HDS-7 Screen Dimming

[ncp]

This may be a two part question that I should have separated into two different posts but I'll start it off and re-post if necessary:

1.

Installed my new HDS-7 on the boat yesterday. It runs through a 10A circuit breaker that receives 12v power from a battery converter (52304). Whenever I would restart the engine after drifting for a bit, the HDS screen would dim quite a bit (to the point that it was hard to see with sunglasses on..yes, we have that problem in Southern California) but keep functioning normally. After a quick reboot with the engine running, the screen would behave normally.

I called Lowrance this morning. Their only suggestion is that there is voltage drop big enough that causes the unit to malfunction (I will go visit the boat tonight and check with a voltmeter). Anyone know of a way to get full screen brightness back without a reboot? Any other explanation anyone has come accross?

2.

They (Navico) suggested adding a house battery. I currently have two 12v batteries in series to run everything 24v on the boat. The 12v panel is connected the battery converter and mentioned above (also see attachment). Is there a simple way to add a charger after the battery converter but before the house battery and then hook up the 12v panel to the house battery? I'm not looking to rewire the entire boat with a bunch of batteries and multiple 3-way switches!!!

Thanks!!!

52204 Battery Equalizer

[geir]

This one is supposed to do that : http://www.furneauxriddall.com/acatalog/Droppers.pdf , and for less than £50 too

[GaryC]

There is a simple solution to voltage drops on the feeding supply system. This was given to me from a guy in our dive club who perceived that when you start your engine it puts a shunt across the main battery thus turning off all your electronic kit that you already have switched on. Never affected me so don't use it.

You provide an additional battery from the main supply. A small lead acid is all that is required. Between that and the main supply you put a thing called a schottky diode. You pick one with a cut off voltage of 10v or so. The theory is that under normal conditions your small battery is under charge. If the main supply drops then the diode cuts off isolating the small battery which will allow it to supply the full 12v as normal. There is no back current. When the main supply comes back the diode forwards again. This system will take down time basically as big as your small battery. If you are talking about seconds of main supply down then you dont need a very big (small) battery. I think the battery I was going to use was an alarm pannel battery.

[ncp]

Hmmm... that sounds like a simpler (and cheaper) idea. Though, I'm sort of liking the house battery/charger idea for those times that I do want the electronics on while on the hook.

So, I enlisted the help of the neighborhood kids and tried a little test last night to see if I could record a voltage drop. I couldn't:

No voltage drop upon start up - YouTube

This was the 2nd or 3rd try because he was having trouble holding the probes on the wires.

(let me know if the youtube link doesn't work)

[jyasaki]

The drop will be while the starter is turning, and may be pulsed. An analog meter may show you more than a dmm.

Have you tried hitting the power button briefly to see if you're kicking down to reduced brightness? My LMS-520 has 4 settings (as I recall) that cycle through.

jky

[9D280]

I also have the 520, and (see other recent posts regarding battery cooking) last trip I had it reset (full off - I had to power it back up) on every engine start.

Granted my battery isn't now in the healthiest state (again, see other posts ), so I may be seeing an extreme version of your issue.

[ncp]

Originally Posted by jyasaki

The drop will be while the starter is turning, and may be pulsed. An analog meter may show you more than a dmm.

Have you tried hitting the power button briefly to see if you're kicking down to reduced brightness? My LMS-520 has 4 settings (as I recall) that cycle through.

jky

Hmm...back in town this weekend after a little r&r. I see how it handles again. Like I stated, it was the first time that I had gone out with the HDS hooked up.

[ncp]

Originally Posted by GaryC

You provide an additional battery from the main supply. A small lead acid is all that is required. Between that and the main supply you put a thing called a schottky diode. You pick one with a cut off voltage of 10v or so. The theory is that under normal conditions your small battery is under charge. If the main supply drops then the diode cuts off isolating the small battery which will allow it to supply the full 12v as normal. There is no back current. When the main supply comes back the diode forwards again. This system will take down time basically as big as your small battery. If you are talking about seconds of main supply down then you dont need a very big (small) battery. I think the battery I was going to use was an alarm pannel battery.

