How Do I Charge a Lithium House Bank and a Lead Acid Starter Battery With My Alternator?
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- เผยแพร่เมื่อ 1 ก.ค. 2023
- Adam sent us an email asking,
"Jeff, I have:
- (1) 900Ah lithium battery bank
- (2) 100 amp alternators on my Crusader 454's
- Both engines are started by a single lead-acid starter battery
- (1) alternator is connected to a battery isolator which also is attached to my house bank
Is this setup safe for my alternators? I heard lithium can overheat alternators, but so far, they don't seem to draw any power whatsoever from the alternator?"
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That was a a lot of potentially confusing unstructured information for a fairly standard "simple" boat installation. Yes, there's a risk of the generator/dynamo overheating, depending on how discharged the Lithium is, and the RPM of the engine (or rather, the rpm/cooling of the generator/dynamo). He should keep an eye on the generator/dynamo temperature. .......... and he should have some kind of current limiting (dc-dc) device with suitable lithium charging output between the charge current from the generator/dynamo (or the diode) and the Lithium battery. ........ Assuming he has the same installation as I have, but many has. ............ And it's important the starter battery remains connected (assuming it has its own diode output) so the generator/dynamo has somewhere to output its power if/when the BMS disconnects the Lithium internaly. ........ As if not,..... a BMS disconnect can cause a destructive voltage spike.
in this example, wouldn't replacing the isolator with a DC to DC charger with a custom lithium profile be best? I'm adding a dual lithium bank to my set up also so this is a great conversation. Thanks for sharing and curious how Adam made out...
I am fitting the Li BIM 225 on my motor home. Alternator is a big beefy Leece Neville 185 amp . Battery 460 amp hour LifePo4 .
Hi I have a 2 renogy 8d agm deep cycle and 4 renogy group 27 battery.
Two of the 27 supplied 2 Yamaha 350.
One of the motor isolater lead charge the house system batters. I do have an 3000w pure sign wave inverter. Also have the renogy 800 watt solar kit. I have a xantrax ech charger Hooked up from the house system to the engine batteries in the event I use the inverter charger.
Everything appears to work great, “my problem is I can’t seam to get rid of the battery lingering charge scent”.
Boat is a 32’ hydro sport, center console with forward cubby cabin.
Any thoughts on that?
Jeff you have no thoughts on my message.
I have battery isolator(100 Amp) feeding bow thruster and engine AGMs. There are 2 Orion 30 Amp chargers feeding 300 Ah Lithium house bank. The alternator is 120 Amp Valeo. Is it worth converting the Alternator to external regulator?
I think the Orion is already limiting the amperage for you and it's regulating the voltage to the lithium profile (assuming that you programmed it for that), so I don't think it's necessary but I would wait for confirmation from Jeff.
Why so complicated?
I use Victron DC/DC Voltage regulators. They are also perfect to stabilize / normalize Voltage on long cable lengths.
And the cool thing is, you may parallel several of them.
In my Motorhome, I have 3 * 12V / 30Amp in parallel.
The Victron products are very robust: most people do not realize how three phase charging work: (Bulk, Absorption, Float). The Victron Smart DC-DC converter in BATTERY CHARGE Mode allows you to customize the charge profile for the battery (not all Lithium or AGM batteries are designed to the same specification for charge profiles). For example: on my Lithium 200 AMP Hour house system and AGM 100 AMP HOUR engine system - the Lithium batteries were not getting fully charged by the standard Lithium spec provided by Victron (14.1 volts). My Renogy Lithium batteries require 14.4 volts.
In my system, I have two VIctron SHUNTS (one for House and one for ENGINE - once those settings were changed I could visually see the current increase to my Lithiums and the voltage rise. I would suggest anyone doing a Lithium/AGM install use two shunts to really verify what is happening in their system. The RENOGY Lithiums have a Bluetooth interface, so I could also see what was happening internally.
Answer , always YES . Set the ext Reg to LifePo4 charging profile . Have a battery isolator between the Alt , Starting battery and LifePo4 house bank .
Explain. What's the external regulator you use?
@@BOREDANDWELLBORED unless I'm misunderstanding, I think this is referring to a DC to DC charger which is really a voltage regulator often with a custom charging profile.
A schematic is king, it is needed to understand the setup and to avoid any kind of confusion or misunderstanding.
I want to charge my lithium bank with my alternator (balmar 170amp) but, start my engine with my agm bank... is there a way to do this?
You could plumb the alternator straight to the house bank and charge the starter via a DC to DC charger. Although in this scenario you run the risk of the BMS opening the bank and blowing your alternator- having the settings right on an external regulator is key with this scenario.
I have a module that protects against that... but, if my alternator is wired to charge the lithium bank does that not also mean it draws from there as well...ie; when I start the engine??
@aphrodite3216 Definitely a good idea to have a dump protection device. I have a sterling on my boat- thankfully haven't needed it ever.
For separation of banks- the starter bank only connects to the engine's starter motor. The alternator is connected to the lithium bank. In this scenario the banks are completely separate.
Instead of battery isolator, hook up a pure sine wave inverter to starter battery, then run AC extension cord to a lithium battery charger dedicated to lithium house batteries. NEVER mix battery types on a circuit.
Why so complicated?
I use Victron DC/DC Voltage regulators. They are also perfect to stabilize / normalize Voltage on long cable lengths.
