Re: [electricboats] Power in and out of battery bank

Great point.  Also, if you're like me and don't necessarily use actual chargers, but instead power supplies used as a 2-or 3-stage charger, consider that as a charger, the power supply needs to be able to handle running in current limit for a long time (most of the charge cycle).  A friend bought a 30amp "charger" for his boat pack but quickly found it would just shut off after long.  I looked into its detail design and the power control chip used and indeed the circuit was doing what it was wired up to do.  In his case, I got this resolved by adding a resistor in one spot that based on the specs of the chip allowed the power supply to run in current limit continuously.  We also found that the subsequent iteration of these "Meanwell" power supply/chargers actual include a switch allowing enabling of 2-stage charging (constant current limit "CI" phase).

 

Also when you are cruising (genset running, chargers delivering and motor pushing), if you really need maximum or some minimum amount of steady power from your genset to the pack, be sure that the pack voltage is BELOW the CV set point for your charger/power supplies.  Listen to the genset and if it starts running easier, there's your clue.  It's very easy to think you're still getting full power to the pack only to find that the voltage rose slightly and now one or more of the supplies starts ramping its current output down.  When this happens you can also experience "motor-boating" or a cycling between full-current, then lower, then full again, then lower again as the chargers drift in and out of the CV ramp.  To avoid this, increase the speed of your motor until the charge voltage drops below the start of the CV ramp.

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Matthew Geier
Sent: Thursday, September 28, 2023 8:41 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Power in and out of battery bank

 

Some battery charges have protection circuits that may kick in if you are drawing down on the battery while the charger is running, as the load looks like a potential battery fault. Many chargers however are fine running a load at the same time. I would check your charger / solar controller documentation. There may even be option settings on the devices for this.

 

 

 

 

 

On Wed, 27 Sept 2023 at 22:16, Matt Foley <matt@sunlightconversions.com> wrote:

They are correct you can't! Not because it will damage the battery, it's just physically not possible. Energy is either flowing in or out. 

 

If the load is greater than the charging source, it will pull from the source(s) simultaneously. If the load is less than the charging source, it will power the load and charge the battery. 

You are fine. Happy motoring. 

Matt Foley

 

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On Sep 27, 2023, at 4:50 PM, rholden@orcon.net.nz wrote:

Hi All
Very fundamental beginner's question here.

I currently have a 160amp hour 48-volt closed cell battery bank running a thunderstruck 10KW motor and all works well. ( Looking forward to lithium in the future).

QUESTION: If I am charging the battery using solar panels - or in some cases a generator - can I run the motor at the same time?

There a several claims on Google search that you cannot charge and discharge a battery bank at the same time. 
If you are running solar panels ( which I am about to install) - I can't imagine that you switch them off each time you want to run the motor.
Can someone please clarify if I can charge and discharge simultaneously, or will this damage the batteries or create other issues?

The expert help from this group is very much appreciated.

Richard