The BEST way to Parallel Batteries on a Boat | Ask The Expert with NIGEL CALDER
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- Опубликовано: 24 июл 2024
- There is a good chance that your batteries are wired in a way that significantly reduces their lifespan. Boat systems guru Nigel Calder explains how to parallel batteries for maximized lifetime.
Check out our Boat Electrics 101 course for much more info on how to safely plan, install, and maintain your boat's DC system: boathowto.com/boat-electrics-...
Whahhooo !!! I've practiced and preached this for years and this is the first time I've heard it confirmed 🤗 (I don't get out much) l first started questioning why on 24v trucks does the same battery die first and give such a different load test result....... And how in second hand power walls the similar same result ........ I've rotated the order of assembly but never thought to equalize as you've explained 🙃 thankyou for making this video !!! 😉🙃😎 New subscriber NZ
The LiFePO4 batteries I bought showed to wire them the way you show at 2:04. I contacted the company and pointed out what I saw as wrong with that configuration. At 2:04, let's say we pull 100 amps. The red cable coming off battery #1 has 100 amps to the load. The cable between #1 and #2 have 80 amps. #2 to #3 has 60 amps and so on. I told them that I recommend connecting all the batteries to a terminal block (one positive and one negative) then connect them to the load. they agree this was better and said they would change there manual.
Very nice that battery manufacturers now also start to recommend this!
@@BoatHowTo Tell Nigel one of my favorite books is Einstein's Universe. I used it to understand Relativity. When he said "Gravity is not a force", I was shocked. I confirmed that with Gravitation by Wheeler, Thorn and Misner. I have refered to it multiple time since around 1985. Great book!
Brilliant idea.
I have seen this method employed on one factory X-yacht installation where the customer opted for a larger consumer bank, resulting in 3 batteries.
Great to hear that manufacturers start to implement this! :-)
This is exactly how I've set up my 6 Firefly batteries. It's not as pretty as some of the not-as-good alternatives (because I have a total of twelve 30" 2/0 AWG cables snaking from all those terminals to the bus bars), but I don't spend a ton of time gazing into the battery bank anyway so I don't sweat it.
Great infov👍🏼👍🏼👍🏼👍🏼
Like your thinking for parallel connections on batteries. Question.....what if you have a large catamaran (46ft) with two banks connected in parallel with 5 meters separating each bank. In total there are 8 x 100ah (12v) batteries connected in parallel with 4 on each side with long, heavy gauge wires joining the first half with the second. I can rewire each bank but how do I charge the two banks evenly? I will have 2.1kW of solar that are connected to the end of the battery banks but this will not evenly charge each bank. I can get even charging within the last bank but.......any suggestions?
Good idea. If we are going to this effort why not taking that concept to the next level. Maybe a circular Bus 'Plate' with the Input leads from the batts around the Circumference equal distance and equal resistance through the Bus bar. Bus bar output connection in the centre of the circular plate. Maybe this is beyond the point of diminishing returns Just a thought.
That would be "next level", but if the busbar is properly rated, this would likely not make much difference. (At least not more than small differences in resistance we have during crimping or in the connections anyways.) What is a good idea for busbars in general though is to attach the source of power in the middle and then balance the loads to the sides, starting with the heaviest ones close to the incoming conductor.
Great video. But, question about the charging input... where and how to best connect that!?
I am not sure what you mean by that question. Both the charger and the loads should be connected at the same point at the batteries. So ideally at the separate bus bars. Or did I get the question wrong? - Jan
@@BoatHowTo You read the question correctly (-: I need to complete your FULL course which I signed up for but wanted to shoot this question out there. So to be clear the input and output are both connected at the bus bar. No worries as I will be utilizing Bruce Schwab for planning... and he is the one that directed me to you and your course! Thx for the reply!
@@hldevoreGreat, Bruce is doing great work! And if you combine that with the knowledge from our courses, you will be ahead of the game! 🙂
What about a “cross-diagonal” set-up with even-numbered (4, 6, 8) battery banks? Each battery has more interconnections than with busbars, but it should also balance each battery concerning inherent resistance?
I tried to add a link/photo of what I meant by “cross-diagonal”. But it didn’t go through
To describe it:
The batteries are connected by “short jumpers” in pairs. Each pair is connected diagonally by “long jumpers.”
Thus, each individual battery has the same total number of interconnections and total wire length to the system (positives + negatives).
