Alternator bypass & engine preheater mod

[paulgato]

Originally Posted by ctgottapee

paulgato: I know you thought the coolant preheat wouldn't be as good as the oil pan preheat, but I think your oil preheated will run into the same problems.
As soon as it makes one pass through the engine, it will cool to ambient as the engine will be cold. I would be willing to wager you would see no change in the oil temp gauge by the time it cycles around.

Hmmm... I always thought that the coolant preheater on its own would be better than an oil pan preheater on its own. But I think that both together would be even better than either on its own.

The Prius' idea of pumping the coolant into an insulated container while parked is great, but why not do the same for the oil? The oil already has a sump into which most of it falls when the engine stops, so why not insulate that sump from the air? One should be able to keep the oil warm for a couple of hours at least between drives. Also, an insulated sump would improve the efficiency of any oil sump heater fitted. The oil is cooled (in my engine at least) via a coolant/oil heat exchanger (aka 'oil cooler') so insulating the sump pan should present no hazard while driving. Maybe there is some kind of spray-on foam insulation that will withstand engine temperatures?

[paulgato]

Originally Posted by ctgottapee

Yeah, it's a 1993 factory AC Delco model.
It's not even the worst offender in the car.
The premium systems in the car use a lot of juice too. I guess the reliability of cold start electronics was low then. My power seat controls/system is always powered so it can auto adjust based on the keyfob used (set per driver) before they sit down when they unlock the car.
The exterior key lock is always lighted, run by a 15w bulb and a long length of fiberglass filament; kinda creative before LEDs existed.
And there is an air compressor that inflates the rear shocks as a ride control mechanism. It's not air tight so it is also always on, and occasionally runs to push the bladder back up while sitting.

I have climate control, but it still uses the resistance elements for fan power.

I have to agree with Oldtamiyafile. That's a huge amount of parasitic battery drain when parked. A 15w bulb for the door lock....!!!???? 15w!? That's more than an amp. Over a weekend that will flatten your battery dead, won't it? Is it really designed that way? That can't be right. If it is then maybe you could remove the bulb, and fit a hard ON/OFF switch for the radio.

My total battery load with key out of the ingintion is 24mA.

[ctgottapee]

Originally Posted by paulgato

I have to agree with Oldtamiyafile. That's a huge amount of parasitic battery drain when parked. A 15w bulb for the door lock....!!!???? 15w!? That's more than an amp. Over a weekend that will flatten your battery dead, won't it? Is it really designed that way? That can't be right. If it is then maybe you could remove the bulb, and fit a hard ON/OFF switch for the radio.
My total battery load with key out of the ingintion is 24mA.

It's the best they could do in design over 25 years ago.
My car came standard with the largest auto battery on the market.

That key hole bulb only runs at night, car has a daylight sensor, and it needs 15w as it can't be placed in the keyhole obviously. It's in a protected shroud with a long length of fiber glass leading to a wrap around the key lock mechanism.

[paulgato]

Originally Posted by RedDevil

That is strange. I cannot see how charging on a low current could be bad for a battery, unless it is has a shorting cell.

To play devils advocate: if they get you to buy an expensive charger for your battery they make sure you will buy another like battery if it goes bad, or you would have wased all that money on the charger...
I would like to see proof that you do need a big charger for a big battery.
At least it does have the benefit of fully charging your battery within a few hours, but that's it.

Well I agree that it seems strange RedDevil, but I can't see that Enersys have anything to gain by telling customers they need a powerful charger when they don't. Quite the reverse: if a customer knows they have to buy a more powerful charger in order to use an Odyssey battery then that increases the cost to them and they are less likely to buy an Odyssey battery in the first place. In fact I think they should make that high charging current requirement clearer up-front, rather than burying it in the user manual, which most people won't read until after they have bought the battery.

However, the guy in Tech Support I spoke to was clearly being truthful, and also was very knowledgeable, both from hands-on experience and from an academic point of view. He also said there was a range of opinion (i.e. nobody really knows but some people think they do) on why this particular battery technology happens to work better and lasts better with higher charging currents in a cycling application.

The technology behind the 'consumer' Odyssey batteries was developed for the SBS industrial battery range apparently, and the tech document for those SBS batteries specifies a minimum 10%-of-Ah-rating charge, and again, no maximum (e.g. a minimum 10Ah charger for a 100Ah battery) The Odyssey batteries are slightly different I guess, in that they are designed for high current output for engine cranking and therefore presumably have a greater number of thinnner plates, ...but the basic chemistry is the same.

