Hello, my name is Rod, I am a Battery Expert, with a BSEE degree.
Lead Acid ( LA), and Nickel cadmium ( NiCad) afe the oldest chemistries, and some specialties as calcium and silver, last ones for medical devices.
20 years ago the Nickel metal Hydride ( NMH) took over NiCad for consumers, but NiCad Prevails in aircraft and submarines, and will continue for long years due safety, working temperatures, vibration and very high output; charging systems are very sophisticate.
Several construction types, for LA were developed for several applications: Valve regulated Lead Acid ( VRLA) was a big improvement, later GEL (not such a great invention), and were replaced by AGM ( Absorbed Glass Mat) the acid is absorbed in kind of sponge, resembling gel, both keeping liquid acid from leaking or evaporating, and can be used sideways…there is a myriad variables: thick plate, ultra thin plate, Coiled (Optima Brand) Bars, Tubulars, also fiberglass pockets filled with lead powder, you name it.
My employer was VARTA Batteries AG a German manufacturer in Hagen, later merged into Johnson Controls, which remains in operation.
Regarding this Thread:
1. A heavier LiPoFe stores more energy than a lighter weight; materials energy density is measured in lbs / Kg
2. LiPOFe Is safer now, if you don’t perforate or smash it on an accident; if a propeller dig into them, that fire is unbearable.
if a whole boat gets in fire for other reason; when LiPOFe will Blow as a gas tank.
NiCad in aircraft are sealed on a stainless steel box for tha same reason.
3. Other Lithium chemistries, are still unsafe, like cheap cell phones, and electronics, airlines are not done in their battle against cell phones using Li Batteries, and shouldn’t be placed over mattresses, couches, or any fire promoter
4. LiPOFe is not made for low temp, nor for starting purposes; so warming blankets and cooling plates can mitigate, but not eliminate the fact.
If bad engine requires heavy start, i.e 5 times for 5 seconds each….. only highly oversized lithium could handle.
Same for Diesel Engines.
5. I add a burst to my LiPOFe with a box of SuperCapacitors, they resemble a battery; can give a tremendous instantaneous energy, for seconds or minutes….. but cannot compete with batteries in several hours. Here the link:
Maxwell’s DuraBlue™ Advanced Shock and Vibration Technology is the company’s latest advance in ultracapacitor reliability and performance.
maxwell.com
6. Power: P ..= VxI is a basic formula, good for resistors, but motors require complex analysis. The MK technician is correct regarding higher currents troubles.
for Lead acid 12Vx 3 =36 V which will drop to 35V instantly.
for LiPOFe 12.89 V x 3 al = 38.67 V
For same torque:
P( lead ) = 35V x100 A = 3500 W
P (LI) = 38.67 x100 A = 3867 W
Torque is proportional to Amp
Other formula: I= V/R= I ; (Amps = volts/ohms )
The resistance ( Impedance) on a motor, varies with certain design parameters.
Excluding some complex variables, lets assume for easy calculation that two motor are already running and both have same identical resistance (R) = 100 Ohm
Amp ( lead) = 3500W/100ohm = 35A
Amp (L). = 3867W/100ohm = 38.67A
In a motor, if you raise the voltage, the current will rise, and the motor will be delivering a higher power than designed for.
When the MK is running full load for 1 hour, the heat cumulated will be higher than its internal thermistor calibration and the electronic control will protect the motor.
Shut down could be avoided using the MK at 75%.
7. Engine alternator.
if the engine alternator is disconnected from the battery, the alternator diodes and regulator will burn.
if the BMS on a LiPOfe disconnects after fully charged, or discharged, or hot or cold….the alternator will be damaged.
The alternator will require a higher voltage to charge the LI, Bss you can find them at BALMAR.
Marysville, Washington – Balmar LLC, the leading manufacturer of onboard DC charging systems for cruising sail and power boats today announced enhanced support for the charging of lithium batteries. Balmar’s MC-614, MC-624 and MC-612-DUAL smart regulators have all been equipped with an...
balmar.net
A small Lead Acid Battery permanently connected to the alternators is necessary to avoid alternator damage when BMS disconnects.
And to protect the small battery from the high LiPOFe charging voltage, you need a DC/DC converter to reduce the Lead Acid battery at 12.8 V when LI are charging at 14.8V.. DC/DC
.
8. Some modern boat computers on Yamaha wakeboards, have malfunction on their computer with 14.8V or higher; Dc/Dc converters are necessary.
9. tachometers read the voltage of the alternator, to calculate the RPMs, need to be adjusted, not to be deceived with RPM real magnitude., Windlass, LEDs, and many more.
10. Lithium advancements still requires several tunning in the periferal systems.
