voltage readings on electronics?

[tkunk]

Recently, I've been having trouble with my Lowrance HDS units shutting down after just a few hours on the water. I used to be able to fish for 12+ hours with them on. The voltage readings (which I just learned how to enable) on the units themselves are hovering around 10.3-10.8 when the power goes out. Is that low? If so, is it likely that my battery is shot? What should my voltage readings be? The units are connected to a house battery that's not responsible for starting the engine.

 

I don't know anything about boats, so I'd really appreciate any advice. Thanks.

[Krux5506]

No expert here either but it sounds low, and  I'm a little surprised it's too low to power the units but then again I keep mine on the cranking battery and typically after I shut the engine down they are reading 13v....After a while without the engine running they are usually between 12.1-12.6 volts. 

 

How often does your house battery get charged?

[tkunk]

  On 10/15/2018 at 4:41 PM, Krux5506 said:

No expert here either but it sounds low, and  I'm a little surprised it's too low to power the units but then again I keep mine on the cranking battery and typically after I shut the engine down they are reading 13v....After a while without the engine running they are usually between 12.1-12.6 volts. 

 

How often does your house battery get charged?

Expand  

Thanks for the info on voltage ranges.

 

If I'm not on the water, the boat's always charging. The last few times I went out, I checked the batteries, and all of them were fully charged.

[Tennessee Boy]

Yeah that sounds very low.   What do you mean by a house battery?

[tkunk]

  On 10/15/2018 at 5:17 PM, Tennessee Boy said:

Yeah that sounds very low.   What do you mean by a house battery?

Expand  

Thanks. The house battery is mainly responsible for running the electronics. It handles the livewell, baitwells, and lights too, but I haven't been using those. I have separate batteries for starting the engine and running the trolling motor.

[DogBone_384]

Are you charging your batteries when not on the water?  If so, take your ‘house’ battery out and take it to your local auto parts store.  They’ll check it with a load tester and tell you whether the battery is still good or not.

 

If you you’re charging your batteries and the ‘house’ battery gets to 10.x volts quickly, it’s likely got a bad cell.

 

Good luck.

[Fishingmickey]

Your battery is low once it goes below 12V output. You should be able to run your electronics on a 12V deep cycle battery (80-105 amp hour) for a long time. If other things are also running off of the same battery and no way for it to charge without being plugged into a charger. I would suspect that your battery has reached the end of it's useful life. 

[tkunk]

Thanks guys. That helps a lot.

[gnappi]

Fishingmickey is 100%right, as long as the battery stays at (or above) 12 volts (~50% capacity) your electronics will work. Your voltage readings are very low. BTW, from the bulk of what I read draining them to below 11.9 or so shortens their life substantially.

 

I used to keep my electronics on the same battery as my trolling motor and every time I goosed the TM or bogged down in weeds the electronics would crap out. 

 

Since you're on a house battery like I am, to keep the battery up longer use only LED lighting because they use far less power than filament lamps, charge phones at home (cell chargers can take 2+ amp charge rates)  and if you're a vape smoker charge them at home also.

 

I guess you're charging more than one battery at home / on the dock and you did not mention how old the batteries are or what type of charger you're using? 

 

All important to know because different battery technologies need differing charge profiles and one battery can be getting an insufficient charge while another boils away or charges just fine.

 

 

 

[Harold Scoggins]

  On 10/16/2018 at 2:07 AM, gnappi said:

as long as the battery stays at (or above) 12 volts (~50% capacity) your electronics will work. Your voltage readings are very low. BTW, from the bulk of what I read draining them to below 11.9 or so shortens their life substantially.

Expand  

You think you folks have problems, try battery management on a kayak.  Some of us are running sonar, lights, and even trolling motors and we're counting every amp and pound. There is light at the end of the tunnel in the form of LifePO4 technology, the latest in lithium advancement. LifePO4 is a chemically more stable, much lighter, and constant power producer and unlike traditional lead acid batteries, breaks the 50% capacity boundary. They also provide thousands of recharge cycles giving you upwards of a ten year life span. The only drawback to LifePO4 is the COST! A LifePO4 battery similar in size to the battery you are now using in that 21' bass boat can set you back $800+. As with any new technology, I believe the cost will eventually go down. (In my lifetime?) These LifePO4 batteries are built using individual cells that are available to the consumer and depending on the source, are as cheap as $20 each. I've been working with a couple of friends in using these individual  3.2V cells to make a battery pack, complete with BMS (battery management system) that I hope will come in under 15 pounds. So far, the high amp draw over time test is not creating any heat issues, so maybe...   

[gnappi]

Very cool Harold, I'm not trying to be confrontational, I have looked at LifePO4 technology with interest and I have more Q's than answers for boating applications on which info is not readily available so don't get offended by my Q's / comments.

 

You are right, LifePO4 is a bit expensive to get current from compared to an AGM battery and like you suggested it may take a while to get the prices down. But with ~2000 charge cycles that's gonna be an option real soon if not already for some.

 

Are those cells in your pic the 38120S 10Ah or 40152S 15Ah?

 

For a house battery (electronics, lights etc.) that's not too terribly expensive ($100 to $160) and the four cells (either one above) should do that with less weight and used space than many AGM out there to run everything except the TM.

 

Your problem may be the TM. I figure to match anything similar to even a small 35Ah AGM battery which runs my 50 lb TM for between 3 and 4 hours (separate battery for the house), you'll have to put a 3 or 4 ($300 or $400) 38120S packs or two or three ($320 or $480) 40152S in parallel to run a TM an equivalent or slightly more amount of time?  That's not very expensive (IMO) for an all electric boat at all. Of course the boat, passenger, cargo weight and thrust of the TM come into play, I used my boat for reference as it's an all electric 10' Lowe.

