewhat discharged as a simple test scenario.

So in summary, the alternator is giving the LifePO4 house bank everything it is allowed to give via the configuration of the DC=>DC charger.

@ice breaker - it looks like you have a Hunter 41AC, I have a 41DS. You probably already know this - you will want to look at the breakers at the top of your main battery panel. There are pair of 150 amp breakers there, one for each battery bank. They connect to a solenoid between them that is activated by the engine ignition key switch to combine the two banks. To keep the charging systems isolated you want those two breakers off. Otherwise you will be putting wrong voltage Hitachi 80 amp alternator juice into your nice new LifePO4 house bank. Unsure how the DC=>DC charger interacts if the two banks are combined during an emergency like the start battery died. I doubt it would be a problem, it probably does little/nothing, and could be shutoff remotely anyway.

 

[ice breaker]

Thanks you everyone that responded! You pretty much confirmed what I was thinking. I do have a gen set, and plan to use it to do rapid charges of the batery bank( ProMariner 50 amp and may add a second one), but wanted to take maximum advantage of charging while motoring. We are coastal cruisers on lake Superior. So we tend to put about 100 hours a season on the Yanmar. Most of our power consumption is refrigeration, and electronics.

Yes MFD, the batery combiner will be disabled, before firing up the yanmar.

As main sail said, "Use a Victron Orion XS50 and set it at 40A ..."

Thanks again to all for your comments.

 

[Zencra]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

have a 170amp Balmar with a Wakespeed 500 external regulator directly charging the 600amp lifepo4 bank I then have a 30 amp DC to DC charger to maintain the AGM spiral start battery. I've had this system installed for over 6 years now and has worked so well.

 

[artboas]

Just wanted to add something…
Belt tension is a very important factor, and it’s challenging to get a belt really tight without some proper tools. This gets even more difficult with high output alternators
Balmar makes something called “belt buddy”
I cannot recommend it highly enough
Suggest you take a look at this .

 

[MFD]

Yes, those little ‘belt buddy’ adapters are excellent to make a simple yet annoying maintenance item much easier..

 

[ice breaker]

Just to close this out. The system has been running great off the Victron Orion XS50. 40 amps works great. I left the combiner installed and functional, however the combiner now sends the yanmar alternator power to the victron box and then back to the lithium bank. The reason I did this is that I have a Fisher panda gen set, and if I used the auto sense on the victron it would have pulled power from the tiny panda alternator. I was very worried that it would destroy that alternator. So when the panda is running, no alternator power is provided to the lithium bank as the combiner is not activated. It was simple enough to remove the copper bus bar on the output side of the combiner, so that I had 2 connection points to rout to the victron and back to the house connection point.

As an aside, the Promariner 50amp charger, has a proper lithium setting, but per promariner tech support, the charger needs to be put in power supply mode, else it will see too many volts from the lithium bank and not stay in float mode.

I am very happy with the new set up.

 

[marcham]

I have a question for all of you that have switched to lithium house banks but kept the AGM start batery. What size DC to DC charger did you install? I have an 80amp alternator on my Yanmar. I would like to go as large as possible in order to facilitate faster house charging, but I do not want to kill the alternator or the start batery. Your comments would be appreciated.

Thanks

What is the charge capacity (maximum / recommended) of your lithium house batteries? Difficult to answer your question not knowing what battery you have installed...

Honestly, to go through the time and expense to replace the house batt with lithium, but not switching the alternator output to the house bank is like putting Ford Fiesta tires on an F1 car.... Instead of spending big money on one or more large DC-DC converters, best practice is to install a programmable alternator regulator, switch the alternator output to the house and then a smallish (20 Amp is plenty) DC-DC converter to charge the start batt. Make sure you get a regulator that has an alternator temp sensor. Then you can regulate the alternator output based on a set temperature (mine are set at 75 deg C)... which translates to roughly 85% output on my Yanmar.

If you want to get there more progressively, then the Victron 50A Dc-DC converter (not cheap!!) is a good option, as if you later choose to upgrade your engine alternator system to more efficiently (and quickly) charge your house bank, you can reduce the charge current on the XS50 and reverse it's output.

Keep in mind, you're not getting the full benefit (fast charge, reduced engine run time) of you nice new batts until you hook them up direct to the alternator.

I wouldn't go much past 50A for the DC-DC charger, as you have no way of monitoring the alternator temperature....

 

[dlochner]

As an aside, the Promariner 50amp charger, has a proper lithium setting, but per promariner tech support, the charger needs to be put in power supply mode, else it will see too many volts from the lithium bank and not stay in float mode.

Float charges are not necessary for LFP batteries. Unlike AGMs LFPs do not need or want to be left in a 100% SOC.

Just to close this out. The system has been running great off the Victron Orion XS50. 40 amps works great. I left the combiner installed and functional, however the combiner now sends the yanmar alternator power to the victron box and then back to the lithium bank. The reason I did this is that I have a Fisher panda gen set, and if I used the auto sense on the victron it would have pulled power from the tiny panda alternator. I was very worried that it would destroy that alternator. So when the panda is running, no alternator power is provided to the lithium bank as the combiner is not activated. It was simple enough to remove the copper bus bar on the output side of the combiner, so that I had 2 connection points to rout to the victron and back to the house connection point.

