Fuse or breaker on battery

[JohnnieB]

Originally Posted by yurtle

At the opposite extreme, Alltrax shows adding a reverse protection diode in the charging circuit, which I think is overkill.

Battery killer is a more correct term than overkill.

A forward biased silicon diode drops 0.6V across its P/N junction, so the charger's battery sense circuit sees an on-charge voltage that is 0.6V higher than the voltage that actually exists the battery pack's main terminals, so the charger shuts off prematurely and the battery pack is undercharged.

Since fuses and circuit breakers must insert resistance into the circuit to function, a similar situation exists when they are placed in the charging loop, but to a lesser extent because the charge rate drops to relatively low amps during the final charging phases.

Chargers that use dV/dT (Change in Voltage over Change in Time) to terminate the charge, will fully charge the pack, but chargers that shut off when the on-charge voltage reaches a predetermined level, won't.

[scottyb]

Hey Johnnie that's interesting info- makes perfect sense....

Alltrax is the only controller manufacture that uses a power source fuse. They use 250a ANA for 400 and under and 400a ANA for 500 and above. I would think that if they were truly necessary - the industry as a whole would have embraced the practice years ago.

[yurtle]

Does Alltrax sell OEM or just aftermarket controllers? Perhaps cheap insurance against DIYers, to protect their reputation?

[scottyb]

Just aftermarket, but they do have stock replacement types. All with main fuses.

[JohnnieB]

FWIW: When my stock motor gave up the ghost, it took out the 400A controller, but not the 250A fuse.

[yurtle]

I would have loved to have had sophisticated data-logging equipment on-board when that happened.

[JohnnieB]

Originally Posted by scottyb

1. Hey Johnnie that's interesting info- makes perfect sense....

2. Alltrax is the only controller manufacture that uses a power source fuse. They use 250a ANA for 400 and under and 400a ANA for 500 and above. I would think that if they were truly necessary - the industry as a whole would have embraced the practice years ago.

1. Since all the chargers I know of have fuses or circuit breakers in their output, the only reason I see for a fuse in the cart's charge loop is when you've got kids around that might stick a metal object in the cart's charge receptacle.

Of course, if you use a fuse in the charge loop, you need a charger that does dV/dT. (Like the DPI. )

2. I don't know how many carts have had fires that could have been prevented with a fuse, but if there were very many, I'm familiar enough with Tort Law to firmly believe the corporate bean-counters wouldn't let a cart leave the factory without one installed.

What I said about fuses in the charge loop also applies to the high current loop. The higher the voltage applied, the faster a motor spins, and fuses have resistance, so they cost you RPM.

I never measured the voltage drop across the 250A fuse that I used to have in my high current loop, so I don't know what the loss is.

[scottyb]

"gave up the ghost" infers a quiet death on a lazy afternoon.....


Don't you mean exploded ?

[JohnnieB]

Originally Posted by yurtle

I would have loved to have had sophisticated data-logging equipment on-board when that happened.

Me too, but the only data logged were fingerprints (embedded in the steering wheel), black stripes on the road and a brown strip elsewhere.

After the fact, the pack voltage was 44.2V (after 7.5 miles of travel) and the motor temp was 225°F.

[JohnnieB]

Originally Posted by scottyb

"gave up the ghost" infers a quiet death on a lazy afternoon.....


Don't you mean exploded ?

The armature grew rapidly and became one with the stator windings.