 

Have you found a commercial charger charge the LifePO4 battery packs?

 

[WRB]

The house battery, what group size is it and is it a deep cycle marine battery??

You OB engine charges the cranking battery while it's running, however most bass anglers charge all the batteries with a onboard charging system after each trip.

My guess is your house battery isn't a deep cycle and only surface charges, if connected to a charger.

Tom

 

[tkunk]

  On 10/16/2018 at 3:13 PM, WRB said:

The house battery, what group size is it and is it a deep cycle marine battery??

You OB engine charges the cranking battery while it's running, however most bass anglers charge all the batteries with a onboard charging system after each trip.

My guess is your house battery isn't a deep cycle and only surface charges, if connected to a charger.

Tom

 

Expand  

It's definitely a cranking battery, but I'm not sure of the group size. I don't keep my boat at my house, so I can't check right now. I have 3 deep cycle batteries for the trolling motor, a house battery, and a starter battery. My onboard charging system charges the deep cycle batteries and the house battery. If I'm not on the water, the boat is plugged in.

 

Until the last couple of months, I could get around 12 hours per trip out of my electronics. Based on what I've seen in this thread, I think I must have an issue with the battery itself.

[WRB]

Your OB engine should charge only the cranking battery. Onboard charger charges the 3 trolling batteries and cranking battery possibly the house battery when plugged in. You have a total of 5 batteries as I read this; 3 TM’s,1 cranking + 1 house. You need a 5 bank onboard charger or a 4 bank with the cranking and house battery wire in parallel. Either the house battery is bad or poor connection to it’s dedicated charging bank.

Test the house battery and replace it if it’s bad.

Good luck,

Tom

[Harold Scoggins]

  On 10/16/2018 at 8:33 AM, gnappi said:

Are those cells in your pic the 38120S 10Ah or 40152S 15Ah?

Expand  

They are the 38120.

Have you seen the Torqeedo 403C? It's a 29V system and they claim it has a range of 120 km/74.5 mi range at low speed. Judging from the size and weight of the battery pack I'm sure they are using LifePO. I would love to get my hands on one so I could take it apart and see how it is configured. If I was a betting man I would bet that it is built like the batteries used in electric cars, only smaller, they are using 38120 or 40152 cells.

[Ski213]

@portiabrat have you checked the voltage at the battery itself to see if it matches the unit voltage?  May well be a bad battery but it could also be voltage drop from a bad connection somewhere between the battery and the units. 

[tkunk]

  On 10/18/2018 at 6:05 PM, Ski213 said:

@portiabrat have you checked the voltage at the battery itself to see if it matches the unit voltage?  May well be a bad battery but it could also be voltage drop from a bad connection somewhere between the battery and the units. 

Expand  

Thanks for the tip! After reading the suggestions here, I found out that I'm getting low voltage readings on both of my graphs. Then, I had someone check the battery, and the voltage is a big higher there, but it's still too low. I'm getting a new battery.

[gnappi]

  On 10/17/2018 at 1:59 PM, Harold Scoggins said:

They are the 38120.

Have you seen the Torqeedo 403C? It's a 29V system and they claim it has a range of 120 km/74.5 mi range at low speed. Judging from the size and weight of the battery pack I'm sure they are using LifePO. I would love to get my hands on one so I could take it apart and see how it is configured. If I was a betting man I would bet that it is built like the batteries used in electric cars, only smaller, they are using 38120 or 40152 cells.

Expand  

I may have seen one, maybe not...I saw something like it on the interstate, but assumed it was a home made wind power generator ?

 

I did get to look it up, thanks and some of it is making no sense to me.

 

They "say" you can charge while underway, on a yak? With a 45 watt (or two 45 watt / 18volt most likely in series for the high voltage) solar cell? A single 45 watt / 18v solar cell with current tech is going to be pretty big (~26" square) unless they had a breakthrough in solar cell technology to get the size down and the voltage up that high. 

 

Anyway, it's Waaayyyy too rich for my blood at $2,300 and $600 and $900 for a spare battery. It makes the LifePO 38120S 10Ah or 40152S 15Ah cells look downright cheap, and I don't think you get the charger with it?

 

If you have done it, how many of the 4 cell arrays have you parallel jumpered?

Are you making your own or have you found jumper kits?

What charger are you using that the LifePO charge profile? I read that you "can" from (powerstream.com)

"Nevertheless, it is common to charge a 12 volt a 4-cell series pack with a lead acid battery charger"

 

Your experiments are very cool keep me / us up to date on what you're finding.

 

 

 

 

 

 

 

 

[Maggiesmaster]

I wouldn’t run anything else on the starter battery; you want it to be able to start the motor. Rather the graphs crap out than the motor not start. You can buy a good quality voltmeter for about $30. It’s your friend!

[FishyGuy]

  On 10/31/2018 at 3:49 PM, Maggiesmaster said:

I wouldn’t run anything else on the starter battery; you want it to be able to start the motor. Rather the graphs crap out than the motor not start. You can buy a good quality voltmeter for about $30. It’s your friend!

Expand  

I'd say that's particularly important if you have the newer 4 stroke or DFI OB.  They have a lot of electronics and it may be impossible to start even if the starter turns over.  Unlike the old school  2 stroke carb motors.