Alternator Voltage Booster?

[indiedog]

I tow a camper and have an Anderson Plug setup so I can charge the camper battery when driving. I've measured the voltage at the back of the car (2002 2.5CRD) and it's only around 13.5 volts, not really that good for trying to replenish a depleted camper battery. Float to the camper battery is 13.6 and realistically would need over 14 to 14.4 to get some effect. Obviously it depends on SOC of the battery. I have wondered about DCDC chargers (pricey) and also getting a more powerful alternator to boost output. I am currently putting permanent solar panels on the camper to try and negate the need for the Anderson plug.

However, I was on MySwag and saw a link to a "Alternator Voltage Booster for Dual Battery Systems". Link is here. I gather these are mainly for Toyotas etc and have emailed him on eBay to see if he has them for Jeeps, will let you know. Link to the eBay site is here.

Was wondering if anyone has heard of this type of thing for Jeeps? Says on MySwag that guys make these things for cheap.

[indiedog]

Got a message back from the seller on eBay. Says he hasn't looked at the Cherokees. To make it work the KJ needs to have a fuse in the charge sensing lead. I'll see if I can determine this.

[JEEPaul]

If you're getting solar panels you might want to consider one of these:

http://www.ctek.com/au/en/chargers/D250S%20DUAL/

[wrench]

The cheap solution to boosting alternator output has been to solder a diode into the battery sense wire to the regulator. This fool's the regulator into thinking actual battery voltage is .5 volt lower and in most cases increases the alternator output. Some ECU controlled systems are smart enough to ignore the modified input signal.

These units are simply putting the diode into a fuse to make it a simple plug in unit. You also have consider any potential voltage drop in your wiring to the camper battery. I suspect you will find .5 to.8 volt drop between the front and rear batteries. In trying to boost voltage to the rear you risk overcharging the main battery.

A Redarc dc/dc charger mounted at the camper battery is the safest and best option but voltage boosting can work provided you test it thoroughly.

HTH
David

[Escapable]

Originally Posted by wrench

The cheap solution to boosting alternator output has been to solder a diode into the battery sense wire to the regulator. This fool's the regulator into thinking actual battery voltage is .5 volt lower and in most cases increases the alternator output. Some ECU controlled systems are smart enough to ignore the modified input signal.

These units are simply putting the diode into a fuse to make it a simple plug in unit. You also have consider any potential voltage drop in your wiring to the camper battery. I suspect you will find .5 to.8 volt drop between the front and rear batteries. In trying to boost voltage to the rear you risk overcharging the main battery.

A Redarc dc/dc charger mounted at the camper battery is the safest and best option but voltage boosting can work provided you test it thoroughly.

HTH
David

The voltage drop across a silicon diode (or silicon transistor junction) is .6 volt - this is a fixed voltage drop, not .5V.

BEWARE if you simply up the output of the alternator as this WILL put a higher charge (overcharging) the battery and also:
BEWARE as the PCM ain't that dumb - it appears to me that it monitors the actual battery output and adjusts the alternator field windings to suit: thus the output will be in fact lower and you WILL get charging problems and you WILL get stranded : BEWARE : these things ain't from Japan so don't compare (maybe to some Euro vehicles).

[indiedog]

Cheers guys. Paul I've looked previously at the D250S and it's had mixed reviews. Wrench, I've also looked at the Redarc DCDC and they are pricey. I think the jury is still out on the DCDC/Solar combined charge units such as these. I've already got a Ctek MXS15 for 240V charging and will source a MPPT controller for the solar panels. I've also got a Redarc isolator installed for the Anderson plug. Note I don't have a dual battery setup for the car, it's just the camper battery that I wanted to charge while driving. The permanent solar panels I believe will do the job of the Anderson plug and will be charging the camper battery while I'm driving through the MPPT controller, as long as it's sunny. I expect most daytime loads will be more than covered by the solar panels.

The booster seemed like an easy solution for trying to charge the camper battery while driving (not counting on the solar panels). I hear what you say about overcharging the car battery. Tell me then how guys can buy alternators with 200Amp outputs and not fry their batteries? Typically they say they are doing this for multiple battery setups.

[anthonygubbin]

It's not so much the amps that cause the issue it is the voltage. If the voltage into the battery is too high then you run the risk of boiling the battery dry.
TBH IMHO I like the Ctek dual battery charger. There is a bloke on Ebay who sells them at the cheapest price I have seen them. Battery Business (AJOR vendor) sells them at the same price as the Ebay bloke they just can't offer free freight. However with BB I am confident they would offer free valuable advice if you got one through them. The advantage of having a DC/Solar charger is that if given enough time say 4hrs thereabouts the battery will receive a full deep charge, unlike using just a solar controller or alternator charging.

Regards A