Solar charging batteries

[redneck joe]

Any pitfalls I need to know?

Planning on one for the main battery and one for the trolling motor bank. I'll use a two pin minkota type male/female connector rather than hard wired. Looking for a panel that can clip on.

 

[redneck joe]

And is this or similar what I want to know how much charge I have left like I can see on my ryobi batteries?


Meter

 

[redneck joe]

Oh and batteries are lifepo with built in bms and old school lead acid in back.

Can't seem to find any clip on ones.

 

[StewartL]

Any pitfalls I need to know?

Planning on one for the main battery and one for the trolling motor bank. I'll use a two pin minkota type male/female connector rather than hard wired. Looking for a panel that can clip on.

And is this or similar what I want to know how much charge I have left like I can see on my ryobi batteries?


Meter

Oh and batteries are lifepo with built in bms and old school lead acid in back.

Can't seem to find any clip on ones.

Yes, a few pitfalls.

You cannot use one meter for two separate battery banks. You must have one meter per bank, permanently wired to that bank's positive and negative. A plug-in connector won't work because the meter needs a constant, tiny power draw to monitor voltage. Unplugging it resets it and makes readings useless.

For LiFePO4, ignore "percentage" meters designed for lead acid. They are wrong. You only care about voltage. A simple digital voltmeter is best. Learn these key voltages for LiFePO4:
13.3V+ (100% charged)
13.1V (~50%)
12.5V (20% - time to recharge)
12.0V (0%, damage imminent)

For your lead acid, a voltmeter is also fine. Look for panels with a digital voltage readout, not just colored bars. Hardwire each meter to its own battery bank.

 

[dingbat]

Yes, a few pitfalls.

You cannot use one meter for two separate battery banks. You must have one meter per bank, permanently wired to that bank's positive and negative

How so?
Both of my banks are wired to a common gauge with a selector switch on the input

 

[tg3690]

You cannot use one meter for two separate battery banks. You must have one meter per bank, permanently wired to that bank's positive and negative.

This is false......my boat came from the factory with one meter with a selector switch for 2 banks. Works just fine.

 

[StewartL]

This is false......my boat came from the factory with one meter with a selector switch for 2 banks. Works just fine.

Factory-installed meters with a selector switch work perfectly. They are the correct and standard way to monitor two battery banks.

 

[StewartL]

How so?
Both of my banks are wired to a common gauge with a selector switch on the input

Because a selector switch only shows the voltage of one bank at a time. You can't see both voltages at once, which is a major pitfall if you're trying to monitor their state.

 

[cyclops222]

Disagree Turn the selector switch back and forth as needed.

 

[redneck joe]

Well for my application I'm not running wires to helm.

 

[Mc Tool]

Disagree Turn the selector switch back and forth as needed.

yeah but Im thinking (analogy ) that on a twin engine set up you have an oil pressure and overheat alarms for each engine ......not one warning display switched between engines because both need to be monitored. Bastards luck would see the unmonitored engine blissfully melting down while your display is switched to the other engine .
I dont have a ton of experience but I think if I had one bank of lithium batteries and one of lead/acid batteries I would want separate monitoring.

 

[tpenfield]

I did the solar charging thing over the past few years. You will probably want a solar charge controller, one that has setting for LiFePO4.

I also found that when the LiFePO4 batteries are full, they shut off charging, so the controller may have current with no place to go. So you may get a voltage spike. Not sure that will break anything on your boat.

As you get things hooked up and working, be ready to make some adjustments, based on the what system likes and doesn't like.