We have considered DC-DC converters and MPPT's but as of now there are none that can singly carry anticipated loads. The Victron converters can be ganged but then becomes a cost and space issue.
Replace genset with lithium batteries and a inverter...
- Thread starter Grateful Escape
- Start date
Our objective is to move away from lead acid; that is the technical challenge. I have the generator start on AGM which is the backup for electrical power. Cascading BMS trips is the principal risk; Charge and discharge limits that we are establishing has substantial margin on the BMS limits; we are establishing 0.2 volts on the top and bottom end beyond what the manufacturer is specifying. The Victron Cerbo GX can alarm when the set points are crossed which partially meets the intent of the new AYBC requirements. The set points allow enough time to evaluate and remove the infringing component. So, this system is set up to tolerate a single or dual BMS internal failure but reduce risk of externally caused BMS cascading trips. Again, they are moving me to keep engine starting on AGM but I don't yet see the technical reasoning to what they want.
For boats and yachts UL certification is not a requirement. Insurance is not concerned with the US UL certifications. Insurance is concerned with meeting USCG and AYBC requirements. The Victron products in this configuration meet all necessary requirements for insurability. I've already been down that road. The open item is the batteries themselves in which the individual BMS are not alarmed per AYBC; we are working on that issue.
Last edited:
Regarding EMC sensitivity - I suspect this won't be an issue due to the history of the lithium battery systems in use today. I'm not concerned anyway.
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
They won’t tell you why?
Do they consider this battery to be mission critical? If so, I doubt they will ever sign off on just one bank to replace two.
Ironically, EMC is likely to not be an issue for you until you start sticking communication ports outside of that metal enclosure, which will increase its susceptibility to noise. That communication requirement may bring in more concerns in that regard.
Do they consider this battery to be mission critical? If so, I doubt they will ever sign off on just one bank to replace two.
Ironically, EMC is likely to not be an issue for you until you start sticking communication ports outside of that metal enclosure, which will increase its susceptibility to noise. That communication requirement may bring in more concerns in that regard.
I think that is a valid question to Battle Born. They do not have metallic enclosures.
- Sep 25, 2016
- 1,258
- Boat Info
- 300 Sundancer 1994, trailered tri-axle LoadRite roller
- Engines
- Mercruiser 5.7 260HP Alpha One Gen II, twin
To get started on my design I bit the bullet and got a copy of ABYC TE-13.
I have to say I was not impressed. It is mostly what we already know, follow the manufactures specifications for each component, you need a BMS, you need circuit protection, disconnects, etc (many things actually reference E-11 and the "normal" battery installation standards). And a lot of "should" not "shall" which is the difference between a rule and a suggestion.
As I've said before every use case is different, @ttmott has diesels, CCA could be north of 800A, @jmauld you have 8.1 gas and I have 5.7 gas, a lot less CCA. I doubt any FET based BMS will ever handle cranking a diesel.
I cant upload the whole document legally but to the last few questions:
I have to say I was not impressed. It is mostly what we already know, follow the manufactures specifications for each component, you need a BMS, you need circuit protection, disconnects, etc (many things actually reference E-11 and the "normal" battery installation standards). And a lot of "should" not "shall" which is the difference between a rule and a suggestion.
As I've said before every use case is different, @ttmott has diesels, CCA could be north of 800A, @jmauld you have 8.1 gas and I have 5.7 gas, a lot less CCA. I doubt any FET based BMS will ever handle cranking a diesel.
I cant upload the whole document legally but to the last few questions:
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
Looks like 13.5.3 covers the push for AGM. Also, the statement about following manufacturer specs. If the engine manufacturers spec Lead-Acid/AGM, the engineers won't recommend that you deviate from that. Doesn't mean you can't, but you should make sure that you document the risks identified and how you address them.
Locked rotor is almost 800 amps; cranking is 350 amps.
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
In the OEM 2 bank system is the generator alternator connected into the circuit with the engine generator? I don’t see the genset alternator mentioned in my manual. The spec sheet for the 7.3ecd says that it has an alternator built in, I just assumed it didn’t.
Also, when you’re underway with the generator running, do you switch off the battery charger?
Also, when you’re underway with the generator running, do you switch off the battery charger?
Last edited:
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
I hate when standards mix the use of should/shall. Clause 13.7.8.1 is particularly good at illustrating this issue: “If necessary, a battery bank should”. No. If necessary, a battery bank shall. Clearly, the committee writing this standard needs to review it again.
According to the internets, I need 650cca for my engines. So a fresh group 31 could handle that.
Pirate Lady
Well-Known Member
And a lot of "should" not "shall" which is the difference between a rule and a suggestion.
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
Do you guys mind critiquing this block diagram.
I’m not sure if the dc-dc chargers need to be switched or not. They are "smart" and are supposed to know if the engines are running in order to activate their charge circuits. There’s more separation that needs to be documented for the ignition circuits. For now, I’m just focusing on the addition of the batteries. My primary intentions are to get the heavy loads, like the windlass and the bow thruster off of the drive batteries.
