Battery-to-battery charger (independant of source charge voltage)

[john61ct]

Yes, so far the thread's been focussed on answering the OP question literally.

Allan's actually admitted several times the overall design is flawed, but we haven't until now actually discussed addressing that.

I agree in general terms with the above, but will wait for OP feedback before derailing with more specific suggestions in that direction.

[Franziska]

@btrafors

If I have two common rails (=1*minus & 1*plus) for all charging sources and connect those directly to the house batteries (gel 270Ah) could I than connect the xantrex echo charge also directly to the above mentioned common rails and than use it to charge a small 90Ah gel backup battery?
Would that work?

Would a BlueSea ACR 120 do the same?

The reason why I'd prefer that is that if for whatever reason the house battery (defect or other) does not charge properly, part of the charging current would still end up in the backup battery.

Thanks,

Franziska

[john61ct]

Note the temp and voltage sensors should be directly attached to the House bank.

Some combiners like Echo Charger are very limited in their amps throughput, so really should only be used for dedicated Starter batteries.

A robust ACR will allow all charge current from any source to be passed to whichever bank needs it most, let acceptance rate "pull" determine that.

​ https://www.bluesea.com/products/762..._-_12V_DC_500A

may well be overkill, but they are very robust, last forever.

[Franziska]

Hey John, as ever thanks.
One more :-)
All sources on house and ACR towards is correct?
Just that I finally understand that.

[john61ct]

Originally Posted by Franziska

All sources on house

That is the ideal, especially when temp compensation and remote voltage sensing is involved, but not always practical.

Those ACRs allow full current to flow in either direction as long as voltage is high, so if the Alt remains on Starter but solar goes to House things will still work to keep either from going flat.

Echo Charger and some other devices are one-way only, so the overall design needs to take that into account.


> and ACR towards

Don't understand that

[Franziska]

Sorry, with towards, I meant this:

ACR to link charging rails to backup battery.

[john61ct]

Yes.

Also, buss (can be spelled bus) rather than rails.

[Franziska]

Thanks.

[Zil]

The correct spelling is bus. Buss means 'a kiss'.