Alternator charging with VSR installed?

[hethj7]

Some may recall my old stereo was stolen last year. I got the replacement in this year and am having an issue where my stereo starts to cut out. I'm pretty sure it is because the house battery is weak each time (test light faintly glows when I troubleshoot and stereo starts working after putting a charge on it). I don't run my stereo that long or loud and prior to the theft, the alternator, I assumed, kept both my starting and house batteries topped off. However, this season somehow that house battery isn't getting charged up or I've got a short somewhere. I'm pretty sure I have it wired up just like the old setup. No perko swtich installed, but a VSR is in place. The head unit is wired directly to the house battery (via the stereo switch on the dash) and a constant power for my clock and presets is straight to the battery as well.

Any obvious things I should go check? The VSR is pretty straightforward 3-wire install, so I can't see that I have that messed up. It is doing it's job as the boat always cranks, but I'm not sure if both batteries are being charged while under way. Oh, the house battery was new this season.

[MLA]

You need a volt meter and a fully charged house battery. Start at the house bank posts with the engine running. You should have alternator voltage at the house battery. If not work backwards through the VSR until you find where the break in the flow is.

Is it an actual VSR or is it just a heavy duty continuous duty solenoid?

[David]

Just a couple of ideas.

A VSR would have three crucial wires only (excluding an LED or priority start terminals) while a simple ignition-triggered solenoid would have four crucial wires (just like a relay).

Rarely does a VSR fail. Easy enough to confirm via Mike's instructions. Without the VSR small gauge ground wire it will be frozen open and will never get a charge to the house/stereo bank.

If the house/stereo battery is toast then it may accept and read a decent charge but it is a short term shallow charge that will decay over time or with the least bit of current demand. If the battery condition is poor enough, once combined via the VSR, the voltage can quickly drop and the VSR will stay open. So a bad battery can influence the VSR behavior, even more so combined with a considerable stereo load.

Btw, with 'some' battery chargers, when the collective draw (memory, etc.) is higher than the maintenance charge, the battery will never shift into a bulk charge stage without being reset (unplugged and re-plugged into AC power). So given enough time the battery runs down even with a charger.

Under some circumstances a VSR can increase your dependence on AC shore charging. So you want to connect the AC Smart charger immediately after an outing rather than just before the next outing.

[David]

Btw, triple check the stereo/house battery ground cable and connections. Sometimes during winterization & summarization terminations get pulled but don't get restored as tight as they should be. Not to mention you have lots of shock and vibration on a towboat plus more potential for corrosion. A bad connection may not be measurable as resistance or as a voltage drop until there is a substantial draw.

All the battery ground interconnects are only as good as the battery to engine block ground.

[hethj7]

Thanks for the replies. It is an actual VSR. I will have to troubleshoot once I get back from our week at the lake and have my volt meter.

[shawndoggy]

what brand VSR?

[hethj7]

I am impatient and bought a volt meter while still on vacation....

Shawn, I can't recall the brand and forgot to look, but it was bought through Earmark several years ago.

David - Thank you!! The "something simple" I was hoping for was the ground wire you mentioned on the VSR. I forgot it was as there and the installer that did my replacement system didn't hook it up. I did the original install and had forgotten the ins and outs of it.

I started up the boat tonight and the voltage on the house battery was running low but it seemed to be charging off the alternator. As MLA suggested though, I know that battery isn't fully charged right now. I have the charger on it tonight and assume I will be good to go tomorrow. Thanks again!