It makes theoretical sense to me, and looks rather elegant (albeit, with potentially greater inherent resistance/more crimps used than with busbars)
@@EBee-gn9xc I think I know what you mean. In this setup, the longer positive leads make up for the shorter negative ones for the batteries and vice versa. I (Jan) think that this should work in theory, but in the discussion we had about this, Nigel remains sceptical whether this actually has the same effect. It would be really interesting to test though. With lack of test data, we would still recommend the busbar-method. The only extra piece of hardware required are the busbars, so the extra costs are rather small. - Jan
If using the buss-bar method, where do you install the fuse and at what distance?
The ABYC E-11 standard calls for the main overcurrent protection device (OCP) to be “as close as practicable to the battery but not to exceed 72 inches (1.83m)”. E-11 was recently amended to make it clear that there can be a busbar within this 72 inches (1.83m). So, assuming the paralleling conductors from the positive battery terminals to the paralleling busbar are less than 72 inches (1.83m), the main OCP device can be installed immediately after the busbar. In this case, the conductors up to the busbar and point of connection of the OCP device are supposed to have additional protection (sheathing) but this is typically ignored and in practice if the positive conductors are separated from the negative there is very little possibility for a short circuit. The other way to wire this is to add an MRBF fuse at each positive battery terminal. However, if this is a 24V or 48V system, the AIC rating of an MRBF fuse may be marginal for the application so this is something that will need to be checked. With the MRBF fuses you still need an additional fuse after the busbar unless the ampacity of the conductor from the busbar is at least as great as the combined amp rating of the MRBF fuses (which is unlikely!). This is because the potential short circuit current at the busbar is the sum of the MRBF fuse ratings. - Nigel
@@BoatHowTo Thank you for such a thorough reply.
does this technique apply to all battery chemistries?
Yes, it does. With lithium-ion batteries it is essential to check the guidelines of the manufacturer, because it is likely that the number of batteries you can wire in parallel is limited. Battery balancing is important. It may be taken care of via the BMS and battery balancing circuits but often is not. You may be required to use an external BMS with balancing capabilities across batteries.
if wiring this way would you have to fuse each individual battery or would one fuse leaving the main conductor wire work?
The ABYC E-11 standard calls for the main overcurrent protection device (OCP) to be “as close as practicable to the battery but not to exceed 72 inches (1.83m)”. E-11 was recently amended to make it clear that there can be a busbar within this 72 inches (1.83m). So, assuming the paralleling conductors from the positive battery terminals to the paralleling busbar are less than 72 inches (1.83m), the main OCP device can be installed immediately after the busbar. In this case, the conductors up to the busbar and point of connection of the OCP device are supposed to have additional protection (sheathing) but this is typically ignored and in practice if the positive conductors are separated from the negative there is very little possibility for a short circuit. The other way to wire this is to add an MRBF fuse at each positive battery terminal. However, if this is a 24V or 48V system, the AIC rating of an MRBF fuse may be marginal for the application so this is something that will need to be checked. With the MRBF fuses you still need an additional fuse after the busbar unless the ampacity of the conductor from the busbar is at least as great as the combined amp rating of the MRBF fuses (which is unlikely!). This is because the potential short circuit current at the busbar is the sum of the MRBF fuse ratings. - Nigel
Thank you Nigel. It is a 12 volt system. What you say makes sense. Since I already have one MRBF fuse holder on hand I think I will just buy one more put them on each battery post and run to a bus bar then add a class T fuse after the bus bar. Thank you. @@BoatHowTo
A distribution like that means a voltage drop.
If you use properly sized conductors and properly crimped connections, the additional voltage drop through slightly longer conductors should be negligible. - Jan
In the diagram showing the use of a positive and negative bus bar, this takes the place of wiring each battery to the next in parallel. Is this correct?
Yes, exactly!
@@BoatHowTo The wires from the batteries to the bus bar are 60 inches, using 3/0AWG. Is this length ok. Thanks for the previous answer
@@KenElston The ABYC states, that if the conductor connected to the battery post is "contained throughout its entire distance in a sheath or enclosure such as a conduit, junction box, control box, or enclosed panel, the overcurrent protection shall be placed as close as practicable to the battery, but not to exceed 72 in (183 cm)." So if you add additional protection to the conductor and it's not possible to put the bus bar any closer, then that's ok. You also have to make sure that all conductors to the bus bar have equal length. Check out our Boat Electrics 101 course for much more info on how to set up a DC system! - Jan