In search of WHICH charger to use

RedDoor

New Member
Region
USA
My spouse bought me a used 2015 OHM 750, on which the previous owner had switched out the rear-hub motor with a mid-frame Bafang conversion. The battery is a Reention (I've since discovered they make the cases but not the battery themselves). The seller didn't provide a charger because his dog had chewed through the cord (I know, I know....) so I'm in search for WHICH charger to use on this battery....From web searches I'm thinking it was produced around 2015 as well. ANY thoughts would be greatly appreciated as I'm simply hitting a wall here. Sadly the frame is too large for me and I'm attempting to sell it, but others are wisely asking for a charger to go along with the bike. Please, I don't need comments about the folly of enthusiastically buying a gift used bike spontaneously.... Thanks

And in case anyone is interested you can contact me if you're interested in buying it (I'm in WA State)
 

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RunForTheHills

Well-Known Member
Region
USA
Honestly, you might be better off buying a new battery. It sounds like that battery wasn't well cared for. If you don't keep a minimal charge on it, it can ruin the battery. It is hard to tell what the voltage of the battery is from that picture and your description. An expensive option would be to buy a programmable charger like the Cycle Satiator from Grin that can charge any voltage of battery. Grin sells various adpaters for different charging connectors, but not all batteries are supported. You would still need to determine the correct voltage before configuring the charger though.
 

Pulsar

New Member
Region
USA
City
DFW
You really need to determine voltage of the battery. Have you pulled the battery off and looked for stickers or anything telling you its 36v, 48v or 52v? If your gonna sell it, no real need to get a fancy multi voltage programmable charger for that’s an overkill. You should be able to find standard fixed voltage chargers out there for under $75. Looks like you want a barrel type connector. Mine uses a 2.2 x 5.5 barrel plug which I think is fairly common for these type batteries. You may have to get an adapter depending which charger you pick so everything plugs together. Highly recommend you also use a volt meter to be sure plus and minus are correct before plugging anything in.
 

RedDoor

New Member
Region
USA
Yes, not knowing the voltage of the battery has been a problem. I'm thinking I need to take it to a bike shop which deals with E bikes to see if we can get the battery cover off (no key). There is nothing I can find on the outside of the battery case to indicate the voltage of the battery itself. It was fully charged when we got it...and has held the charge for 2+ months (with no riding expect trial runs to try to convince my 5'5" frame that perhaps I could safely use a 18.5" bike frame....nope). So, I think the battery is fully functional. Is there any way to determine battery voltage without direct access to the battery itself? (only through the charger inlet). Thanks you guys....
 

RunForTheHills

Well-Known Member
Region
USA
If you have a multimeter, you can measure the charge on the battery. However, 48V and 52V batteries have some overlap in the range of their state of charge. If it is a 36V battery, it should be obvious. People don't usually run Bafang mid-drives at 36V though. 48V is the most likely, but it could be 52V.
 

RunForTheHills

Well-Known Member
Region
USA
Another option is to move the Bafang motor kit to bike that fits you. You can pick up good donor bikes on Craigslist for $200-300 or you might have one in your garage. You still have to figure out the battery voltage or replace the battery if you do that. A lock smith could probably take care of the missing key for you.
 

RedDoor

New Member
Region
USA
RunForTheHill, sadly you're probably right. It has occurred to me. So this morning I'm going in to our local police Dept to see if it's on a stolen register (hoping the register is statewide, I'm certain this bike is not local from my rural area, someone would have seen my ad and responded). Because it's an unusual manufacturer (in the US), I'm hoping I don't have to take the Bafang motor off to access the serial number on the bottom of the frame. Thanks for the advice and the nudge. If it's not on a register, then I'll take it to our large metro area and an E bike shop to see if they can help me determine the battery voltage. You've been helpful (and kind).
 

antboy

Well-Known Member
MTA: Also, with the missing charger and missing key, it is possible that this is a stolen bike. You might check with the police department if it has been reported stolen.
If the serial number is still on the bike, it might be worth sending an email to OHM via their contact page.


The whole "dog chewed the cable" + "no key" combo is super sketchy.
 

RedDoor

New Member
Region
USA
the Bafang conversion to a mid frame motor means the motor now is over the serial number of the frame; not being familiar with now to remove the motor I think my best option is to take the bike to an E bike dealer in the city and ask for some assistance. Our local police/sherrif was a bust: they weren't in the office at the first stop; the second office was closed; the phone call linked me to the dispatch which wanted to open a case file....I did check the online bike register (for folks who register their bikes and then can note if they've been stolen), sadly there no luck either. It's more complicated to "do the right thing" sometimes than to just perpetuate the theft by reselling it. But I'll do what I can to find out if there is a police report on a theft; if not I'll find the battery voltage and get a charger and with a clearer conscious be able to sell it on to the next person. Many lessons learned, indeed. Thanks to you all.
 

harryS

Well-Known Member
You can determine the battery voltage by measuring at the charger input plug. Cut off a junk 5.5mm connector from a wall wart, stick it in the battery, and use a meter to measure the wires.

Some batteries have anti-short circuits which leave that port inactive until a charger is plugged in, but I've only seem one like that.

A lot of the older Ohm bikes used Bionx batteries/motors.

A 2A charger isn't very expensive. You're getting a 54.6V charger for 40V, or a 42,0V charger for 36V, both around 20 bucks.