I’m not sure if the dc-dc chargers need to be switched or not. They are "smart" and are supposed to know if the engines are running in order to activate their charge circuits. There’s more separation that needs to be documented for the ignition circuits. For now, I’m just focusing on the addition of the batteries. My primary intentions are to get the heavy loads, like the windlass and the bow thruster off of the drive batteries.
Last edited:
- Sep 25, 2016
- 1,258
- Boat Info
- 300 Sundancer 1994, trailered tri-axle LoadRite roller
- Engines
- Mercruiser 5.7 260HP Alpha One Gen II, twin
couple of things and a couple questions...
Is the three battery charger in the middle the AC charger? Is it lithium aware (configurable per battery)?
If not don't use the existing AC battery charger
If you use the alternator on the generator to charge lithium you will likely over heat it and burn it out unless you are using an external (Balmer type) regulator with temperature sensor.
Is the three battery charger in the middle the AC charger? Is it lithium aware (configurable per battery)?
If not don't use the existing AC battery charger
If you use the alternator on the generator to charge lithium you will likely over heat it and burn it out unless you are using an external (Balmer type) regulator with temperature sensor.
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
It is a 3 bank AC charger. My current charger will be replaced with one that has lithium profiles built in. Good point about the regulator for the alternator.
Shunts are always the first device off of the battery negative terminal.
For sure you will toast the genset alternator
Having a common charger for both types of batteries will render the batteries that are either lowest charge or requiring the longest charge to be undercharged.
I don't quite understand the DC to DC converter configurations....
Sorry not enough time to really help here...
Tom
For sure you will toast the genset alternator
Having a common charger for both types of batteries will render the batteries that are either lowest charge or requiring the longest charge to be undercharged.
I don't quite understand the DC to DC converter configurations....
Sorry not enough time to really help here...
Tom
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
are you saying that a 3 bank charger isn’t configurable per bank? Victron specifically shows a diagram with two lead acid batteries and one lifepo4 charging off of the same charger.
I’m updating my diagram with the suggestions and also adding info to clarify. I initially called this a schematic when it’s really a block diagram. I am not showing the detailed connections.
Last edited:
- Sep 25, 2016
- 1,258
- Boat Info
- 300 Sundancer 1994, trailered tri-axle LoadRite roller
- Engines
- Mercruiser 5.7 260HP Alpha One Gen II, twin
Most multi bank chargers do not have per battery, they just have isolating diode bridge between the banks.
So they assume all banks will be the same chemistry FLA or AGM or Lifepo4
You could keep your current for the FLA an get a single bank charger for the LifePo4
Personally, I'd ditch the idea of trying to use a 'one size fits all' 3 bank charger for both the starters and the lithium bank. Those are two radically different requirements, one being just a maintenance role and the other being primarily a bulk-charging role. I'd go with a fairly small two bank charger for the starters and probably use a decent inverter/charger as the main charger for the lithium. You don't really need to use the inverter feature, but it could provide some limited power for convenience when the genset is not running. Or you could just go with a dedicated charger just for the lithium (but it would probably cost just as much) that can deliver a good punch back into the lithium to get it full again.
jmauld
Well-Known Member
- Jun 9, 2020
- 2,845
- Boat Info
- 2010 Sundancer 390
2016 Sea Hunt Ultra 211
- Engines
- Twin 8.1l of gas guzzling iron
That's a good thought.
Any thoughts on those DC-DC chargers that are charging the lithium battery from the the drive alternators (I should indicate the direction of those chargers on the diagram, for clarity) I'm curious if that constant 18A load would be an issue for the alternators.
Any thoughts on those DC-DC chargers that are charging the lithium battery from the the drive alternators (I should indicate the direction of those chargers on the diagram, for clarity) I'm curious if that constant 18A load would be an issue for the alternators.
Last edited:
The caution is the lithium charge amperage can be far greater than the lead acid batteries and voltages can be different as you know. The challenge is to have a common charging source that can deliver the high amperage yet still ensure all of the batteries are fully charged. Lithium batteries do not enjoy constant trickle charging like lead acid and absorption is for the most part eliminated they need to be charged at bulk then the charge current shut off unless an electrical demand is on the batteries. So once the batteries are at the manufacturers specified voltage (14.4 for example) terminate further charge current. I believe the Victron DC to DC chargers can do this but their largest is 70 amps which may be Ok for your alternators but they will be working at full tilt until the batteries are charged. So, I would have a dedicated AC charge system for the lead acid batteries and another for the lithium batteries. Then all of the engines and their alternators including generator on the lead acid batteries. This way the alternators are not at risk and you can get rid of the APD on the gen. So in this format your lithium bank can be charged through the dedicated charger and/or the DC to DC chargers. What I would do is combine the two lead acid banks and have a cross-over solenoid for emergency start between the lithium bank and the lead acid bank. Then have another shunt on the lead acid bank so now you are monitoring all of the battery systems. Another thing I would do is to reduce your lead acid bank to two Gp 27 batteries for starting and operating the engines then move all of the boat's 12 volt systems to the lithium bank.
