Need advice, quick fix of alt charge path

[Ween]

I start by saying I've learned so much from you all on this forum. My low post count is mostly because I search hard and usually find answers, but now I need specific advice.

Situation - leaving shortly to bring new to me boat home from broker's marina - 4 day trip

Recently re-powered for selling - discovered they rewired from alternator to house bus to alternator through starter solenoid to start battery only (they claim they simply followed the Yanmar installation instructions...okay....)

So engine not charging house as start batt on charged side of echo charger (one way)

Quick (but relatively safe) options?

1. Jumper cables make start and 5 house batteries one big 12v parallel bank? Alt now charges whole thing via what looks like a 10g wire from alt to starter solenoid then the beefy cable to the start batt

2. Move the starter cable from the start batt to the house (harder as the wire routing and possible length issues) anything else potentially need to be mover to do this?

3. Get a cable made to connect the ALT directly to the house bus (probably do not have time to do this right now) Also on this one is it best to reroute the alt ground somewhere other than engine?

4. ???

I don't want to be the guy that did something hasty and stupid due to a schedule needing to be met - I'd like to have a house bank functional for the trip though

[Ween]

OK simplified version original might have been confusing

Boat recently re-powered for selling - I bought it

Discovered now:

Originally cruiser-wired "alternator to house bus"

New install lazy yard wired "alternator to starter solenoid"

So starter battery getting charged

House is not as start batt on charged side of echo charger (one way)

I need advice of quick options:

1. Jumper cables make 1 start and 5 house batteries one big 12v parallel bank?

2. Move the starter cable from the start batt to the house (harder as the wire routing and possible length issues) anything else potentially need to be mover to do this?

3. Get a cable made to connect the ALT directly to the house bus (probably do not have time to do this right now) Also on this one is it best to reroute the alt ground somewhere other than engine?

4. ???

[MerMike]

Your best option is to wire the alt to the house bank, but it's not clear how the start batt is wired or how the system is grounded.Ideally all DC loads go to a common ground. That can be the engine block, but a bus bar is better. You are limited to 4 terminals on a single post.

If it were me I'd map out the wiring in hopes that a simple and quick solution arose. Otherwise make a cable or get one made (auto parts store?) or try an online source.

[Ween]

Thank you. Yes I get the impression the dedicated real 4g cable to the house is the best approach. No one is recommending the other two options. This particular valeo alt is dumb regulator and grounded to engine chassis. Stock production setup. Whole feed to starter solenoid via dual 10g wires thus undersized for 100+A possible current.

I will also wire the ground to the common bus.

thanks again.

[guyrj33]

House is not as start batt on charged side of echo charger (one way).

Would changing the direction of the echo charger solve your problem?

[motretu]

is it possible to reverse the leads to the "echo charger" so that the start battery is on the input side and house bank on the "charged" side? this assume all other wiring left as it is/was..

[caffel]

Re: quick fix
Take your jumper cable idea and add a switch.
Once the engine's been running long enough to charge the starting battery, close the switch to the house bank. (heavy gauge wires).
Check for voltage loses (while charging) between alternator ground and the two battery's ground as well.

[stormalong]

Yes, reverse the echo charger. That will get you home.

The way it was installed is the standard method of connecting the alternator output. An internal regulated alternator is not designed to charge your house bank - it is designed to put the power back into the start battery from the starting load.

In the long term you should decide how you want to charge your house bank. That depends very much on how you intend to use the boat. If you are keeping the boat plugged in at a marina with an automatic multi step charger you are fine. If you plan to cruise and not plug into shore power regularly you should study the issue carefully. A smart alternator regulator with an alternator that is capable of high output for an extended period of time is one step in the process. Solar and/or wind is the next step. These options are topics within themselves and a lot has been written about it.

How much power you use also plays a big part of your charging methods decision. If you don't have refrigeration or autopilot loads your solution becomes much simpler.

PS. I don't like the jumper wire charging idea. There is too much downside if things go wrong.

[seabreez]

Originally Posted by Ween

OK simplified version original might have been confusing

Boat recently re-powered for selling - I bought it

Discovered now:

Originally cruiser-wired "alternator to house bus"

New install lazy yard wired "alternator to starter solenoid"

So starter battery getting charged

House is not as start batt on charged side of echo charger (one way)

I need advice of quick options:

1. Jumper cables make 1 start and 5 house batteries one big 12v parallel bank?

2. Move the starter cable from the start batt to the house (harder as the wire routing and possible length issues) anything else potentially need to be mover to do this?

3. Get a cable made to connect the ALT directly to the house bus (probably do not have time to do this right now) Also on this one is it best to reroute the alt ground somewhere other than engine?

4. ???

I recently rewired a tug boat with the same issues and we installed a battery isolator to accept battery voltage from two sources ie: two engines, two battery banks and going to charge two other battery banks, emergency lighting and radio emergency bank. What this does is any engine can power up the separate battery banks. We also installed a separate voltmeter and ammeter to check the charging rate of both banks. Both engines have their own separate voltmeters and ammeters. In addition from the positive of both engines we wired a master switch to act as a booster switch in case one engine would not start. (if someone forgot to shut something off). You switch it on, start the engine, wait for the voltage to come up a little then shut the booster switch off...

[Ween]

Thanks for all the feedback. I just wanted to avoid stupid. I made a 2g cable from the alternator to the house battery post on the live side of the house switch.

I recognize that the stock valeo 125A alternator is internally regulated and, even worse, has internally-set excitation field. Ouch.

For the short-term I imagine I will be taxing the alternator a bit charging the 625Ah house bank, probably a long-term alt life issue. Guessing the direct wiring vs. reversing the echo charger max 15A output might not have made a huge output difference due to the dumbed down valeo.

I'll get the Balmar MC614 regulator and the valeo "de-stupify" kit as a start once I get home. This season I'm in a slip but after that I'm out. I have 300W of solar but no idea yet if it is effective. Also have a 5kw genset if needed but I'm ambivalent about that - would like the space back - probably go with a bit more solar area and battery.

Ideas on grounding the alternator at the battery as there is no ground post?

thanks again. Excited about finally having my boat soon.

[stormalong]

Originally Posted by Ween

Ideas on grounding the alternator at the battery as there is no ground post?

The alternator ground is just a case ground. Look for a threaded hole in the back half of the case. If you can't find a hole You could probably drill and tap one yourself. Just be sure that you are in a part of the case that is thick enough to tap. Also be careful not to damage any internal parts on the alternator while drilling - dis-assembly is suggested. Be sure to clean out any drill tailings before re-assembly.