Battery isolator?

I lectured Frank Oropeza about rectifier type isolators back in 1982. Sure Power and just about everyone else selected 35 ampere 50 PIV 1/2" press fit rectifiers. Pure garbage. Bottom of the barrel. He decided on 50 amp 200 PIV rectifiers. And had few if any warranties. When social butterfly Steven Scheidler took over Sure Power from his father Ralph (the founder and brains) he started bleeding quality for profit. Thank God the battery separators were designed exclusively for Essex or White Rogers relays.

Regardless only a few companies use good rectifiers in diode based isolators. If Blue Seas has a diode based isolator it most probably has good rectifiers.

A White Rogers or Essex relay is tp say conservatively 1000% tougher than metal can trash.I still have 7 or 8 new 200 amp mercury filled relays. The pick of the litter.

You did a bypass
You directly connected the two batteries and the alternator
The GM stop power thingy would be in the truck circuit
Not between the battery and main or you would NOT be able to start the truck at all, with out some kind of system reset/re-connect

I'm not sure what's in there, and will get the brand next time I go out to the truck - it's not here at the moment. That's might answer some Q's?

I know for certain, before I bypassed it, the truck alternator would not charge the house battery. After I bypasses it, the alternator charged both. Then it drained both the truck and camper battery while sitting at the CG - and we were obviously using power - but did not know it was also draining the truck battery. I thought the GM trucks had a 'stop power' program after a period of sitting, and have no clue why or how that allowed the dual drain - I'm not an electronics person.

Will look at the "isolator" and see what it is, but it's the stock one from a Lance Camper 845 in 2009 ... this one was actually under recall by Lance, and replaced. Then the replacement failed also, so replaced it once more under warranty - the third failure, then I bypassed it.

I did a whole lot of boat work before the depression hit here. I replaced many more combiners than I replaced isolators.

Adding and isolator to any truck no made for it will be a serious tear-up and it would void any warranty.

Are you sure it is an Isolator and not a Combiner?

In the years since, I have only seen one truck with an isolator. I have seen many with combiners. The combiners all have contacts. Those contacts fail. Isolators require that the main engine alternator have a remote sensing capability.

Matt

Relay is just an automatic version of manual disconnect

You know what kills a diode style isolator

Starting up the engine and taking off down the high way with a low battery
The battery is drawing all the amps it can take, which may be near or even over the rating of the diodes

10 minutes at idle while breaking camp, will help reduce those failures
But I'm curious
Most diode failures, result in open diodes, like a blown fuse
If this happens the camper can not drain the truck battery

You would need a shorted diode to drain the truck battery

How ever an open diode to the truck battery, would mean the truck battery got discharged while driving to the campsite, instead of getting charged

Oldfordman wrote:

ScottG wrote:
The diode based units just aren't rebust, even if you get one that's way over rated for your demands.
They always seem to fail at the worst time.
I ended up using a solenoid type relay from Napa on my old truck. It went for many years until I traded it in.

If using a solenoid type just make sure it's a) rated for continual use and b) designed to handle 100 amp or more.

Many solenoids from "NAPA" (and others) are only rated for intermittent use such as sending power to the starter or running a hydraulic pump, etc. When used to connect batteries for charge they often fail.

On the current rating, if you have a fully charged battery that's suddenly connected to a discharged battery there is a sudden inrush of current. The internal arcing will take it's toll on lower rated solenoid/relays.

Good point. I should have stipulated that it was rated for 100% duty cycle.

MrWizard wrote:
the advantage of a Relay over Diode based
is no voltage drop from the diodes
this means higher voltage faster better charging for chassis and house batteries

if you 'want' manual operation
use a battery disconnect switch
just put in-between the camper battery line and the alternator chassis line
open hood close switch ..drive
get to camp, open hood, open switch

total isolation

I pretty much thinking I'll just insert the disconnect switch - two reasons :: It (probably) won't fail, and I can carry a spare. And, if the truck battery ever goes dead (why it would, I don't know if it's isolated, it shouldn't), then I can either jump start, or close the switch, and it will combine the batteries enough to start.

But I'm more concerned with not draining the truck battery because we camp a lot with no electric onsite. When the last one failed, we ended up with a dead truck battery as it drained with the house battery.

But then again, it's nice to have a relay that will fast-charge the house battery even after the start battery charges. Maybe the best alternative would be to install the isolator, and then a bypass switch for when/if it fails. Gotta think about that one ...

ScottG wrote:
The diode based units just aren't rebust, even if you get one that's way over rated for your demands.
They always seem to fail at the worst time.
I ended up using a solenoid type relay from Napa on my old truck. It went for many years until I traded it in.

If using a solenoid type just make sure it's a) rated for continual use and b) designed to handle 100 amp or more.

Many solenoids from "NAPA" (and others) are only rated for intermittent use such as sending power to the starter or running a hydraulic pump, etc. When used to connect batteries for charge they often fail.

On the current rating, if you have a fully charged battery that's suddenly connected to a discharged battery there is a sudden inrush of current. The internal arcing will take it's toll on lower rated solenoid/relays.

The diode based units just aren't rebust, even if you get one that's way over rated for your demands.
They always seem to fail at the worst time.
I ended up using a solenoid type relay from Napa on my old truck. It went for many years until I traded it in.

the advantage of a Relay over Diode based
is no voltage drop from the diodes
this means higher voltage faster better charging for chassis and house batteries

if you 'want' manual operation
use a battery disconnect switch
just put in-between the camper battery line and the alternator chassis line
open hood close switch ..drive
get to camp, open hood, open switch

total isolation