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Old 15-08-2014, 07:19   #91
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by T1 Terry View Post
A simple diode in one of the cables would eliminate that problem, but if the system is connected to mains then the charging system would kick in at the 13.4v mark and top the system back up. A good mains charger has separate voltage sensing that connects directly to the target battery, the diodes would not effect the charging voltage. The last thing you would want to do is disconnect the charging source on a low voltage event.

T1 Terry

I would say however that , there is a point where once the voltage goes low enough you have to perform low current pre-qualification charging. At this point you don't want auto connection of high powered charging sources

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Old 18-08-2014, 23:56   #92
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Re: Baqon drop-in LiFePo battery systems with BMS

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You don't have a way to disconnect the chargers on a LVC event. Aren't you concerned they might drain the batteries over maybe a long period when you are away or if one of them goes doolally and consumes excessive power it might kill off your batteries quickly, maybe overnight?

When I am away from the boat my LiFePo are completely disconnected after I discharged them down to about 50%. I connect my 2 LA starter batteries to each other and to the house and program the solar down to a max of 20A (normally I see over 100A on my solar) and 14.4V absorption. No need to cycle and endanger the LFPs when they like sitting at 50% doing nothing, while the LA like to be topped upped all the time. Should the LAs die, I can still start the engines using my LFPs, and the LAs are cheap to replace.


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Old 20-08-2014, 08:59   #93
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Re: Baqon drop-in LiFePo battery systems with BMS

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When I am away from the boat my LiFePo are completely disconnected after I discharged them down to about 50%.
Hi Rolf,

trying to gather tips for my own 400Ah bank soon to be installed (so maybe excuse the dump question). So what do you do if you still have 90% capacity? Is it a problem (for the cells) to disconnect them when (almost) fully charged?

Thanks!

Carsten
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Old 20-08-2014, 09:07   #94
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by roetter View Post
When I am away from the boat my LiFePo are completely disconnected after I discharged them down to about 50%. I connect my 2 LA starter batteries to each other and to the house and program the solar down to a max of 20A (normally I see over 100A on my solar) and 14.4V absorption. No need to cycle and endanger the LFPs when they like sitting at 50% doing nothing, while the LA like to be topped upped all the time. Should the LAs die, I can still start the engines using my LFPs, and the LAs are cheap to replace.


Rolf
But then I can't leave my refrigerator, freezer, bilge pumps, etc turned on.
Why not just set your solar controller to a Max voltage output of 13.4v going to your LeFePO4 battery bank and leave everything alone? I know I'm not risking a sub 10% battery condition due to the size of the solar and load and at 13.4v I can't over charge the battery either. Maybe it's the difference between a weekend boat and living aboard, but I want my 400AH LiFePO4 bank to be as "set-it and forget-it" as possible while we are living aboard here on a mooring. If I had to remember to connect and disconnect my batteries every time we left the boat.....
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Old 20-08-2014, 13:11   #95
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by CarstenWL View Post
Hi Rolf,

trying to gather tips for my own 400Ah bank soon to be installed (so maybe excuse the dump question). So what do you do if you still have 90% capacity? Is it a problem (for the cells) to disconnect them when (almost) fully charged?

Thanks!

Carsten
Hi Carsten,

A day or two before I leave I "tune" the solar down to 13.4V so I don't get a full charge anymore. I then run the water heater with my inverter and blast some energy out that way.
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Old 20-08-2014, 13:26   #96
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by SV THIRD DAY View Post
But then I can't leave my refrigerator, freezer, bilge pumps, etc turned on.
Why not just set your solar controller to a Max voltage output of 13.4v going to your LeFePO4 battery bank and leave everything alone? I know I'm not risking a sub 10% battery condition due to the size of the solar and load and at 13.4v I can't over charge the battery either. Maybe it's the difference between a weekend boat and living aboard, but I want my 400AH LiFePO4 bank to be as "set-it and forget-it" as possible while we are living aboard here on a mooring. If I had to remember to connect and disconnect my batteries every time we left the boat.....
To clarify:

I have two boats. One I use for the winter in the Bahamas. I am either on or off the boat.

I have anoth smaller boat up here in Canada, with 360Ah LFP. When I am in the Bahamas the Canada boat gets this treatment.

In Winter:
LFP drained to ~50% and disconnected.
Shore power charger connected - only to LA starter battery, which is also now connected to the house. Our area has very little below freezing and I run two moisture Air Dryr which habe a fan and a very small heater, enough to keep the temperature in the boat above the dew point.

In summer when I use the boat now and then.
Low usage times - i.e. i am working down the "honey do" list:
- LFP are connected.
- No shore power connected.
- I have a 12V-100W solar panel directly connected (no charger - cheap, cheap).
- The programable voltmeter is set to 13.8V HV off , 13.25V HV back on.
Only the drain for the electronic panels, battery monitor are slowly draining the battery down. It takes about 10-15 days to go from full and HV chargers disconnect - down to reconnect and solar charging - to full and chargers disconnect.

High use time:
When I am likely to go out soon again I plug into shore power and switch the fridges on. Now the cycle time is about 1.5-3 days.
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Old 23-08-2014, 12:54   #97
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Re: Baqon drop-in LiFePo battery systems with BMS

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Originally Posted by Gary H View Post
Let me first confess that I did something that I was warned against and should have known better than to do: I ordered 4 700Ah cells from Balqon. I know, dumb - but the free shipping and the fact that the cells were advertised as "in stock" suckered me in.

I ordered, got a confirmation email, had my credit card charged for the full amount - all good.

Fast forward more than five weeks, I can't get a response via phone messages or email when I might actually expect delivery.

Before I give up and call my credit card company, does anyone have an alternate contact or phone number at Balqon?

Also, I would be remiss if I did not thank the many generous minds who post here. You have my deepest respect and appreciation.

What is the status of your order? Did you try using their online chat? You might get someone to talk to that way.

Regards
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