This is a really awkward and unnecessary workaround. It is easily avoided by providing a small dedicated start battery for the generator that is charged by the generator's alternator.

 

[Johann]

As an aside, the Promariner 50amp charger, has a proper lithium setting, but per promariner tech support, the charger needs to be put in power supply mode, else it will see too many volts from the lithium bank and not stay in float mode.

This advice worries me a bit. It doesn’t sound right. Doesn‘t the PS mode only output a single voltage? If so what voltage? If it’s above 13.6V that will damage your LFP over time.

 

[Tally Ho]

I am working on a new LFP house bank…and bought a new Victron charger for the LFP bank. On my workbench last night, I hooked up each battery (individually ) to the Victron 20 amp charger and charged the batteries to 100%. Then I paralleled them, and hook the charger up to the bank. I left the charger on for several hours and monitored both the charger and the batteries via BT.

The charger maintained 13+ volts and amps were 20 for the bulk charge. But as the batteries hit full charge, the charger went into Absorption mode where volts increased to 14.2 and amperage dropped down. Eventually, the charger went into storage mode (float mode is disabled in the Li Ion charge profile.

Using the charger as a Power Supply in a battery charging application for any length of time doesn’t seem right.

 

[dlochner]

I am working on a new LFP house bank…and bought a new Victron charger for the LFP bank. On my workbench last night, I hooked up each battery (individually ) to the Victron 20 amp charger and charged the batteries to 100%. Then I paralleled them, and hook the charger up to the bank. I left the charger on for several hours and monitored both the charger and the batteries via BT.

The charger maintained 13+ volts and amps were 20 for the bulk charge. But as the batteries hit full charge, the charger went into Absorption mode where volts increased to 14.2 and amperage dropped down. Eventually, the charger went into storage mode (float mode is disabled in the Li Ion charge profile.

Using the charger as a Power Supply in a battery charging application for any length of time doesn’t seem right.

The BMS in a LFP battery will periodically draw a high current even when the battery appears to be fully charged. This is normal. When this happens the BMS is trying to balance the individual cells in the battery to an equal charge level. Over time and charge/discharge cycles the cells in each battery can become unbalanced, and this BMS demand for a high voltage current is trying to correct that imbalance. This is very different from what happens in an LA battery and should not be confused with equalizing a LA Battery. The short story, what you observed is normal.

You are also correct, using a charger in a Power Supply mode where it provides a constant voltage is fine when the batteries are disconnected, but not as a charging option. Again, the self-discharge rate for a LFP battery is very low and they are best stored at less than 100% SOC. Float charges are not necessary and can be damaging.

With that said, my solar controller (a Victron) does go into a float mode with the LFP batteries. This happens when the batteries are at or near 100% SOC and the BMS puts the battery into a "Standby" mode and there is a current draw on the system which the solar panels can supply at a low current.

 

[Johann]

Honestly, to go through the time and expense to replace the house batt with lithium, but not switching the alternator output to the house bank is like putting Ford Fiesta tires on an F1 car.... Instead of spending big money on one or more large DC-DC converters, best practice is to install a programmable alternator regulator, switch the alternator output to the house and then a smallish (20 Amp is plenty) DC-DC converter to charge the start batt. Make sure you get a regulator that has an alternator temp sensor. Then you can regulate the alternator output based on a set temperature (mine are set at 75 deg C)... which translates to roughly 85% output on my Yanmar.

If you want to get there more progressively, then the Victron 50A Dc-DC converter (not cheap!!) is a good option, as if you later choose to upgrade your engine alternator system to more efficiently (and quickly) charge your house bank, you can reduce the charge current on the XS50 and reverse it's output.

Keep in mind, you're not getting the full benefit (fast charge, reduced engine run time) of you nice new batts until you hook them up direct to the alternator.

Well you get benefits whether you charge directly from the alternator or not. Some of these benefits are operating in a PSOC without damage, 100% DOD without damage, higher operating voltage, and less voltage sag with high loads. Also, if you don’t use your alternator as a primary charger for the house (generator or solar instead), there isn’t really a need to upgrade, and you get the charging benefits from the other sources. Price wise you are looking at:

1. Stick with the 80A Hitachi
Orion XS 50A - $328

2. Upgrading the alternator
Balmar 6 series 120A $766
Balmar MC618 $328
Orion DC-DC 12A $160
(+ maybe a serpentine kit $560)

Thats a big difference $$ wise…especially if you were happy with the 80A alternator when it was feeding the AGM house.

Of course you are right about best practice, but in many cases I don’t think it justifies the cost.

I wouldn't go much past 50A for the DC-DC charger, as you have no way of monitoring the alternator temperature....

I think he really should stick with 40A on the Orion XS. Ours have been fine with 40A output. But the Hitachi will sort of let you know if it’s getting too hot by how low its’ output voltage gets.