So quite why the Odyssey battery only gives its full number of deep cycles with a 40%-of-Ah-rating current charger, I don't know, but I believe it to be true.

I kind of needed a new charger anyway because I definitely in any case need a 2nd temperature compensating charger for the 2nd battery. 40% of the Ah rating for my PC1220 battery would actually be 25.8A, but I'm going to compromise very slightly I think and get a CTEK 25A charger, as I can't find a decent charger that is both more powerful and even vaguely affordable. (The Ring 35A or 50A chargers are fairly cheap, and they look good on paper, but I'm not sure I'd trust them. The manual has glaring errors in it for example, and that's never a good sign. The CTEK chargers are well-respected and come with a 5-year warranty)

[paulgato]

Originally Posted by ctgottapee

I saw the mention of HID headlights a while back and didn't see if you switched over.

I found that my HIDs were so bright, I went down to just using one HID headlight @ 35w. For the other lamp, I purchased a 3w LED bulb that illuminates the headlight socket so it looks like there is a headlight.
They do draw a heavy inrush current at start up; possibly more expensive ones compensate for this. They have their own power supplies so voltage drops are not an issue.

I'm surprised your radio uses so little power. My uses half an amp when it's off just to store it's settings.


lots of good info in this thread

Thanks. No, I didn't fit HiD's, and probably won't. I use the LED sidelights in street-lit urban areas at night (and everywhere during the day). They use almost no power (5 or 6 watts, or half an amp total for all six bulbs: tail, numberplate and front sidelights.) The front sidelights are surprisingly bright.

[ctgottapee]

Originally Posted by paulgato

Hmmm... I always thought that the coolant preheater on its own would be better than an oil pan preheater on its own. But I think that both together would be even better than either on its own.

The Prius' idea of pumping the coolant into an insulated container while parked is great, but why not do the same for the oil? The oil already has a sump into which most of it falls when the engine stops, so why not insulate that sump from the air? One should be able to keep the oil warm for a couple of hours at least between drives. Also, an insulated sump would improve the efficiency of any oil sump heater fitted. The oil is cooled (in my engine at least) via a coolant/oil heat exchanger (aka 'oil cooler') so insulating the sump pan should present no hazard while driving. Maybe there is some kind of spray-on foam insulation that will withstand engine temperatures?

The oil sump is part of the heat emitting system, most cars have no oil cooler at all. The oil and its system is also designed for lubrication, not for heat transport. Even cars with a bit of oil cooling don't often use the old combined exchanger, which should probably be the first mod one undertakes as you get the full package of heating/cooling/stabilization.

Trying probably can't hurt, but it's not cost effective in comparison to the engine coolant. In a few seconds after that warm oil makes its first pass, it will have lost any benefit; remember the engine oil flows through a system designed to reject heat and in which heat is not a benefit. If the oil is too thick, you need a lighter viscosity.

Heck I've seen systems that try to pre-heat the fuel with warmed engine coolant; maybe it helps, but not likely.
You could even try pre-heating the tires, just like they do at the race track.

[paulgato]

Originally Posted by ctgottapee

The oil sump is part of the heat emitting system, most cars have no oil cooler at all.

Exactly so. The last thing I want to do is overheat the oil by insulating a necessary cooling device (sump pan). I think I can rely on the 'oil cooler' (oil/coolant heat exchanger) to do any necessary oil cooling, as my VW TDi engine doesn't seem to produce a whole lot of heat, but I'd want some way of closely monitoring the temperature of the oil in the sump to check I'm not overheating it.

You could even try pre-heating the tires, just like they do at the race track.

I'd not considered pre-warming the tyres but I considered prewarming the transmission. For whatever reason, my mpg continues to climb until I've been driving for a good couple of hours or so. Even though that mpg improvement over a long drive is less pronounced now I'm starting with a pre-heated engine, it still takes two hours to reach its absolute peak. That's probably a combination of things, including having a thoroughly heat-soaked engine, and including warmer fuel, as my car recirculates warmed fuel back into the tank, but I guess the transmission warms up - both with internal friction and with conducted heat from the engine/clutch housing - and the transmission oil becomes less viscous as it heats. Then there's CV joints, wheel bearings, and then tyres, all of which will have been designed to run most efficiently when thoroughly warmed up.

