Ground wire connection on a Balmar XT 170 with case ground?

[skippeer]

2022 did I replace 6 old AGM batteries with 2P4S GBS LFP cells and installed X2 BMS from BatteryBalance.
The old no-name alternator with a Balmar MC-614 regulator from 2011 can charge with 75 A did I monitor last summer when we were day sailing from Netherlands to France.
95% of the nights with shore power so the domestic battery bank was having high SOC all the time, this season I expect that we will be using our anchor a lot and need to improve the alternator capacity.

Have payed for a Balmar XT-SF170-J10-KIT (170 A) alternator kit and serpentine pulley rebuild kit, it will take some weeks for the shipment from US and while waiting I am doing some detailed planning.
The old no-name alternator do have a minus & plus terminals and 35 mm2 wires to busbars in the engine compartment.
The new XT alternator is case grounded and I would like to continue use a ground wire connected to the alternator.

Possible connection points:

• My VP D2-55 (A) have a 2" single foot and according to Balmar info should a M10 bult be used holding alternator fixed to the engine foot (pivot bolt).
• At the top there are 5 holes for the tension arm, 3 of them have M8 threads, sanding of the paint around one of these holes could be a possible connection point.
• ?

Anyone with ideas/experience of fixing a perfect electrical minus connection on a case grounded alternator?

 

[skippeer]

Due to adaption of agile thinking the installation of the XT170 has been put on hold for a year.

XT-170 do not have D+ / 61, W or DF.
Warning lamp and tachometer on engine panel in cockpit needs to get signals from Balmar regulator for some Penta engines,
D2-55 A has a dedicated sensor for tachometer so I only need to route a new cable for warning lamp.


The Balmar manual suggest 2 different points for the case grounded high output alternator (HOA), it took some time for me to find it.
RTFM ;-)

Negative (Ground) Terminal (B-) - While the alternator is grounded through its case, an additional ground terminal
is provided.
If grounding a heavy cable, it is better to ground at either the adjustment arm mount (Single foot) or
one of the two case mounts (Vortec mount).

Also did I today learn the importance to mitigate future cable issues related to engine vibrations.
Secure heavy battery cables to the engine within 12 inches (30 cm) from the alternator. The cables MUST be attached to
the engine first, before transitioning to the vessel or a surface that is not part of the engine.

Found a pdf file with an image helping me to see the big picture.
https://oceanplanetenergy.com/wp-content/uploads/2023/01/Alternator-wiring-diagrams.pdf

 

[skippeer]

Late update of my grounding point on a VP D2-55A:
Today 35 mm2 black minus / red plus cables from alternator to busbars in the engine room.
Will be replaced with a 50 mm2.

From start engine do I have another 35 mm2 cables to the same busbar in the engine compartment.

Due to issues with overheating have I limited the max current to 100-110 Amp.
Considering ventilation improvements.

Focus this year is to complete solar panel arch installation and some other high priority maintenance tasks.

 

[PaulRainbow]

Late update of my grounding point on a VP D2-55A:
Today 35 mm2 black minus cable from alternator to busbar in the engine room.
Will be replaced with a 50 mm2.

From start engine do I have another 35 mm2 cable to the same busbar in the engine compartment.

Due to issues with overheating have I limited the max current to 100-110 Amp.
Considering ventilation improvements.

Focus this year is to complete solar panel arch installation and some other high priority maintenance tasks.

View attachment 191392

What's the purpose of the 50mm cable ? If it's connected to the engine block for starting etc then just connect a cable from here to the alternator. 25mm is enough for a short cable, but if you have 35mm that's fine too.

 

[skippeer]

Alternator and start engine has today 5 dm plus / minus 35 mm2 cables to busbars in the engine compartment ( 4 cables in total).
50 mm2 between engine room and electrical cabinet, roughly 2 metre.
95 mm2 between electrical cabinet and LFP cells / start AGM battery, roughly 1,5 metre.

Good point regarding cable size.

I think the 50 mm2 was from a recommendation related to possible max alternator current.
Need to carefully measure cable lengths and size from alternator to LFP.

As long as I am forced to limit max charging due to heat issues I will postpone any cable improvements.

Thx for wakeup call ;-)