2008 Hunter 36 here. Not interested in the expense and work of converting to lithium batteries. Currently have a single lead acid group 24 as starting battery, and house bank of 2 Group 31, also old school lead/acid. Considering adding more to the house bank. Currently located in port cockpit locker but no real room for more and the boat already lists a degree to port. What are the trade-offs of locating part or all of the house bank perhaps under a settee forward? To get it done would require nothing more than some new longer cabling of the proper AWG. Without measuring I suspect that would be 2 AWG
basic battery connections question
- Thread starter George Braun
- Start date
Assuming the new batteries would be wire in parallel to form a bank of 4 batteries, there is a lot of wiring that will need to be modified. When batteries are wired in parallel all of the connecting wires must be of the exact same length in order to charge and discharge them correctly. If the wires are of different lengths, the batteries with shorter connections to the charging sources and loads will charge and discharge faster than the more distant batteries. This has the potential to become a real rats nest of fat cables. There are ways to mitigate this, however, they entail some significant rewiring and system design changes.
Charging will also be an issue. How big is your charger? Is it a three stage smart charger? Currently you have about 200 ah of capacity doubling that will halve the charging current available to recharge the batteries. If you have a 40a charger, with 2 batteries each get 20a which is OK, with 400a each battery will only get 10a. Charging times will significantly increase. If your current charger is only 20a or 30a, it will take even longer. The alternators' output will also be divided between all the batteries, sharply reducing charge times.
In short, there will be significant rewiring to do to maintain an efficient system and longer charge times. The only upside will be greater capacity. Whether this is worth it really depends on how you use the boat and how you intend to use it.
Charging will also be an issue. How big is your charger? Is it a three stage smart charger? Currently you have about 200 ah of capacity doubling that will halve the charging current available to recharge the batteries. If you have a 40a charger, with 2 batteries each get 20a which is OK, with 400a each battery will only get 10a. Charging times will significantly increase. If your current charger is only 20a or 30a, it will take even longer. The alternators' output will also be divided between all the batteries, sharply reducing charge times.
In short, there will be significant rewiring to do to maintain an efficient system and longer charge times. The only upside will be greater capacity. Whether this is worth it really depends on how you use the boat and how you intend to use it.
For the reasons above plus others not mentioned, you would be better served using the 2 new batteries in a second separate bank charged independent of the old pair. This will provide a good compromise and the extra capacity desired with the least complications.
