Charger and battery location on J40/42

[Walter Caldwell]

Our batteries (2 lithiums and an AGM starting) and chargers (AC and DC-DC) are installed under the nav station along with the water pump and water heater. It’s getting crowded in there!
So I am curious where you J40s and 42s have your batteries, chargers and inverters installed?
Thanks!

Walter
J40 #007

[Sjors van der Woerd]

Hi Walter,

Lay-out on our J42 Felice is probably different but we recently fitted three new 314 amp lithium batteries that fit perfectly under nav-station-seat without any adjustments, together with switches and big breakers.

The inverter, charger and solar smtp are in the hanging locker, we created a dubbele layer of equipment there with a simple woodboard.

The starter battery is on the floor in the same locker.

We went from 3 x 125 amp lead to 2 x 314 amp lithium, a game changer for us. It feels like almost unlimited energy with less weight and less use of space.

Batteries are from www.solar-moble.nl, the rest is all Victron.

See pictures attached.

Wish you all a good weekend,

Sjors van der Woerd

J-42 Felice, hull# 7, Amsterdam

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[Joseph Ruzzi]

My J/40, Spada, has the forward-facing nav station.   For the house bank, she has 4 125 Ah lead acid batteries in a box at the bottom of the port lazarette in the cockpit.   The Magnum 1500 inverter/charger sits on the shelf in that same locker.  The starting battery is on the shelf under the nav station.  The battery monitor control panel is mounted just behind the hinged work surface of the nav station.

As noted in an earlier post, I don't fill the port freshwater tank to keep from inducing a list to port due to the combined weight of batteries and water on that side.

Joe

To view this discussion visit https://groups.google.com/d/msgid/j4x-owners-group/67AEAACD-3B2C-4C1D-85DA-6EFEFDDA0D46%40skinnybridge.nl.

[Paul DeFreitas]

We have a J40 with a sit down, forward facing navsta and a bulkhead mounted salon table.  Our battery bank consists of 4 6v golf cart t105 batteries installed in the forward end of the cockpit lazarette in 2 Blue Seas battery boxes.  The charger is next to the trashcan under the companionway ladder.  The inverter is under the forward end of aft-cabin berth.  We added some ventilation slats in both spaces to avoid over heating.  We run full time on the house bank and do not use a separate starting battery.  We have a small jump-start gizmo in the unlikely event that we run the house bank flat.  This arrangement takes a good size chunk of your laz space and induces a bit of port heel, but it has served us well.  It's obviously old school, pre-dating lithium.

Paul

J40 #30

On Fri, Feb 20, 2026, 9:12 PM Walter Caldwell <j40shaken...@gmail.com> wrote:

Our batteries (2 lithiums and an AGM starting) and chargers (AC and DC-DC) are installed  under the nav station along with the water pump and water heater. It’s getting crowded in there!

So I am curious where you J40s and 42s  our batteries, chargers and inverters installed?
Thanks!

Walter
J40 #007

[Todd Stevens]

On Wild, the charger/inverter was originally installed way out in the sail locker on the port side. The start battery was under the vanity in the head, and the house batteries under the nav station seat. The shore power inlet was in the cockpit footwell next to the helm on the starboard side. This meant that incredible lengths of 2/0 (12VDC) and 10/3 (120VAC) cables wrapped all the way around the boat and back.  Holy Voltage-Drop Batman!

I’ve since replaced the 3 AGM house batteries with 4 100 Ah LiFePO4. The 4th one is in the bottom of the hanging locker, just behind the nav station. Although with all the hysteria about BattleBorn batteries lately, I’ve been looking hard at putting two newer, bigger, smarter batteries in the seat, as per Felice, noted above.  Just not ready to dump the current investment, absent any actual problems.

More recently, I’ve moved the charger/inverter into the hanging locker. I also fit the Victron Isolation Transformer in there.  Along with the solar charge controllers and an ELCI and surge protector. Together, they almost fit.  

Just outside the hanging locker, on the aft side of the bulkhead, I installed a Victron Lynx system, which contains main positive and negative busbars and fuses.

I may post some pictures later (preparing to get under way) but I still consider this a work in progress. Things I’m not entirely pleased with: 

I ended up butchering the woodwork in the hanging locker more than intended. Although it was never much use for storage - I kept the extra PFDs in there.  (Now where do they go?)

Routing all those 2/0 cables neatly in the hanging locker is harder than it looks. I can do better. Need to relocate the solar chargers. Again. 

