Inexpensive voltmeter

[rabbit]

I accept the rephrase to the distilled essence of the question. Yes, jumper cables in parallel from the trailer house batt to the vehicle starting batt as normal for jumping. No negative consequences except the possibility that the vehicle battery may not take a charge? Sounds like an acceptable non-risk. The Wizard idjot light is showing float and the multimeter says the house batt's getting float current (13.17V) so it's as juicy as it's gonna get. I'm going to Indiana and Michigan next week. If I can get the charge up on the starter battery, maybe I won't have to worry about anything except what to do later to correct discharge in a battery that's sitting a lot and not receiving the tender ministrations of the alternator. It's a Diagnostic! No it's a Solution! It's Muddledthought!

jack

[rabbit]

I looked a second time at your reply, Tom. I wondered the first time what you meant by back power. No trailer connector involved; jumper cables between the two batteries is what I envisioned. I guess maybe your scenario would work also as the charging circuit thru the connector is closed when the ignition is open. Anyway, I've got nothing but time and the tug can sit there headon with the hood up. I am sort of wary about the vehicle circuitry as I know less than anything at all about it.

Unfortunately, Fig 9 in the battery tender info says I can't just jump red to red and black to black between the two batteries so I guess I should steer clear of a method which requires a bit more in the way of rerouting connections to batt terminals. I could fiddle it with a coule of set of jumper cables maybe but I think I'll let this half-baked idea die. Boo hoo.

jack

[rabbit]

OR? Could take the house battery out of the equation. Remove the converter cables from the battery on the tongue and jump directly to the truck batt.

jack

[Thomas G.]

Originally Posted by rabbit

I looked a second time at your reply, Tom. I wondered the first time what you meant by back power. No trailer connector involved; jumper cables between the two batteries is what I envisioned. I guess maybe your scenario would work also as the charging circuit thru the connector is closed when the ignition is open. Anyway, I've got nothing but time and the tug can sit there head on with the hood up. I am sort of wary about the vehicle circuitry as I know less than anything at all about it.

Jumper cables should work, too. I assumed connection via trailer plug. At low amps, you could just wire a plug in for the cigarette lighter, too, assuming it is live with the key off.

Unfortunately, Fig 9 in the battery tender info says I can't just jump red to red and black to black between the two batteries so I guess I should steer clear of a method which requires a bit more in the way of rerouting connections to batt terminals. I could fiddle it with a coule of set of jumper cables maybe but I think I'll let this half-baked idea die. Boo hoo.

I don't read that (below). Did you look at the wrong figure?

In Figure 9 we see a pair of 12-volt batteries connected in parallel. This 12-volt battery pack is connected to a single 12-volt charger. Note the blue wire designated W1. The purpose of this wire is to balance the voltage drop evenly across both batteries and each wire during charging. This is not critical for lower current chargers, but when you start to get into the 10 amp and above range, the voltage differential can be significant. The blue wire W1 must be connected to the opposite end of the battery pack as the black wire at the top of the battery pack.

Originally Posted by rabbit

OR? Could take the house battery out of the equation. Remove the converter cables from the battery on the tongue and jump directly to the truck batt.

jack

Yes, that should work as well. All you are doing is using the converter as a battery maintainer, except for your truck. At this low charge rate you could use a much lighter wire with alligator clips

[rabbit]

I had the correct Fig. 9. Too lazy to deal with the more complicated physical connection. Thanks for the advice. I'll wait until Monday and, if the weather is decent, I might try charging the tug batt. Leaving later in week. Possible that the battery will react well to extended driving and pick up some charge.

Jack

[Thomas G.]

Originally Posted by rabbit

I had the correct Fig. 9. Too lazy to deal with the more complicated physical connection. Thanks for the advice. I'll wait until Monday and, if the weather is decent, I might try charging the tug batt. Leaving later in week. Possible that the battery will react well to extended driving and pick up some charge.

Jack

Yea, drive it and charge it. The solar mini-charger is not a bad recommendation if you can plug into a hot cigarette lighter socket.

