How to avoid blowing up batteries
This conventional battery died at the hands of a guy who is notoriously bad at maintaining batteries — me. I left it to trickle-charge for the winter and something went terribly wrong.
The evidence suggests the battery was cooked from the inside. The popped caps and cracked casing indicate there was heat, and this can happen if the amperage is too high on the charger.
So, did I use the wrong charger, or was the battery itself compromised to begin with?
What goes wrong
If a charger doesn’t automatically shut off, or go into “float,” bad things can happen to good batteries. When a battery is fully charged, the automatic charger stops delivering current, switching into an energy-efficient monitoring mode, known as float. The charger will periodically apply optimization charging to the battery, but this will not damage the battery.
The charger used in this situation is discontinued, and the manual long gone, so there’s no way to know if it shut off automatically, but most modern ones like it do. In fact, chargers have come a long way in recent years. Many have on-board computers that monitor the battery and adjust the charge level to meet the battery’s needs and optimize the health of the battery.
Since a quality charger rated for the correct amperage was in fact used, the battery itself must have been the problem. Maybe.
There’s always the chance that a load or large parasitic drain was constantly pulling the battery down while storing. In that case, the charger could have continued to deliver the required current to keep filling the depleted battery. Over time though, this constant load can take its toll and damage the battery.
Check after charging
With this particular battery however, operator error was the real culprit. It was removed from the boat and hooked directly to a charger. However, the cells were not topped up with distilled water before storage, and not checked during charging. If you are using a flooded battery, they are designed to lose water and need to be refilled occasionally.
It is best to check this on your batteries regularly, especially after each charge.
The new breed of lithium batteries would be ideal for the operator making the errors in this story. For starters, they are as close to maintenance free as it gets. “Connect it and forget it” has never been more true. They charge quickly, and discharge slowly compared to conventional batteries: around 5% per month. That means it takes six months for one to self-discharge to the same level a conventional battery reaches in just 30 days. So, come winter, the battery would be charged, stored indoors, and not see a charger again until it is put back to work.
And, they shave a bit off the fuel bill. Lithium is the lightest metallic element, and this translates to batteries that tip the scales at a third of what a lead-acid with equal power would weigh.
The biggest selling point of these batteries, however, is that they last. In fact, it is a little hard to believe the claims of a battery lasting 11, or even more, years, but that’s what manufacturers are saying. End of life is indicated when a battery reaches a self-discharge rate of 50% or more in a 24-hour period. This typically happens between 2,000 to 3,000 recharge cycles, or roughly five to 11 years with regular use.
Lithium: Price vs awesomeness
With a traditional battery lasting for just several hundred cycles, it is easy to see the attraction of lithium. However, they’re priced at around $1,000 for a modest, trolling motor-powering 12-volter.
Lithium batteries — which got their start during the 1970s oil crisis — may soon see technologies that allow them to charge faster, and last longer.
Many batteries contain liquid or gel electrolytes, but higher performance solid-state lithium batteries are emerging. They offer greater safety and increased energy density — which is how much energy the battery can store for a given volume.
One prototype solid state battery has charged to more than 80% of its capacity in 15 minutes. The company expects the batteries to boost electric vehicle range by more than 80%.
Note that charging lithium batteries requires a lithium-specific charger. Charging a lithium battery with a lead-acid charger can damage the battery, though some older chargers can be switched to a lithium mode. Older chargers operated at 14.2V for lithium but current chargers charge at 14.6V.
Sticking with lead
Geoff Cook, a marine technician at Walsten’s Marine in Kawartha Lakes uses lead-acid in all his ATVs, RVs, boats, and lawn tractors and keeps them charged in the off-season with a $10 solar panel. He is careful to keep them filled with distilled water and puts them on a piece of wood rather than the concrete floor of his shed.
Regardless of the type of battery, to keep power running to the battery while you are on the water, Cook recommends a DC-to-DC charging system.
This takes power from the alternator on the engine and feeds it to your starting battery and then relays it to a trolling motor or electronics battery. The best ones are capable of sensing which battery is full and which one needs the most energy and compensate accordingly.
General rule
To avoid overcharging, use a battery charger that supplies a minimum of 10% of your battery’s ampere hour rating, but not more than 20% of its maximum capacity.
That means with a 50-Ah battery, for example (this info is found on the battery label), you should use a charger rated at 5 amps minimum and 10 amps maximum; and for a 100-Ah battery choose a charger that is in the range of 10 to 20 amps.
Originally published in the August 2023 issue of Ontario OUT of DOORS