Sizing A Charger For Multiple Battery Banks

[@besearchingforwisdom6267]

Thank you for your videos, I have been fortunate to have discovered your teachings recently and I am binging on them. Excellent job

[@PacificYachtSystems]

Thanks!!! Glad our videos resonate with you.

[@fionamolloy9554]

Thanks Jeff for picking up my question 😊

[@PacificYachtSystems]

Glad to Fiona!

[@daniellatif4615]

Hi Jeff. Great videos! I have a 35' sportfish with two 200Ah separate starter batteries. Using the minimum 10% rule, should my charger size be 20A (10% of 200Ah) OR 40A (10% of the combined 400Ah)? Thanks

[@davidlee62]

Hello , On the Argofet with 3 outputs and one alternator input . Do you recieve the full alternator input ie voltage and current to all of the 3 outputs equally ?

[@PacificYachtSystems]

With a battery isolator (e.g. ArgoFET) all 3 batteries will get a charge, the size of the battery bank, the level of discharge, and the ability of the battery to take a recharge will all affect where the current from the alternator goes.

[@steventylerbray]

Hey follow up question on the 10% rule I'm looking to upgrade my outboard on my small sailboat to an electric start. The outboard I'm looking at has a built in 4 amp alternator, but my house battery bank is about 120 amp hours. Would it be better to not tie the two battery banks together at all and just keep charging my house battery at shore as I do now, or is this a take whatever I can get situation like you've said with solar panels? Thank you for your time

[@PacificYachtSystems]

Great question Tyler, with a 4 amp alternator, like you suggested, it's better to have the house battery of 120 amp-hour be charged separately and not from alternator. With an alternator of this size, suggest the engine battery should be charged instead.

[@dariusmartinez7923]

Hey Jeff, thought I'd try here given the no response to my email after that AGM battery purchase. I have a 3 bank battery charger (ProMariner ProSport 20 Waterproof Battery Charger Gen3 20A), Blue Seas ACR, Blue Seas Switch (5511e) and Blue Seas Safety Hub 150. Should I connect 1 lead of the charger cable to the switch on the house side, and one lead of the charger on the starter side of the switch? Alternatively, I can only imagine that it would be 1 lead connected to the positive distribution bar and negative distribution bar for the house bank. Any help would be appreciated, but I understand that maybe my 26' boat may be a bit small for your consideration.

[@PacificYachtSystems]

Hey Darius, battery chargers should connect to batteries directly (e.g. positive via a fuse).

[@dariusmartinez7923]

@@PacificYachtSystems Nice timing....a response 8 days after an email, 2 days after a youtube comment.....and 45 minutes after a bad google review, hmmm..........maybe provide customer service prior to a bad review...could be helpful.....but that's just me....a paying customer.

[@paulnazar3312]

Jeff, thank you for all you videos! I watch them religiously! I watched a youtube video from victron on recharging lithium batteries via an alternator at low RPMs (think 1500). The alternator burnt out on lithium but not on lead acid because the lithium pulls as much current as possible even at low RMP while the lead acid does not...I think...if i am wrong please help? My question is i have 3 battery banks; 2x 90amp/hr lithium, 1x starter AGM and 1x thruster AGM banks...all are hooked up the a 3 channel battery isolator (Cristec 180-1E-3IG)...can i burn out my alternator (14v, 125amp) at low RPMs ... is there anything on the market i could add to help prevent any damage to my alternator?

[@PacificYachtSystems]

In short yes, stock alternators have a very hard time recharging Lithium batteries, you might want to consider a high output alternator and external regulator.

[@paulnazar3312]

@@PacificYachtSystems Thank you