8 awg wire. Can I run 45 amp charger?

[Fugitive861]

My motor home has an older magnetech 40 amp "dumb" charger with 8 awg wire connecting it to the house batteries. I want to upgrade to the Progressive Dynamics 45 amp (pd9245cv) converter/charger. I've done searches but haven't found if the 8 awg wire is adequate. The 8awg wire is about 15 feet. Thoughts?

[BFlinn181]

Using a calculator like this:

Voltage Drop Calculator

You're losing over 7% of the current flow through that 8 AWG wire. If you're taking the time and expense to improve the charger, I'd improve the wiring too.

[Fugitive861]

Terrific. Thanks for your help!

[nothermark]

There is a gotcha or two in that advice. If the wire from the converter runs to the battery then on to the house feed solenoid then you can pull the full load through the wire with the drop. OTOH if it is a short run to a common point with branches from there to the house and the battery the actual loss will be reduced by the distance. In essence your converter puts out the rated current. Some goes to run the house and some goes to run the battery. If you split power at or near the converter output then the battery share is whatever is left after the house gets it's share. That can be a lot less than the 45 A rated output.

[KRum]

You might consider relocating the new charger to be next to the battery and then rewire the 110v with standard romax.

[TLGPE]

On the other hand, if the charging voltage is more like 14.4, the loss is only 5.8V. The end voltage is 13.5. It might work just fine, and will be a great improvement over what you had.


Remember, after the high initial charge rate, the drop will me much less, and the float charge will be the same as if you had huge cables on it.

Try it, try it, you'll like it!

After that, if you still need to improve, add more parallel wires or run new ones.

Tom

[vsheetz]

40a changed to a 45a unit? I would not change the wiring.

However. Depending on how many batteries you have and if dry camping and wanting to minimize generator time. Then I might consider a even bigger converter and change the wire.

[TQ60]

Depending on location and use...

The converter may have two current paths with one going to load center and one to battery.

Your battery will take anything the converter can output if it is low so as large of wire as needed to carry current is nice but it only carries high current when bulk charging so unless it is a short easy run there is no need for a 5 amp increase in capacity.

If you want to do something you could get some multi conductor cord and install it between where the battery (s) are and with fuses supplement the existing wire.

Reason for multi conductor is you may wish to install something else like a battery monitor or ??? In the future and the wire will already be in place