fuses lowering voltage?

Just a simple question. Upon adding 150a AMG fuses about 18" from front and rear batteries (yellowtops, no isolator/circuit breaker. dist block about 18" from rear fuse holder) I noticed a .3 voltage drop.

Before fuses (straight wire between fr and rr batteries) the idle voltage stayed at 14.7, now it stays at 14.4v. During bass peaks it would drop to 14, now to 13.8. 

Details: I used standard Bussman AMG fuses (copper) and standard copper lugs that I sanded down for best connection. -Is the fact that I used copper lugs and fuses the reason? If I used gold plated ones would it help? Thanks, Javin

I used standard AMG(wafer type) 150a copper-colored fuses. I used RF 4g cable from batts to fuseholders, then MonsterStandard 4g in between. I used regular 4g copper lugs for all connections. During both low and heavy loads the difference stayed about .4v lower on average. I didn't change anything else.

I forgot to mention in the first post. Before the fuses, I had all 17' of the power wire ran even though I only needed about 10'. Meaning, I had about 5-7' of wire just coiled under the rear seat. When I added fuses, I was able to remove about 5-7' of wire! I would think that in itsself would increase voltage!

Also, when I added the fuses I added larger grounds for rear battery and amps. -Had Big3 done before adding fuses. Volt gauge is in rear, connected to distro-block.

I did do that. Thanks. though.

You probably have this covered but i replaced the rusty corroded blocks of lead that were my battery terminal connectors with tsunami gold clamps and I gained a half a volt.

Yes, I did. I used 4g (only 105a factory alt.) and copper lugs (sanded down for connections). I covered all 3 parts.

That's probably a good idea. I do have standard lead-ones. I bought all 4 new (2 for each battery) and i've been using them since the start so I don't see how they could just start adding resistance (.4volt) after adding fuses but mainly removing 5ft worth of wire.

-Thanks everyone.