House Battery Isolation

[TomT13]

Like all Hatteras boats (according to Hatteras) the port battery doubles as the house battery. During starting I get a voltage drop that knocks out my electronics. This causes some of the settings to reset to factory defaults. I was wondering if anyone has successfully isolated the DC house power circuits from the port starting circuit. I can add another battery and see if this corrects the problem but my goal was to go even further and isolate the two batteries during starting. I am considering installing an Blue Sea Systems ACR with Starter Isolation. The only problem is the way Hatteras wires the DC circuits off the buss bar for both starting and house power. This would bypass the ACR. Any help would be appreciated.

 

[agblizzyb]

wHY NOT SET UP A BATTERY Bank just for the electronics with the isolator.
I had the same problem until I went to a 110 amp alternator and I dont lose the electronics during startup
Al

 

[luckydave215]

I have a seperate 12V bank (two 8D's) to power the electronics and start the generators. There's another one (single 12V group 27 AGM) dedicated to power the morse engine controls. Each bank has it's own smart charger, and I can switch the loads between them with breakers if need be. I can also tie the inverter battery farm into this circuit in an emergency.
The advantage is no issues when starting the mains, and no worry about being able to start the gens even if I run the standard port house bank way down. Also, if I need to replace a gen starter (cummins) it'll be a bunch cheaper.
Tha obvious disadvantage is lots of batteries to fool with. But what the hell, once you get the battery watering gear out, who cares how many holes you pour water into?
I know, it's way more complicated than it needs to be but..........
So far it's worked great.

 

[Trojan]

Just try adding a diode in line and a 10uf/20volt capacitor to ground in line to your electronics main feed. The diode prevents a back feed and the cap carries you over the starting bump.


BILL

 

[MikeP]

As you state, that is the standard config for Hatts and our 53MY which is totally oem as far as the battery banks and their connection is concerned, never exhibits that behavior. Are you sure something isn't causing this problem (poor connections, bad batts, etc)?

I know some folks feel differently but I've seen no need to revise anything in the oem Hatt electrics. I see no need to create another battery bank since the Starboard batt bank can be paralleled to start the port engine should the port bank be drained. Along those lines, we have run our Outback 3200W inverter for up to 24 hours (fridge, microwave, stereo, hair dryer) using the port bank and it would still start the engines without paralleling. I ran the inverter for 36 hours (running just the fridge) and again, no parallel start was necessary.

 

[luckydave215]

I don't know if I'd change mine from original configuration either, but that's the way things were when I bought the boat.
It all seems to work just fine, so if it aint broke........

 

[TedZ]

Bill's idea on the capacitor/diode circuit is a good one...wish i thought of it as if an engine stalls, the restart does knock out some electronics on most boats. On mine the sounder and autopilot for sure.

Don't forget a 10 microfarad cap is big and if ,when you are hooking it up, you have occasion to unhock a wire on a charged cap you will scare yourself. The energy storage is real. Don't hit your head when you jump!

Also make sure the wattage on the diode is enough...twice the ampacity draw of the electronics times 12 volts should work.

Ted

 

[REBrueckner]

I'm not sure for how long a dip in voltage during start a diode and capacitor will sustain electronics...it depends in part on the electronics current draw. That is, in part, how many electronics you have running...sounds like a good idea!!

I experienced the same electronics reset at engine start and so when I added a third battery bank for new accessories, with its own electric panel, I ran a wire directly from the panel to the flybridge for all electronics. There I installed a two way switch...one postion from port start batteries (original layout) the second position connecting all electronics to the new house bank (now the normal mode) . In the event of a failure, I can switch to another power supply right from the helm.

An close alternative would be to install a moderate size battery just for electronics and charge it via a combiner. Some advocate such a battery be installed at the flybridge so as to have a relaible power source for communications in case of flooding in the engine room or sinking. Had I not installed big 8D's for other accessories down below, this is the route I would have chosen.

 

[Trojan]

I would first check my wire connections through the string. Clean them all with a deoxit. Then take a voltage reading during the start cycle at the electronics and see how low the voltage drops. How well the diode and cap works depends on how low the voltage goes and long of a duration the start cycle last. You could use two diodes and just feed your electronics from both banks at the same time. But both feeds must be fed with a fuse before the diode. I think I would use the twin diodes. Adding the extra battery would be nice. But I like the kiss system and adding the extra battery to me, just says I don't watch my systems close enough. A back up for a backup for a backup. I don't like to over complicate my systems.



BILL

 

[luckydave215]

Some advocate such a battery be installed at the flybridge so as to have a relaible power source for communications in case of flooding in the engine room or sinking.

This is an excellent idea, and I plan to do it when I "getaroundtoit"
I'm going to move my engine controls dedicated battery up to the bridge and provide switching so I can have flexibility as what it powers, with the radio's coming first.

