Problem charging start battery

[Wolf24530]

I own a Hunter 410, year 1999 and have a problem charging my starting battery with the engine. The charging is fine on all batteries when I am on shorepower. I noticed under my chart table a panel with the windless breaker and behind this panel is a solenoid which prevents the starting battery from being drained when I am on the hook out on the water without the engine running. This solenoid has a white and a black wire besides the two heavy red cables one from the house selector switch to the solenoid and one from the solenoid to the starter battery selector switch. The white wire is supposed to lead to the starter switch in the cockbit and the black to the ground. By turning the key to start the engine the solenoid should close and lets the current go to the starting battery when the engine is running. This is not happening. According to Hunter there should be a fuse somewhere in the line to the starter switch which I can not find. Can anyone with this same set-up help me out to solve this mystery or give me some idea how to trouble shoot it.

Wolfram Milz

 

[Bill Murray]

"By turning the key to start the engine the solenoid should close and lets the current go to the starting battery when the engine is running."

This is not quite the way the boats were wired.... I too have a 1999 Hunter 410 -- hull # 178

The wiring includes solenoid like you describe but it is wired to the starter switch not the engine power side. It only closes when the key is in the start position. This was Hunter's idea to give you a bigger boost when starting the engine. Of course that assumes that you have not depleted your house batteries! There is not a way to disable the function in such a case without disassembling the switch connections. When the starter is disengaged, the circuit opens -- disconnecting the battery banks. The schematic I have does not show a fuse in teh circuit from the starter switch to the solenoid.


The system also contained a big "battery isolator" ( diode) this allowed any charging circuit (alternator or batt charger) to simultaneously charge both battery banks but "isolate" them when no charging was occurring. Mine was a big blue box and was also found behind the access panel you mention -- it hung on its wiring behind the lower panel. the problem with diodes is that they always under charge batteries by virtue of the way they function.


There was also a solar panel that trickle charged the starter battery only. It too has a fuse that may be blown. The fuse is located on the house battery switch panel.

Not a clue why yours is not working - not enough info. Start by getting a schematic (in your owners manual) and check all connections are still as original and that all parts are working as designed.

 

[Don12364]

Wolf,
My H376 (1996) has exactly the system you describe. It has worked extremely well over the years and I am a big supporter of this over the "Off/1/2/Both" switches. The last time I bought a house battery was in 2003 and the engine start battery is the original from 1996.
Once a year I do a 50 amp discharge test and all the batts hold up okay.
I do not have the diode splitter mentioned by Bill Murray.

The solenoid you refer to is called a 'Combiner' for obvious reasons.
My alternator is rigged to charge the engine battery and then the combiner passes the charge current to the house batt, but this would make no difference to the arrangement, other than a combiner failure would not inevitably mean failure to start the engine! Clue here?

To come to your point, my combiner developed a high resistance across its main switching terminals (the ones with the thick red wires). This was evident when I was charging from the engine when each battery read a different voltage. Differences of 0.1v or occasionally 0.2v were normal but half a volt difference indicated a problem. I have a Link battery monitor which reads the voltage of each.
Being me, and realising I would probably have to buy a new combiner anyway, I decided to take a look inside. I chucked it in my lathe and very gingerly turned off the small flange which held the two halves of the casing together.
All was revealed, some time previously when I was swinging on a spanner (US wrench!) making sure it was 'really' tight, I had inadvertently caused one of the large battery connecting studs to rotate by about 45°. On the other end of this stud was the main combiner contact which was now no longer correctly aligned. It made contact but could no longer carry a heavy current. I little turn to line it up and some araldite to join and seal the two halves of the body back together and I was back in business.
Altogether it took less time than going to several chandleries looking for a replacement combiner.

BTW I also have overcome the difficulty of charging both batts from a single output shore charger. Anyone interested please PM me.

 

[Bill Murray]

I should have mentioned that I modified the system I described to get rid of the isolator diode....

I replaced the Diode with a Blue Seas Combiner relay (available at WM) designed specifically for this task. It connects the banks together whenever any charging source is present and disconnects them otherwise. It is automatic and works well and does not result in any voltage loss. I replaced the "on starter only" solenoid with a manual battery switch which allows me to parrallel both banks in an emergency.

I had a similar set up in my H29.5. It works flawlessly without thinking about and it is very good to my batteries too.

 

[Bill Roosa]

Does the solenoid operate

Can you get the solenoid to operate by connecting the hot side low current solenoid terminal to a known 12 volt source?
This would confirm that it is or is not the solenoid. I suspect that if you did not see a fuse near the starter switch or the solenoid then they did not put it someplace "in line"
If the solenoid checks out test the hot side low current wire for 12 volts by using a multi meter while the first mate fusses with the ignition switch.

I've seen systems that allow you to start the boat with a combiner off and then the alternator voltage engages the solenoid. Uses multiple diodes in the alternator circuit and the start bat is totally isolated except through the combiner solenoid. You should check for where the solenoid low current wires actually run.

FWIW