Fish finder battery woes

I bought a 7.2 Ah battery for my Hook 5 earlier this year: https://www.amazon.com/ExpertPower-EXP1272-12V-Rechargeable-Battery/dp/B00FNXBTMC

At first it worked fine, but now my Hook 5 consistently shuts off after an hour and a half. I measured the voltage on the battery after getting home and it was 13.6 volts. This is also close to the voltage I measure on the cheap charger I'm using. I've accidentally shorted the battery for a second or two several times-- could that have wrecked it? Or is the charger suspect? I was surprised that the FF would shut off when the voltage was still so high. Any suggestions?

According to a quick google the Lowrance hook 5 has a voltage input range of 10 to 17 V @ 1.1 A. Try seeing what your FF is pulling for amperage if your Multi meter is capable of measuring amps.

Does the lowrance have a battery saver shutoff? I seem to remember my humminbird having a setting that shuts it off at a specified battery voltage. It is designed to prevent your boat starting battery from being run dead while fishing. If it does have that feature you can change the setting to a lower number and see if that helps.

Krishna, what voltage does it read when under load? Defective batteries can show normal voltage when no load, but drop dramatically under load. Is it a SLA battery? I've been screwed by this same problem before during a Islander trip several years ago. I had since got rid of all of my SLA battery and moved to all lithium. Battery may not be the reason why your ff shuts down after an hour, but it's the first thing I would check. Check it under load.

ernest

It could be a bad battery.  I bought an Expert Power 8aH battery from Amazon that died in about 9 months powering an Elite-4.  Like lucky13 said, it looked fine right off the charger, but as soon as even a low load was placed on it, the voltage dropped off.

We have no idea how long the batteries sat before they were shipped to us.

It could be a bad battery.  I bought an Expert Power 8aH battery from Amazon that died in about 9 months powering an Elite-4.  Like luck12 said, it looked fine right off the charger, but as soon as even a low load was placed on it, the voltage dropped off.

We have no idea how long the batteries sat before they were shipped to us.

Yes, I think I scored a bad battery 10ah that was dying on my livewell pump after 1.5 hrs, went to a 15ah now, not expert power

... Battery may not be the reason why your ff shuts down after an hour, but it's the first thing I would check. Check it understand load.

This.

If the battery is OK, it could be a problem with the wiring. I had voltage measuring fine at the ff, but ff kept shutting down---replaced part of the power cable and problem was fixed.

usually, I'd say ry turning down the brill....  Backlight can go way low and you can still see it. That saves tons of power.

But if it's reading 13.5 after you F goes dark, there's something else going on.  could be a crimped power wire that quits conducting as it heats up?

Bushy

Thanks for the great suggestions, everyone.

Does the lowrance have a battery saver shutoff?

Oh, interesting. I just did a search in the Hook series manual and don't see any mention of a feature like that, so I don't think it has a battery saver shutoff.

Krishna, what voltage does it read when under load?

Good point about the voltage dropping under load. I will measure voltage and amps once the unit has been running for a while. The annoying thing about troubleshooting my FF is that it and the battery have to be wired to the kayak, and the kayak is normally on top of my car or hanging upside down in the garage.

Which lithium battery did you choose, Ernest? I'm interested in this option.

Thanks again, everyone.

Which lithium battery did you choose, Ernest? I'm interested in this option.

Thanks again, everyone.

I'm rocking the Nocqua 10AH, 12 hours on the water and haven't killed it yet!

https://nocqua.com/product/pro-power-kit/

Which lithium battery did you choose, Ernest? I'm interested in this option.

Thanks again, everyone.

There are literally thousands of choices. I'll send you some pix of my setup tomorrow. I normally buy my lithium batteries from HobbyKing and BatterySpace because these guys know their stuff. Not only do they publish the full specs, the specs they publish are fairly close to the actual specs. I test every battery I buy to verify their specs. I do not buy from sellers that do not publish the full specs, regardless of how good they claim.

Krishna, I sent some info with pictures. Let me know if you didn't get them. I had some trouble with the picture upload and not sure if they got sent.

Krishna, I sent some info with pictures. Let me know if you didn't get them. I had some trouble with the picture upload and not sure if they got sent.

Thank you! The pictures came through nicely. I appreciate the detailed writeup.

It looks like once you add in a charger, enclosure, and connectors, the DIY option is roughly the same cost as turnkey kayak batteries, while involving more fiddling and trial-and-error. The two main turnkey battery contenders I see are the Nocqua and Wilderness Systems. Wilderness Systems botched some design details: a current limit that won't allow some larger fishfinders to boot, and requiring you to turn the battery back back on if you shut down the fishfinder (really?! I will climb out of my kayak and swim to the front hatch if I need to, but that doesn't mean I'm going to be happy about it).

I'm currently leaning towards the Nocqua, but I'd be happy to be talked out of it:
https://www.thegpsstore.com/Nocqua-10Ah-Pro-Power-Kit-for-Electronic-Devices-P4950.aspx

Mystery mostly solved. After the fishfinder had shut down, when I got home I turned it on with the multimeter connected to the battery leads. The voltage started off at 13 and steadily dropped. Within a few minutes it was all the way down to 8 V. Amazingly, the fishfinder was able to stay on all the way down to 7 V. The voltage reported by the fishfinder matched what I was seeing on the multi meter. I also tried reading current, and never saw the fishfinder drawing more than 0.7 amp.



I have ordered the Nocqua battery, so we’ll see how that goes.

After doing net research, one of the biggest things in favor of the Nocqua (IMO) is that there are a fair number of reviews, where as for the Wilderness there are almost none, and then reading between the lines the Wildy does have issues and traits that make it look less desirable at the moment.