 

[TedZ]

To answer how long the voltage will be sustained, here is how long it will take to decay to one half of the voltage

t (time for the voltage to decay in half) = log base e (2) × RC = 0.693 × RC

I know no one is too interested in that but the point is if you make a circuit that decays too quickly i.e. the electronics still panic, all you have to do is increase the resistance or the capacitance...better the capacitance so you don't reduce the current too much.

Ted

 

[MikeP]

I think an awful lot of work is done/money spent to re-engineer a system when all that was necessary was some routine maintanance on the oem components.

Frankly, unless the original system is ruined/rotted out/been underwater, whatever, I don't see the point of adding battery banks and their associated additional weight, wiring and related complexity. The oem setup - 2 32v banks and several 32 to 12V voltage reducers located at the lower and upper helm for the electronics does the job perfectly well.

If more AH is required, there are 8V batts with more enough capacity to do anything you want done. Although I haven't seen any need for increased capacity, to me this is a far better solution than adding another system to the boat.

 

[Trojan]

You must also consider how much voltage is left to start with. How low does it dip. It doesn't have to go to 0 to reset the electronics. I would go with the the diodes before I put a heavy acid filled battery on my fly bridge. They do enough damage with fumes in the bilge. Let alone up under all my instruments and expensive electronics on the bridge.


BILL

 

[luckydave215]

I would go with the the diodes before I put a heavy acid filled battery on my fly bridge. They do enough damage with fumes in the bilge. Let alone up under all my instruments and expensive electronics on the bridge.

Use an AGM battery and this isn't a problem. In addition, the weight of a single battery is an issue, or it isn't.............
It depends on the size and weight of the boat in the first place. I have enough room under my "dash" to stow a 15' rigid bottom inflatable.....AND a Cadillac. I'll never notice a battery.

 

[Boatsb]

If you put diode on a standard batter in the bilge between the main bank and the electronics feed it will act like a UPS. That way it will be recharged by the main engines but the isolating diodes will not allow it to drop voltage when you start the engine. Its easy, does not require major changes and keeps batteries in th ebilge where they belong.

FYI I cleaned my terminals and topped the water on my batteries after experiancing the same problem. As long as the 10K radar is not transmitting I have no problems with the electronics being reset.

 

[TomT13]

Boatsb,

In effect, that is what I am going to do with the ACR. After speaking with Hatteras {unofficially}, Blue Sea Systems, Odyssey Batteries and marine electrical professionals the real issue is that when I switched to the Group 31 AGM batteries I changed my AH’s from 220/battery to 100/battery {actually 94}. It is going to take two of the AGM Group 31's to make up the difference from the original configuration. I have been assured that the AGM’s over the long period will not “slough off” like the lead acid batteries do. Time will tell. As for the maintenance of the electrical system as others have commented, that isn't the issue here because it is maintained very well. I believe that after the addition of another AGM battery and the installation of the ACR which has the diodes as a component of the ACR the problem should be eliminated.

 

[Boatsb]

The other option is lose the AGM and go to the beefier lead acid batteries so the drop is not an issue. I looked at the AGM and still went with regular lead acid batteries for the cost and power.

 

[REBrueckner]

"....I don't see the point of adding battery banks and their associated additional weight, wiring and related complexity..."


There are two main reasons to consider adding another battery bank and its own electric panel.

One is to handle additional equipment: I added one additional radar, three GPS plotters, two heating systems, two salt water washdown pump systems forward, one additional searchlight forward, a 12v refrigerator,a 12 volt freezer,a scanning sonar, ...I forget what else. So I used, I believe, eight additional circuit breakers in addition to those available in the Hatteras electric panel.....The autopilot never had it's own circuit breaker (Never did find the power source so I used a dedicated circuit breaker).

The second reason is diversity. When cruising six months a year, I like to serve different house loads (accessories) from different battery banks. So if, for example, my frig door opens and the 12v frig compressor runs continuously,then only the battery bank under drain is dead....I have backup available immediately. It also gives me the ability to manually parallel another battery bank if needed to start an engine...And I can switch between loads to control depth of discharge.

 

[MikeP]

Sure - it makes sense if you are adding sufficient additional loads that the oem DC system does not have the capacity to support it.

In our case, the only additions I've made to our boat was newer nav/comm equipment which required less elec power to operate than the original 1980 equipment. Same was true of the new fridge - takes less power than the original. So in my case, I actually reduced the power needed from the system.

The only other equipment I plan to add that takes any noticible power to run is a watermaker but since I'll be getting an AC version, power isn't an issue - I don't plan to connect it to the inverter circuit.

 

[60hatt]

go to newmarpower.com they have a product called start gaurd. works great and will solve your problem.