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LiFePo4 charging


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#31 PaulT

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Posted 28 August 2019 - 10:01 PM

AHA! I knew it!.... this must be where my energy went too. It happened when I plugged the camper into the truck. Since bottom balancing I have since not plugged the camper into the truck...really no need. I have the Blue Sea and could switch them back and forth but for a small gain I see no reason to have to do it. (BTW I do have the Victron with bluetooth app) 

I ordered the Iota controller for the LifFePo4 .... how difficult is it to swap out the two? I have the DLS 30 with smart charger.

 

Unplug shore power if attached.

Unscrew the one screw holding the IQ4 to the camper.

Unplug the wire (telephone connector) from the IOTA.

Plug in the IQ4-LIFEPO  connector into the IOTA.

Replace the screw into the same screw hole to mount the IQ4-LIFEPO.

Plug in shore power.

Done.

 

Paul


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#32 PaulT

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Posted 28 August 2019 - 10:28 PM

The marketing description of their LiFePo4 module describes both float and a maintenance cycle.  I don't like the sound of that.  

 

Paul, can you speak to what the IOTA actually does with that module in it?

As I recall my conversation with them, the specification is that it bulk charges at 14.6 volts until the battery stops accepting charge, then drops to "float" where it sits. If the battery is used or a week passes, the unit switches back to bulk at 14.6 volts.  At the time I learned this back in May/June, I was having either telephone, email, or website conversations with Battleborn, Bogart Engineering, and IOTA asking questions to see if they were compatible. Unfortunately, conversations over telephone are lost in time and memory. Email is lasting, but other modes such as web page chats are not. A quick search of email did not turn up the specifics for the IQ4-LIFEPO. However, at the time I was satisfied that all would work together.

 

At any rate, the "maintenance" float mode was acceptable to Battleborn.  My 30aH Bioenno LiFePO4 battery & Bioenno AC charger does the same except that I manually unplug the charger 20 minutes or more after the light turns from red to green. The delay is to allow the BMS to balance the cells.

 

Paul


Edited by PaulT, 28 August 2019 - 10:30 PM.

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#33 PaulT

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Posted 29 August 2019 - 11:14 PM

Dawned on me that the battery monitor was being misled by thr truck electrical system behavior. The battery monitor measures & accumulates the amp hours consumed. It then manages the solar charge controller to replace the amp hours consumed plus a little to account for conversion inefficiency.

The unit can’t determine if the amp hours consumed came from the truck battery or the camper batteries. I told the monitor that the battery capacity is 200 aH. This ignores the 85 aH of the truck AGM battery so the monitor is working from inaccurate data plus using LiFePO4 parameters on the AGM truck battery

Just disconnected the camper power wiring under the hood. Monitor now shows 0.1 amps. That is about what the monitor plus the propane/CO detector use and heard the isolator relay clunk open. Going to run it this way for a while to see how it works.

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#34 rando

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Posted 30 August 2019 - 02:12 AM

Isn't the shunt for the trimetric installed on the ground wire to your camper battery? 

 

In which case it would only be measuring the current in/out of the camper battery and it would see the truck and battery as just another load/charge source and it shouldn't affect the charging algorithm.   The charge efficiency of lithium is much higher than lead acid, so make sure you change those settings as well. 


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#35 PaulT

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Posted 30 August 2019 - 04:02 AM

Yes. All grounds terminate on one side of the shunt including negative back to truck. One wire from other side of shunt to negative on battery. That’s how I caught what was happening.

After hitting the camper kill switch, no internal loads were active. That left the truck electrical system as the only possible load. Opening the positive to the camper at the breaker under the hood caused an immediate drop in current out of the camper batteries.
At least, that’s the only thing that makes sense to me.

With the kill switch pulled out, only the Trimetric and the propane/CO detector are energized. I made sure all appliances were off. Now I see about 0.1 to 0.2 amps which is reasonable. Turning on any light, fan, pump etc is reflected in the Trimetric amps display.

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#36 buckland

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Posted 01 September 2019 - 12:36 PM

Update on the rebalanced homemade battery... the four cells seem to be staying within .03 V of each other over a week...mostly of sun with the Isotherm fridge on. Voltage drops at night to 13.1 and up to 13.45 in the day (never got higher than that). I intend to leave on LED lights today for a few hours and also the vent fan to see how it copes. We will be camping for a three day weekend coming and will be a better test. I will keep the truck and camper separate from now on. I guess I won't need my Blue Seas ACR anymore. 


Edited by buckland, 01 September 2019 - 12:36 PM.

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#37 rando

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Posted 01 September 2019 - 02:31 PM

Buckland,  sounds like things are now working as they should.   

 

What are the state of charge percentages you are getting from the BMV during this test?   If your solar is only getting it up to 13.45V during the day, you may not be getting it above 60-70% SOC during the day, and maybe the solar is not keeping up with the fridge?


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#38 buckland

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Posted 01 September 2019 - 02:51 PM

Okay... to be honest I don't know what a BMV is.... where do I read the % of charge? But I was thinking that it was odd the voltage never got higher even with fridge off. 

I do not have my shunt hooked up but it could be as it is all there but detached. My App Victron settings are as they were set up originally. 

I have a 'similar' voltage Renogy 100 flex panel I could plug in to add to the solar if you think that would help (my roof panel is 160 Watt). The manual for the Victron states I should not have two panels on the same Controller? (they are set up parallel now to a terminal block in the battery box)

Any advice to investigate?

 

Just thought I have the IQ4 for LiFePo4 Iota that I could attach and plug in the shore power?


Edited by buckland, 01 September 2019 - 02:55 PM.

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#39 rando

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Posted 01 September 2019 - 03:04 PM

Sorry, BMV - Victron battery monitor (ie BMV-712).    It sounds like your fridge/lights/fan may be using more power than the solar panel can put back in, but the BMV would tell you if that is the case.

 

You can plug in your Renogy panel in parallel - you won't get the full power out of it, but it should provide at least a little more power and maybe enough to bring your energy budget into balance.

 

You could also plug in the IQ4 for a few hours to get everything full, but I wouldn't leave it plugged in - even with the IQ4, the float voltage isn't ideal, also this doesn't really help with simulating real use, unless you also plug in while camping.


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#40 buckland

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Posted 01 September 2019 - 03:11 PM

Thanks Lars. I have the Victron 100 20 controller with the bluetooth App but no separate battery monitor. I had the battery setting in the victron  set at 13.6 V 'absorption' which I just changed to 14.2V... (not sure if this will affect anything) 

I will plug in the other panel and watch it and if it does not increase I will plug in shore power (never did that before). Will get back and post thereafter (I usually use my iPhone WTW app when working in the camper but the WTW site is not allowing me to log in at this time so have to run into the house computer to post)


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