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In Line Thermostat


robthemuso
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The inline stat will give give you back your 1/2 way on the temp gauge. Add the 99p worth of Screwfix lagging will 1/2 the time in minutes it takes to get the 1/2 way on the temp gauge. Add the 'button battery mod' will give you back your 'old school' battery charging voltage rate.

 

Inline stat, £10 + 10 minutes.

Air dam lagging, £1 + 10 minutes.

Battery mod, 20p + 5 minutes.

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I've not been impressed with the way the battery is being charged on my Grand Voyager. Here is a practical and easy way to alter it -- no messing with the alternator.

1) Measurements over time indicated that initial alternator voltage after starting was 13.9volt. This dropped to 13.4 after a few minutes. This was consistent over time, and results in the battery being consistently under charged for most modern batteries. Measurements were done on a professional "Fluke" digital multimeter. Trust me, it's accurate.

2) Since most batteries sold over the counter are either lead-acid-calcium, or lead-acid-calcium-calcium, these type of batteries are undercharged at the above alternator voltages. Possibly these voltages are intended for some other type of battery.

Fortunately, there is an easy way to raise the charge voltage to 14.4volt without over stressing anything, as the design of the system is intended to do this -- I refer to the maker's own design here, not mine. 14.4volt is the 'old' charging voltage as used to be.

It consists of inserting a 33K0 (33,000ohm) half or one watt simple carbon film type resistor (worth about 10p.) in series with the live 5volt lead to the "cold battery sensor" mounted under the battery tray. On my GV, the leads are easily accessible coming out from under the battery tray, and on mine are colored blue and brown. The blue is the earthy one, the brown is the 'live' at around 5volt. I just used a small connector block to do the job. The circuit is "dead" at ign. off, there's no need to disconnect anything. Cut the brown lead, strip back and insert into a small connector block of the 2A. type. Fit the 33K0 resistor on the other side of the connector block so the resistor becomes in series with the brown lead.
Caution: These colors are on MY diesel GV., they MAY be different on yours! But the sensor is easy to find, just slip your hand under the battery tray.

Explanation:--
The voltage used to charge any type of lead-acid battery is crucially important even down to a few tenths of a volt.

Types of lead acid batteries:
"Wet" type: The acid is visible and can be topped up with distilled water. These were charged at 14.4volt from the alternator in the old days by a regulator either inside or outside the alternator. Wet batteries are rare on domestic cars nowadays.
"Sealed" type: Or sometimes called no-maintenance. The proper charge

 

voltage here is anybody's guess. Some are vented, some aren't. Some only vent under pressure by blowing out a rubber plug. They work by catalyzing the hydrogen and oxygen produced under gassing back to water. Thusly the SG (specific gravity) of the acid comes back to 1.28 at full charge.
"Calcium" type: The positive lead dioxide grid is laced with about 1% of calcium. This improves the self-discharge condition markedly.
"Calcium-calcium" type. Both the positive lead dioxide grid AND the spongy lead negative plates are calcium laced, reducing the self-discharge condition even more. Both the calcium types are advised by the battery manufacturers to be charged at a higher voltage, 14.8 to 15volt is advised for calcium-calcium types, 14.5 for calcium types.

The alternator is not controlled the "old" way by a separate or included regulator. Nowadays, and certainly on Chrysler motors, the field/rotor current to the slip rings is provided by the microprocessor system, and is pulse-width-modulated to control the effective current to the rotor.

Therefore, altering the cold-battery sensor to improve the charging voltage does not make either the alternator or the charge-control system do anything it wasn't intended to do in the original design. In this design, if the sensor (which is a simple -ve. temp. coefficient resistor) goes o/c, the micro defaults to exactly 14volt. And it does, I've measured it.

It's crucially important to get the charge voltage right for the type of lead-acid battery you have fitted -- it's not "fit and forget". If you don't get the charge voltage right, the result will be a short battery life, made worse by short-trips. Add to that the parasitic battery drain, and you have the dreaded "heavy-click" no-start when you come to use the car after a few days rest.

Finally, there is a new type of lead-acid battery coming. It's a lead-carbon containing a supercapacitor built in. They are already being called "supercabatteries". It is said they are capable of thousands of charge-discharge cycle.

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BatteryMOD

 

ButtonMOD

 

Changing the 33K Ω @ 1/2 watt to 22K Ω @ 1/2 watt keeps it under the 4.6[ish] [although I'm sure it would be safe a little higher]. I did get the extra .3's @ 14.4+ I was aiming for. This will better recover the winter loss more quickly. Of course in the summer the ALT output will be limited by the lower battery replenishment needs.

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Sorry just saw this, yes I just used a cheap siphon pump from ebay, similar ones are http://www.ebay.co.uk/itm/DELUXE-SYPHON-SIPHON-PUMP-KIT-MANUAL-PUMP-EXTRACT-OIL-PETROL-DIESEL-FUEL-LIQUIDS-/262809527857?hash=item3d30ab2631:g:hP8AAOSwNnRYfBh6

 

I found that by pumping out all of the fluid from the expansion tank and squeezing the pipe a few times and repeating to pump out of the expansion tank there was no leakage when I disconnected the pipe to add the inline stat.

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