Civic EPES: Alternator Delete Project (with additional lithium battery...)

[Daox]

Any pictures of the setup?

[oil pan 4]

Originally Posted by brucepick

I think it's quite possible the mostly discharged battery will soak up as many amps as the alternator can deliver.

Yes they will. Lead acid (flooded, gel and AGM) will do this but a lot of times they are so massive the battery can handle hard fast charging for a few minutes to replenish the drain from start up.
They cant take that for extended amounts of time repeatedly.
Need to slow it down a little.

LiFePO4 packs are even worse about soaking up all the alt power they can get, due to low internal resistance compaired to lead acid.
Uncontrolled charging is not recomended. Slower is better (less really is more in this case).

[California98Civic]

Originally Posted by oil pan 4

Yes they will. Lead acid (flooded, gel and AGM) will do this but a lot of times they are so massive the battery can handle hard fast charging for a few minutes to replenish the drain from start up.
They cant take that for extended amounts of time repeatedly.
Need to slow it down a little.

LiFePO4 packs are even worse about soaking up all the alt power they can get, due to low internal resistance compaired to lead acid.
Uncontrolled charging is not recomended. Slower is better (less really is more in this case).

So this is really important, as I move toward trying to create a plug-in and solar external power combination to keep my alternator off nearly all the time. I need to replace the battery I seem to have ruined with deep discharges (live and learn). I'll go larger this time, and might directly imitate brucepick's design described in this thread. Can I get a single power controller that would regulate charging of the larger deepcycle second battery from all of three inputs, solar panels, the alternator, and plug in? I imagine yes, but I am unfamiliar with the hardware.

[ps2fixer]

Originally Posted by California98Civic

So this is really important, as I move toward trying to create a plug-in and solar external power combination to keep my alternator off nearly all the time. I need to replace the battery I seem to have ruined with deep discharges (live and learn). I'll go larger this time, and might directly imitate brucepick's design described in this thread. Can I get a single power controller that would regulate charging of the larger deepcycle second battery from all of three inputs, solar panels, the alternator, and plug in? I imagine yes, but I am unfamiliar with the hardware.

Off my past solar research, there are off-grid systems that are designed to automatically charge a battery bank via the solar panels, but if they are not outputting power, then it uses the grid power to charge. For your 3rd power input, I would think you could use the same solar side to charge the battery.

I can't seem to find what I'm talking about, but maybe someone else knows what I'm talking about. It was some sort of inverter / charger controller.

[oil pan 4]

I know what you need, just have to find it.
I'm not big into off grid stuff but I do follow it a little.

[brucepick]

Daox,
Sorry, no pics yet. Car actually looks pretty messy inside; parts and tools all over the place. I have a circuit diagram but haven't made it into a .jpg yet for posting on photobucket. See below though, for notes on the circuit design.


oil pan 4,

I recognize your post re. charging was mainly re. California98Civic's battery issues. So I'll just say that in my setup the alt doesn't ever charge the lithium, but could be used to charge the lead acid starter battery and also power the whole car if needed on occasion.

There are two circuits, I need to state this clearly. One circuit is the regular battery up front; hooked up ONLY to the starter full time. Later the front battery will have a + cable going to the alt via an under-hood switch. The other circuit is the Lithium pack, wired to the main fuse box from where it powers the entire car, except of course the starter.

The alternator + cable is currently DISCONNECTED and in any case, I don't plan to use it to charge the lithium pack except possibly in some unexpected emergency situation. It can still charge the oem starter battery if needed.

There is a JUMPER from the front battery to the main + wire from the lithium pack (and thus also to the main fuse box), with a switch in the jumper line. After disconnecting the lithium's ground, the jumper can serve either of two purposes when the jumper switch is closed: (1) to power the main fuse box [and computer and MPGuino etc.] during lithium charging, and (2) to power the main fuse box from the main battery + alternator if I should need it, such as for a very long drive.

California98Civic,
A multi-charger system like you discussed here looks like a really good idea, but it has to be very well thought out.

If you develop it, I believe you'll need to know exactly the charging as well as discharging "needs" of each battery type you are using. Then you'll be able to (possibly) provide the environment they need. I've tried to keep this aspect of my setup relatively simple by 1) charging the lead-acid only from a plug-in charger built for lead acid batteries, and optionally off the alt, which is designed to support the lead acid pack. And 2) charging the lithium pack only from it's dedicated charger, which is set up for lithium packs of that size and voltage. Ultimately I hope to replace the front lead acid with a deep cycle lead acid, which will be able to power the headlights for a good while. But that's still a lead acid pack so can be charged by the same hardware I have now.

[oil pan 4]

Be advised, Lowes has LiFePO4 1000mah batteries in their shelves for those little solar lights. They are in the lighting section.
They are a bit expensive, 2 for $14. But if you want to run a quick dirty small scale test they would do the trick.

[brucepick]

Made some progress this weekend.
Took some pics but I haven't had time to post them yet, or the schematic (sorry ) You know the story: wife, mortgage, job.

Relocated the lithium battery to the trunk, was formerly on the floor behind driver's seat. Installed one fuse (one more is planned) and all three planned switches. Two of the switches still need to be mounted on a project box so they don't float around on the floor behind the driver's seat.

The switches as set up enable quickly switching between the lithium pack and the lead acid main battery so that either can support the car. You do have to stop the car to make these changes. This will be used most often to switch to lead acid power for the car while charging the lithium pack. Also with the lead acid pack in the circuit, the alternator can be switched on to support long night trips with headlights, which the Lithium pack can't handle. The lithium is good for at least three hours drive time without headlights.

Gotta edit that circuit schematic to show what I actually built, and post it... and the pics too.

[Daox]

What kind of voltage sag do you get while running off the lithium?

[brucepick]

Originally Posted by Daox

What kind of voltage sag do you get while running off the lithium?

The lithium pack is nominally 12.8V. I finally recognized it's based on a multiple of 2. 2 to the 7th power = 128. Anyway, after startup it settles in around 12.6-12.7V with engine running. Driving without headlights but with simple radio running, it sags to about 12.5V after about 1 hour and 15 to 20 minutes drive. I can drive home at the end of the day - without headlights - and get home with it around 12.3-12.4V or so.

Turning on the headlights is enough of a draw that voltage drops about .4V, regardless of where it was before switching them on. Not a problem when the pack is freshly charged but for running headlights on the trip back home, I will delay turning them on so I'll have enough charge to complete the trip with lights on. I'm sure the headlights draw more current than the computer + fuel pump + radio combined.

With this past weekend's work on the switches and wiring, I can easily reactivate the front lead acid battery and the alternator without tools. So the car is fully capable of going as far as one would want, just might need a refueling stop after ~500 miles or so