Connecting an Unregulated Blanket to charge my caravan batteries through the Grey Anderson Plug

DIY
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1

I have a 75/10 MPPT in my ute that charges my AGM for the fridge.

I want to charge my caravan batteries, 2 x 170AH Lithiums, through the grey Anderson Plug on the A-frame.

If I unplug the Ute’s Solar Panel and run the Blanket through the Solar Input and then run an Anderson lead to the Grey on the A-frame, will. this be OK?

Will I need to change the settings on the MPPT from AGM to Lithium?

2

Welcome aboard @Chappo - hopefully some folks here can offer some suggestions.

So far, I’ve figured out the Ute is the vehicle towing the Caravan and there’s a power input to the Caravan via a 50A Anderson plug.

Can you share a bit more detail about your batteries? For example:

  1. specific make/model, LiFePO4 or Li-On,
  2. is there an internal BMS (Battery Management System) or external BMS like for Victron NG.
  3. What are the temperature extremes that the Caravan batteries will experience?
  4. How are the 2 x 170 Ah batteries charged right now? e.g. what’s between that Anderson plug and the batteries.

Changing the MPPT to Lithium is a good step; however, to keep them safe, it’s better to have a bit more info, as you might need to have a GX "Brain’ like a Cerbo etc.

3

And what is an “Unregulated Blanket” ?? Something that keeps you warm in your bed?

4

Gee, that is really helpful. Thanks.

5

Is that sarcasm? I can’t tell. But I can concur with @Buzzy that I would need some clarification on the terminology you are using. I also do not know what a UTE is. And my best guess from the context is an unregulated blanket is some sort of solar panel. However I don’t want to answer questions on assumptions.

6

The Lithiums are 2 x 170Ah Giant Power LiFePo4

The battery uses prismatic LiFePO4 cells and includes an integrated 100A Battery Management System (BMS) to manage charge and discharge, protect against overcurrent, and support safe operation. The unit is IEC62619 compliant and built for reliable performance in a range of environments.

  • Terminals: M8 removable

  • IP Rating: IP65 (dust and water resistant)

The temperature extremes I would expect to be no less than -10 C or higher than 45 C

They are currently charged from 2 x 160 Watt panels on the van running through a iTech Power 40 Amp MPPT Solar Charge Controller.

My comment re ‘Unregulated’ reflects what is said in the User Manual. I figure that it means it DOES NOT have a built in MPPT.

7

A Ute is what we call a ‘Truck’ here in Australia.

Mine is a Ssangyong Musso that tows my caravan, called a Trailer in the US

8

So if I understand you correctly, basically you want to charge your caravan batteries using the MPPT in your Ute. You want to disconnect the Ute solar and plug the portable solar panel (blanket) into the MPPT input. And then connect using a cable an anderson plug from the output of the mppt to the anderson plug on the caravan. I assume you mean to bypass completely the AGM battery in the Ute. Is that accurate? In theory this should work with the following considerations.

  1. Yes you will need to change the MPPT settings to LiFePO4.
  2. Sounds like a very long run from the MPPT in the Ute to the caravan plug. Voltage drop would be a big concern. The MPPT needs accurate battery voltage to perform properly.

Why not just add an MPPT to the caravan? A 75/10 is relatively cheap. You could install it close to the battery bank and then build a dedicated anderson plug and harness on the input side to plug the portable panels into. No changing charge setting, no voltage drop.

9

Excellent response, Thank You.

Your understanding is correct.

Your last paragraph about installing a second, stand alone MPPT, solely for the 240 watt blanket, is probably the way I will go. I guess I was trying not to duplicate what I already have.

I appreciate everyones input and advice.

Chappo

10

Very good. If you like the response clicking “solution” is much appreciated.
Thanks