The Stovebolt Site Forums The Shop Area The Electrical Bay Battery maintainer

I installed a battery maintainer. Then plugged it and the blk heater in with the same multi female end 12" cord. This i plugged into an extension cord to house hold current.it seemed to work fine. Later i unplugged the extension and left the short multi end attached to the bliock heater and the battery maintainer on the truck.i drove away. An hour later i turned off the truck later to find no 12 v electrical powerto anything. I unplugged the block heater from the multi block and the maintainer .all was good once again. Question : did i back feed battery power to the blk heater and kill or short the battery while i was driving .i believe they were hooked together because of the multi connector. And also is it ok to both charge the battery and run the blk heater from the same extension cord at the same time. Thanks

The maintainer shoudn't work like an inverter if you leave it connected to the battery. I think something is wrong with your battery maintainer for it to discharge the battery (I'm assuming thru the block heater). I've use the same arrangement without any issues. You might want to check if there's voltage on the power plug of the maintainer with it connected to the battery. There shouldn't be any at all.
As long as the battery charger and block heater don't draw more current than the extension cord is rated for, it would be fine.
A block heater at 1000W would draw about 8 amps. It would take a pretty big battery charger to draw even that much and overload the extension cord.

Well I took it all off. Took it for a drive and had the same result. I think you are right I will test and probably replace the battery. I just checked and it is close to 5 years old. At that age it is almost certain to be a battery problem . It just happened to show up at the exact time when I completed this instal of the battery tender. I will also check for current at the end of the battery tender when hooked up. That being said I believe I have been fooled into thinking it was a bad tender or hook up . When it is more than likely just an old battery causing problems or shorting. Thanks. By the way After I lose power I can wait a half hour and have current again. I then get 8 volts with the key turned ahead and 13 while running. This also in my opinion sounds like a bad battery. Any opinions? Thanks

Either a bad battery or possibly bad connections. Corroded cables or connections can cause weird stuff. Connections can "heal" themselves and then be bad again.
If it were me, that would be the first thing I would check. A buddy with a starting problem on his diesel came by and we discovered a big voltage drop between battery post and it's cable clamp when he cranked it. He couldn't keep batteries charged enough for dependable starting, and that one battery wasn't getting charged at all. A cleanup of the post and clamp fixed him up.

Update. Battery tender tests nothing at the 110 side. I think I was chasing the wrong gremlin. The tender seems to be fine. Upon further testing I have a short to ground. I clipped a test light between the negative battery post and the neg cable. Reads a positive. So either a short to ground on frame or to a wire or internally to starter ....I pulled one fuse at a time but the light never went out. Next I will pull them all at once. If it goes out I may have more than one wire grounding out or fused and grounding as well. Any helpful ideas would be greatly appreciated. Thanks

You didn't say what you're working on. If I'm understanding your test light connection correctly, it sounds like you have something that's always switched on. A short to ground would either blow a fuse or burn a wire in two.
Do you have an alternator installed? If a diode went bad on it, that would drain the battery.

Sorry for the lack of info. 59 Apache 261 . Yes alternator. I unplugged the wires without the light going out. I did not take off the field I think it is called. One with the nut. Could you explain more on how iam getting a positive reading Between the neg post and neg cable. Also the pos post and cable a neg test. Besides a short to ground . Why would the test light be lit with something on? The way I see it it just tells me I have a neg draw on the pos line. Sorry for the lack of understanding Thanks so much for all the help.

Another question. !The alt seems to put out good. Is it still possible to have a burnt diode or some other problem to cause a drain to both the pos and neg line. And then heal it’s self . It seems to run fine for short trips but after a 45 min trip no restart because no electrical power . After 15min it will resume electrics and start right up. Almost like a breaker. Thanks

I assume you want a battery maintainer because your truck will sit for a while.

I have a Walmart battery disconnect on a terminal and if I'm going out of town for a month or more, I disconnect the battery. The '48 jumps to life when I get back. Frankly, I think it would start just fine after sitting for a month or more with the battery connected.

An alternator with a leaky diode bridge will charge normally, or at least have partial output. Try disconnecting the charging lead (the big one "with the nut"). That's the wire that's connected to the diodes. An alternator is a 3-phase AC generator with a rectifier to turn the AC into DC to keep the battery charged. A shorted leg of the stator will cause the alternator to charge at less than 1/3 of its rated output- - - -like 10 or 15 amps from a 65 amp stator. This will keep a battery charged during the day, but it won't support headlights, heater blower, etc. If you can't test the maximum amperage output with an accurate ammeter, you can't test an alternator properly.
Jerry