[Rover] Primary Batteries

Wed Apr 8 20:22:49 EDT 2020

Hi Dean,
That last paragraph is gold.  It gives me real insight into how you are configured and why.  

I need to think about how to transpose that into how I hope to operate.

Thanks, Dean!
Ev

On Wednesday, April 8, 2020, 7:56:01 PM EDT, Dean Denter <va3cdd at rac.ca> wrote: 

LiFEPO4 is lightweight but lots of money, but you can use most of their rated capacity (use a BMS to make sure you don't damage the battery -- a lot of the commercial batteries have BMS circuits already built in, make sure the BMS supports the configuration if you plan to use them in series and/or parallel configurations) -- I use a 30AH battery for my 10GHz hilltopping setup, it needs to be lightweight since it is part of a gear pack that gets carried on my back occasionally.

SLA & AGM are both heavy weight but less expensive, be careful to not discharge these below 11.5V or you will damage the cells and you will likely only get 50-60% of the rated AH capacity without damaging the batteries -- I usually use an automatic cutoff set to 11.8V to turn off the power before the batteries get damaged.

For my rover I used standard wet-cell lead-acid marine batteries in my rover -- make sure they have ventilation & are properly restrained to not tip.  If you go with 12V wet-cell marine batteries, be careful to look for DC-type and not DP or Starting batteries (DC = Deep Cycle).  As mentioned above, I have an old commercial cut off circuit that shuts down the power if the voltage drops too low.  I was running about 400AH of series/parallel Group24 DC-type marine batteries to power the rover with a 20A charging circuit that is relay switched from an ignition-only circuit so it only charges when the engine is running.  The rover has an FT847 (~2A RX / 20A TX), an IC746 (~2A RX / ~25A TX), a dual band FM mobile (1A RX / 10A TX), & 3 transverters (.5A RX / 10A TX) with a couple of HTs and other gear -- I still paper log, but would like to add in a laptop at some point.  I usually have enough power to make it thru a VHF contest weekend -- but recent contests have only been local 6-8 hour sprints due to work commitments.

regards,
Dean -- VA3CDD

On Wed, Apr 8, 2020 at 7:29 PM Ev Tupis via Rover <rover at mailman.qth.net> wrote:
> Adding to this thread...I see that there are three options to consider: Absorbent Glass Mat (AGM) Sealed Lead Acid (SLA) batteries, and lithium iron phosphate (LiFePO4).
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> Any comments on these in a high current environment?
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> Ev
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> On Wednesday, April 8, 2020, 7:12:44 PM EDT, Ev Tupis via Rover <rover at mailman.qth.net> wrote: 
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> Thanks, Sean.  I'm hearing either golf cart batteries or marine batteries from others, too.
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> -Ev
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> On Wednesday, April 8, 2020, 5:23:48 PM EDT, Sean Waite <waisean at gmail.com> wrote: 
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> The 100Ah AGMs I use top out at 30A or so continuous pull. We run a pair of them with a worst case of about 45-50A worst case draw and usually much less. With 75A expected draw you're looking at 3 of those in parallel or more likely going for heavier batteries. 
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> A lot of people like the 6V golf cart batteries in series+parallel to get 12V at the expected capacity and current rating. I'm using 12V batteries, it's what I found. 
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> I'm topping them off from the car while in motion. Definitely get some heavy power poles, or rather the Anderson SB series connectors. You don't want to overdraw your car battery while stopped. We disconnect when parked and then reconnect in motion. I need to pick up a big marine battery switch or something so I don't have the mechanical cycles on my connectors and also to make it easier to switch (our first rove required a wrench to disconnect 200Ah of battery from the car at each stop while on a rush. Not my idea of fun) 
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> I found really heavy gauge jumper cables, 4AWG or so, and have been using that wire for connecting things. The jackets are probably overly thick but it was the best price I found for that wire. 
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> I fuse with 80A fuses. I probably could reduce that rating but I wanted to leave headroom for the battery string to charge. 
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> I've thought about all sorts of other enhancements but there are other priorities and this works. Bring a fire extinguisher. 
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> 73/Yours in Scouting
> Sean Waite, WA1TE 
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> On Wed, Apr 8, 2020, 16:27 Ev Tupis via Rover <rover at mailman.qth.net> wrote:
>> Hi List,
>> 
>> Could you offer me some insights?
>> 
>> I have a need to supply ~75 amps @ 12v during TX.  My plan was to put a battery (or two?) in my trunk along with the amplifier to keep leads short.
>> 
>> I'd keep that battery "topped off" by running some 6AWG from my under-the-hood battery.
>> 
>> Any recommendations for a battery for the trunk (or other insights)?
>> 
>> Ev, W2EV
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