[Raz]

Originally Posted by rabbit

Got one of those "auxilliary port" voltmeters which is showing 9+/- cranking voltage in my truck.

jack

A battery measuring below 10.5 volts is usually considered in need of replacement. Might want to have it tested. If it tests ok then perhaps your "auxiliary port" voltmeter might be in need of calibration . Raz

[rabbit]

I'll run out and put the multimeter on it. No question it's at "rest" most of the time

jack

12.19V slowly rising for about 1.5 minutes. Maybe the electrons were just waking up. My stick it in the socket gadget cost about as much or more than my multimeter. I trust the multimeter because it always reads .04V under stated charging voltage for all three rates of the Progressive Dynamics converter. That's precision. There's something else that this reinforces. What was it?

[Raz]

Originally Posted by rabbit

There's something else that this reinforces. What was it?

With retirement come new challenges .

[rabbit]

vetustior humo!

[Raz]

Originally Posted by rabbit

vetustior humo!

Not yet but I'm working on it.

[rabbit]

Any recs for a solar battery maintainer? I have the impression that cheap junk predominates here as elsewhere so I'm willing to dig deep to swing something over $2.50.

jack

[Bob Miller]

A few notes
Trying to charge 2 dissimilar batterys in parallel usually results in neither getting a decent charge. As the voltage will usually rise more quickly in one battery, it will start shutting down the charger before the lower battery is charged. Been there-done that...

The local auto supply store has a mini-jumper set intended to connect one accessory socket to another vehicles for purposes of an emergency jump. You hook it up and let it cook for about 30 minutes with the good vehicle running.

I bought three DELCO versions on a clearance site for $5 each about a year ago. My daughter-in-law used hers to get a friends car started and it worked just fine. Much safer than jumper cables for the non-mechanical...

BTW: It has a current limiter built in to prevent blowing any fuses. Just running a wire and two male connectors is sure to blow the usual 10-15 amp fuse, I've also done that trying to charge a battery from the accessory socket.

[Raz]

Originally Posted by rabbit

Any recs for a solar battery maintainer? I have the impression that cheap junk predominates here as elsewhere so I'm willing to dig deep to swing something over $2.50.

jack

I have no recommendation for you. Our friend Tom posted this site for Black Friday sales. I think the prices are still in effect. Raz

Solar Cell, Solar Panel, Renewable Energy, Wind Energy, Charge Controller, Solar Trackers

p.s. Remember, he started this thread.

[Thomas G.]

Originally Posted by P. Raz

I have no recommendation for you. Our friend Tom posted this site for Black Friday sales. I think the prices are still in effect. Raz

Solar Cell, Solar Panel, Renewable Energy, Wind Energy, Charge Controller, Solar Trackers

p.s. Remember, he started this thread.

Other possibilities here: Amazon.com: solar car charger: Automotive

The Harbor Freight model gets good ratings when you get a good one.

1.5 Watt Solar Battery Charger

[rabbit]

I've been thinking about switching the connectors on my 80W solar panel hookup and extension cord from Anderson to 2 conductor flat connectors that the dogs can't unplug every whip stitch. While at it, I'll add pigtail with flat two to the batt terminals and have an actual charger rather than <2 amp output maintainer. See how I make out on the Xmas pilgrimage and whether the alternator can get this battery up to 12 1/2V. I may also get a solar maintainer. Thanks for the help with the spitballed converter lashup also.

jack

[Thomas G.]

Six pages and 76 posts later, after pointing out a cheap voltmeter......what a long, strange trip it's been.

[rabbit]

Don't try it with a prize from Cracker Jacks. We could worry that bone a looong time!

jack

[Robert Johans]

Fellas, that was entirely entertaining and educational. thank you.

[Byron Kinnaman]

Originally Posted by rabbit

Any recs for a solar battery maintainer? I have the impression that cheap junk predominates here as elsewhere so I'm willing to dig deep to swing something over $2.50.

jack

What's a solar battery, let alone a solar battery maintainer?