I had good success with a transmission oil change. VW claim the (manual) gear oil never needs changing for the life of the vehicle, but after 150,000 miles and ten years I decided to change it anyway, and also added a small tube of Molyslip gear additive (UK version!) The difference was immediate and obvious, both in the way the car drove and in observed mpg. I got my mechanic to change the oil up on his four-post lift. Took him ten minutes.

That was so cheap and easy, I'd recommend anyone to do it every few years, whatever the manufacturer says. (Manufacturers have an interest in claiming long - or infinite! - maintenance intervals because that sells cars.)

I calculated that 'gear oil change mod' would have paid for itself easily in a year, unlike this blessed 'alternator delete' mod, which is taking far too much time and is costing way too much! I think I may have passed the point of maximum benefit-vs-cost-n-trouble some time ago with that, but having paid for all the kit and done half the work, I'll carry on and finish it.

I've generally been having fun with it, but I'm still smarting from having accidentally damaged my alternator last week. I guess any project worth doing has moments where you wonder why you started it.

[paulgato]

Originally Posted by RedDevil

That is strange. I cannot see how charging on a low current could be bad for a battery, unless it is has a shorting cell.
What is known to limit the life of a battery is how deep you discharge it; dicharging beyond 40% SOC does indeed reduce the life of a battery; you can discharge a lead acid battery to 75% many thousands of times, but discgarging to say 10% will kill it within a few 100 cycles.
40% may well be the most economical point; beyond that the damage you do to the battery outweighs the benefit of prolonged running without alternator.
IMHO instead of charging it hard you might well focus on avoiding deep discharge.

An update: I phoned Enersys UK this morning, but a different department in a different city from last time and got some different advice on charging Odyssey batteries that is at odds with the advice in the owner's manual.

The guy I spoke to today said that from the charging point of view, the Odyssey batteries are identical to their PowerSafe SBS industrial/telecom batteries, and will deliver similar numbers of cycles. The reason they recommend at least a 0.4C (40% of Ah rating) charge current for Odyssey batteries is because people tend to underestimate the length of time it takes a charger to achieve 100% charge. Aside from repeated deep discharges of course, the thing that really reduces the number of deep cycles one will get out an SBS/Odyssey battery is failing to achieve 100% charge between discharges, and in many applications the best way of ensuring a 100% charge is to specify a high current charger. They reckon that industrial users are able to control the charging/discharging regimes much more closely than users in 'extreme' environments and situations, so for industrial users (of the very similar SBS bateries) they specify a minimum bulk charge of only 0.1C.

There is no upper current limit, and these batteries can be recharged from 0% SOC to 95% SOC in 20 minutes. But the final part of the charge up to 100% always takes 6 or 7 hours regardless of the power of the charger, so if a user is thinking of charging 'overnight', i.e. for 8 hours, then they will need a powerful charger to avoid undercharging.

The guy I spoke to today reckoned that my existing 10A charger would be absolutely fine for charging the Odyssey PC1220 battery with its 70Ah capacity, assuming a good 10 hours per night on charge and up to 18 hours on charge after a particularly deep discharge. (18 hours will be enough to recharge a battery discharged to 100% DOD, which will never happen with a starter battery in a vehicle which is used every day, so I think I'll be alright.)

So that's one less thing to worry about. I thought I was going to have to install a larger charger and route yet more cables through the firewall.

By the way, I'm fairly close to getting this mod installed in a permanent and non-prototype-ey kind of way now. HOWEVER, ...If I were starting this project again, without having invested time and money in doing it the way I am doing it, I would do it in the following manner instead...

I would not use a DC\DC converter at all but would simply get the biggest, baddest AGM deep cycle-capable battery I could find, and put that in the rear - in the spare wheel well. I would ground that to the chassis in the rear and connect the +ve to the +ve battery terminal connector in the engine bay (or direct to the starter motor) via a fat cable and some proper fuse protection. I would dispense with the battery in the engine bay completely.

The battery I would buy would be the Odyssey PC1800, which is kind of wide and flat and the perfect shape for fitting in the spare wheel well. It is rated at 215 Ah, has a CCA of 1300A and Reserve Capacity of 475 minutes at 25A. (That's up to 8 hours of rainy roads in the dark!) I would install a 50A charger in the vehicle so it is assured of being fully charged every night. (25A would be OK, but 50A would be better.)

