The 8000mAh lipo battery lasted 6hrs 52 minutes on my Marcum LX7 today which consumes a whopping 700mA/h due to the LCD screen—average temperature was -5ºc outside. Non LCD units like the Marcum LX5 consume roughly half the amperage at 350-400mAh so it is reasonable to assume 12-13 hours of runtime. For LX7 users that fish long days, perhaps the 9800mAh version would be a better fit. I'll order one and see.
The standard 12v 9Ah SLA battery on the scale
weighing in at a whopping 5lbs 12 oz.
The new 12v 8A/h Lipo "Blue Brick" on the same scale
weighing in at a measly 9.9 oz
Weight saved: 5lbs 2 oz. or 50% of the LX7's total weight.
The weight savings on a non LCD based flasher will be higher as a percentage since the unit's overall weight is lower.
Step 1. Order a battery
The "blue brick" comes in various capacities but the only two sizes relevant for this application are the 8000mAh aka 8Ah or the larger 9800mAh aka 9.8Ah. It's possible that the 9800 would be better for a unit with an LCD but time will tell and I'll update this thread. The 8000mAh SHOULD be adequate for non LCD based units. These batteries come with chargers equipped with a light to show state of charge. Red light means dead, amber means halfway and green means full charge. Be forewarned that lipo batteries are quite sensitive to being overcharged. My LX7 has a voltage meter and I know the battery is fully charged at 12.6 v so I shut it down at that point.
To avoid brokerage fees and the high exchange rate, I ordered mine from amazon.ca but better deals might be available so shop around.
This is the 8000mAh model
http://www.amazon.ca/dp/B015RKEKAI/ref= ... 5157053535
9800mAh model here
http://www.amazon.ca/SINEDY-Li-ion-Rech ... ds=9800mAh
Step 2. Wait
It took 3-4 weeks from order placement until the battery was at my door.
Step 3. Cut and splice power wire
There are two cables coming out of the battery. One cable fits/connects to the supplied charger and one doesn't. Cut the cable that doesn't fit the charger to expose 2 tiny wires (one red and the other black)
Step 3. Buy and crimp on 2 of these
I bought them locally at Gervais electronics
http://www.gervaiselectronics.ca
Simply crimp one of these on the black wire and one on the red wire and now your are able to connect the battery to your fish finder.
I used shrink wrap after crimping, perhaps soldering wouldn't be a bad idea but not mandatory.
Step 4. Charge the battery and go fishing
Because the new lipo battery is much smaller than the original it floats in the battery tray. I just cut some insulation foam that I had lying around to fill the empty space without adding much weight. Notice the charging cable comes out the back just like the original! No modification needed.
Notes and tips
- There is a switch on the battery to turn it off and on. To accept a charge, you must simply turn it to the on position.
Charging the battery with the switch in the off position will not work
- Lipo batteries are quite sensitive to overcharging and while the supplied charger turns green when a full charge (or close to one) has been reached, I don't believe it shuts off.
The LX7 comes with a volt meter and a full charge for these batteries is when the voltage reaches 12.6 v. Overcharging these batteries even once can render them useless. They charge so slowly that unless you forget them on the charger it shouldn't be an issue.
- because the LX7 is so light now the balance is different. Because the weight of the LCD screen was counterbalanced (and then some) by the heavy battery, the unit's balance point has been altered dramatically. Carrying the unit by the hard handle rather than the handle on the soft pack ensures it won't fall out face down. The reduction in weight is well worth this side effect for me.
