Running on 16 Volts

[jray3]

I'm considering running with two 8 volt deep cycle batteries on my 1987 F250 diesel (and any other vehicle with no electronics). Thinking is, I'll have more starter torque, brighter lights, and unload the alternator during most driving (for better FE and performance), but the alternator will kick in and carry the load right before the bottom discharge limit (14.0 V).
I'd grid-charge the battery when parked, floating it at 19.6V.
Anyone tried this mod? I may need a dc-dc converter and even a 12V buffer battery for 'house' loads to prevent frying the radio and lights, only using 16V for the starter.

An old-school diesel technique is a series-parallel switch to feed 24V when the starter is engaged, but that does send a voltage spike to everything else as well...

There won't be any change in weight, as the truck normally runs on two parallel 12V batteries.

[Daox]

I believe orange4boy tried this on his minivan. He toasted his headlights.

Personally, I don't think the starter needs the extra voltage (not that it'll hurt). The one thing I'd like to boost the voltage to on an alternatorless setup is the ignition coil(s).

[oil pan 4]

Try a gear reduction starter if they make them for the 6.9/7.3L and custom battery cables in 2ga, 1ga, 0ga or 00ga.

I was going to do something like this, run a 6 and 8 volt optima (for an alt delete) and regulate down to 14.4v to all the electronic bits. Then I discovered 00ga welding cable and that my suburban had a cheap 4ga battery replacement cable installed.

Now I run LiFePO4 batteries. The larger battery runs on 2ga cable to the starter and the smaller battery runs 4ga to the starter. 2ga+4ga equals something like 00ga or 000ga.

[jray3]

Thx Daox- I've searched but not found those posts by OrangeBoy. I asked this because I just traded for a good batch of T-875 batteries, but this 'mild PHEV' strategy might be much better suited for four Lithium cells. They would be fully charged at 16.8V, much kinder to the light bulbs, and when the alternator kicks on at 14.4V, they would be 95% discharged. That's a deeper cycle than I'd normally want to go, but that point in time could be chosen via cell capacity, and stopped sooner with a battery disconnect switch. I've still got a 3000 uF ultracap pack to run in parallel with the alternator and smooth out the loads. I'm trying to avoid the complexity shown in the failed People's Hybrid venture.
http://www.peopleshybrid.com/news.htm#feb_09

[Daox]

Here is the link:

http://ecomodder.com/forum/showthrea...e-up-7551.html

[jray3]

Xcellent- so the bulbs need careful feeding and his relays ran hot too. I've got 4x100 AH LiFePO4 to try out, but am tempted to just go alternatorless with a 48V-12V dc-dc converter and buffer battery, which would add the utility of a 1.8 kW 120 VAC UPS that currently resides in my garage.

[ijames]

Lots of drag racers convert to 16 volt systems, to get more volume from the fuel pump and more output from the ignition. This is almost always for dedicated track cars, not street/strip cars. Alternators (or adjustable voltage regulators), batteries, and chargers are readily available, they usually pull most of the bulbs except what the track requires (one taillight at a minimum; and replace them frequently or come up with a way to regulate the voltage down), and these are usually pre-ecm cars with no other electronics left on board. Another option is a switching step up power supply to boost 12-14 V up to 16 V at 5-10 amps (or adjustable from 12 to 16 V) just to power the ignition coil(s) and/or fuel pump. Several companies sell these. Good places to browse just to see what is out there are www.summitracing.com and JEGS Performance Auto Parts - Holley - Billet Specialties - Edelbrock - MSD - Moroso - Mr Gasket - Free Shipping on All Orders @ JEGS, the two big hot rod suppliers. As for the starter, your diesel has two 12 V batteries in parallel now, so the cold cranking amps add. Put two 8 V batteries in series and you get more voltage, which will try to push more current through the starter, but now the maximum current available from the pair is the rated CCA of one battery - you lose a factor of two there. (That assumes both batteries in each pair are perfectly matched, I know.) Overall I really don't think changing the batteries to 16 V is the way to go here, and since you don't have an ignition system I don't think you would even benefit from one of the step up power supplies.

[Cobb]

Your better bet is to get 2 deep cycle 12 volt batteries and a 24 to 12 volt converter to back feed your electrical system. Recharge the deep cycles before driving off. I have something like this in my insight and its netted me 5 mpg.

https://www.youtube.com/watch?v=XmZ4EfGJRqU

[BobS]

jray3, looking at your setup, two solutions come to mind:
1. Using the old-school diesel setup, it is easy to separate the starter circuit from the circuit feeding the other systems in the car. If you permanently hook the system circuit wire across one battery, hook the batteries in series and hook only the starter circuit (or whatever circuits you want) across both batteries, you will have what you have said you want. But you must charge each battery separately, charge one one night and the other the next. That way you only need one standard charger if you use 12V batteries and, hopefully, no alternator will be needed unless you have a long commute.
2, Separate the starter wire from the wire to the rest of the systems. Run the 16V to the starter and run the other wire thru 4 silicone power diodes (with heatsink, preferably in front of the radiator) to get a 2.4V drop. You would be upping the voltage about 3V to 17.1V max on your lights, fuel pump, etc. so you should get better performance but shorter life for those components. Then you can run an alternator or not, your choice.
Bob

[jray3]

Thanks All,
I commute in an EV, so the truck is only for projects that require grunt and it goes weeks without use. (If the truck is running, it's hauling!) So, I use a battery disconnect switch to kill the vampires, and like the simplicity of Bob's approach #2 for this job. Regarding starter voltage and amperage, it will spin faster on 16V, which means faster diesel starting, and will pull fewer amps on the same load, so I'm still comfortable trying the 16V series setup rather than 12V in parallel. Will post results.