regular battery chargers

[OPCOM]

I appreciate the pointers to high-tech thingies, but this is already mounted on the wall, and it's orange panel lamp has kind of grown on me. Even set at the lowest output level, it keeps 28VDC on the battery after 1 week. Should it not be more like 27.64V at 43 DEG F? (translating from standard 24v flooded non-sealed lead acid battery 26.4 volts at 80 DEG F, plus .0028V per degree per cell) Seems like splitting hairs, but with battery voltages, hairs are to be split. It's charging (28VDC) as though the temp is -4.6 DEG F. I am contacting LaMarche for the manual and schematic, I hope they can help. I don't want a foreign made item, I'm intrigued by the saturable reactor, and I am willing to repair or modify this unit as necessary. It's the fun part of electronics.

 

[CCATLETT1984]

you might need to drop the resistance in the charging cables, do you have a extra set of jumper cables that you could try hooking up in parallel to spread the load across more copper. Before buyin gso heavier guage stuff for a perminant solution.

Also on battery life, the batteries that I have in my m1008 are 6TL's that were manufactured in 1991, they stll charge to within 10amps of there rated capacity. Boy you should have seen the look on the guy's face at the parts store when I brought them in to be tested.

 

[OPCOM]

I could use larger cables for faster charging. The real issue though is the ending voltage. at the end point where the voltage settles to 28V, the current is so little (80mA) that the drop on the cable is only .037V. I took pains to solder the battery clips and the crimp-on ring lugs at the charger end to the actual cabling.

This set of measurements tells me I have .46 ohms in the cables, so it would certainly hinder charging at high rates. If I leave this disconnected and the batteries settle for a week to 26.5V or so, and then connect it, I get about 4A for a few minutes and then it drops off quickly because the batteries are pretty much full. That's OK for me.

I want to use this mainly to float-charge the batteries at a very low current. Do you think the long cables would hinder this? I don't think it can explain the excessive voltage.

Sure enough, about battery life, I have had these "big car batteries" in there for >2 years, no issues, but I am sure 6TL's would be mch better. Next time they need replaced, I'll go for the right betteries.

 

[CCATLETT1984]

I dont think that would give you a voltage issue, I wonder if you could put a potentiometer (rhiostat) on the charging wire to more acurately control the ending voltage.

I got these batteries in a pair of parts blazers i had last year, they more than paid for themselves.

 

[OPCOM]

I'll have to work on a circuit to switch over to float after full charge is done. in the meantime, I have made alot of notes on this little beastie and how it works, so I'll post it here in case anyone is interested in how a saturable reactor is used to regulate. I was not able to upload it as a article forwhatever reason, I hate PCs, maybe one of the big shots can do it.

 

[OPCOM]

Here is the file as a PDF.