Charging or integrating 48V Dinghy from 12V House Bank

Sandy Frank

New Member
Joined
Aug 11, 2021
Messages
2
Hello All,

I searched and found several variations of this question, but have a variation on it.

Background:
I am currently rebuilding a rat's nets of electrical from several previous owner(s). Some of the components of the boat are good, new alternator, 4KW diesel genset, etc. All of the (owner added) wiring is terrible, undersized, too long, and complete with several burn marks after electrical tape splicing when I pulled and rebuilt the AC side. Standard 12VDC lifepo4 upgrade underway to the house bank: DC-DC charger, lifepo4 capable inverter/charger, some solar sized for normal house loads. In an effort to keep gas off the boat, I bought a Elco 9.9 outboard and 100 AH @ 48V of lifepo4 to power it.

Questions:
  1. Long-shot question: After use of the dinghy, presuming the house battery is at float and the dinghy batteries are lower, can the dingy batteries just be dropped into the house battery banks for an extra 400 AH of capacity/direct charging? (My understanding of lifepo4 is this is a no go).
  2. Separate bank question: I have found 1 12VDC to 48VDC lifepo4 compatible charger, expensive and will pull a lot of current very quickly from the house bank. Seems that the concensious through search is it is better to break the 48V bank down to 12V and have DC-DC charging?

Thanks
 

BobR

Solar Addict
Joined
Jan 4, 2021
Messages
197
Hello All,

I searched and found several variations of this question, but have a variation on it.

Background:
I am currently rebuilding a rat's nets of electrical from several previous owner(s). Some of the components of the boat are good, new alternator, 4KW diesel genset, etc. All of the (owner added) wiring is terrible, undersized, too long, and complete with several burn marks after electrical tape splicing when I pulled and rebuilt the AC side. Standard 12VDC lifepo4 upgrade underway to the house bank: DC-DC charger, lifepo4 capable inverter/charger, some solar sized for normal house loads. In an effort to keep gas off the boat, I bought a Elco 9.9 outboard and 100 AH @ 48V of lifepo4 to power it.

Questions:
  1. Long-shot question: After use of the dinghy, presuming the house battery is at float and the dinghy batteries are lower, can the dingy batteries just be dropped into the house battery banks for an extra 400 AH of capacity/direct charging? (My understanding of lifepo4 is this is a no go).
  2. Separate bank question: I have found 1 12VDC to 48VDC lifepo4 compatible charger, expensive and will pull a lot of current very quickly from the house bank. Seems that the concensious through search is it is better to break the 48V bank down to 12V and have DC-DC charging?

Thanks
Do you have an inverter on board?
Edit - I see you have ac you might consider this: https://www.powerstream.com/48VDC-720W.htm
Breaking down a 48volt pack every time you need to charge seems like a pain
 

CB-OTB

New Member
Joined
Mar 26, 2022
Messages
52
You know what... You are absolutely right to keep it simple and have an external AC charger. Will let me pull up to a dock and charge it as well.
How do you like the 9hp Elco? How much runtime do you get and does it get your dinghy on plane?
 
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