12v-24v How do they do that?

[Red Rider]

I have some 24v surplus military items that I want to use on one of my boats. Of course the boat has 12v batteries and a 12v charging system. Yes I know that you can connect two 12v batteries in series and get 24v.<br /><br />I need both 12v and 24v power on the boat. So if I connect two batteries in series, I can take 24v by using the neg terminal of one battery and the pos terminal of the other battery, or I can get 12v by using the the neg and pos terminal from one battery.<br /><br />But how do I connect the batteriers to my 12v charging system? I am worried about doing it wrong and getting 24v feedback into the charging system and burning something up.

 

[JB]

Re: 12v-24v How do they do that?

If they are connected in series to get 24V you can't charge them both at the same time, RR.

 

[Barnacle_Bill]

Re: 12v-24v How do they do that?

A solution would be an on board charger. Plug it in and forget it until the next time you go out.

 

[18rabbit]

Re: 12v-24v How do they do that?

Pretty much anything you want to do with changing voltage can be done with a voltage converter. My boat is ex-military, everything is 24v except the VHF. I use a step-down converter to reduce the 24v in to 12v for the radio. To go the other way, to change 12v into 24v, you would use a step-up converter. Batt charging is done at the same voltage as the batt installation. My batts are all installed as pairs in series for 24v, so I have a 24v batt charger system.<br /><br />Depending on what 24v toys you want to play with, it may be less expensive and a lot less hassle to stay on a 12v system with your 12v batt charger and add a small 12v to 24v step up transformer.<br /><br />I use one of these Newmar critters:<br /><br /> http://www.newmarpower.com/dc-dcconvertersstandard/dcdcconvertersstandard.html <br /><br /><br />The Newmar 12-24-6i, 12v input, 24v output, 6amps, isolated, will set you back about $600, new. This is the kind of thing Ebay was made for. I think I paid something like $35 for my Newmar converter, used, on Ebay. Google “12 24 converter” to see a bunch of other brands for significantly less money if you want to buy new.