This set-up would add a few kilos to the vehicle's weight overall, but not a massive amount as I would be losing the front starter battery and the spare wheel. It would not be cheap, but would certainly pay for itself over time. It would be very simple, efficient, and would work well for many years. The alternator-off driving range would be HUGE, and would cover virtually any journey I might contemplate driving in a single day, whilst for everyday commutes and so on, the battery would be discharged so slightly that it would be capable of lasting for thousands of cycles.

But, I am where I am, so I'll stick to Plan A, which is a 70Ah Odyssey battery in the front and a 100Ah Yuasa YPC-100-12 deep cycle AGM battery in the rear feeding into the car's main electric system via a 12A/14v DC/DC converter and using the car's existing wiring to carry that very modest current. The Odyssey battery has a 10A CTEK charger (MXS10) attached, and the Yuasa battery will have a 25A CTEK marine charger (M300). Both chargers are temperature compensated. I'll summarise and post some pictures up when it's all properly installed.

[paulgato]

Originally Posted by California98Civic

I had learned about the expanding problem during my own long conversations with the Odyssey techs, but this home-remedy never came up. Thanks for that. I have a smaller Odyssey battery I could adapt in this way.

In the end I decided on plywood for reinforcement rather than aluminium. Mainly because it is non-conductive - both thermally and electrically, but also because it is easier to work with and just as rigid, if a bit more bulky. (I did have to shave away some of the side pieces to accomodate the battery clamps and various protrusions in the battery compartment, and that involved a bit of trial and error, so I'm glad I didn't go for aluminium.)

It seems the only real issue with these batteries is longitudinal expansion, where the lead plates separate and the battery fails. So I've got two thick plywood end plates (18mm or 3/4 inch) and two side pieces of 5mm plywood, screwed and glued into the 'end grain' of the end plates. I used 'Cascamite' resin glue.

18mm ply is overkill in terms of stiffness, but putting screws into the edge of thinner ply is not so robust, so I used 18mm to get a good width for both screws and glue to hold well.

Anyway it seems to work just fine, and still fits in the car's battery tray. Mine is the PC1220 battery which is the standard 096 pattern and has a 'wedge-shaped' hold-down base that can be clamped down in the car, so a 5-sided box is not possible. The four-sided thing is fine though - just can't be removed. Well, if I ever do need to remove it I can cut through the glue joint on one side. I sprayed the battery casing lightly with silicone so the glue wouldn't bond to the plastic.

(But I have to say it was a disappointment to find that you can't use these batteries (these standard car-battery-shaped batteries, sold as car batteries!) at above 40 degrees C without mechanical restraint. That makes the batteries not really 'fit-for-purpose', as car engine bays will routinely get hotter than 40 degrees C, even on a cool day.)

But California98Civic, I'm still getting contradictory advice from Enersys tech people about the proper charging current for Odyssey batteries, and whether this minimum 0.4C charge they talk about is really necessary or not. What did you conclude about that?

I had one Enersys techie say, "Yes, you get more cycles with a >0.4C bulk charge, but no one really knows why," and another, equally confident Enersys techie said that as long as I make sure the battery really does get 100% recharged between discharges then I'll be fine, but that I must recognise that a FULL charge will need a 'float' charge of 6-8 hours AFTER the bulk/absorption charge has done all it is going to, and that 6-8 hours is 6-8 hours regardless of the charger's max power output, so if I can get the bulk/absorption charge down to two or three hours then there's a much better chance that an overnight charge will recharge the battery to 100% than if the bulk/absorption charge is itself taking ten hours.

I came across these guys today on a powered wheelchair forum. One recounts a conversation with the head bloke at Hawker (before Enersys bought them out) about their pure lead thin plate batteries and their charging requirements (scroll down a bit) ...

WheelchairDriver • View topic - Another battery from Enersys

...and this guy seems to have re-designed his wheelchairs for maximum performance and range. He rates Odyssey batteries, MK and Sonnenshein and advises against ever using anything else...

WheelchairDriver • View topic - AGM & GEL BATTERY INFO for POWERCHAIRS

...I reckon that if anyone is going to know about batteries it will be someone (with an engineering background!) who absolutely relies on batteries for their everyday personal mobility in a wheelchair. This guy seems to have re-designed his wheelchairs for maximum performance and range.

[mikeyjd]

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