DIY onboard charger/ or cheap on board charger

[Strahm]

Well, i went and bought it. we met at wlamart, and they tested the battery and said it was good, and i had him plug in the charger and show me that it lit up, and showed it could charge the battery. I should have used an amp meter or something to be sure it worked, but i was lucky and got it home and everything seems to work. i hooked it up to4 batteries and checked the voltage before it was on and after it was turned on, and the voltage went up consistantly on each battery.
glad i got a good deal,
1 question, say i have a battery that i think is bad mut im not sure, will it hurt anything to hook it up to the charger? i didnt know if it would make the charger run non stop and fry either the charger or the battery. ideally i would just go buy two new batteries but im a poor college student, so im trying to do with what i have.

also if a battery shows 12 volts, but only like 8-10 under a load, will it still last awhile on a charge or is the battery just trash? could it be used for a trolling motor?

[jimp]

you can test the battery with a volt meter before you charge it, then charge it, let it rest for 8 hrs (i've read this time frame) then test with the volt meter, wait 8 hrs again, and test with volt meter. If you've got a bad battery, it will lose it charge slowly but surely.

[crappiholic]

I have a MK 345D brand new for sale.

[Barnacle Bill]

I have a MK 345D brand new for sale.

Post it in the Personal Classified Ads forum. It will sell quicker.

[Strahm]

I have a MK 345D brand new for sale.

sorry i got a steal of a deal on the mk-460 thanks for the offer though