Lithium battery setup for camper truck

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Re: Lithium battery setup for camper truck

Postby Tracker » Thu Sep 17, 2015 5:14 pm

davef wrote:A good suggestion. Gets around the hassle of trying to integrate an alternator into the system. .


and, the higher the voltage, the lower the current..
so if you were trying to get 12V from the engine to the trailer at say 200W, then that is a current of 16A
but at 24V the current is 8A, and so on, so the higher you could get the voltage, the easier it is for the cable..

So the best way would be to find out what the Solar-Charge-Controller limit is

http://www.aliexpress.com/item/12V-switch-56V-2A-112W-12V-solar-battery-charger-liter-56V-2A-48V-battery-converter/32306220917.html?spm=2114.031010208.3.149.eRXLBT&ws_ab_test=201526_5,201527_4_71_72_73_74_75,201409_3

this one puts out 56V but only 112W, so the line current would be just 2A, for a final charging current of more like 10A... there are likely bigger ones if one searches.. ;)

here's 192W..., = 13A battery charge for 48V line voltage and just 4A and about $30au
http://www.aliexpress.com/item/DC-DC-Booster-12V-to-48V-4A-192W-STEP-UP-DC-DC-Power-Converter-Regulator/32368736011.html?spm=2114.031010208.3.184.eRXLBT&ws_ab_test=201526_5,201527_4_71_72_73_74_75,201409_3
..
.
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Re: Lithium battery setup for camper truck

Postby Privatteer » Wed Sep 23, 2015 2:19 am

Most alternators put out about 14.4V.

Something like the morningstar relay driver might be a better option.
Use 1 input for fault input from a battery management system (if chosen)
Use 1 output for a high current relay from alternator supply.
Set it to monitor supply voltage.

At 14.4V, or 3.6V a cell disconnect the relay after x time. Therefore charging at whatever current the alternator throws out which should be well over some of the linked ebay options.
It can be set to reconnect after x time at x voltage. ie 10mins at 13.2V. There is also option to set minimum off time for the relay, so if you really wanted you could lock it out for 8 hours. All depends on how you want to manage it.

The 200w solar panel/reg should do the rest if programmed correctly and assuming the camper has no high loads while driving will maintain float for quite a while.

A standard dual battery relay/diode/switch depending on preferred option can then be used to protect the car battery from being discharged while stationary. Or if you picked up a accessory supply could be used to interlock with the relay in several methods to disconnect it once ignition off.

I
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