I like this idea because it seems simple (and cheap). But will the small 12v battery that add be properly charged by my 24v-12v converter? Or, will that converter just keep pumping 12v into the aux battery?

I have other 3 options, below.

[ncp]

I went back out on Saturday and added the voltage indicator to my HDS screen.

1. I had the dimming problem happen 2 of the 5 times that I restarted my boat. Both times, the voltage never registered a change while starting the engine but I had to reboot.

2. One time, upon starting the engine, the voltage dropped to 9.8v...this time the screen stayed bright!!!

I am thinking of adding a house bank (or single battery) to combat this and give me some extra "juice" to play the radio, leave the VHF/GPS on without stressing about the battery level.

Current set-up:

24v DC / 24v alternator ---> 24v-12v converter ---> 12v switch panel ---> loads
-Currently have two 12v batteries in series powering the starter, nav lights, and bilge pump
-All 12v electronic (VHF, GPS, etc.) run off the 12v panel.

Proposal #1

24v DC / 24v alternator ---> 24v-12v converter (existing) --->12v-12v battery charger (NEW ADDITION) ---> 12v house battery (NEW ADDITION) ---> 12v switch panel ---> loads

-I only found one 12v-12v batter charger while googling: DC Input Battery Chargers for 12 volt Lead Acid and SLA Batteries useful for electric golf trolley
-Cost: $154 + [1 x new deep cycle 12v battery]

Proposal #2

24v DC / 24v alternator ---> 24v-12v converter/charger (NEW ADDITION) ---> 12v house battery (NEW ADDITION) ---> 12v switch panel ---> loads

-There are are a few of these out there:
http://www.furneauxriddall.com/acatalog/Droppers.pdf
12V battery charger with 24V input, heavy duty industrial, marine and military grade DC Input Battery Chargers for Lead Acid and SLA Batteries, for 12V batteries in 24V vehicles
-Cost: $300-$350 + [1 x new deep cycle 12v battery]

Proposal #3

24v alternator ---> Blue Seas Add-a-Battery (NEW ADDITION)---> 24v House Bank (NEW ADDITION) ---> 24v-12v converter (existing) ---> 12v switch panel ---> loads

-The Blue Seas Add-a-Battery works with 24v systems: Add-A-Battery - PN 7650 - Blue Sea Systems
-Basically, I would have two 24v banks which charge simultaneously while the engine is on, and separate automatically when the engine is off. All 12v electronics would run off the house bank and, in an emergency, I could combine the circuits.
-I need to see if I have room for 2 more batteries! (One I can handle!)
-Cost: $100 + [2 x new deep cycle 12v batteries]

Comments about the above or other ideas are welcome!!! (and ask questions to clarify if I typo'd anything)

Thanks!

[jyasaki]

Originally Posted by ncp

1. I had the dimming problem happen 2 of the 5 times that I restarted my boat. Both times, the voltage never registered a change while starting the engine but I had to reboot.

It likely won't, especially if the problem is due to a low voltage that the Lowrance doesn't like.

Sort of like looking at a thermometer, but having no light when you want the reading.

You really need to get something fast (analog meter again) that can be temporarily hardwired in for troubleshooting.




[quote
2. One time, upon starting the engine, the voltage dropped to 9.8v...this time the screen stayed bright!!! [/quote]

Means little, other than the fact that you've got a drop. Electronics get unpredictable outside their comfort range.



All the proposals cut, sorry. Too many beers to make sense of it all right now.

Seems to me that if your base system is 24 volts, you should be able to find something that will reliably convert 24V to 12V, and run the electronics off that. Leave the motor on whatever 12V conversion you have now (especially as it seems to be working.)

jky