New DC to DC Charger From Renogy-20 amps or 40 amps-Flooded/AGM/GEL/Lithium

[Amp34]

I sent an email last night complaining about the price. The response today was that they’re not currently in their Canadian warehouse and are shipping direct form the US. They’ve added them to to the Canadian site early due to interest.

Apparently when they arrive properly in September they'll adjust the price.

 

[RigidYota]

I sent an email last night complaining about the price. The response today was that they’re not currently in their Canadian warehouse and are shipping direct form the US. They’ve added them to to the Canadian site early due to interest.

Apparently when they arrive properly in September they'll adjust the price.

Thats an awesome find, I am making my decision by September as ill be near their warehouse then. Would much rather deal Canadian only

 

[baltik]

Was curious if anyone could shed some light on this requirement, Renogy tech support has been less than helpful

In theory it should be fine to ground anywhere but concerned that they have a current shunt as a means to regulate the output and using a different ground will break that functionality

Dumb install question, directions say: "Connect the negative cable directly to the negative terminal of the battery, and not to the chassis of a vehicle or boat."

I have a fairly complex run from starter battery to Dc/DC converter and was planning on running an 8AWG + wire only and grounding the converter on a clean chassis ground nearby. any reason the instructions are specifically against this?

 

[dreadlocks]

Safety Reasons, ground straps can fail.. if you wanna use chassis add some redundancy to engine and battery so they are not just attached at one location, with one strap that may or may/not be capable of handling your desired loads.

 

[baltik]

How can you be sure it’s not due to an internal shunt?

 

[dreadlocks]

ok lets say it does.. shunts are used to measure current, it does not regulate current.. if it had a shunt, it would be measuring whats going into the Aux/House battery.. wire that the dc charger up directly to the aux battery at the battery and use whatever ground incoming you'd like.. and it'd just be used to drive a display showing how much current its outputting.

 

[baltik]

Fair point - but couldnt theoretically they be measuring output current and using that information to limit output 40A?

 

[dreadlocks]

even if it was the shunt would not care as long as it was directly connected to the output and the output was not using chassis because it'd be flowing through the shunt.. this shouldent be a problem because on a remote battery location you want the DC2DC charger as close to the battery its charging so it is correcting for any voltage drop..

Internally the circuitry is limiting the current, active limiting would not be responsive enough to prevent damage.. its all passive.

 

[baltik]

Helpful, to be a devils advicate, couldnt it be shunting on the input side and limiting overall wattage that way?

 

[dreadlocks]

sigh, it would not matter regardless where the ground came from on input side..

Ground Input -> Shunt -> Ground Output -> Battery.. unless you bypass the shunt by hooking the battery to chassis it will have to flow through the shunt regardless if the input comes from a battery, an alternator, or a chassis ground.

 

[john61ct]

I would love to find a way to actively limit current without varying the voltage.

Even with a custom designed external device costing more than most battery packs.

You give the pack makers too much credit thinking such would be "sneakily" added for free within.

They don't even throw in fuses for free.

Apparently some vendors have claimed to have controllers logging usage data, but haven't actually seen a breakdown that verifies the claim.

And BTW definitely run a return wire for negative right back to source, matching length and awg. Don't rely on the chassis path for anything expensive, important or high current.

 

[dwh]

If it has a shunt to measure current (it almost certainly does), the shunt is internal and has no idea what's happening outside. It wouldn't know if it was grounded through the chassis, a wire direct to battery neg, or through the neighbor's cat.

So if they are insisting on a dedicated wire rather than a chassis ground, it's because a whole lot of chassis grounds are undersize or just plain unreliable.

 

[TommyArgh]

Does anyone know if this can work safely in conjunction with a solar charging system? I already have a solar charging system in place. Would having this charger in place require some sort of switch in between the two?

 

[dreadlocks]

Yes it'll work fine

 

[FJR Colorado]

Does anyone know if this can work safely in conjunction with a solar charging system? I already have a solar charging system in place. Would having this charger in place require some sort of switch in between the two?

It would be good for an expert on here to do a quick wiring diagram...