[Rover] Primary Batteries

[Dean Denter]

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).
>
> Any comments on these in a high current environment?
>
> Ev
>
>
>
>
>
>
>
> On Wednesday, April 8, 2020, 7:12:44 PM EDT, Ev Tupis via Rover <
> rover at mailman.qth.net> wrote:
>
>
>
>
>
> Thanks, Sean.  I'm hearing either golf cart batteries or marine batteries
> from others, too.
>
> -Ev
>
>
>
>
>
>
> On Wednesday, April 8, 2020, 5:23:48 PM EDT, Sean Waite <waisean at gmail.com>
> wrote:
>
>
>
>
>
> 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.
>
> 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.
>
> 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)
>
> 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.
>
> I fuse with 80A fuses. I probably could reduce that rating but I wanted to
> leave headroom for the battery string to charge.
>
> I've thought about all sorts of other enhancements but there are other
> priorities and this works. Bring a fire extinguisher.
>
> 73/Yours in Scouting
> Sean Waite, WA1TE
>
> 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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