The Lynx shunt lasted approximately one hour before frying. Victron customer service is next to non-existent and just ghosted me when I asked for a replacement. They do not honor their warranty.

The Victron Isolation Transformer does not meet its specs, and will not work in Mexico where dock voltage is around 130VAC. Victron shuts down at 128VAC. So I have a messy bypass on it right now

It’s poor form to install grounded equipment in front of an AC panel within a certain distance. In residential construction, I think it’s supposed to be farther than arms-length. Of course, this isn’t really possible on a sailboat.  In this case, I mean the AC isolation transformer and inverter/charger in the back of the locker and all the stuff mounted on the bulkhead, including the main DC busbar. When reaching into the locker, you almost can’t help pressing your shoulder against the lynx.  If the covers were off, you could set up a nice little circuit running through your body.  Not sure what to do about out it now except exercise extreme caution, but should have thought about it in the design phase.  Also, don’t skip the chassis ground cables!

Todd

On Feb 21, 2026, at 08:40, Joseph Ruzzi <jmru...@gmail.com> wrote:

My J/40, Spada, has the forward-facing nav station.   For the house bank, she has 4 125 Ah lead acid batteries in a box at the bottom of the port lazarette in the cockpit.   The Magnum 1500 inverter/charger sits on the shelf in that same locker.  The starting battery is on the shelf under the nav station.  The battery monitor control panel is mounted just behind the hinged work surface of the nav station.

As noted in an earlier post, I don't fill the port freshwater tank to keep from inducing a list to port due to the combined weight of batteries and water on that side.

Joe

On Sat, Feb 21, 2026 at 4:55 AM 'Sjors van der Woerd' via J/4X Owner's Group <j4x-owne...@googlegroups.com> wrote:

Hi Walter,

Lay-out on our J42 Felice is probably different but we recently fitted three new 314 amp lithium batteries that fit perfectly under nav-station-seat without any adjustments, together with switches and big breakers.

The inverter, charger and solar smtp are in the hanging locker, we created a dubbele layer of equipment there with a simple woodboard.

The starter battery is on the floor in the same locker.

We went from 3 x 125 amp lead to 2 x 314 amp lithium, a game changer for us. It feels like almost unlimited energy with less weight and less use of space.

Batteries are from www.solar-moble.nl, the rest is all Victron.

See pictures attached.

Wish you all a good weekend,

Sjors van der Woerd

J-42 Felice, hull# 7, Amsterdam

<IMG_7279.jpeg>

<IMG_7280.jpeg>

<IMG_7281.jpeg>

<Vd Woerd Felice J42_1.jpeg>

Op 21 feb 2026, om 05:24 heeft Walter Caldwell <j40shaken...@gmail.com> het volgende geschreven:

Our batteries (2 lithiums and an AGM starting) and chargers (AC and DC-DC) are installed  under the nav station along with the water pump and water heater. It’s getting crowded in there!
So I am curious where you J40s and 42s have your batteries, chargers and inverters installed?
Thanks!

Walter
J40 #007

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[Larry Romano]

J40 #67 had a forward facing navstation. I removed it and did the following 

That is a 300amphour house, start battery, Mastervolt charge system, top loading 12v drink cooler and an air conditioning unit. I never used the sit down nav station.

On Feb 21, 2026, at 11:50 AM, 'Todd Stevens' via J/4X Owner's Group <j4x-owne...@googlegroups.com> wrote:

On Wild, the charger/inverter was originally installed way out in the sail locker on the port side. The start battery was under the vanity in the head, and the house batteries under the nav station seat. The shore power inlet was in the cockpit footwell next to the helm on the starboard side. This meant that incredible lengths of 2/0 (12VDC) and 10/3 (120VAC) cables wrapped all the way around the boat and back.  Holy Voltage-Drop Batman!

To view this discussion visit https://groups.google.com/d/msgid/j4x-owners-group/10B18612-16A4-45AC-BB79-DE6B87C23306%40me.com.

[Adam Ruscitto]

My J/40 has the engine under the galley sink and side facing nav station with cabinets below and no seat. I have 4 - 105 Ah LiFePO4 batteries and a Victron Multiplus under the companionway stairs. AGM Starter battery and AGM critical systems battery along with DC2DC chargers and solar controllers are under the nav station. Sorry, couldn't find any photos and i'm a long way from the boat, currently. 

Adam

To view this discussion visit https://groups.google.com/d/msgid/j4x-owners-group/9EDD8903-556B-423A-9A99-6E3CB3E15C1C%40gmail.com.