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- 16 240 sedan, 91 240 wagon, 92 960 wagon, 90 740 GLE 16 sedan, 940 GL wagon 7 seater, 360 GLT 5 door, 84 240 GLT wagon manual, 240 sedan parts car
Yep, as an ECU designer I'm fully aware of fan strategies including high current PWM and stepped resistor banks like Volvo use on some cars and is often adapted around. I'm all four e-fans, mostly against e-pumps (can be done right, but not often), I was only commenting on front/back and the noise straight blades make relative to curved ones (and that noise being a parasitic loss that shows up as current draw and alternator load which is amortized over time by the battery.
An important consideration on whether to suck or blow (outside the bedroom) is that air has inertia, and air blown goes in a direction and doesn't want to turn sharp corners, whereas a vacuum pulls from all directions. If you have a seal around your shroud as you should, then suck beats blow any day (outside the bedroom), but without a seal blow will cool the area in front of it pretty well regardless thanks to that inertia and suck will draw air in around the radiator instead. You might have noticed the monstrous shroud on the 240 stock, that's Volvo ensuring the fan works on the entire surface of the radiator equally and good frontal protection at the same time :-D Also - be ready for it - straight blade fans are noisy AF. I thought that on your first post but didn't want to ONLY be negative, so now I'm being helpful and negative and the world is in balance :-D
Allow me to share my solution to:
- self discharge
- sulphation during even slight discharged states (read short trips, especially infrequent)
- limited life span with close to full starting performance of 2-5 years if treated well, months if not
- acid fumes eating car chassis and other parts
- excessive weight, 2.8kg for 4S2P shown below
- environmental hazard of lead
The DIY Headway 38120HP 4S2P pack will easily start any of my 4 and 6 cylinder engines, and quite likely the 8 litre diesel in our boat which I already started (only just) with a similar pack with only 4 cells and half the capacity. These should see me to my grave given thousands of full discharge cycles before 20% degradation in capacity and no full discharge cycles being applied to them.
That's wired into my 360 with the original rusty tray removed. And this is in another car:
- cannot run them flat, flat = dead
- should not run them over 14.8
- should not run them unbalanced
- balance circuits for alternator and starting currents not easy to come by - alternative arrangements needed
- low capacity comes with small size/light weight despite high starting ability
In summary, I plan to run these in my cars using an isolator switch on the firewall to keep them safe and a balance circuit that is not in series with the pack and the car such that it can balance the cells but not prevent over charging or over discharging - that's up to the regulator in your alternator and your isolator switch or frequent use. Having said that, the 16AH pack above has spent two periods of 1 month unattended in my 360 on the side of the road and started like a CHAMP with no sign of being drained after each period, so the switch may be paranoid, but I have a lot of cars so none of them are daily used, weekly to fortnightly for the frequent ones.