And the cool thing is, you may parallel several of them.
In my Motorhome, I have 3 * 12V / 30Amp in parallel.
@@MrRossi1805 Sound like good option. I already have inverter to run Induction Stove and already have battery charger when I am hooked up to dockside power, so I am using what I already have to charge batteries while maintaining isolation. Plus, AC can run long distance at much thinner (& cheaper) wire. Over distance, AC is my preferred choice (Tesla vs Edison).
@@miken7629 thank you
@@MrRossi1805 I have 2 for 60 Amps that best matched the 60 Amp house charger and 120 Amp alternator. If using an external regulator at the additional cost have higher output but raises the temp of the unit. In order for the alternator to put out the higher amps would that not raise the voltage into 15V range thus would tend to cook the agms?
What if the starter batteries are small lithiums? does that solve the problem ??
Pretty much- you'd want to connect the two lithium banks with an Automatic Charge Relay so there's no voltage drop similar to a diode style isolator. Although I think the transistor style isolators are pretty good- better than the old school diode style at least.
But isn't the issue that the internal resistance of a lithium battery is much lower than a lead acid battery, so, consequently, a lithium battery will draw far more than the (say) 40 or 70A intended current from a standard (say) 13.9V alternator output? (which is potentially a fire hazard). How do we overcome that issue?
That's not a hazard, unless your cables are much too thin for the current the alternator can deliver. .............. How "happy" the lithium is about having 14.0volts instead of 13.5 float over a long period of time, I do not know.
@finnerutavdet Sure, the battery can take it, but isn't the issue that an alternator designed to deliver (say) 40A finds itself delivering (say) 80A, because the internal resistance of the battery is so much lower.
@@stephenburnage7687 The alternator will deliver as much as it can at the RPM it has, and if it dos not get to warm doing that, then that is ok. If it gets too warm that is a serious risk.
@finnerutavdet That is what I understood ie you cannot simply drop in a lithium battery where a lead acid was, as you risk overheating the alternator (and probably the cables too). Put it another way, configuring an existing lead acid system to lithium requires some thought, with overheating or even fire a possible outcome if you get it wrong. Personally, having researched Lithium on my boat, I decided to ultimately go with AGM's, as it a much simpler system.
@@stephenburnage7687 Yes, that should make it simple. ......... I just removed my 5 lead acids (once upon a time 100AH each). ....... I'm gonna do something most are NOT doing, which is to combine lead and lithium, but it's not optimal, expensive, a lot of re-search and a lot of work (building my own banks), and I'm not even 100% sure I'm gonna succeed. The reason I want lithium instead of like you, go for AGM, is that I want to be able to re-charge them from a noisy generator in the shortest possible time, and only Lithium can do that. ........ If the cables were o.k. for lead they would have been o.k. for lithium as well though, as the BMS in the lithium limits the current to less than wat a lead can put out. ..... The main problems with lithium is the small possibility of some generators overheating which one needs to test for or take care of, and the other main problem that most seem to be unaware of is that the BMS can disconnect the lithium battery (internally), and then there has to be lead in the system as well, as if the BMS disconnects and you don't have any lead in the system (for instance the starter battery), then you can get a voltage spike when the current from the generator suddenly has nowhere to go because the lithium BMS disconnected to save itself from for instance overcharging, and that spike can destory much of your electronics (in the worst case). ...... I'm an electronics engineer, and this is kind of new to me, but I'm still learning. But for a simple solution, yes, stay with Lead. .......... The channel of Clark has nice videos on the subject (most of what I know I picked up from him, and some from the off grid garage). ............ B.R.
SORRY I AM CONFUSED why dose he have two starters. Two engines why. And 100 amp alternator is a bit much for a lead acid battery. Usually they are 70 AMP. And Whats charging the lithium battery bank. I would not expect an isolator to cause a voltage drop. And i am not familiar with them . But i would expect an isolator to come with battery temperature sensing thermometer. Alternators have their own internal voltage regulators.
an isolator by definition had FETs that have .1th the voltage drop that the older diode ones.
Cats have 2 engines…
Many, many powerboats have two, or more engines. This topic is not just for sailors.
Sorry, but we never find out if these are (dumb) internal regulated or (smart) external regulated and programmable alternators.
And aren't battery isolators passe, out dated, etc.?
First off, external regulation is a must, a no brainier.
Second, both alternators should combine thru a device, maybe center fielder by Balmar.
Then that output should go to an AGM battery, then to a DC to DC programmable charger, then to the lithium bank.
Size the DC to DC accordingly to meet the demands of the lithium bank.
Is this not a better way?
Unfortunately, you did not really answer the question. One that would be interesting to have answered is “how does lithium react to charging under lead acid profile?”
If you consider 14,25 V absorption voltage, a lithium battery would never reach the full capacity
@@MrRossi1805 This is from the RsLion data sheet Charge Voltage 14.2-14.6
Balancing Voltage 14.4
Float Voltage 13.3-13.8
This is the 2 Orion settings Absorption V 14.20
Float V 13.50
I think it creates excessive demand on the alternator/charging circuit and eventually causes premature failure. I'd expect it to work till it breaks down. I've heard instances like this where temp was monitored at the alternator and found to be pretty high in under 20min. I think almost all lith batt manuf (unless certified 'drop in ready') are firm on using a custom charge profile vs wide open.