Charging trolling motor battery from house bank with SG200?

[kayakerChuck]

I just ordered a Lifepo4 trolling motor battery to power the trolling motor of my dink. A friend provided me with a 30 amp, 12-12v, Victron Orion smart DC-DC charger. Connection & programming all looks pretty straightforward (I think), but I have questions.

My current battery set up in the boat is (2) Trojan T-105 6v golf cart batteries, which serve as both start & house bank. It's not ideal, but space is at a PREMIUM in my O'Day 30. We have 240 watts of solar and an externally regulated 70amp Balmar alternator.

It looks like the Victron Orion gets connected to the main (+) and (-) 12v buss bars. Will this affect my SG200?

With such little battery power, I tend to jealously guard the amps & want to be able to trust what the SG200 is telling me about the boat batteries. The new Lifepo4 has bluetooth monitoring, so I'm only concerned with using the SG 200 with the Trojans.

[Statistical]

As long as it doesn't bypass the shunt then its load will be counted just like any other load as it should.

From the point of view of the housbank a charger of another battery is a load no different than anything else.

Connecting it to the primary postive and negative busbars is the correct aproach. Usually where people run into problems is when they connect loads directly to the battery terminals which bypasses the shunt at which point those loads can't be seen.

[kayakerChuck]

Thanks!

[Bill O]

Chuck,
Agree w/Statistical to attach to the shunt to properly monitor your house bank.
Not certain of your daily load usage in the boat or how much you will need to recharge the trolling battery. Will you have enough power onboard to keep everything happy with the solar only? Does your solar controller allow for adjustment of the aux. out V for the lith. charging? Using the aux. out is often overlooked when you have enough solar/go into float early, why not use the extra 2.5A to charge something?

[kayakerChuck]

Hi Bill,

I'm hoping we don't have to charge the trolling motor battery too frequently. It should power the little trolling motor for 2+ hours at WOT, and maybe 6 or 8 hours at "cruise". I don't think we'll ever be dinking more than about an hour/day.

We don't have enough solar to keep everything running (fridge, Admiral's gadgets, etc) without running a daily deficit of 20-30 ish amps unless it's a really sunny day. We'll be in the North Channel of Georgian Bay, so motoring will be needed each day we move. I'm thinking if we are not actually using the trolling motor, we can use the Li battery to run some of our easily separated house loads, like the CPAP machine.

Using the solar controller aux out to charge the Li battery never crossed my mind. I love the idea! I'm currently using that output's low voltage cutoff ability to power our fridge, but you got me thinking.... ;-)

[kayakerChuck]

I connected everything today and it's working as hoped. :-)

Thanks all!