expenses, data from the last 20 alternator charging runs

Sept expenses will break the pattern

I had a run of sub-$400 months recently while boondocking. I figured being in town and ordering off Amazon would break that trend, and I’m on track for ~$750 for [fiscal] September (ending Oct 15th).

Part of this was a rare eating out splurge.

• $9 for a hamburger and fries at the locally-famous Blake’s Lotaburger. Burger was a B but the fries were not even cooked through (D-). Overall C, not worth it.
• $25 for pho and goi cuon at Pho Kim. Solid A, worth it although I was shocked to see ~$15 pho.

I harvested 2L of water from each for the supply.

data from a week of direct-charging LiFePO4

I’ve noted before that when I stealth camp in cities my charging percentage from alternator increases from ~5% to ~10% of total production. The increase isn’t needed (solar could cover it) but the alt gets a chance to play.

Since I am moving at least twice a day (3x with PF showers) I’ve had an opportunity to record a higher frequency of engine starts and LFP bank acceptance. The setup:

• 180A alternator that typically runs at 14.2v
• Battery Doctor VSR setup left over from my previous FLA bank
• 150Ah 12v LFP bank
• SoC and voltage measurements below taken from BMS before engine start
• current measurements taken from BMS though it agrees with shunted battery monitor. (I can see the BMS via bluetooth from the driver’s seat but I can’t see the monitor)
• solar contribution and loads ranged widely, leading to variance.

Over the last ~20 runs, the average state of charge was 72%, bank voltage 13.20v, charge acceptance 0.183C (27.39A)

    SoC Vbatt       C       A
    60	13.07	0.245	36.75
    72	13.15	0.130	19.50
    69	13.13	0.120	18.00
    27	12.95	0.270	40.50
    80	13.29	0.150	22.50
    80	13.27	0.240	36.00
    81	13.30	0.170	25.50
    77	13.22	0.165	24.75
    39	13.03	0.260	39.00
    95	13.30	0.115	17.25
    48	13.06	0.235	35.25
    86	13.56	0.120	18.00
    90	13.25	0.220	33.00
    90	13.26	0.165	24.75
    62	13.08	0.240	36.00
    92	13.27	0.084	12.60
    92	13.27	0.090	13.50
    58	13.07	0.235	35.25
    89	13.26	0.140	21.00
    84	13.26	0.215	32.25
    49	13.07	0.225	33.75

Given average charge acceptance of 27.39A, the obvious comparison here is to a 30A DC-DC like the Orion-TR at 4x the price. The DC-DC would have a much more stable charge rate, typically ~30A except late in the charging process when acceptance at Vabs tapers.

reddit

I’m getting increasingly tired of error-correcting in general and on /r/vandwellers in particular. People will believe (and repeat) foolishness and my desire to protect them from themselves is waning.

I am considering a different approach that might be more productive, protect my frazzled nerves, and match up with a willing audience. More on this by the end of the year.