Did you know…

[Tools]

A lead acid battery can be charged backwards? Making the + negative and the - positive.

Who knew?

Wanna talk REALLY weird stuff happening.

I may need therapy to get over this….

There seems no doubt the prop musta spun backwards, and the engine fired right up no issues at all. 1940s clutched starter, no bendix….

The radio, ICS and little wobble fuel pump, no worky.

Anyone need a battery that had a sex change?

 

[Bell206]

A lead acid battery can be charged backwards? Making the + negative and the - positive.

You mean like a positive ground system from the old days?

 

[Tools]

Well, that’s what I inadvertently created! Geesh… NEVER seen, heard or even knew that was possible.

Left my master on… musta hooked battery charger up backwards. Totally dead, it didn’t complain a lick. Next morning, it’s an alien!

I was googling mental wards into which I was gonna admit myself when I finally figured it out!

 

[fast99]

A friend installed a new battery in a Honda Gold Wing that was charged backwards + was -, - was +. Fried a lot of electronics. So possible, but the only time I heard of it.

 

[asicer]

A lead acid battery can be charged backwards? Making the + negative and the - positive.

Well, a lead acid battery is made of lead and acid. At the time of manufacture and before charging, the lead plates are identical.

 

[Flatiowa]

I’ve actually done it in a pinch on purpose to get another year out tractor batteries. I have an old sealed beam headlight and it’s socket wired to alligator clips in my tool chest. Hook it up to the battery and let it drain completely, absolutely completely, then charge it up backwards, hook the light back up, drain it all the way down again then charge it again with proper polarity. Not something I would do on an airplane, but an old farmer trick to desulfate a battery that has sat to long with a low charge and won’t deliver starting amps after charging but tests good on voltage in each cell.

 

[Barrett50]

Yes I knew. You can reverse charge it. Just put a load on the leads until it is fully discharged. Then best to drain all the acid. Fill with distilled water, and drain that off. Fill with battery acid and charge it as normal with plus to plus and minus to minus. It'll charge but will likely not have much life left as the plates are now partially coated.

 

[Capt. Geoffrey Thorpe]

There seems no doubt the prop musta spun backwards, and the engine fired right up no issues at all. 1940s clutched starter,

Spins the same way - you reverse both the armature and the field currents so the rotation stays the same.

Permanent magnet DC motors on the other hand...

Had a '59 Sunbeam Alpine that was supposed to be positive ground, but when I bought it someone had installed the battery as negative ground. Everything worked (there as no radio).

Your engine will not run backwards (assuming it's not a two stroke) - if you spin it backwards it sucks from the exhaust and puffs out the intake. You have to change the cam to get it to run the other way.

 

[Tools]

Oooooh… whew, was thinking that shoulda got my attention. My tiny pilot brain couldn’t figure out how a dc motor would run the same way regardless of polarity. It was compromised by my confusion yesterday anyway.

Knew it wouldn’t run, but I start port timed 2 strokes (won’t run backwards… generally) by flipping backwards all the time. And you hand prop Hispano Suizas (spelling) backwards… so figured…

Thanks!